National Weather Service United States Department of Commerce

Dangerous Heat Continues Across the South for Memorial Day; Severe Thunderstorms Along the East Coast

A dangerous early-season heat wave over south Texas, the Central Gulf Coast, and southern Florida will persist through Memorial Day. At or near record daily high temperatures and heat index readings over 115 degrees are possible. Along the eastern seaboard, strong to severe thunderstorms are expected to develop this afternoon and linger into the evening hours. Read More >

Quick Synopsis:

 

Mountain snowpack and associated snow water equivalents (SWEs) across central through western Wyoming continued to be much above average by the middle of March; while SWEs across basins in southeastern Wyoming were generally above average.   SWEs at the peak snowmelt runoff elevations (8,500’ – 10.000’) were the highest across the Wind and the Upper Green Basins at 170 to 180 percent of median.  The Tongue and Powder River Drainages had SWEs at 85 to near 100 percent of median at the peak snowmelt runoff elevations.

This outlook is based on various diverse hydrological factors such as:  snow water equivalents (SWEs) in the mountain snowpack, basin morphology (i.e. how basins respond to snowmelt runoff),  antecedent soil moisture, amount of forest canopy damage, recent burn scars, low elevation snow depths, and likely temperature and precipitation trends during late spring/early summer. 

HIGHLIGHTS:

 

Moderate to High potential for flooding associated with snowmelt is expected over several basins across the Little and Big Wind Watersheds… 

Moderate to High potential for flooding associated with snowmelt is expected over several headwater basins of the Upper Green Basin…

Moderate to High potential for snowmelt flooding is expected over headwater basins of the Snake River Basin (to include the Salt River Drainage)…

Moderate to High potential for snowmelt flooding is expected over portions of the North and South Forks of the Shoshone River Basin…

Moderate potential for flooding associated with snowmelt is also expected across the upper to middle portions the of the Little and Big Wind Watersheds, the middle to upper portions of the Upper Green Drainage, the lower and/or upper potions of the North/South Forks of the Shoshone Basin, the upper and lower sections of the Upper Bear Watershed, and several basins across the Snake River Watershed...

…All other headwater basins across Wyoming can expect a generally Low potential for flooding due to springtime snowmelt...

The next outlook will be issued by the 20th of April. 

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Other hydrological information for Wyoming can be found at the NOAA hydrology website:

https://www.weather.gov/riw/local_hydrology

Monthly Wyoming Hydrologic Summary and Graphics:

(updated monthly around the 15th of every month)

https://www.weather.gov/media/riw/hydro/hydro_report.pdf

Wyoming Drought Information Page:

(updated at least once a month)

https://www.weather.gov/riw/drought

Wyoming Graphical Water Supply Outlook:

(updated by the 10th of every month—January-June)

https://www.weather.gov/images/riw/hydro/watersupply.png

Wyoming Average Precipitation by Basin:

 (updated monthly)

https://www.weather.gov/images/riw/hydro/wyomingprecip.png

Wyoming Spring Snowmelt Runoff Flood Potential Graphic:

(updated around the 20th of the month---February-May)

https://www.weather.gov/images/riw/hydro/floodoutlook.png

Current and Forecast Wyoming Streamflows and/or River Stages:

https://water.weather.gov/ahps2/index.php?wfo=RIW

https://water.weather.gov/ahps2/index.php?wfo=CYS

https://waterdata.usgs.gov/wy/nwis/rt

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The current Wyoming Spring 2017 Snowmelt Runoff Flood Potential Outlook graphic: