Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 357 PM EDT Tue May 12 2020 Valid 00Z Wed May 13 2020 - 00Z Fri May 15 2020 ...Pattern change across much of the nation with warmer weather for the eastern U.S. and unsettled conditions from the southern Plains to the Great Lakes... The deep upper level trough that has been anchored over the eastern U.S. and much of Canada has resulted in a late season freeze for many areas, especially from the Ohio Valley to the Northeast states. Temperatures have been running a good 10 to 20 degrees below normal over the past couple of days, and another night of unseasonably cold temperatures is expected for this same general area along with some record lows. With Canadian high pressure overhead and calm to light winds, frost and freeze advisories/warnings are in effect from Wisconsin to Maine, and extending south to the central Appalachians and northern portions of the Mid-Atlantic. These cold conditions will be a thing of the past by the end of the week as a strong warm front lifts through the region ahead of the next storm system, and this will herald the arrival of above normal temperatures by Friday as an upper level ridge builds in. With the Pacific front crossing the Intermountain West and then emerging across the Plains by Thursday, a corridor of enhanced moisture from the Gulf of Mexico will surge northward ahead of the front and on the western periphery of the surface high that will establish residence over the Southeastern U.S. Multiple disturbances along the front and shortwaves aloft will provide multiple rounds of showers and storms going through the middle of the week, and some of these storms could be severe, particularly across parts of western Texas and Oklahoma where an Enhanced Risk of severe weather exists on Wednesday near the dryline. Flooding may also be a concern across portions of the Midwest by Thursday with widespread 1 to 2 inch rainfall amounts likely. Elsewhere across the continental U.S., heavy showers are likely from northwest California to western Washington near the Coastal Ranges and the foothills of the Cascades with a steady onshore flow through midweek. Dry and warm conditions are expected to continue for the southwestern quadrant of the U.S., and this also holds true for much of the Southeast states. With the exception of some heavier showers and storms for South Florida, most of the Sunshine State should live up to its nickname with high pressure governing the overall weather pattern. D. Hamrick Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php