Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 326 PM EST Wed Nov 20 2013 Valid 00Z Thu Nov 21 2013 - 00Z Sat Nov 23 2013 ...Temperatures will be 10 to 30 degrees below average over parts of the Northern/Central Rockies and Northern/Central High Plains.... ...Heavy rain possible for the Middle/Lower Mississippi Valley and Southern Plains... ...Heavy rain possible over parts of the Southwest... A strong front extending from the Upper Great Lakes to the Northern Rockies/Northern Plains will advance southward to the Southern Plains and eastward to the Great Lakes/Lower Mississippi Valley by Friday. Rain will develop along and ahead of the boundary from the Great Lakes moving into the Ohio/Tennessee Valleys by Friday. Snow will develop behind the front over the Upper Great Lakes into parts of the Middle Mississippi Valley Thursday into Friday. Moisture will flow northward from the Western Gulf of Mexico into the Southern Plains and the Lower/Middle Mississippi Valley by Thursday morning developing showers and thunderstorms over parts of the Southern Plains and the Lower/Middle Mississippi Valley. Behind the front, cold air will advance southward over the Plains. Clockwise circulation around the associated surface high will produce upslope flow over parts of the Northern High Plains/Northern Plains producing light snow over the region moving southward into the Central Rockies/Southern High Plains by Friday. Upper-level energy will coalesce into a closed upper-level low just off the Southern California Coast by Friday. The energy will produce rain and embedded thunderstorms over parts of Southern California/Great Basin and the Southwest Wednesday into Friday. Snow will also develop over the higher elevations of California and the Great Basin. The snow will move into parts of the Central/Southern Rockies Thursday into Friday morning. Elsewhere, a lingering boundary over Florida will aid in developing showers and thunderstorms over parts of the peninsula through Friday. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php