Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 356 AM EDT Mon May 20 2019 Valid 12Z Mon May 20 2019 - 12Z Wed May 22 2019 ...A significant severe weather and flash flood event is likely today across parts of Texas, Oklahoma and Kansas... ...Heavy snow expected for the central Rockies with well below average temperatures extending from the central and northern High Plains into much of the West through Wednesday... ...Above average warmth for the East Coast today with much cooler temperatures for the Northeast on Tuesday... A major spring storm system is set to affect the Great Plains today with the potential for widespread severe weather and flash flooding from northwestern Texas into Oklahoma where the Storm Prediction Center is forecasting a High Risk of severe thunderstorms. Severe threats include very large hail, damaging straight line wind gusts and tornadoes, some of which may be long-track and rather significant. Thunderstorms are expected to be ongoing early this morning across eastern New Mexico into the Texas and Oklahoma panhandles with convection expanding north and east during the day today. Additional thunderstorm development is expected across western Texas this afternoon resulting in multiple rounds of strong to severe thunderstorms with heavy rain resulting in a High Risk of flash flooding, centered over Oklahoma but with a Moderate Risk extending northward into Kansas and southwestward into northwest Texas. Forecasts of rainfall ending Tuesday morning are for 3 to 6 inches across a considerable area extending from southwestern Oklahoma into southeastern Kansas and the Ozarks, with locally higher totals likely. The threats for severe weather shift east for Tuesday into the Arklatex through Missouri and while still noteworthy, do not look as extreme as the forecasts for today/Monday. A large Slight Risk of flash flooding is forecast on Tuesday from South Dakota into eastern Kansas and Missouri. As a strong area of low pressure and its attendant fronts advance east, the cold front over Texas will weaken but continue to provide a focus for strong to severe thunderstorms. To the north and west of the low center, high temperatures will be 20 to 30 degrees below average for portions of the central and northern High Plains today and Tuesday, with clouds and rain keeping many locations across the Intermountain West and north of the warm front unsettled. A second storm system will enter the western U.S. tonight bringing rain and higher elevation snow to Oregon, Nevada and northern California. By Tuesday, temperatures should fall low enough to support heavy mountain snow for Wyoming and Colorado where 1-2 feet could fall in the higher elevations through Wednesday with minor accumulations even possible for the lower elevations in eastern Wyoming. Out East, high temperatures will be well into the 80s and low 90s from Florida and Georgia to New England today. These temperatures are 10-20 degrees above mid-May averages. A cold front will change that for Tuesday however, with high falling back into the 50s and 60s for the Northeast with 70s into the northern Mid-Atlantic region. Cooler weather is also expected across the Ohio Valley for Tuesday, although rain should hold off until late Tuesday night into Wednesday. Otto Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php