Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 309 AM EST Thu Dec 04 2014 Valid 12Z Thu Dec 04 2014 - 12Z Sat Dec 06 2014 ...Heavy rain possible over parts of the West Coast... ...Freezing rain possible over parts of the Pacific Northwest... ...Rain to develop across Mississippi Valley to the Ohio/Tennessee Valleys... Initially, weak upper-level energy over the Ohio Valley will move eastward off the East Coast by Thursday night. The energy will trigger light rain over parts of the Middle/Lower Mississippi Valley that will move to the Southern Ohio Valley/Central Appalachians by Thursday evening. Another region of upper-level energy over the Southwest will move northeastward to the Middle Mississippi Valley by Friday evening. The energy will induce a wave of low pressure over the Southern Plains that will move eastward to the Middle/Lower Mississippi Valley by Friday evening. The second area of upper-level energy will produce light rain over parts of the Southwest into the Southern/Central Rockies on Thursday, with snow over some of the higher elevations of the Central Rockies. As the energy moves onto the Plains, moisture from the Gulf of Mexico will move northward and overrun the associated surface front producing light to moderate rain over parts of the Middle Mississippi Valley by Friday morning. An area of showers and thunderstorms, with moderate rain, will develop over the Lower Mississippi Valley by Friday evening. In addition, light to moderate rain will move into the Ohio Valley and expand into parts of the Northern Mid-Atlantic by Friday evening, too. Meanwhile, weakening upper-level energy over the Pacific Northwest will dissipate as upper-level ridging develops over the Rockies by Friday evening. The energy will produce rain over parts of Northern/Central California on Thursday. Rain will also develop over parts of the Pacific Northwest with areas of rain/freezing rain over parts of the Washington State. Snow and lower elevation rain will develop over parts of the Northern Rockies on Thursday, ending of Friday afternoon. On Friday, a plume of moisture from the Pacific will move into the California Coast on southerly flow. The moisture will produce light to moderate rain along the California Coast by Friday evening and light rain over the Pacific Northwest Coast. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php