Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 309 PM EDT Wed Jun 19 2019 Valid 00Z Thu Jun 20 2019 - 00Z Sat Jun 22 2019 ...Late spring and early summer snows for Yellowstone National Park and higher elevations of the northern Rockies Thursday into Saturday... ...There is an enhanced risk of severe thunderstorms near the ArklaTex through tonight... ...A moderate risk of excessive rainfall exists across Illinois, Indiana, and Ohio through tonight... ...An elevated risk of fire weather is forecast for portions of the Sacramento Valley Thursday... A high amplified flow pattern for June remains across the lower 48 over the next few days. Highlighting the anomalous flow is a deep layer low which is expected to drop southeast out of southwestern Canada which eventually carves out an upper level trough bringing cold temperatures aloft across the West, continuing a pattern seen since late winter/early spring. The related instability should bring skirmishes of showers and thunderstorms, possibly severe, through portions of the northern Rockies tonight before temperatures cool off on Thursday. Snow levels are expected to fall as low as 6500 feet, about as low as can be expected this late in June, with the Storm Prediction Center highlighting the potential for thunderstorms within the snow area. The highest probabilities of 8" of snow in 24 hours -- near 50% -- center near Yellowstone National Park near the Wyoming/Montana/Idaho border between Thursday and Friday morning. Ahead of the system, areas of low pressure slowly shift eastward bringing periods of moderate to heavy rain are expected across portions of Montana and the northern Plains through Friday before moving east into the Upper Mississippi Valley Saturday. From the Midwest eastward, a potent low pressure system for June shifts from near St. Louis this evening eastward while slowly consolidating, bringing more heavy rainfall across portions of the Ohio Valley and Northeast where there is a risk of excessive rainfall. A Moderate risk of excessive rainfall/flash flooding exists across portions of Illinois, Indiana, and Ohio through tonight within an area that has seen much above average rainfall this past week. Near the end of its trailing cold front and an outflow boundary left behind from rainfall overnight/this morning, thunderstorms with heavy rain carry an enhanced risk of becoming severe across northeast Texas and the ArkLaTex region per the Storm Prediction Center into tonight. As the low strengthens while moving through the Northeast Thursday and Friday, a cold front whisks through the Mid-Atlantic States into the Carolinas bringing brisk winds and refreshingly mild conditions on Friday and Saturday to a good portion of the East, with the front settling in the Carolinas on Friday. As a cold front tries in vain to invade California's Sacramento Valley, downsloped winds with low relative humidity bring the threat of elevated fire weather danger on Thursday afternoon and evening. Thursday looks windy across the Mojave Desert when wind gusts of 35-50 mph are expected. While the Desert Southwest and the Deep South/Florida should be hottest in the lower 48 this period south of the polar front, record low afternoon high temperature records are possible near Las Vegas and Lake Havasu City where temperatures will struggle to rise into/through the 90s on Friday -- average high temperatures for that area are above 100F in late June. Roth Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php