Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 334 PM EDT Fri Jun 20 2025 Valid 00Z Sat Jun 21 2025 - 00Z Mon Jun 23 2025 ...There is a Slight Risk of excessive rainfall over parts of the Upper Mississippi Valley/Upper Great Lakes on Friday... ...There is an Enhanced Risk of severe thunderstorms over parts of the Northern Plains/Upper Mississippi Valley/Upper Great Lakes on Friday... ...There is a Slight Risk of severe thunderstorms over parts of the Upper/Lower Great Lakes on Saturday... ...There is a Critical Risk of fire weather over parts of the Great Basin/Southwest... A front extending from the Great Lakes to the Northern High Plains and then southwestward to the Great Basin/Central California will have a wave of low pressure over the Northern High Plains that moves to the Upper Mississippi Valley by Sunday evening. Moisture from the western Gulf of America will stream northward over the Mississippi Valley and overrun the boundary, triggering showers and thunderstorms with heavy rain over the Upper Mississippi Valley and into the Upper Great Lakes. Therefore, the WPC has issued a Slight Risk (level 2/4) of excessive rainfall over parts of the Upper Mississippi Valley/Upper Great Lakes through Saturday morning. The associated heavy rain will create mainly localized areas of flash flooding, with urban areas, roads, small streams, and low-lying areas the most vulnerable. Furthermore, upper-level dynamics and upper-level energy will create showers and severe thunderstorms over parts of the Northern Plains into the Upper Great Lakes. Therefore, the SPC has issued an Enhanced Risk (level 3/5) of severe thunderstorms over the Northern Plains/Upper Mississippi Valley/Upper Great Lakes through Saturday morning. The hazards associated with these thunderstorms are frequent lightning, severe thunderstorm wind gusts, hail, and a few tornadoes. However, there will be an added threat of EF2 to EF5 tornados over North Dakota and northwestern Minnesota. In addition, there will be an increased threat of severe thunderstorm wind gusts of 65 knots or greater and hail two inches or greater from the Northern Plains to the Upper Great Lakes. Moreover, low pressure over Eastern Canada will move farther northeastward over Canada, producing scattered rain with embedded thunderstorms over parts of Northern New England through late Friday night. Additionally, moisture and upper-level energy will produce scattered showers and thunderstorms over parts of the Gulf Coast States and the Southeast/southern Mid-Atlantic Coast through Saturday morning. On Saturday, the axis of severe thunderstorms moves eastward to the Upper Great Lakes and Lower Great Lakes. Therefore, the SPC has issued a Slight Risk (level 2/5) of severe thunderstorms over parts of the Upper Great Lakes and Lower Great Lakes from Saturday through Sunday morning. The hazards associated with these thunderstorms are frequent lightning, severe thunderstorm wind gusts, hail, and a few tornadoes. Likewise, on Saturday, moisture and upper-level energy will produce scattered showers and thunderstorms over parts of the Gulf Coast States and the Southeast/southern Mid-Atlantic Coast through Sunday evening. Showers and thunderstorms will also develop over parts of the Northeast. Meanwhile, an upper-level low will move across the Pacific Northwest into the Northern High Plains by Sunday. The energy will produce rain and snow at the highest elevations over the Cascades overnight Friday into Saturday afternoon. Rain will continue over the Northwest through Sunday afternoon. Further, wet mountain snow will develop over parts of the Northern Rockies late Friday night, prompting a Winter Storm Warning over parts of Glacier National Park from early Saturday morning to Sunday afternoon. At lower elevations, showers and thunderstorms will develop over the region through Sunday evening. Also, showers and thunderstorms will move into parts of the Northern Plains and Upper Mississippi Valley on Sunday. Elsewhere, deep boundary-layer mixing is expected across the Great Basin during the afternoon, with surface temperatures climbing into the 90s to 100 F and relative humidity falling into the single digits. The deep boundary-layer mixing into the strong flow aloft, coupled with a tightening regional pressure gradient, will contribute to an expansive area of 20-25 mph sustained southwesterly surface winds (with higher gusts) have prompted a Critical Risk of fire weather over parts of the Great Basin/Southwest Friday into Saturday. Ziegenfelder Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php