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WFO Gaylord Hydrologic Service Area Training Prepared by: John Boris, Hydrology Focal Point February 2003 Updated January 2008.

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Presentation on theme: "WFO Gaylord Hydrologic Service Area Training Prepared by: John Boris, Hydrology Focal Point February 2003 Updated January 2008."— Presentation transcript:

1 WFO Gaylord Hydrologic Service Area Training Prepared by: John Boris, Hydrology Focal Point February 2003 Updated January 2008

2 Introduction This self paced slide show is intended to serve as both an introduction and a refresher to Hydrologic Operations here at WFO Gaylord. The show consists of 58 slides (including this one and the title slide...so only 56 to go), and will cover the following topics: Basic Terminology Basic flood terminology River gage types Hydrologic Service Area Description Flood/Flash flood warning area of responsibility River Flood warning/NCRFC area of responsibility and drainage basins Overview of the major rivers in the HSA, plus information on each forecast point, major data points, and other hydrologically significant locations. Map of Cooperative Observers WFO APX Hydrologic Operations Overview Data Acquisition and Quality Assurance. Hydrologic Products Overview Ice Jam Basics Dam Breaks Basics HSA Backup A brief overview of the Advanced Hydrologic Prediction Service

3 Hydrologic Terminology The following are definitions and examples of some of the terms you’ll run into during this presentation. Flood: Inundation of a normally dry area caused by increased water level in an established watercourse, such as a river or stream. Flash Flood: A flood caused by excessive rainfall in a short period of time. The National Weather Service defines this time frame as flooding which occurs within six hours of the causative event. Flooding associated with a dam failure is considered flash flooding. In order to better define what constitutes a flash flood for operational personnel, Central Region Headquarters has provided the following guidelines as to what events would verify as a flash flood: River or stream flowing out of it’s banks. Ice jam, possibly with rapid snow melt, backing up a river or stream causing the river or stream to rise out of its banks. Dam break or breach that causes out of bank river or stream flows downstream. Where no clearly defined stream exists, the following apply: Approximately six inches of water flowing over a road surface. Any amount of water in contact with or flowing into an above ground residence or public building which was caused by runoff from adjacent grounds. This does not, however, include basement flooding. A maintained county or state road closed by high water. Water over any bridge. Person or vehicle swept off walking surface or road by flowing water from runoff that inundates adjacent grounds.

4 Hydrologic Terminology River Flooding Terms: Headwaters: The streams at the source of a river. Main Stem: The reach of a river formed by the tributaries that flow into it. Forecast Point: A gaged point along a river for which specific stage and flow forecasts are prepared by a River Forecast Center. Specific stage forecasts are used as guidance for issuing Flood Warnings and Flood/River Statements for these points. Flood Stage: River level at which flooding begins to cause damage to property along a reach of river. Not necessarily the same as bankfull stage (the point at which the river begins to spill out of its’ natural banks). Flood stages are predefined at forecast points. Also defined at each forecast point is the “degree” of flooding based on stage. These categories of floods are defined as follows: Minor flooding: Minimal or no property damage, but possibly some minor inconvenience. Moderate flooding: Inundation of secondary roads, transfer of property to higher elevations necessary. Major flooding:Extensive inundation and property damage. Forecast Issuance Stage: The stage (observed or forecast) at which a River Forecast Center will begin issuing forecasts for that point. Typically, FIS is set 2 feet below flood stage, but it is determined independently at each forecast point. Since it is expected that we will begin issuing products once we begin receiving forecasts, some Flood Issuance Stages are set lower in order to provide more notice to users of rising stages. Reach: A defined length or section of a river or stream. In reference to forecast points, the reach is defined as the stretch of river for which a river forecast is considered valid. In other words, a flood stage at a particular forecast point does not necessarily pertain only to the area immediately adjacent to the river gage. It can extend some distance up and/or downstream as necessary, provided that the length of channel is reasonably uniform with respect to flow, depth, cross-sectional area, and channel slope. Gage Zero (Zero Datum): An arbitrarily defined elevation at a gage site relative to which stage measurements are taken. The gage zero is set a couple of feet below the river bed, such that zero flow will not be measured as a negative stage value. In other words, river stage is the height of the water above the gage zero, not the height of the water above the river bed. SHEF: Standard Hydrometeorological Exchange Format. A documented set of rules for coding of data in a form for both visual and computer recognition. It is designed specifically for real-time use and is not designed for historical or archival data transfer. WHFS: Weather Forecast Office Hydrologic Forecasting System. A series of AWIPS applications designed to assist in conducting hydrologic operations. WHFS operational components included Hydroview, Hydro Time Series, and RiverPro.

5 Hydrologic Terminology More River Flooding Terms: WS Form E19: Also known as the Report on River Gage Station, it provides detailed information on each forecast point. Copies of E19’s for our forecast points are located in the Hydrologic Operations Manual. WS Form E19a: Single page abridged version of the E19, contains basic information on a gaging station. Copies of E19a’s for each river gage in the Hydrologic Service Area can be found in the Hydrologic Operations Manual. WS Form B44: Provides information on co-operative observers, including observer name, location, network type, latitude, longitude, elevation, station topography, type of instrumentation, and frequency of reporting. Rating Curve: A graph showing the relationship between stage and discharge (flow) at a cross section of river. A rating table shows the same information in a tabular format. Hydrograph: A graph showing stage or discharge plotted as a function of time. Hydrographs can be prepared for both observed and forecast data. The example below shows observed flow and stage values (where flow is derived from the measured stage via the rating curve. NWSRFS: National Weather Service River Forecasting System. A system of hydrologic data and models used by River Forecast Centers to produce river forecasts. These models forecast discharge (flow) at particular points along a river system...rating curves are used to convert the forecast flow to a forecast stage.

6 River Gage Types: Stilling Wells: Usually designed of concrete or steel pipe, sometimes made out of wood, these gages are usually located immediately adjacent to a river, although some are actually in the stream itself. The stilling well dampens out stream fluctuations as water enters and leaves the well through an intake pipe, such that the level of water in the well is at the same elevation as the river. A float tape gage is used to measure the water level, and consists of a tape passing over a pulley, with a float in the well attached to one end, and a counter weight to the other. The float follows the rise and fall of the water level, and stage can be read either directly from the tape or attached to a recorder. An electric tape gage is also often found in stilling well gages as a reference (i.e., non- recording) gage. It consists of a metal tape measure connected to a reel, a cylindrical weight (attached to one end of the tape), a battery, and a voltmeter (which is connected to the weight). The weight is lowered toward the water by reeling out the tape...when the weight comes in contact with the water, it completes a circuit between the battery and voltmeter, and a signal is registered on the voltmeter. The height of the water level at this point is read off the tape, which is graduated in feet and hundredths. Concrete stilling well, Rifle River near Sterling, and associated float tape gage. Float and electric tape gages, Platte River at Honor Float Tape Gage Telemetry Electric Tape Gage Float Tape Gage Electric Tape Gage Hydrologic Terminology

7 More River Gages: Staff Gage: Simply a glorified ruler (sort of) graduated in feet and hundredths. The staff gage is usually made of metal, and can be attached to a wood plank and buried in the river bed, or attached to a gage house or a bridge (vertical staff gage). Staff gage markings can also be painted on bridges, or on a sloped surface near the river such as a boat ramp (inclined staff gage or slope gage). In areas of high stages, sectional staff gages can be used, which consists of a series of staff gages mounted at different elevations on a sloping river bank, such that one gage will be in contact with the water at all times. This allows for the reading of higher stages when the gages closer to the river are submerged by high water. Staff gage on wood plank, Platte River at Honor Staff gage on bridge, Rifle River near Sterling Wire Weight Gage: Consists of a drum wound with a single layer of cable and a weight attached to the end, a graduated disc (in tenths and hundredths), and a counter attached to the disk. All of this is contained within an aluminum box, and typically attached to a bridge rail. The weight is lowered by a crank attached to the drum, and the gage is set so that when the bottom of the weight reaches the water surface, the water elevation is given by the combined readings of the counter (whole feet) and the graduated disc (tenths and hundredths of a foot). Wire weight box and safety railing, Tobacco River at Beaverton Components of a wire weight gage Counter Graduated discDrum and cable Cylindrical weightCrank Hydrologic Terminology

8 Still more gages: Bubbler Gage: Measures stage as a function of the pressure required to maintain a flow of gas bubbling freely from an orifice submerged in the river. The system consists of a gas purge system (usually nitrogen, though some gages are now using compressed air), a length of tubing which connects the gas regulator to the stream, and a pressure transducer to measure the gas pressure required to balance the water pressure above the orifice in the stream, which is a function of water elevation. Pressure Transducer Glass sight feed (controls bubble rate into stream) Line to stream Gas line Regulator Bubbler gage system using nitrogen gas, Au Sable River near McKinley Closer view of bubbler gage components Rating Table Hydrologic Terminology

9 Hydrologic Service Area HSA Description -- Flood/Flash Flood Watch and Warning coverage area For the purposes of issuing Flash Flood Warnings, Flood Watches, and non-forecast point Flood Warnings, our HSA comprises 25 counties across Eastern Upper and Northern Lower Michigan. The HSA’s for Marquette, Grand Rapids, and Detroit all correspond to their respective County Warning Areas as well.

