Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 457 AM EDT Sun Oct 27 2013 Valid 12Z Sun Oct 27 2013 - 12Z Tue Oct 29 2013 ...Clipper systems will deliver precipitation to the Great Lakes region... ...Showers and thunderstorms possible for portions of the southern Plains... ...Snow and cold temperatures will be possible for the Northern Rockies and Intermountain West... Multiple weak clipper systems will move over the Great Lakes from Canada. From Saturday through early Monday, these disturbances will mainly effect the upper Great Lakes and portions of the lower Great Lakes. Since these disturbances are weak, widespread precipitation is not expected. A mix of rain and snow will be possible. A cold front will begin to drop through the Upper Midwest and Ohio Valley by early Monday which will begin to push the precipitation further east towards the lower Great Lakes. By Tuesday night, surface high pressure will have settled over the eastern half of the U.S. Consequently, drier conditions will ensue over these regions. Currently, a convective system ahead of the dipping cold front is moving into southeastern Texas and will move south-southeasterly into the lower Mississippi Valley. This complex will gradually weaken over time on Sunday and will become more scattered and less organized by Sunday evening as the cold front dissipates. However, despite weak forcing, scattered showers and thunderstorms will continue through the short term period in the lower Mississippi Valley. A very deep upper level low will continue to dip down along the California coast. As it moves south, the low will close off and begin to approach the Desert Southwest by Monday night and into Tuesday. Preciptation will start in the western Canadian provinces and begin to move southward over the Pacific Northwest and Northern Rockies. Higher elevation precipitation will fall as snow, and the coast of the Pacific Northwest will get showers. As the upper low becomes closed off, a cold front begins to form at the surface and will progress southeastward towards the Intermountain West. Widespread snow across the mountains is expected, with a mix of rain and snow in the lower elevations. This swath of precipitation will continue through at least Wednesday morning as the surface front moves toward the Four Corners. The Canadian surface high will nose into the Plains and Upper Great Lakes from Sunday through Wednesday. Colder air will spill into the Plains and Northern Rockies and temperatures are expected to be well below normal. Fanning Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php