Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 342 AM EDT Sun May 15 2016 Valid 12Z Sun May 15 2016 - 12Z Tue May 17 2016 ...Heavy rain possible over parts of Texas and the Western Gulf Coast... ...Temperatures will be 10 to 20 degrees below average from the Northeast to the Carolinas southwestward to the Central/Southern Plains... Rain will spread from the Great Lakes across the Northeast and into Mid-Atlantic as an upper-level low tracks eastward offshore of Maine by Monday. The surface cold front will be slow to exit the Northeast. Additional showers will develop over the Upper Mississippi valley and Upper Great Lakes as embedded energy rotates around the upper low. Much of the Eastern Seaboard and parts of the southern and central Plains will be cooler than average for mid-May. Afternoon temperatures will range from 10 to 20 degrees below normal. Surface high pressure over the much of the central U.S. will keep the southern extend of that front nearly stationary. Showers and thunderstorms will focus along that boundary, and with very little directional wind shear, heavy rain will be possible across the southern Plains and western Gulf Coast. Flash flooding will be possible - excessive rainfall outlooks have been issued for this region over the next couple of days. Another upper-level low will move onshore over the Pacific Northwest and push inland to Northern Rockies by Monday morning. The energy will produce rain over the Pacific Northwest Coast through Monday while rain with embedded thunderstorms will develop over parts of the Northern Intermountain Region and the Northern Rockies. Showers and thunderstorms will develop across portions of the Great Basin, Central Rockies, the Desert Southwest and western Gulf Coast today through Monday as a cold front slowly moves through Great Basin and Four Corners Regions. Snow will develop over the highest elevations of Wyoming. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php