Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 406 PM EDT Wed Oct 30 2013 Valid 00Z Thu Oct 31 2013 - 00Z Sat Nov 02 2013 ...Flash flooding and severe thunderstorms possible from the Southern Plains to the Ohio Valley... ...Scattered rain and higher elevation snow possible across the Pacific Northwest and Rockies... The kids are going to need umbrellas for trick-or-treating on Thursday for much of the nations midsection as a deep upper trough slowly edges eastward out of the Rockies and into the Plains. Strong southerly flow ahead of the surface cold front will fuel organized bands of heavy rain and thunderstorms from the Mississippi Valley to the Ohio Valley. Severe weather will likely be a threat with these storms and the slow progression of the cold front across the region makes flash flooding an additional concern. The threat for heavy rain and strong storms shifts eastward with the front overnight Thursday and into Friday as the front pushes into the Great Lakes and eventually the Southeast. By early Friday morning, a surface low over the Upper Great Lakes begins to rapidly intensify which could also lead to some strong and gusty winds for both the Upper and Lower Great Lakes regions. Meanwhile, out west, the snow showers across the higher elevations of Colorado and Wyoming should become less numerous on Thursday as the above mentioned upper vortex moves out of the Rockies. In the Pacific Northwest, a system out over the Eastern Pacific will weaken as it moves onshore. Very light and scattered rain and higher elevation snow showers are possible Thursday in the Pacific Northwest and Northern Rockies and a second Pacific system moving towards the coast keeps conditions wet on Friday as well. Monarski Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php