NOAA’s National Weather Service Middle Atlantic River Forecast Center Weather Forecast Office State College Ted Rodgers Hydrometeorologist Cody Moser Hydrologist

Weather Forecast Offices 122 WFOs

River Forecast Centers 13 RFCs

Hydro Challenges: Precip drives our rivers Access to Gulf &Atlantic Moisture Topographically enhanced precip Coastal Storms Lake effect Mixed cool season precip Ice jams Snow melt Flashy headwaters Fast responding streams (6 – 12 hrs) Densely populated – lead time critical Towns established (as early as 1600s) along the rivers Chesapeake Bay – coastal inundation, water quality Recent repetitive major flooding Political pressure to end flooding Mid-Atlantic River Basins

Forecast Responsibility  7 days a week including holidays  6am to 11pm  24 hrs during flooding  ~160 Daily Forecast Points  ~8 Flood-Only Forecast Points  ~300 Supplemental Points  4 daytime shifts  1 Hydrometeorologist  3 Hydrologists  1 evening shift  Flexibility in floods

Delaware, Passaic, Raritan Susquehanna HAS Forecaster Potomac, James, Rappahannock WFO State CollegeConference Room Mt Nittany

How the National Weather Service Forecasts River Stages

1,467 Precipitation Gages

Basin average, 6 hourly resolution

MPE = Multisensor Precipitation Estimator Radar and Gages info combined

River Basins

1 st step in forecast process is determining the amount of runoff produced by precipitation in the basin.

◦ Accounts for seasonal relationship of soil moisture conditions and surface moisture conditions ◦ Computes incremental surface runoff based on surface and overall soil- moisture conditions ◦ Computes what portion of the precip that does not become surface runoff enters groundwater storage.  Now that we know the runoff – we apply the unit hydrograph to compute the flow at the basin outlet.

Hydrograph resulting from 1 inch of runoff occurring uniformly over space and time. Shape is affected by the slope of the basin.

 K and Lag ◦ Attenuation and timing ◦ Determined through calibration ◦ Can be variable with different flows

River Model (CHPS)

 Precipitation does not occur uniformly over space and/or time  Adjust model parameters ◦ Precipitation Amount ◦ Runoff Rate ◦ Rain/Snow ◦ Snowmelt Rate

 6-8am – Hydrometeorologist (HAS) Function ◦ Past precipitation data collection (24 hours ending 7am) ◦ Quality Control of RADAR, MPE, gage precip/temp data ◦ Create 72-hr Quantitative Precipitation Forecast (QPF)  8am –Three Hydrologists Begin River Forecasting ◦ Briefing from HAS ◦ Quality control of streamgage data ◦ Run river model ◦ Make manual adjustments to model ◦ Coordination with Weather Offices ◦ Issue forecasts (around 10am) ◦ Monitor and update forecasts as needed

From the River Forecast Center to our Weather Forecast Offices

 Emergency Managers/Public ◦ Flood awareness and safety  Fisheries Management ◦ Wildlife ◦ Fisherman  Agriculture  Reservoir Managers ◦ Recreation ◦ Flood control  Hydropower ◦ Power generation Who uses our river forecasts?

 Flood Outlooks  Flood Climatology  Water Supply  Precipitation  Flash Flood Guidance  Expansion into Water Resources  Customer Advisory Board What else do we do?

The Future in River Forecasting

 Free online learning modules meted.ucar