Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 316 PM EDT Wed Apr 12 2017 Valid 00Z Thu Apr 13 2017 - 00Z Sat Apr 15 2017 ...Heavy snow possible over parts of the Cascades and Sierras... ...Heavy rain possible over parts of the Pacific Northwest... ...Severe thunderstorms and heavy rain possible today near the Southern Rockies in New Mexico and Texas... A deep upper level trough will move into the Pacific Northwest bringing heavy rain and higher elevation snows to much of the region. Heavy precipitation will begin with the arrival of a surface cold front this evening. Snow is expected across the higher elevations, with snow levels falling across the Pacific Northwest and Northern Rockies behind the cold front as it crosses the region. See the Winter Weather page for more details. Light to moderate precipitation will continue from Northern California to western Oregon and Washington with onshore flow behind the front. A warm front will lift north across the Central U.S. through the short range period. Broad southerly flow will transport warmth and moisture northward across the central and southern Plains setting the stage for the development of showers and thunderstorms. Organized thunderstorm activity is possible across parts of the southern Plains this afternoon. Some thunderstorms could become severe, and heavy rainfall associated with these storms could lead to flash flooding across parts of Northwest Texas. The threat of thunderstorms will move northward across the central Plains as the warm front lifts north over the next few days. Ahead of the deep upper trough over the western U.S. broad south to southwesterly flow will allow warm air to surge northward from the Rockies eastward. Temperatures will be above normal for the eastern two thirds of the nation. Downsloping "Chinook" winds will lead to enhanced warming to the east of the northern Rockies leading to high temperatures as much as 20 degrees above normal on Thursday. Cooler temperatures can be expected across the Pacific Northwest and portions of the southern and central Plains where dense cloud cover and precipitation are expected. Krekeler Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php