10 Hydrologic Service Area HSA Description -- Responsibility of the River Forecast Center For the purpose of issuing Flood Warnings for specific river gaging points, WFO Gaylord falls under the responsibility of the North Central River Forecast Center in Chanhassen, MN. River Forecast Centers have forecast responsibility for main stem rivers and larger tributaries, and issue specific stage and flow forecasts at various gaging sites along these rivers. Based on pre-established flood stages, warnings and statements are then issued by WFO’s using these forecasts as guidance. In the WFO Gaylord HSA, we have five points for which flood stages have been established and river forecasts issued: Pine River near Rudyard (RUDM4) – FS 17.0 feet Boardman River near Mayfield (MYFM4) – FS 7.0 feet Manistee River near Sherman (SHRM4) – FS 15.0 feet Au Sable River near Red Oak (RDOM4) – FS 7.0 feet Rifle River near Sterling (STRM4) – FS 6.0 feet The map shows forecast points in purple, and data points in red.

11 HSA Description -- More about NCRFC The river systems within the NCRFC area of responsibility are shown in the map below. Hydrologic Service Area

12 HSA Description -- NCRFC basins specific to the Western Great Lakes More specifically, the drainage basins within the HSA reside in the western portions of the St. Lawrence River basin, as water from the Great Lakes drains into the St. Lawrence River, and eventually the Atlantic Ocean. In the map shown below, our HSA basins lie in the eastern portion of the UPM (Upper Michigan) drainage, all of the NLM (Northern Lower Michigan) drainage, and the extreme northern portion of the SMW (Saginaw, Muskegon, White Rivers) drainage. Hydrologic Service Area

13 HSA Description -- Michigan Drainage Most of the drainage basins across the HSA are confined within our 25 county area of responsibility. Little inflow comes in from surrounding areas, the main exceptions being the Tahquamenon River (from Luce County into northern Chippewa County), and the headwaters of the Tobacco River (from Clare County into Gladwin County). Most of our rivers and streams either flow directly into the surrounding Great Lakes, or into larger tributaries which flow out of the southern counties of our HSA, such as into the Muskegon and Saginaw Rivers. The map on the next slide shows the drainage basins within the WFO Gaylord HSA that are defined in the river forecast model run at the NCRFC. Hydrologic Service Area

14 HSA Description -- WFO Gaylord defined drainage basins Hydrologic Service Area

15 HSA Description -- Major Rivers The map below shows the major rivers running through the HSA. The Muskegon and the Tittabawasse Rivers are the two major rivers that flow into adjacent HSAs. Most of our major tributaries empty out into the surrounding Great Lakes. Hydrologic Service Area The remaining slides in this section will focus on some of these rivers individually, as well as hydrologically significant locations you need to be aware of.

16 HSA Description -- Manistee River Hydrologic Service Area Length: 232 miles Drainage: 1780 square miles Number of Gages: 4 Dams Along River: 2 High Hazard Dams: 2 Hodenpyl Dam (Manistee County)/EAP Tippy Dam (Manistee County)/EAP EAP = Dam has an Emergency Action Plan in case of dam failure. EAP’s can be found in the drawer labeled “Dam Emergency Action Plans” in the Operations area. The Manistee River has three gages on it, near Sherman, Mesick, and Wellston. One gage is located on the Pine River near Hoxeyville. The Pine River joins the Manistee at the Tippy Dam Pond. Sherman (SHRM4) is defined as a forecast point with a flood stage of 15.0 feet. The Mesick and Wellston gages are immediately downstream of Hodenpyl and Tippy Dams, respectively. The banks around the Hoxeyville gage are steep and not subject to flooding. Greatest flood threat will be to recreational users due to the many canoeing and campground facilities along the river, as well in the area upstream of the Sherman gage.

17 HSA Description -- Manistee River near Sherman (SHRM4) Hydrologic Service Area Flood Stage:15.0 feet Bankfull Stage: 14.0 feet right bank Forecast Issuance Stage:14.0 feet Highest Crest: 15.99 feet 3/18/1990 Minor Flooding:15.0 feet Moderate Flooding:Not established Major Flooding:Not established Gage Type: Float tape gage/stilling well with Sutron telemetry (voice modem available). Location: On right bank 50 feet downstream from M-37 bridge, 1 mile north of Sherman. Gage marked by the red arrow, river flows from right to left There are homes adjacent to the river upstream of the M-37 bridge, as evident in the topographic map. The yards of these homes will be impacted at a stage of 15.0 feet, but it would probably take a stage over 16.0 feet to impact the homes themselves. This is beyond the record crest, so it will likely take an extreme event to cause problems here, but there is cause for concern. NCRFC issues daily forecasts for Sherman under MSPRVFNLM. View of the gage house Looking upstream from M-37 bridge

18 HSA Description -- Au Sable River Hydrologic Service Area Length: 157 miles Drainage: 1600 square miles Number of Gages: 6 Dams Along River: 7 High Hazard Dams: 7 Salling Dam (Crawford County) Mio Dam (Oscoda County)/EAP Alcona Dam (Alcona County)/EAP Loud Dam (Iosco County)/EAP Five Channels Dam (Iosco County)/EAP Cooke Dam (Iosco County)/EAP Foote Dam (Iosco County)/EAP The Au Sable River has five gages on it, near Red Oak, Mio, McKinley, Curtisville, and Au Sable. One gage is located on the South Branch near Luzerne. Four hydroelectric dams across Iosco County create almost a continuous impoundment as the tailwater of one dam leads right into the pond of the next dam. This volume of water will have significant impacts in a dam failure situation. One forecast point at Red Oak (RDOM4) with a flood stage of 7.0 feet. Some locations around Grayling, downstream of Mio, and Oscoda could be impacted by high water, as well as recreational users with many campgrounds along the river.

19 HSA Description -- Au Sable River at Red Oak (RDOM4) Hydrologic Service Area Flood Stage:7.0 feet Bankfull Stage: 6.0 feet Forecast Issuance Stage:6.0 feet Highest Crest: 6.85 feet 1/26/1996 Minor Flooding:7.0 feet Moderate Flooding:8.0 feet Major Flooding:9.0 feet Gage Type: Float tape/stilling well with Sutron telemetry (voice modem available). Location: On left bank 100 feet upstream from Parmalee Bridge (County Road 489). Gage marked by the red arrow in the left map, river flows from left to right. At flood stage, water will inundate area between Parmalee bridge and state boat launch ramp (upstream of the bridge). Water will reach the bottom of Parmalee bridge at a stage around 8.0 feet. River is susceptible to ice jams. NCRFC issues daily stage forecasts for Red Oak under MSPRVFNLM. Looking downstream from Parmalee Bridge View of Parmalee Bridge looking downstream Topographic area around Red Oak. River flows from left to right.

20 HSA Description -- Au Sable River at Mio (MIOM4) Hydrologic Service Area Flood Stage:Not established Bankfull Stage: Not established Forecast Issuance Stage:Not established Highest Crest: 6.37 feet 4/1/1998 Minor Flooding:Not established Moderate Flooding:Not established Major Flooding:Not established Gage Type: Bubbler gage with Sutron telemetry (voice modem available). Location: On right bank 150 feet upstream from M- 33 bridge in Mio...500 feet downstream from Mio Dam. Gage marked by the red arrow in the left map, river flows from left to right on both maps. The right map is about 5 miles east of Mio Dam, the area the pictures are from is marked by the arrow. Areas downstream of Mio dam are susceptible to out of bank flows during spring snowmelt. The pictures on the left were taken during April 2001 in the Comins Flats area, along County Road 600 (McKinley Rd) about 5 miles due east of Mio dam. At the time, the Mio Dam pond was at capacity, and the spillway gates were open about 1 foot (stage at MIOM4 at the time of the pictures was 4.80 feet, it had crested at 5.37 feet earlier). Keep this area in mind when stages at MIOM4 climb above 5.0 feet, as cottages and homes along the river in this area could be impacted. Comins Flats, about 5 miles downstream Close up of cottages along river Topographic area near Mio Dam Topographic area around Comins Flats

21 HSA Description -- Boardman River Hydrologic Service Area Length: 50 miles Drainage: 141 square miles above Brown Bridge Dam Number of Gages: 1 Dams Along River: 4 High Hazard Dams: 4 Brown Bridge Dam (Grand Traverse County)/EAP Boardman Dam (Grand Traverse County)/ EAP Sabin Dam (Grand Traverse County)/EAP Union Street Dam (Grand Traverse County) The Boardman River contains one forecast point, located on Brown Bridge Rd near Mayfield. The gage is located at Ranch Rudolph, a private campground about 3 miles upstream from Brown Bridge Dam. Traverse City Power and Light operates the four dams across Grand Traverse County, with the Union Street Dam located in Traverse City right before the river empties into Grand Traverse Bay. Some property does exist in the flood plain downstream of Brown Bridge Dam that is subject to flooding during high flows.

