Building a Weather-Ready Nation 2015 Spring Flood Outlook National Weather Service Valley/Omaha National Weather Service Sioux Falls 1

Building a Weather-Ready Nation 2 Outline  Area of focus is:  the Missouri River from Gavins Point to Rulo.  Eastern Nebraska and Western Iowa  Review of Past Weather  Current state of the basin  Weather forecast for the next four weeks  Spring Flood Outlook

Building a Weather-Ready Nation What you need to know  The potential for flooding this Spring can be characterized as near to below normal.  However…  There is a corridor along and south of I-80 (in Iowa and Nebraska) where soil moistures are relatively high.  Persistent rains in this area would lead to flooding much quicker than other areas. 3

Building a Weather-Ready Nation 4 Past Precipitation

Building a Weather-Ready Nation Past Precipitation Since September 1st 5

Building a Weather-Ready Nation 6 Past Precipitation Since November 1st

Building a Weather-Ready Nation Plains Snowpack 7

Building a Weather-Ready Nation Mountain Snowpack Missouri River Headwaters 8

Building a Weather-Ready Nation Mountain Snowpack Platte River Headwaters 9 By March 1 st, around 80% of the mountain snowpack has accumulated.

Building a Weather-Ready Nation Mountain Snowpack Platte River Headwaters 10

Building a Weather-Ready Nation

Missouri Basin Runoff Forecast

Building a Weather-Ready Nation Frost Depths 13

Building a Weather-Ready Nation Latest River Conditions  During the winter months flow values are hard to come by due to ice effects.  Most rivers going into freeze-up were tracking near to above normal.  The Missouri River is above normal due to slightly elevated increases from Gavins Point. 14

Building a Weather-Ready Nation Weather Forecast through March 16 15

Building a Weather-Ready Nation Beyond March 18 Low confidence forecast 16

Building a Weather-Ready Nation Spring Flood Outlook Where is there a 90% chance of flooding? 17

Building a Weather-Ready Nation 18 Spring Flood Outlook Where is there a 50% chance of flooding?

Building a Weather-Ready Nation 19 Spring Flood Outlook Where is there a 25% chance of flooding?

Building a Weather-Ready Nation 20 Spring Flood Outlook Where is there a 10% chance of flooding?

Building a Weather-Ready Nation 21 Spring Flood Outlook Where is there a 5% chance of flooding?

Building a Weather-Ready Nation Summary  The overall spring flood threat is near to below normal, however…  Along and south of I-80 is an area to watch due to high soil moistures.  This outlook only covers through June 3 rd.  A low Plains snow cover and overall lack of significant late fall/winter precipitation keeps the overall threat low.  Still a lot of time to accumulate mountain snowpack, need to monitor this. I will provide another update, via , in two weeks. 22

Building a Weather-Ready Nation Questions?  Contact Information  David Pearson  NWS Omaha/Valley    Michael Gillispie  NWS Sioux Falls   x493 23