Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 414 PM EDT Thu May 15 2014 Valid 00Z Fri May 16 2014 - 00Z Sun May 18 2014 ...Severe weather and widespread heavy rainfall expected from the Appalachians to the Eastern Seaboard... ...A cooling trend along the West Coast should put an end to the record breaking heat... The stage is set for a large scale heavy rainfall event from the Appalachians to the Eastern Seaboard late this week. A rich ribbon of moisture funneling northward out of the Gulf and Atlantic will fuel widespread moderate to heavy rains along and ahead of a cold front slowly crossing the Appalachians...and a surface wave along the boundary will only help enhance precipitation while it steadily lifts through the Mid-Atlantic states Thursday night into Friday. Intense rainfall rates and long duration of the event will make flash flooding likely. Also...ample amounts of instability will pose a threat for strong to severe thunderstorms within the heavy rains. Behind the system moving through the Eastern U.S...temperatures will stay below normal beneath a large upper low closing off over the Upper Mississippi Valley and Great Lakes. Conditions will even be cold enough to support snow across the Upper Peninsula of Michigan Thursday night and Friday morning. Farther south...weak pieces of energy rotating within the closed upper vortex should encourage widespread...but light...shower activity across the Middle Mississippi and Ohio Valleys. Impulses of energy diving southeastward out of Canada will trigger light shower activity across the Northern to Central Rockies and adjacent High Plains the next few days. As the energy continues it's southeastward track...it should also streak some light to moderate precipitation over Arkansas and the Tennessee Valley. The breakdown of a highly amplified upper ridge will start a cooling trend along the West Coast and put an end to the recent record breaking heat. As the ridge suppresses and a deep closed low approaches from the northeast Pacific...light showers will become increasingly numerous in the Pacific Northwest. Gerhardt Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php