22 HSA Description -- Boardman River at Brown Bridge Rd/Mayfield (MYFM4) Hydrologic Service Area Flood Stage:7.0 feet Bankfull Stage: 5.0 feet Forecast Issuance Stage:5.0 feet Highest Crest: 5.44 feet 4/2/1998 Minor Flooding:7.0 feet Moderate Flooding:Not established Major Flooding:Not established Gage Type: Bubbler gage with Sutron telemetry (voice modem available). Location: On right bank 200 feet upstream from bridge at entrance to Ranch Rudolph, 3 miles upstream from Brown Bridge Dam. Reach of river covered by forecast point: From the gage site downstream to Brown Bridge Pond (about 3 miles). Gage marked by the red arrow, river flows from right to left Forecasts received under: MSPRVFNLM This is a forecast point still in development, replacing the old MAYM4 data point downstream of Brown Bridge Dam. At 6.0 feet, water will reach the bottom of the small bridge just downstream of the gage, though the bridge deck will likely not flood until the stage is above 9.0 feet. Brown Bridge Rd will flood above 7.0 feet. This is a relatively new gage (since 1997), and not a lot is known at this point about extreme flows or their impacts, so use the above stages with caution. Gage intake pipe and staff gage Looking upstream from gage

23 HSA Description -- Boardman River/Brown Bridge Dam Hydrologic Service Area Brown Bridge Dam is the first in a series of four hydroelectric dams along the Boardman River operated by Traverse City Power and Light. The downstream dams include Boardman Dam, Sabin Dam, and Union Street Dam. Although no official flood stages have been established for the area downstream of the dam, some flooding along the river does occur during high flows which may impact some property owners which have built in the flood plain. Though no automated gaging exists, a staff gage is located immediately downstream of the dam (noted by red arrow in bottom left picture). During times of high flow, personnel at the dam will call the NWS to report stage readings (in feet above MSL). They have determined that some downstream flooding can occur at a stage of 742.0 feet MSL. This information can be used as a basis for issuing a Flood Warning, though be sure to mention the source of your information in the warning text (i.e., Traverse City Power and Light personnel). You should corroborate this information with actual reports of flooding, since overall impacts are not well known given recent development in the area. Looking downstream from top of dam Close up of staff gage facing dam Back side of Brown Bridge Dam Front side of Brown Bridge Dam showing spillways

24 HSA Description -- Pine River Hydrologic Service Area Length: 32 miles Drainage: 184 square miles above Rudyard gage Number of Gages: 1 Dams Along River: None The Pine River has one forecast point near Rudyard. The gage is located off Mackinac Trail about 3 miles south of Rudyard, south of the confluence of the mainstem Pine River, the North Branch Pine River, and Bear Creek. The river banks near the forecast point are steep and not subject to overflow. The banks are lower as the river widens where it empties into Lake Huron. The Pine River is susceptible to ice jams in winter.

25 HSA Description -- Pine River near Rudyard (RUDM4) Hydrologic Service Area Flood Stage:17.0 feet Bankfull Stage: Not established Forecast Issuance Stage:15.0 feet Highest Crest: 19.31 feet 3/30/2004 Minor Flooding:17.0 feet Moderate Flooding:19.0 feet Major Flooding:Not established Gage Type: Bubbler gage with CR10 telemetry. No voice modem available Location: On right bank 15 feet upstream from bridge on Mackinac Trail, 3.2 miles south of Rudyard. Reach of river covered by forecast point: From Prairie Road Bridge downstream to Mackinac Trail Bridge (about 1 mile). Gage marked by the red arrow, river flows from top to bottom. Forecasts received under: MSPRVFUPM At 17.0 feet, the river will reach the bottom of the Prairie Rd Bridge, about 1 mile upstream of the gage. The bridge itself will begin to flood when the stage is above 19.0 feet. The bridge was raised in 1986 after being inundated almost annually by snowmelt runoff. The banks around the gage are steep and will not flood, however the river is subject to frequent ice jams, which can adversely affect gage readings. The highest two crests at RUDM4 were the result of ice jams. View from the gage house, note steep banks Prairie Rd. Bridge, 1 mile upstream of RUDM4 Prairie Rd. Bridge

26 HSA Description -- Tobacco River/Tittabawassee River Hydrologic Service Area Length: NB Tobacco:20 miles MB Tobacco:18 miles SB Tobacco:25 miles Tobacco: 3 miles Tittabawassee: 86 miles Drainage: 2,620 square miles Number of Gages: 2 Dams Along River System in HSA: 6 High Hazard Dams: 4 (Gladwin County) Secord Dam (Tittabawassee River)/EAP Smallwood Dam (Tittabawassee River)/EAP Edenville Dam (Tittabawasse River) Chappel Dam (Cedar River) The main stem Tobacco River starts at the confluence of the North, Middle, and South Branches of the Tobacco River, and the Cedar River, which join at Ross Lake in Beaverton. The Tobacco River then joins the Tittabawassee at Wixom Lake on the Midland County line. Two gages are located within the basin...BEVM4 is located on the South Branch Tobacco around 9 miles upstream from Beaverton. BVTM4 is a wire weight gage read by a co-operative observer twice per week...and daily when the stage is above 6.0 feet. Although three high hazard dams on the Tittabawassee River are located in Gladwin County, the Edenville Dam is on the Midland County line, so any impact from a dam failure at Edenville will occur downstream in Midland County.

27 HSA Description -- Rifle River Hydrologic Service Area Length: Main Stem Rifle: 60 miles West Branch Rifle: 20 miles Drainage: 320 square miles above Sterling gage Number of Gages: 1 Dams Along River System: 2 High Hazard Dams: None The Rifle River begins at Devoe Lake in northeast Ogemaw County, and collects several smaller creeks before joining up with the West Branch Rifle River west of Lake Ogemaw. One gage exists on the Rifle River, located near a canoe livery off Melita Road about 3 miles north of Sterling. Only one low hazard dam is on the Rifle River itself, which is located at Devoe Lake at the river’s headwaters. A significant hazard dam (20 feet in height) is located at the West Branch Mill Pond on Ogemaw Creek, upstream of the city of West Branch.

28 HSA Description – Rifle River at Sterling (STRM4) Hydrologic Service Area Flood Stage:6.0 feet Bankfull Stage: 4.5 feet Forecast Issuance Stage:5.0 feet Highest Crest: 13.74 feet (3/28/1950) Minor Flooding:6.0 feet Moderate Flooding:9.0 feet Major Flooding:12.0 feet Gage Type: Float tape/stilling well gage. Sutron telemetry (voice modem available). Location: On left bank, 30 feet downstream from bridge on Melita Road, 2.8 miles north of Sterling. The Rifle River at Sterling is the most recent forecast point to be established...having started on 27 November 2007. Flood concerns are the proximity of several campgrounds within one mile of the gage location...as well as homes both up and downstream. Ice jams are a frequent problem. Gage house– Rifle River at Sterling Campground across from White’s Canoe Livery White’s Canoe Livery seen from Melita Road

29 HSA Description -- Platte River Hydrologic Service Area Length: 30 miles Drainage: 118 square miles above Honor gage Number of Gages: 1 Dams Along River: 2 High Hazard Dams: None The Platte River originates out of Lake Ann in northeast Benzie County, and flows into Platte Lake with a short outlet from Platte Lake into Lake Michigan. Although the drainage basin is small (contained entirely within the northern half of Benzie County), the terrain adjacent to the river is fairly steep in some areas. Thus the response to a heavier rainfall event will be quicker on the Platte River than on most of the streams in the HSA. No forecast points exist on the Platte River.

30 HSA Description -- Platte River at Honor (HONM4) Hydrologic Service Area Flood Stage:Not established Bankfull Stage: 3.0 feet Forecast Issuance Stage:Not established Highest Crest: 4.37 feet (8/22/2002) Minor Flooding:Not established Moderate Flooding:Not established Major Flooding:Not established Gage Type: Float tape/stilling well gage. Sutron telemetry (voice modem available). Location: On right bank 20 feet downstream from U.S. 31 bridge, 1 mile west of Honor. Gage location marked by red arrow, river flows from right to left on the map. This basin poses a significant flash flood threat. The basin above the town of Honor is small and steeply sloped, so heavy runoff will result in a rapid streamflow response. Typical river stages range from 1.2 to 1.5 feet, bankfull stage is around 3.0 feet. Notice in the bottom right picture how shallow the river banks are...you can see the backyards of homes right up to the river. The flash flood event of 22 August 2002 resulted from nearly 4 inches of rainfall in a couple of hours. The river rose nearly 3 feet by midnight, cresting at 4.37 feet...very close to the homes along the river but not impacting any dwellings. So beware of stages rising above 4 feet. A voice modem is available to query the gage, so keep this in mind during heavy rainfall events across Benzie County. Corrugated pipe stilling well gage Riverside Dr bridge, 1 mile upstream from gage

31 HSA Description -- Thunder Bay River Hydrologic Service Area Length: 70 miles Drainage: 586 square miles above Bolton gage. Number of Gages: 1 Dams Along River System: 10 High Hazard Dams: 2 Seven Mile (Norway Point) Dam (Alpena County)/EAP Four Mile Dam (Alpena County)/EAP The Thunder Bay River originates out of McCormick Lake in Montmorency County, collecting several large tributaries before emptying into Thunder Bay at Alpena. A river gage is located southwest of Bolton on Herron Road. No forecast points exist on the Thunder Bay River. Two high hazard dams are located 4-5 miles upstream of Alpena, Seven Mile Dam (known in its EAP as Norway Point Dam) and Four Mile Dam. The Ninth Street Dam (in the city of Alpena) and Hubbard Lake Dam on the Lower South Branch are considered significant hazard dams, and also have Emergency Action Plans.

