Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 418 PM EDT Tue Apr 03 2018 Valid 00Z Wed Apr 04 2018 - 00Z Fri Apr 06 2018 ...A strong cold front is expected to bring severe weather and heavy rain through tonight across the Ohio Valley... ...Snow heavy at times is expected for the Upper Midwest into the Great Lakes through Wednesday morning along with gusty winds... ...Another round of moisture will move into the Pacific Northwest as arctic air continues to filter into the northern Rockies with snow developing... As a blocking pattern continues to persist across the high latitudes, arctic air will continue to filter into the northern and northeastern U.S. through mid-week with fast-developing low pressure systems moving from west to east along the arctic boundary. One such low pressure system has continued to intensify today as it makes its way across the Midwest, with a strong cold front sweeping eastward across the eastern U.S. through Wednesday. Severe weather is forecast for the Ohio Valley through tonight ahead of this strong cold front with a slight risk of flash flooding. Meanwhile, snow heavy at times will overspread the upper Midwest into the Great Lakes tonight as the center of the low passes rapidly just to the south. Warm air will then surge northward across the Mid-Atlantic toward New England tonight, changing the snow and mixed precipitation over northern New England to rain during the day on Wednesday, as the storm center is forecast to pass north of the U.S.-Canadian border. Arctic air will once again spill into much of the eastern U.S. behind the storm on Thursday with temperatures more than 10 degrees below normal in the Northeast. Meanwhile, another batch of moisture is expected to reach the Pacific Northwest Wednesday morning followed by a stronger surge of moisture reaching northern California during the latter half of Thursday. As the Pacific moisture continues to penetrate inland, another surge of arctic air from Canada is forecast to reach the northern High Plains Thursday morning. The interaction between the arctic air and the Pacific moisture will increase the chance of snow across northern Rockies, and the snow should become more widespread later on Thursday. Farther to the west, rain will also become widespread from the Intermountain region through the Pacific Northwest and down into northern California ahead of a strong Pacific front. Temperatures will remain above normal across much of the western U.S. and so will the Deep South. The Desert Southwest and southern Rockies will remain dry. Meanwhile, moisture will begin to increase across Texas on Thursday as a return flow from the Gulf develops. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php