Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 401 PM EDT Wed May 15 2019 Valid 00Z Thu May 16 2019 - 00Z Sat May 18 2019 ...Unsettled weather across much of the West, with heavy snowfall likely for the highest elevations of the Sierra Nevada... ...Much above normal temperatures from the Central Plains to the Upper Midwest on Thursday with near record highs possible... ...Stationary boundary draped from the Great Lakes to the Northern Plains will support several days of locally heavy rainfall and potentially severe thunderstorms... ...Multi-day severe weather event possible beginning Friday across the Central U.S.... A strong upper level system arriving into the Western U.S. by tomorrow morning will bring several days of unsettled weather to much of the the Northwest and into the Rockies. Locally heavy to excessive rainfall is possible, especially along the favored terrain of central/northern California tonight, and the northern Rockies tomorrow. This system will usher in much below normal temperatures (10 to 20+ degrees below average) which will support moderate to heavy snowfall in some of the highest elevations. The best chance for significant snows will be in the Sierra Nevada where up to 2 feet of snow is possible and winter storm warnings are in effect. Meanwhile ahead of the trough, daytime temperatures from the Central Plains to the Upper Midwest will be very warm with daytime highs as much as 20 to 25 degrees above normal and a handful of record or near record highs possible. Showers and thunderstorms developing across the Northern Plains this afternoon will continue into tonight, with favorable conditions for scattered strong to severe storms. Rain will expand eastward Thursday and Friday into the Great Lakes and Midwest as a quasi-stationary boundary sets up across the region. This boundary will provide focus for convection and SPC has highlighted a narrow region along the front from the Central Plains to the upper Ohio Valley within a slight risk for severe weather on Thursday. Storms may contain locally heavy rainfall as well and WPC has placed roughly this same region in a marginal risk for excessive rainfall/flash flooding tomorrow. As the Western U.S. trough kicks out into the Rockies on Friday, moist southerly flow ahead of it will allow for the development of showers and thunderstorms by Friday afternoon across much of the Plains. Conditions will likely be favorable for strong to severe weather and heavy rainfall from Texas to South Dakota where SPC has a large slight to enhanced risk for severe thunderstorms. The best chance for excessive rain or flash flooding by Friday will be for portions of the Northern Plains/Upper Midwest where the stalled frontal boundary may provide additional focus for multiple rounds of heavy rain. As the upper level system moves slowly east into the weekend, this will kick-start what could be a several day severe weather event across the Central states extending into the medium range period. Santorelli Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php