32 HSA Description -- Thunder Bay River between Atlanta and Hillman Hydrologic Service Area No gage exists along this stretch of the Thunder Bay River between Atlanta and Hillman. The pictures below were taken in April 2001 at the M-33 bridge over the Thunder Bay River about 9 miles downstream from Atlanta in southeast Montmorency County. This is another area where homes and cottages are located along a shallow sloped area adjacent to a river. The arrow on the map denotes the M-33 bridge where the pictures were taken. The river flows from left to right in the picture. These pictures were taken after the water had receded, thus it is likely the cottage in the left picture was impacted at some point This is a harder area to monitor with the lack of gaging along the river, but if other nearby rivers and streams are running high, this may be another location you’ll want to keep tabs on. Looking upstream from M-33 bridge Looking farther upstream along river from M-33

33 HSA Description -- Cheboygan River Basin Hydrologic Service Area Length: Sturgeon River:40 miles Pigeon River:43 miles Black River:60 miles Cheboygan River: 7 miles Number of Gages: 2 Dams Along River System: 16 High Hazard Dams: 1 Alverno Dam (Black River/Cheboygan County) The Cheboygan River basin is a conglomeration of rivers and streams draining the higher terrain areas of northeast Lower Michigan north of the Au Sable and Thunder Bay drainages. The Sturgeon River and Pigeon River flow north from Otsego county and empty into Burt and Mullet Lakes, respectively, which are connected by the Indian River. The Black River also emerges from eastern Otsego county, flows into Black Lake in Cheboygan county, emerging again from the northwest outlet of the lake. The Cheboygan River itself starts as the outlet from Mullet Lake, merges with the Black River just south of Cheboygan, then flows through the city and into Lake Huron. No forecast points are located within the Cheboygan River system.

34 HSA Description -- Cooperative Observers Hydrologic Service Area An important component to the National Weather Service River Forecast System is the accurate depiction of hydrometeorological variables important to the runoff generation process. The Cooperative Observer Network not only provides additional climatological data for a particular area, many stations are also established for purposes of supporting hydrologic operations. The map on the left is a snapshot of all cooperative observers across the HSA. The center map shows locations of observers that report data to the NWS on a daily basis. This typically includes max/min temperature, precipitation, snowfall, and snow depth, with some stations reporting additional data such as snow water equivalent, soil temperature, and river stage (only the co-op at BVTM4 reports river data in our HSA). This data is important in helping to determine mean areal precipitation, rate of snowmelt, and other factors that affect runoff. The map on the right shows locations that have Fisher-Porter recording rain gauges, which record accumulated precipitation every 15 minutes (the data is published hourly). This time series of precipitation is important for hydrologic model calibration. Data from co-op observers that report daily is transmitted to WFO APX via ARBRR3APN. Data about each co-op observer is contained in a WS Form B44...a binder containing all of the B44’s for our observers is located on the data acquisition desk. WFO Gaylord Cooperative Observing Network Daily reporting network Fisher-Porter Rain Gauge Network

35 Acquisition of River Stage Data WFO APX receives river gage data through a program called GETUSGS...which runs every six hours in AWIPS. The program goes into the USGS web site via LDAD, and grabs the latest available stages. It then formats this data in a.B SHEF encoded message, and sends the data out via ARBRR2APN, and is then written to the hydro database for use in products. If there are problems with us accessing the internet, problems with the USGS web site, or LDAD problems, we will have missing data in the RR2. In some cases (such as LDAD problems), we can still get the data ourselves from the USGS web site and send the data out manually. Some gages have voice modems which can be queried, and the data obtained and sent out that way. Phone numbers for gages with voice modems are available in the Hydrologic Operations Manual. Be sure to QC the data as it comes in, checking for missing or suspicious looking data values. River data can easily be monitored using the River Monitor application in AWIPS. RR2APN RIVER STAGE REPORTS FROM HTTP://WATER.USGS.GOV/NWIS.B APX 0220 E DH0510/HGIRZZ SHRM4 DM02250445/11.25: MANISTEE RIVER NR SHERMAN HOXM4 DM02250445/ 3.88: PINE RIVER NR HOXEYVILLE MYFM4DM02250445/ 3.12: BOARDMAN RIVER NR MAYFIELD RUDM4DM02250400/ 2.91: PINE RIVER NR RUDYARD WOLM4DM02250445/ 3.35: STURGEON RIVER AT WOLVERINE BEVM4DM02250445/ 5.48: SOUTH BR TOBACCO RIVER NR BEAVERTON STRM4DM02250430/ 2.12: RIFLE RIVER NR STERLING HONM4DM02250445/ 1.33: PLATTE RIVER AT HONOR MSKM4DM02250115/ 3.57: MANISTEE RIVER NR MESICK (HODENPYL DAM) WLSM4DM02250445/ 8.51: MANISTEE RIVER NR WELLSTON (TIPPY DAM) MIOM4DM02250100/ 2.46: AU SABLE RIVER AT MIO LUZM4DM02250100/ 4.37: SOUTH BR AU SABLE RIVER NR LUZERNE RDOM4DM02250415/ 3.02: AU SABLE RIVER NR RED OAK VGCM4DM02250415/ 2.48: CLAM RIVER AT VOGEL CENTER ASBM4DM02250115/ 8.25: AUSABLE RIVER NR AU SABLE CSVM4DM02250200/ 7.64: AU SABLE RIVER NR CURTISVILLE.END WFO APX Hydrologic Operations

36 Data Quality Assurance Both co-operative data and hydrologic data needs to be checked for errors. A data quality checker is running as part of the hydrologic applications within AWIPS, which checks defined data for gross errors (which will kick it out of the hydro database automatically, but will still send the data out to external users such as NCRFC), or data that falls outside of predefined bounds. When a certain data element falls outside of these values, an alert message will be sent to AWIPS under ARBACRAPX. These messages are designed to alert the data acquisition person that a particular piece of data or observation needs to be checked to make sure it is valid. You do not need to place these messages in the hydro focal point’s mailbox...they are for the benefit of the operational staff. Some of the alert/alarm values set in the quality control program are defined similarly for a given data type (precipitation/snowfall/snow depth/temperature) while others such as river stage are defined at each site. Some of the more common data ranges for which an ARBACRAPX text message will be generated are as follows (Alert threshold exceedence will just send the text message to the text workstation, Alarm threshold exceedence will give you the message plus the alarm bell): Data TypeAlertAlarm Precip- 1 hour (ASOS)1.00 in2.00 in Precip- 3hr/6hr (ASOS)2.00 in3.00 in Precip- 12hr/24hr (ASOS/Coop)3.00 in5.00 in Snowfall - 24hr (Coop)8.0 in12.0 in Snow Depth - 1 June-30 September1.0 in (warm season snow depth report check) River stageStation dependent The report at the right is an actual report from the Traverse City ASOS, after reporting 4.1 inches of rain in 6 hours, which is greater than the 3 inch/6 hr alert threshold. ***REPORT OF ALERT/ALARM DATA FROM THE HYDRO DATABASE*** CREATED AT:Fri Aug 23 00:37:10 2002 PRODUCT ID:ARBACRAPX REPORT MODE: UNREPORTED DATA FILTER:All alerts/alarms considered (i.e. no filter) PE FILTER: All physical elements are considered (i.e. no filter) ------------------------------------------------------------------------------------------------------ TRAVERSE CITY (TVC) GRAND TRAVERSE County, Michigan Precip Increment Observed (PP RZ) Limits: Value=3.0/5.0 ROC= undef/undef value > alert Fri-Aug23-00:004.1 (1 Day) 1 ALERT/ALARMS REPORTED. ------------------------------------------------------------------------------------------------------ Limits: shown above are the alert threshold/alarm threshold. Info grouped by location, physical element, type-source and check type. Single value and rate-of-change limits are shown for each group. Columns shown are: threat type > level, time value [details]. For forecast data, the time of the forecast is also given. Threat types:roc =>value shown exceeded rate-of-change threshold value=>value exceeded threshold REPORT MODE: UNREPORTED Listing of all unreported records. WFO APX Hydrologic Operations

37 Basic Overview of WFO APX Hydrologic Operations This next section will focus on the main points regarding hydrologic operations here at WFO Gaylord. Given the excellent drainage provided by the surrounding Great Lakes, short length of mainstem rivers, and the overall sandy and porous nature of our soils, flooding concerns are typically few and far between in this area. But...it is important not to get too rusty with your hydro skills, so that you’ll know how to react when faced with a hydrologic situation (without having to call the hydro focal point at home!). This section will touch on the following: Hydrologic Product Basics Brief ice jam flooding overview Brief dam failure overview Support from the North Central River Forecast Center HSA backup A brief overview of AHPS

38 WFO APX Hydrologic Operations Product Basics: Hydrologic Outlooks The WFO Gaylord Hydrologic Service Area covers the same 25 counties as our County Warning and Forecast Area. Within our HSA, we are responsible for issuing flood watches and warnings, as well as flood outlook products and various river statements. Hydrologic Outlooks are issued several days in advance of a potential flood event, and discuss the reasons behind the increased flood threat. Outlooks are typically issued for flooding potential beyond the next 36 hours (fourth period of the public Zone Forecast and beyond). Outlooks can also be used to disseminate a forecast flood crest from the River Forecast Center that is heavily influenced by forecast meteorological variables. Special Snowmelt Flood outlooks are issued during late February and late March, using guidance from the River Forecast Center, to detail the potential for spring snowmelt flooding. Issued under the ARBESFAPX header, and can be issued through RiverPro (for disseminating NCRFC forecasts), or WWA. Very general hydrologic information can also be included in the Hazardous Weather Outlook (issued under ARBHWOAPX). HYDROLOGIC OUTLOOK NATIONAL WEATHER SERVICE GAYLORD MI 500 AM EST FRI APR 18 2003...POSSIBLE HEAVY RAINFALL THIS WEEKEND MAY INCREASE FLOOD THREAT... A DEVELOPING STORM SYSTEM OVER WESTERN KANSAS TIHS MORNING IS FORECAST TO STRENGTHEN OVER THE NEXT 72 HOURS AS IT MOVES TOWARD THE GREAT LAKES. MOISTURE DRAWN NORTH AHEAD OF THIS SYSTEM WILL BEGIN TO SPREAD RAIN ACROSS NORTHERN MICHIGAN SUNDAY...WITH PRECIPITATION EXPECTED TO BECOME HEAVIER SUNDAY NIGHT AND INTO MONDAY. THE POTENTIAL FOR HEAVY RAINFALL COULD LEAD TO FLOODING OF LOW LYING AREAS AS WELL AS CAUSING SOME SMALLER STREAMS AND CREEKS TO RISE OVER THEIR BANKS. THE GREATEST POTENTIAL FOR FLOODING PROBLEMS WILL COME MONDAY. ALTHOUGH THE EXACT STORM TRACK AND RAINFALL AMOUNTS ACROSS NORTHERN MICHIGAN ARE STILL UNCERTAIN...THE POTENTIAL EXISTS FOR A HEAVY RAIN EVENT ACROSS THE AREA FOR BEGINNING OF NEXT WEEK. PERSONS ACROSS NORTHERN MICHIGAN SHOULD REMAIN AWARE OF THE FLOOD THREAT...AND MONITOR LATER FORECASTS AND STATEMENTS FOR UPDATED INFORMATION REGARDING THIS POTENTIAL HEAVY RAIN EVENT. NNNN

39 WFO APX Hydrologic Operations Product Basics: Flood/Flash Flood Watches Flood/Flash Flood Watches are issued to address both the potential of long term flooding along larger rivers and streams, and flash flooding due to heavy convective rainfall, ice jams, or potential dam breaks. The type of flood threat is dependent on the timing of the flooding in relation to the causative event. Flood TypeFlooding OnsetFlooding DurationRainfall Character Flash FloodRapid (< 6 hrs)Short to Long TermConvective/Heavy Stratiform Flood Semi-quick (> 6 hrs)Long Term Stratiform Potential dam breaks should always be considered a flash flood threat. Possible flooding due to ice jams can represent both a flash flood and a “regular” flood threat. Both of these issues will be covered in later slides. Flood watches are issued under the ARBFFAAPX header (using Zone codes in the UGC), and are prepared using the GFE Product Generator. URGENT - IMMEDIATE BROADCAST REQUESTED FLOOD WATCH NATIONAL WEATHER SERVICE GAYLORD MI 637 AM EDT FRI SEP 28 2007...HEAVY RAINFALL FROM THUNDERSTORMS MAY BRING RAPID FLOODING TODAY....HEAVY RAIN PRODUCING THUNDERSTORMS TRACKING REPEATEDLY ACROSS THE AREA MAY RESULT IN RAPID FLOODING ON RIVERS AND STREAMS ACROSS NORTHWEST LOWER MICHIGAN TODAY. MIZ019>022-025>028-031>034-281900- /O.NEW.KAPX.FF.A.0001.070928T1037Z-070928T2100Z/ /00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/ CHARLEVOIX-LEELANAU-ANTRIM-OTSEGO-BENZIE-GRAND TRAVERSE-KALAKASKA-CRAWFORD-MANISTEE-WEXFORD-MISSAUKEE-ROSCOMMON- INCLUDING THE CITIES OF...CHARLEVOIX...LELAND...BELLAIRE...GAYLORD...FRANKFORT...TRAVERSE CITY...KALKASKA...GRAYLING...MANISTEE... CADILLAC...LAKE CITY...HOUGHTON LAKE 637 AM EDT FRI SEP 28 2007...FLASH FLOOD WATCH IN EFFECT UNTIL 5 PM EDT THIS AFTERNOON... THE NATIONAL WEATHER SERVICE IN GAYLORD HAS ISSUED A * FLASH FLOOD WATCH FOR A PORTION OF NORTHERN LOWER MICHIGAN... INCLUDING THE FOLLOWING AREAS...ANTRIM...BENZIE...CHARLEVOIX...CRAWFORD...GRAND TRAVERSE...KALKASKA...LEELANAU...MANISTEE... MISSAUKEE...OTSEGO...ROSCOMMON...AND WEXFORD. * UNTIL 5 PM THIS AFTERNOON. * THUNDERSTORMS PRODUCING HEAVY RAINFALL SPREADING ACROSS NORTHEAST LOWER MICHIGAN THIS MORNING MAY RESULT IN RAPID FLOODING LATER TODAY. A FLASH FLOOD WATCH MEANS THAT CONDITIONS MAY DEVELOP THAT LEAD TO FLASH FLOODING. FLASH FLOODING IS A VERY DANGEROUS SITUATION. YOU SHOULD MONITOR LATER FORECASTS AND BE PREPARED TO TAKE ACTION SHOULD FLASH FLOOD WARNINGS BE ISSUED. $$

40 WFO APX Hydrologic Operations Product Basics: Flood Warnings Flood Warnings can be broken down into two types: Flash Flood Warnings: Issued to cover rapid flooding which occurs within 6 hours of the causative event. The average amount of rainfall required to produced flash flooding over a roughly county sized area is estimated by NCRFC and provided to WFO APX via Flash Flood Guidance (issued twice daily under MSPFFGAPN). Flash Flood Warnings are also issued to cover flooding due to dam breaks. Issued under the ARBFFWAPX header, and prepared using WarnGen. Flash flood follow up statements are issued under the ARBFFSAPX header. MIC011-281545- /O.NEW.KAPX.FF.W.0001.070928T1144Z-070928T1545Z/ /0000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/ BULLETIN – EAS ACTIVATION REQUESTED FLASH FLOOD WARNING NATIONAL WEATHER SERVICE GAYLORD MI 744 AM EDT FRI SEP 28 2007 THE NATIONAL WEATHER SERVICE IN GAYLORD HAS ISSUED A * FLASH FLOOD WARNING FOR... ARENAC COUNTY IN NORTHERN LOWER MICHIGAN... * UNTIL 1145 AM EDT * AT 742 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED VERY HEAVY RAIN FROM A THUNDERSTORM OVER THE RIFLE AND AU GRES RIVER BASINS IN ARENAC COUNTY. RADAR RAINFALL ESTIMATES OF 3 TO 4 INCHES OF RAIN HAS FALLEN OVER THE PAST HOUR. * OTHER LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO...TURNER...AND AU GRES. * A FLASH FLOOD WARNING MEANS THAT FLOODING IS IMMINENT OR OCCURRING. IF YOU ARE IN THE WARNING AREA...MOVE TO HIGHER GROUND IMMEDIATELY. RESIDENTS LIVING ALONG STREAMS AND CREEKS SHOULD TAKE IMMEDIATE PRECAUTIONS TO PROTECT LIFE AND PROPERTY. DO NOT ATTEMPT TO CROSS SWIFTLY FLOWING WATERS OR WATERS OF UNKNOWN DEPTH BY FOOT OR AUTOMOBILE. LAT...LON 4404 8363 4401 8367 4398 8368 4399 8374 4398 8383 4394 8387 TIME...MOT...LOC 1144Z 288DEG 7KT 4404 8384 $$ COUNTY FLASH FLOOD GUIDANCE NWS NORTH CENTRAL RIVER FORECAST CENTER 0820 PM CDT THU AUG 22 2002...GAYLORD HYDROLOGIC SERVICE AREA... AVERAGE INCHES OF RAINFALL FOR GIVEN DURATIONS REQUIRED TO INITIATE FLASH FLOODING ON SMALL STREAMS. GENERAL FLASH FLOOD GUIDANCE FOR STEEP TERRAIN AND URBAN AREAS ARE ONE TO TWO INCHES OR MORE IN ONE TO TWO HOURS OR LESS RESPECTIVELY..B MSR 020823 Z DH00/DC0308230220 /DUE/PPHCF/PPTCF/PPQCF : :IDENT 1HR 3HR 6HR COUNTY NAME :====== ==== === ==== ============================ : : * * * MICHIGAN COUNTIES * * * : MIC001 1.5/ 1.8/ 2.2 : ALCONA MIC007 1.6/ 2.0/ 2.3 : ALPENA MIC009 2.2/ 2.5/ 2.7 : ANTRIM MIC011 2.1/ 2.5/ 2.9 : ARENAC MIC019 2.5/ 2.8/ 3.1 : BENZIE MIC029 2.1/ 2.4/ 2.7 : CHARLEVOIX MIC031 2.1/ 2.3/ 2.6 : CHEBOYGAN MIC035 2.3/ 2.6/ 3.0 : CRAWFORD MIC047 2.8/ 3.5/ 4.4 : EMMET

