Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 422 AM EDT Thu Apr 17 2014 Valid 12Z Thu Apr 17 2014 - 12Z Sat Apr 19 2014 ...Snow continues across the Upper Midwest... ...Several storm systems will move across the Pacific Northwest... ...Thunderstorms and periods of heavy rainfall to impact the Gulf Coast... An upper level low is driving a surface occluded front across the Great Lakes and Upper Midwest region. This is bringing April snow showers across these areas and showers in the southern portion of the precipitation shield. The snow will lift north of the Upper Peninsula of Michigan by Thursday afternoon as the surface low progresses into Canada. The upper level low is fairly slow moving and weakens as time progresses; this translates to the surface as the front also weakens. However, showers are expected to move from the northern fringe of the southern Plains on Thursday afternoon along the cold front and move northeast towards the Great Lakes by Friday morning. The Pacific Northwest can expected several storm systems to impact their area through the short term period. By Thursday morning, the first system begins to approach the coast and will generate showers along with high elevation snow. There is also a stationary boundary along the surface high pressure dipping across the Plains that will provide focus for snow showers in the northern Rockies. The front will strengthen as the surface low deepens as it moves into the Intermountain West by Thursday night. A broad area of showers and thunderstorms can be expected and periods of snow for the mountain ranges. By Friday evening, another Pacific system will approach the Pacific Northwest, and showers once again will move onshore. An active period of showers and thunderstorms will impact the Gulf coast states through the beginning of the weekend. On Thursday, a warm front begins to lift north over south Florida which will bring thunderstorms for the southern half of the state. This front will meander in a northerly direction through Friday evening. With daytime heating providing support, scattered showers and thunderstorms will be expected for the central and eastern Gulf coast states. A surface low takes shape to the south of the Louisiana coast on Thursday night and lifts north over northern Florida by Friday evening. Along this surface low, heavier bouts of rain and thunderstorms are expected and may give way to potential of flash flooding. The precipitation will begin to diminish for the central Gulf coast states by Friday evening. Meanwhile, precipitation along the Georgia and Carolina coastlines will ramp up just in time for the weekend as the low continues on its northeast journey into the Atlantic Ocean. Fanning Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php