Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 347 AM EST Tue Nov 18 2014 Valid 12Z Tue Nov 18 2014 - 12Z Thu Nov 20 2014 ...Heavy lake effect snows are expected throughout the period... ...Incoming Pacific system will bring showers to the Pacific Northwest and Intermountain West... The cold front exiting the East Coast will cause precipitation to dwindle across the Northeast on Tuesday. However, despite the precipitation coming to an end, Arctic air currently over the central U.S. will sweep across eastern half of the country. Temperatures as much as 20 degrees below average will be felt from the Gulf Coast and northward into the Northeast. These chilly conditions will continue on Wednesday and although Thursday will still be cold, temperatures won't be quite as bitter. Light snow showers will linger across the Upper Midwest, Ohio Valley, and Canada through Thursday. Specifically for the Great Lakes, heavy snow on the lee side of the lakes will persist throughout the short term period. From Tuesday and into Wednesday, Lake Eerie and Ontario will see impressive snow totals, with the WPC winter weather desk suggesting snowfall amounts approaching 2 feet downwind of these two lakes. On Wednesday and Thursday, snow will continue but not be nearly as heavy for the Upper Great Lakes. High pressure is to be blamed for the quiet and warm weather across the western states. Nonetheless, by Wednesday evening conditions will change especially for northern California and Oregon. A frontal system will begin to approach the Pacific coastline by Wednesday night. Scattered showers will move onshore in northern California on Wednesday, and precipitation will begin to spread into the Intermountain West by Wednesday night. Fanning Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php