41 WFO APX Hydrologic Operations Product Basics: Flood Warnings continued Flood Warnings: Issued to cover flooding which has a slower onset (more than six hours after the causative event). Flood warnings can be issued to cover entire counties, or can be issued for specific forecast points along a river, using NCRFC stage and crest guidance. Both general “county wide” flooding and specific forecast point flooding are both covered under the ARBFLWAPX header, with follow up statements issued under the ARBFLSAPX header. Non-forecast point warnings and statements are prepared using WarnGen. BULLETIN – EAS ACTIVATION REQUESTED FLOOD WARNING NATIONAL WEATHER SERVICE GAYLORD MI 1051 PM EDT FRI SEP 28 2007 MIC055-291500- 1051 PM EDT FRI SEP 28 2007 THE NATIONAL WEATHER SERVICE IN GAYLORD HAS ISSUED A * FLOOD WARNING FOR... GRAND TRAVERSE COUNTY IN NORTHERN LOWER MICHIGAN... * UNTIL 1100 AM EDT SATURDAY * HEAVY RAINFALL OVER THE PAST WEEK HAS PUSHED THE BOARDMAN RIVER AND SOME OF ITS TRIBUTARIES OUT OF ITS BANKS. SOME FLOODING HAS BEEN REPORTED IN AND AROUND TRAVERSE CITY. A FLOOD WARNING MEANS THAT FLOODING IS IMMINENT OR HAS BEEN REPORTED. PERSONS IN THE WARNED AREA SHOULD TAKE STEPS TO PROTECT PROPERTY FROM RISING WATER LEVELS. LAT...LON 4460 8535 4463 8571 4475 8569 4478 8556 4472 8534 TIME...MOT...LOC 0251Z 180DEG 0KT 4465 8558 $$

42 WFO APX Hydrologic Operations Product Basics: Flood Warnings continued Flood Warnings for forecast points use specific guidance provided by the River Forecast Center. Forecasts are issued when the forecast stage at a point is expected to rise above Flood Issuance Stage (sometimes also referred to as Action Stage). NCRFC guidance for our HSA is issued under the MSPRVFXXX header, where XXX represents the three letter identifier of the river basin the forecast covers. In our case, this would be one of the following: UPM (Upper Michigan Drainage), NLM (Northern Lower Michigan Drainage), or SMW (Saginaw, Muskegon, White River Basin). Hydrographs that decode RFC guidance can be viewed via the Hydro Time Series application in AWIPS. Flood Warnings and Statements for forecast points are also issued under the ARBFLWAPX and ARBFLSAPX headers respectively, however, these products are disseminated through RiverPro. BULLETIN – IMMEDIATE BROADCAST REQUESTED FLOOD WARNING NATIONAL WEATHER SERVICE GAYLORD MI 614 AM EDT SAT SEP 29 2007...THE NATIONAL WEATHER SERVICE IN GAYLORD HAS ISSUED A FLOOD WARNING FOR THE FOLLOWING RIVERS IN MICHIGAN... MANISTEE RIVER NEAR SHERMAN AFFECTING WEXFORD COUNTY.RECENT HEAVY RAINFALL IS EXPECTED TO PUSH THE MANISTEE RIVER OUT OF ITS BANKS AROUND SHERMAN. SAFETY MESSAGE... PERSONS IN THE WARNED AREA SHOULD TAKE STEPS TO PROTECT PROPERTY FROM RISING WATER LEVELS. MIC165-292214- /O.NEW.KAPX.FL.W.0001.071001T0320Z-000000T0000Z/ /SHRM4.1.ER.071001T0320Z.071001T0900Z.000000T0000Z.UU/ 614 AM EDT SAT SEP 29 2007 THE NATIONAL WEATHER SERVICE IN GAYLORD HAS ISSUED A * FLOOD WARNING FOR THE MANISTEE RIVER NEAR SHERMAN. * FROM SUNDAY EVENING UNTIL FURTHER NOTICE...OR UNTIL THE WARNING IS CANCELLED. * AT 06:00 AM SATURDAY THE STAGE WAS 11.2 FEET. * MINOR FLOODING IS FORECAST. * FLOOD STAGE IS 15.0 FEET. * FORECAST...RISE ABOVE FLOOD STAGE BY TOMORROW LATE EVENING AND CONTINUE TO RISE TO NEAR 15.4 FEET BY MONDAY MORNING. * IMPACT...AT 14.0 FEET...LEFT BANK OF RIVER BEGINS TO OVERFLOW. FLOODING OF PROPERTY ALONG RIGHT BANK OF THE RIVER UPSTREAM FROM THE M-37 BRIDGE BEGINS. $$ RVFSMW : This product contains preliminary data that may be subject to : revision. Refer to your local WFO for the latest official river : forecast. : : North Central River Forecast Center, Chanhassen, MN : : River Forecast : : 1422 GMT Friday November 15 2002 : :Tobacco R Beaverton MI -- BVTM4 HSA:APX FS: 12.0 FT :CREST FORECAST.A BVTM4 1117 Z DH15/DC11151422/HGIFFX 13.8 :.E BVTM4 1115 Z DH12/DC11151422/HGIP/DIH06 : Observed.E1 9.7/ 9.9/ 10.2/ 10.8/.E BVTM4 1115 Z DH06/DC11151422/HGIFF/DIH06 : Forecast.E1 11.4/ 11.9/ 12.3/ 12.6/ 12.9/ 13.1/ 13.4/ 13.6/.E1 13.8/ 13.7/ 13.6/ 13.5/ 13.2/ 12.8/ 12.6/ 12.5/.E1 12.1/ 11.9/ 11.7/ 11.6/ :.END NOTE...This product includes observed precipitation, plus forecast precipitation for the next 24 hours. FCSTR Ext:512

43 WFO APX Hydrologic Operations Product Basics: Other River Related products Hydrologic Statements are issued to disseminated RFC forecasts when a crest above flood stage is not expected to occur. Issued under the ARBRVSAPX header and prepared in RiverPro. HYDROLOGIC STATEMENT NATIONAL WEATHER SERVICE GAYLORD MI 148 PM EDT WED APR 21 1999...RISING RIVER LEVELS FORECAST... FOR THE TOBACCO RIVER...THE FOLLOWING LOCATIONS ARE INCLUDED...BEAVERTON. HEAVY RAINFALL IS FORECAST ACROSS UPPER PORTIONS OF THE SAGINAW RIVER BASIN...BEGINNING THIS AFTERNOON AND CONTINUING INTO THURSDAY. THIS IS EXPECTED TO RESULT IN A SIGNIFICANT INCREASE IN RIVER LEVELS ON THE TOBACCO RIVER AROUND BEAVERTON. THE NATIONAL WEATHER SERVICE IN GAYLORD WILL CONTINUE TO CLOSELY MONITOR RIVER LEVELS...AND WILL ISSUE ADDITIONAL STATEMENTS AS CONDITIONS WARRANT. && FLD OBSERVED FORECAST 7AM LOCATION STG STG DAY TIME SAT SUN MON TOBACCO RIVER BEAVERTON 12 2.6 WED 7AM 4.6 7.1 10.7 DAILY RIVER AND LAKE SUMMARY NATIONAL WEATHER SERVICE GAYLORD MI 1015 AM EST WED JAN 9 2002 OBSERVED24 HR LOCATIONSTAGE (FT)TIMECHANGE PINE RIVER RUDYARD: 2.83WED 04 AM- 0.05 STURGEON RIVER WOLVERINE: 2.85WED 01 AM 0.06 PLATTE RIVER HONOR: 1.29WED 01 AM 0.03 BOARDMAN RIVER MAYFIELD: 3.23WED 01 AM 0.01 MANISTEE RIVER SHERMAN: 11.62WED 05 AM 0.06 MESICK: 3.86WED 05 AM - 0.04 WELLSTON: 8.63WED 05 AM - 0.03 PINE RIVER HOXEYVILLE: 4.13WED 01 AM 0.04 Hydrologic Summaries are issued daily at WFO APX to summarize recent observed stage information at each of our gage points, whether they are forecast points or not. Data is collected automatically four times daily from the USGS web site, and disseminated via ARBRR2APN. The actual summary product is issued under ARBRVDAPX via RiverPro.

44 WFO APX Hydrologic Operations Product Basics: Snowmelt Flood Outlooks Snowmelt flood outlooks are issued each spring, using guidance provided by NCRFC (issued under MSPESGMSR and MSPESGMI). One outlook is issued in the third week of February, and contains a narrative summary of the factors affecting this season’s snowmelt potential. A second outlook is issued in the latter half of March, and contains a numerical outlook for forecast points if these points are expected to rise above flood stage based on normal spring temperatures and precipitation (an assumed rate of snowmelt runoff). Another model run using no future precipitation is also included for comparison. It is important to note that any significant departure from normal can change the potential flood threat. These outlooks are issued under ARBESFAPN. HYDROLOGIC OUTLOOK NATIONAL WEATHER SERVICE GAYLORD MI 704 AM EST FRI FEB 22 2002...SNOWMELT FLOOD OUTLOOK FOR EASTERN UPPER/NORTHERN LOWER MICHIGAN... THE SNOWMELT FLOOD OUTLOOK FOR SPRING 2002 INDICATES THE POTENTIAL FOR MINOR FLOODING. MINOR FLOODING REFERS TO MINIMAL OR NO PROPERTY DAMAGE...BUT POSSIBLY SOME PUBLIC INCONVENIENCE. THIS OUTLOOK COVERS CHIPPEWA AND MACKINAC COUNTIES IN EASTERN UPPER MICHIGAN...WHICH INCLUDES THE PINE RIVER BASIN...AND THE NORTHERN HALF OF LOWER MICHIGAN. CONDITIONS THIS WINTER ACROSS NORTHERN MICHIGAN HAVE BEEN DOMINATED BY ABOVE NORMAL TEMPERATURES... ESPECIALLY JANUARY AND FEBRUARY. MEAN MONTHLY TEMPERATURES FOR JANUARY RANGED FROM 8 TO 11 DEGREES ABOVE NORMAL...WHILE THROUGH MID FEBRUARY MEAN TEMPERATURES RANGED FROM 5 TO 8 DEGREES ABOVE NORMAL. PRECIPITATION HAS BEEN BELOW NORMAL AS MILD WEATHER HAS LIMITED OPPORTUNITES FOR LAKE EFFECT SNOWFALL. JANUARY SNOWFALL TOTALS WERE 50 TO 75 PERCENT OF NORMAL. FEBRUARY PRECIPITATION HAS BEEN NEAR NORMAL DUE TO RECENT RAIN AND SNOWFALL.

