Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 310 PM EST Wed Nov 19 2014 Valid 00Z Thu Nov 20 2014 - 00Z Sat Nov 22 2014 ...Heavy rain possible over parts of the Pacific Northwest Coast... ...Snow over the Great Lakes... ...Temperatures will be 15 to 20 degrees below average from the Northern Plains to the Great Lakes/Ohio Valley... A storm over the Upper Great Lakes will move northeastward to Northeastern Canada by Friday. The system will produce lake enhanced snow over the Great Lakes through Thursday evening. In the wake of the storm, northwest flow over the Lakes will aid in producing lake effect snow downwind from the Great Lakes Thursday night into Friday morning. Meanwhile, high pressure over the Plains will move eastward to the Ohio Valley by Friday. Clockwise circulation around the high will pull moisture off the Western Gulf of Mexico that will overrun a east-west front over the Southern Plain/Lower Mississippi Valley producing showers and thunderstorms along the Western Gulf Coast Thursday evening into Friday morning. Rain will develop over parts of the Central/Southern Plains and the Lower Mississippi Valley by Friday morning. Upper-level trough over the Pacific will move onshore over the West Coast by Friday. The energy will produce rain over Northern/Central California on Wednesday evening that will move into the Pacific Northwest on Thursday into Friday. Snow will also develop over parts of the higher elevations over Northern California on Thursday that will move into parts of the highest elevations of the Pacific Northwest by Friday. In addition, rain/freezing rain will develop over parts of the Pacific Northwest late Wednesday night into Thursday morning. Additionally, snow will develop over parts of the Northern Rockies on Thursday evening into Friday. Furthermore, rain will develop over parts of Southern California by Friday morning. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php