Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 510 AM EDT Tue Apr 28 2020 Valid 12Z Tue Apr 28 2020 - 12Z Thu Apr 30 2020 ...Widespread severe weather is expected today from the Midwest to the Southern Plains... ...Scattered flash flooding is possible over parts of the Southern Plains into the Lower Mississippi Valley... ...Temperatures will be 10 to 20 degrees above average over the Southwest into parts of the Great Basin... A developing weather system over the Plains/Mississippi Valley will produce severe thunderstorms over of parts of Mississippi Valley and central/southern Plains today and tonight. The threat of damaging thunderstorm winds is especially high. A damaging squall line is expected, with perhaps hurricane force winds in some places, along with wind-driven hail. The greatest threat exists from eastern Oklahoma into adjacent parts of Arkansas and Texas. In addition, there is a Slight Risk of excessive rainfall. Some of the storms may produce 2 inches of rain in 45 minutes. The aforementioned storm will become the main weather story across the central to eastern U.S. during the next few days. This system is forecast to begin intensifying across the Plains on Tuesday as an upper-level trough dives into the Northern and Central Plains while ingesting very warm and moist air from the Gulf of Mexico. By Wednesday, the highest threat of heavy rain and thunderstorms should be pushing east of the Lower Mississippi Valley toward the interior Southeast. In addition, rain and some thunderstorms will be spreading across the Great Lakes ahead of the intensifying storm. Many areas of the East Coast will begin to see rain arriving later on Wednesday. Meanwhile, much above average temperatures will continue in the Desert Southwest as upper-level ridging lingers over the region through Wednesday. Forecast high temperatures for much of California and the Great Basin eastward to Texas will be in the 80s and 90s, while many areas in the Desert Southwest will surpass the century mark. These readings will challenge daily record high temperatures. Excessive Heat Warnings remain in effect for a large portion of the Desert Southwest. The very warm air will spill out of the Southwest and into the southern Plains on Tuesday before cooler air arrives Wednesday behind a cold front. The front will produce a period of gusty winds which will push the warm and dry portions of the High Plains and nearby Rockies toward elevated wildfire conditions both today and Wednesday. Ziegenfelder/Burke Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php