45 WFO APX Hydrologic Operations Ice Jams Types of Ice jams, courtesy of the U.S. Army Corps of Engineers Cold Regions Research and Engineering Laboratory: Freezeup jams: Freezeup jams primarily occur during early to mid winter. Floating ice may slow or stop due to a change in water slope from steep to mild, because it reaches an obstruction (such as additional ice), or because other river channel characteristics slow the movement of the ice (channel bends or bridge constrictions, for example). Jams are formed when floating ice stops moving downstream, forms an “arch” across the river channel, and begins to accumulate. Freezeup jams are characterized by low air and water temperatures, and fairly steady water and ice discharges. Breakup jams: Breakup jams occur during periods of thaw, generally in late winter and early spring, and are composed primarily of fragmented ice formed by the breakup of an ice cover or freezeup jam. The ice cover breakup is usually associated with a rapid increase in runoff and corresponding river discharge due to a significant rainfall event or snowmelt. Late season breakup is often accelerated by increased air temperatures and solar radiation. The broken, fragmented ice pieces move downstream until they encounter a strong, intact downstream ice cover or other surface obstruction to flow, or characteristics of the river channel contribute to a reduction in ice flow (such as a reduction in water surface slope). Once they reach such a jam initiation point, the fragmented ice pieces stop moving and begin to accumulate. The ultimate size of the jam, and the severity of the associated flooding depend on flow conditions, the available ice supply from upstream reaches of the river, and the strength and size of the ice pieces. Combination jams: Combination jams involve both freezeup and breakup jams. For example, a small freezeup jam forms in a location that causes no immediate damage. Before the thaw, the jam may provide a collecting point for fragmented ice that floats downstream. Since the jam is usually much thicker than sheet ice (the typically smooth ice cover seen on lakes and slow moving rivers during the winter), it significantly increases the volume of ice available to jam downstream.

46 WFO APX Hydrologic Operations Ice Jams Continued The map below (also from the CRREL) shows historically where most ice jams occur in the APX HSA. The incidence of ice jams is depicted by the color of the bars, with the number of ice jams increasing from yellow (fewer) to orange to red (higher number of jams). Some of the river locations depicted by the colored bars are labeled. The Rifle River, Thunder Bay River, Pine River, and portions of the Manistee River upstream from the hydroelectric dams tend to be most susceptible to ice jamming in our HSA. Pine River Manistee River Black River Rainy River Thunder Bay River Rifle River Muskegon River Sturgeon River Most ice jams in Michigan are of the breakup jam variety (more common during spring thaw), with the typical threat due to ponding of water behind the ice jam. In some cases, rapid break up of the ice blockage could send a wall of ice and water rushing downstream, creating a flash flood threat. More typically, however, what occurs is a rapid fluctuation of river level as the ice jam breaks, moves downstream then reforms again.

47 WFO APX Hydrologic Operations Ice Jams Continued Handling ice jam flooding: Situations involving upstream ponding of water with no downstream flash flood threat: Backwater flooding is the most common type of flood associated with ice jams, and can be handled using a Flood Warning (ARBFLWAPX). If an ice blockage develops without immediate flooding, a Flood Watch (ARBFFAAPX) can be issued to address the backwater flood potential, if it exists. In addition, a Flood Watch can address any threat for rapid flooding downstream of the ice jam as the blockage breaks up. Since ice blockages may persist for several days, and the severity of any flooding is dependent on a lot of unknown factors, the length and type of watch or warning should match the forecaster’s best judgment of the duration of the event, taking into account forecast meteorological conditions (especially temperature and precipitation). Situations involving downstream flash flooding: If an ice jam suddenly breaks and sends a wall of water and ice rushing downstream resulting in rapid flooding, then a Flash Flood Warning (ARBFFWAPX) should be issued. It is technically correct to have both a Flood Warning for points upstream of an ice jam, and a Flood Watch downstream. However, in order to minimize confusion, it is best to try and handle the event with one product covering both the upstream and downstream flood potential. Use your best judgement to decide which is a greater threat to life and property, then issue the appropriate product(s). Be sure to mention the various flood possibilities and dangers in the products that are issued. For example, a Flood Warning for upstream ponding of water can also mention the threat for downstream flash flooding should the ice jam break suddenly. Coordination with local Emergency Managers and Law Enforcement officials can also be used to identify the main flood threat. Also note that ice can have an adverse affect on river gages, as backwater can raise stages without a corresponding increase in streamflow (rating curve is violated). Freezing of gage intakes can also affect stage readings. Watch for sudden large rises and falls in river stage at a gage, as illustrated in the hydrograph for the Sturgeon River at Wolverine. Sharp changes in stage could be a sign of ice affecting river levels. Also note that forecasts from the RFC will not be accurate in ice jam situations, as the higher stages are not being caused by high flows being routed downstream.

48 WFO APX Hydrologic Operations Dam Breaks Dam breaks represent a unique flood warning problem, as they may occur for a variety of reasons and over varying time intervals. A dam may simply erode and empty slowly, or under catastrophic conditions, a dam may fail during a heavy rainfall event or dam burst. The latter of these presents a dangerous flash flood situation. There are 219 dams of various sizes located within the WFO APX HSA; of these 74 dams are considered high or significant hazard dams. A dam is considered hydrologically significant if it is 25 feet or more in height above the stream bed and has a storage of at least 15 acre-feet, or has an impounding capacity of 50 acre-feet and is at least 6 feet above the stream bed (one acre-foot = 43,560 cubic feet of water). Notifications of dam breaks require a quick response. The action to take upon receiving notification of a dam failure or a potential dam failure depends upon the time interval through which the failure is occurring or will occur. Instantaneous - failure has begun and should take less than 6 hours Rapidly Developing - the failure event will take 6 to 48 hours to complete. May have begun to fail or may only be imminent. Slowly Developing - the failure event will take more than 48 hours to complete, and has likely not yet begun. Tippy Dam/Manistee River Hodenpyl Dam/Manistee River Mio Dam/Au Sable River Brown Bridge Dam/Boardman River

49 WFO APX Hydrologic Operations Dam Breaks Dams within the WFO Gaylord Hydrologic Service Area

50 WFO APX Hydrologic Operations Dam Breaks Continued Emergency Action Plans: There are 18 dams in the WFO APX HSA that have Emergency Action Plans, which are formal procedures followed by dam operators during a dam failure. The main part of an EAP is a notification diagram, used to notify various agencies (including the NWS) of a potential dam failure. Exactly who notifies the NWS of a potential dam failure depends on the EAP, but each plan uses the same terminology when it is activated. If an EAP is activated under Condition A, that means a dam failure is imminent or is about to occur. If a Condition B is declared, that means a potentially hazardous situation is developing at the dam, but failure of the dam is neither certain or imminent. Condition C means a non-failure emergency condition has developed (such as a discharge from the dam that will likely flood downstream locations).

51 WFO APX Hydrologic Operations Dam Breaks Continued Basic procedure for handling dam failures: Imminent dam failures, regardless of whether or not the dam in question has an EAP or not, will be handled through issuance of Flash Flood Warnings (ARBFFWAPX). If you are dealing with a dam that has an EAP, you will find preformatted Flash Flood Warnings for each of these dams in WarnGen. In these situations, quite often the only information you will receive is that Condition A has been enacted for the dam in question; you will probably have no other initial information regarding such things as the cause of the failure or the timing of the event. The preformatted warnings are set up with this in mind...and purposely contain minimal information so that the only editing required is to put in the time of the report, and who reported the failure. MIC101-290815- /O.NEW.KAPX.FF.W.0001.070929T0222Z-070929T0815Z/ /0000.3.DM.000000T0000Z.000000T0000Z.000000T0000Z.OO/ BULLETIN – EAS ACTIVATION REQUESTED FLASH FLOOD WARNING NATIONAL WEATHER SERVICE GAYLORD MI 1022 PM EDT FRI SEP 28 2007 THE NATIONAL WEATHER SERVICE IN GAYLORD HAS ISSUED A * FLASH FLOOD WARNING FOR AN IMMINENT DAM FAILURE IN... MANISTEE COUNTY IN NORTHERN LOWER MICHIGAN... * UNTIL 415 AM EDT AT 1016 PM EDT...AN IMMINENT FAILURE OF THE TIPPY DAM ON THE MANISTEE RIVER WAS REPORTED BY MANISTEE COUNTY DISPATCH. LOCATIONS DOWNSTREAM FROM TIPPY DAM INCLUDE: HIGH BRIDGE CAMPGROUND 3.5 MILES DOWNSTREAM BLACKSMITH BAYOU CAMPGROUND 4.5 MILES DOWNSTREAM MANISTEE 20 MILES DOWNSTREAM PEOPLE IN LOW LYING AREAS ALONG THE MANISTEE RIVER BELOW THE TIPPY DAM...INCLUDING AREAS ALONG BEAR CREEK BETWEEN SKIDMORE AND RIVER ROADS...SHOULD MOVE TO HIGHER GROUND IMMEDIATELY. FOLLOW EVACUATION INSTRUCTIONS PROVIDED BY YOU LOCAL EMERGENCY OFFICIALS. FURTHER STATEMENTS WILL BE ISSUED AS ADDITIONAL INFORMATION BECOMES AVAILABLE. STAY TUNED TO NOAA WEATHER RADIO OR LOCAL MEDIA OUTLETS FOR THE LATEST INFORMATION CONCERNING THIS DANGEROUS FLOODING SITUATION. $$ Later information is provided via Flash Flood Statements (ARBFFSAPX), and must be coordinated with local authorities and NCRFC. The RFC can provided crest height and timing of crest at downstream locations by running a simplified dam break model. It is important that all of the agencies involved in a dam failure situation are putting out a consistent message. Complete protocol for handling dam failures can be found in the hydrologic portion of the Station Duty Manual, with additional information provided in the Hydrologic Operations Manual. Be familiar with this.

