Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 358 AM EDT Mon Jun 29 2020 Valid 12Z Mon Jun 29 2020 - 12Z Wed Jul 01 2020 ...Locally heavy precipitation, including snow, likely over the Northwest along with colder temperatures... ...Severe thunderstorms and flash flooding are possible in the Northern Plains especially Tuesday and Wednesday... ...Fire danger is expected to continue over the Four Corners states to High Plains... ...Flash flooding will be possible with thunderstorms over parts of the Mississippi and Ohio Valleys... ...Saharan dust continues to linger across Florida while another round of dust could affect the western/central Gulf Coast on Tuesday... A large upper-level low is forecast to settle into much of the western U.S. during the next few days. This will bring a surge of unseasonably cool to cold temperatures through the western U.S., where high temperatures of 15 to more than 30 degrees below average are forecast. Widespread precipitation is also expected over the Northwest, where elevation-enhanced rain totals of 1 to 3 inches are likely in the northern Rockies. Wet snow is even possible for higher elevations of the northern Rockies as temperatures drop to near freezing during the next couple of nights. In fact, a foot of snow is possible at the peaks of the Bitterroot mountains in Idaho. By Tuesday morning, wet snow is forecast to reach the Yellowstone National Park, the higher elevations of northern Utah, and as far south as the Colorado Rockies as the cold air mass continues to plunge southward through the southern Rockies. To the east of the upper-level low, thunderstorms are forecast in the vicinity of a slow-moving surface frontal system in the Northern Plains. A few thunderstorms could be strong today, but should increase in intensity on Tuesday and Wednesday, leading to Slight Risks of severe weather. Flash flooding could also be a threat with these storms, and similarly a Marginal Risk is forecast in the Northern Plains today but a Slight Risk is outlooked for Tuesday. Above normal temperatures are also forecast for the Plains ahead of this front. Meanwhile, widespread Red Flag Warnings and Critical Risks of fire weather are in effect for much of the Four Corners states today due to gusty winds and low humidity. As a cold front moves through ahead of the upper low, temperatures will cool and increase humidity, so the threat of fire weather should diminish farther west and north, but remain across the Southern Rockies to Southern High Plains Tuesday. Farther east, a cold front is forecast to slowly move southward down the Eastern Seaboard during the next couple of days as the trailing end of the front remains nearly stationary across the Ohio Valley and Midwest through Tuesday. This will favor bouts of scattered thunderstorms across the Mississippi Valley, Ohio Valley, and toward the Southern Appalachians. Widespread severe weather is not forecast, but a few strong storms are possible. The bigger threat will be flash flooding, and Slight Risks are in place for portions of the Mississippi Valley, Upper Great Lakes region, and Ohio Valley over the next couple of days. Rain and cool temperatures are also expected to continue across the Northeast through midweek as another upper-level low sits over top the region. A significant amount of the Saharan dust is forecast to linger over Florida for the next few days as another dust plume from the Sahara could reach the western Gulf Coast and Lower Mississippi Valley by Tuesday. The main impacts of the Saharan dust will be hazy skies during the day, locally reduced visibility, degraded air quality, but with potentially colorful sunrises and sunsets. Lower concentrations of dust are forecast to spread up the Plains states ahead of the western U.S. upper low, while some is expected to spread eastward into the Southeast and the Mid-Atlantic. In the meantime, temperatures over Florida will remain hotter than normal, and could even set records with highs in the upper 90s. Tate/Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php