52 WFO APX Hydrologic Operations Dam Breaks Continued Basic procedure for handling potential dam failures: Potential dam breaks, where the danger of a dam failing is neither certain nor imminent (Condition B for dams with an EAP), are handled through the issuance of Flash Flood Watches (ARBFFAAPX). The threat for flash flooding due to a potential dam failure will be specifically spelled out in the watch statement. Later information is provided in Flood Statements (ARBFLSAPX), again this information must be coordinated with the dam operators to ensure a consistent message to the public. You will also want to call NCRFC and give them a “heads up” so that they are prepared should the dam fail. URGENT - IMMEDIATE BROADCAST REQUESTED FLOOD WATCH NATIONAL WEATHER SERVICE GAYLORD MI 723 AM EDT FRI SEP 28 2007...POSSIBLE FLASH FLOODING DOWNSTREAM OF TIPPY DAM ON THE MANISTEE RIVER....OFFICIALS AT CONSUMERS ENERGY REPORT THAT PROBLEMS WITHIN THE POWERHOUSE AT TIPPY DAM MAY HAVE COMPROMISED THE STRUCTURAL INTEGRITY OF THE DAM. THERE IS A POTENTIAL FOR A SUDDEN FAILURE OF THE DAM...WHICH WILL RESULT IN RAPID FLOODING OF LOW LYING AREAS ALONG THE RIVER BETWEEN THE DAM AND THE CITY OF MANISTEE. MIZ031-281930- /O.NEW.KAPX.FF.A.0001.070928T1123Z-070929T1200Z/ /00000.0.DM.000000T0000Z.000000T0000Z.000000T0000Z.OO/ MANISTEE- INCLUDING THE CITY OF...MANISTEE 723 AM EDT FRI SEP 28 2007...FLASH FLOOD WATCH IN EFFECT THROUGH SATURDAY MORNING FOR THE POTENTIAL FAILURE OF TIPPY DAM ON THE MANISTEE RIVER... THE NATIONAL WEATHER SERVICE IN GAYLORD HAS ISSUED A * FLASH FLOOD WATCH FOR A PORTION OF NORTHERN LOWER MICHIGAN... INCLUDING THE FOLLOWING AREA...MANISTEE. * THROUGH SATURDAY MORNING. THE STRUCTURAL INTEGRITY OF TIPPY DAM MAY HAVE BEEN COMPROMISED...WHICH COULD LEAD TO A CATASTROPHIC FAILURE OF THE DAM...AND FLASH FLOODING DOWNSTREAM ALONG THE MANISTEE RIVER IN SOUTHERN MANISTEE COUNTY. THIS IS A DANGEROUS SITUATION. PERSONS ALONG THE MANISTEE RIVER BETWEEN TIPPY DAM AND THE CITY OF MANISTEE ARE URGED TO CLOSELY MONITOR EVENTS. $$

53 WFO APX Hydrologic Operations Support from the North Central River Forecast Center NCRFC puts out a daily Hydrometeorological Discussion (issued under MSPHMDMSR), usually issued by late morning. This product (which you should be looking at every day!) describes precipitation across the NCRFC area of responsibility during the past 24 hours, a general QPF for the next 24 hours, and a summary of hydrologic conditions, including a list of basins for which forecasts have been issued. Non routine messages from the RFC will be sent as a Hydrometeorological Coordination Message (issued under MSPHCMMSR), discussing such things as changes in NCRFC hours, or data quality control issues, to name a few. Normal hours of operation at NCRFC are 6:00am to 10:00pm CT daily, although during significant flood events the RFC will be staffed 24 hours (this change in operating hours will be communicated to the offices via the MSPHCMMSR). If you need assistance from the RFC during non-office hours (significant river flooding, dam failure), you will find at the bottom of the daily Hydromet discussion the Emergency Call Back List. This list is a series of initials of who to contact in an emergency. On the first page of the Hydrologic Operations Manual, you will find a list of employee names (to match up the initials) and home phone numbers. Try each person in the order listed until you contact someone. The hydrologists at NCRFC “rotate” through the different basins on which they work. Each hydrologist is assigned several basins for which they are responsible for issuing forecasts. If you have a question about a forecast issued from the RFC, or would like to request a forecast for a particular point, you can call the RFC and ask for the person working the basin in question. The initials of the primary hydrologist working a particular basin is listed on the second page of the Hydrologic Operations Manual.

54 WFO APX Hydrologic Operations Hydrologic Service Area Backup Backup provided by WFO APX: Backup provided for WFO APX: Flash Flood Warnings/Statements: Primary Backup -- MQT Secondary Backup -- DTXHydrologic Service Area (all long term Flood Warnings/Statements): Primary Backup -- MQT Secondary Backup -- DTX Flash Flood Watches/Hydrologic Outlooks: Primary Backup -- MQT Secondary Backup -- DTX Flash Flood Warnings/Statements: Primary Backup --MQT Secondary Backup -- DTXHydrologic Service Area (all long term Flood Warnings/Statements): Primary Backup -- MQT Secondary Backup -- DTX Flash Flood Watches/Hydrologic Outlooks: Primary Backup -- MQT Secondary Backup -- DTX

55 WFO APX Hydrologic Operations Hydrologic Service Area Backup: WFO MQT HSA WFO APX serves as the primary backup for HSA operations for WFO Marquette. WFO MQT has nine forecast points in their area, and 35 gaging points overall. Most of MQT’s non-forecast points have flood stages defined for them, and this data should be used when assessing the overall hydrologic situation across western and central upper Michigan. E19’s for each MQT forecast and data point can be found in the intranet version of the Hydrologic Operations Manual. Flood Warning/Statement backup templates for MQT’s forecast points are available in RiverPro. Forecast points are marked purple in the map below.

56 WFO APX Hydrologic Operations Hydrologic Service Area Backup: WFO DTX HSA WFO APX serves as the secondary backup for HSA operations for WFO Detroit. WFO DTX has 29 forecast points in their area, and 44 gaging points overall. E19’s for each DTX forecast point can be found in the intranet version of the Hydrologic Operations Manual. Flood Warning/Statement backup templates for DTX’s forecast points are available in RiverPro. Forecast points are marked purple in the map below.

57 WFO APX Hydrologic Operations A few slides about AHPS AHPS stands for Advanced Hydrologic Prediction Services. Like the Interactive Forecast Preparation System for forecasting, AHPS is the way of the future for presenting hydrologic data and forecasts to our users. It is important that you become familiar with what AHPS is. Paraphrased from the horse’s mouth (so to speak): Advanced Hydrologic Prediction Services (AHPS) are a new component of National Weather Service Climate, Water, and Weather Services. AHPS is a web-based suite of information-rich forecast products. They display the magnitude and uncertainty of occurrence of floods or droughts, from hours to days and months, in advance. These graphical products are useful information and planning tools for many economic and emergency managers. These products will enable government agencies, private institutions, and individuals to make more informed decisions about risk based policies and actions to mitigate the dangers posed by floods and droughts.

58 WFO APX Hydrologic Operations AHPS locally at APX Our local AHPS page can be accessed from our office home page under “Rivers and Lakes”. The initial page consists of a map showing our forecast points, from which you can click on these points to get the latest observed and (if available) forecast hydrographs. Gage data are also available via a series of drop down menus located next to the main map. Information Impacts 19.0 Feet Water reaches the deck of the Prairie Rd bridge...and begins to flood the roadway. 17.0 Feet Water reaches bottom of Prairie Rd bridge deck. Additional information on each individual gage’s page include past and forecast precipitation amounts, and E-19 type impact information.

59 WFO APX Hydrologic Operations The future of AHPS In addition to the short term hydrographs, the real crux of what AHPS is all about is the ability to provide users with probabilistic river forecast guidance. AHPS forecast products include information about probabilities of flood (or of drought). Information such as the forecast river crest, and time to crest, is shown through hydrographs. Other products include information such as: 1) The probability of a river exceeding minor, moderate, or major flooding. 2) The chance of a river exceeding certain level, volume, and streamflow at specific points on the river during 90 day periods. 3) A map of areas surrounding the forecast point that provides information about major roads and landmarks likely to be flooded, levels of past floods, and other information. The probabilistic forecasts are derived using Ensemble Streamflow Prediction (ESP). Starting from the current conditions, past temperature and precipitation data are used as input into a model run to determine “future” streamflow based on historical records. Typically 30 years of data are used (thus 30 model runs) in order to come up with the probabilities. This is an example of a 90 day exceedance probability graphic for the Manistee River near Sherman. This graphic shows the probability that a particular stage will be exceeded over a 90 day period. This is also an example of a 90 day exceedance probability graphic, but it shows probabilities for each week during the 90 day period.


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