Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 PM EDT Sat Jun 27 2020 Valid 00Z Sun Jun 28 2020 - 00Z Tue Jun 30 2020 ...Severe thunderstorms are possible across the northern Mid-Atlantic/Northeast this evening and for parts of the northern Plains and southern Appalachians on Sunday... ...Heavy rain could lead to flash flooding for parts of the Mississippi and Ohio Valleys through the weekend... ...Saharan dust should continue to affect the Gulf Coast states and Tennessee Valley today, easing some Sunday... ...Much cooler temperatures and increasing precipitation likely for the Northwest, while the Central Great Basin and Southwest will see fire danger... A frontal system is forecast to push eastward through the Great Lakes region and then through the Northeast and Mid-Atlantic Sunday into Monday. Ahead of the front, conditions will be favorable for severe weather, particularly high winds, for northern portions of the Mid-Atlantic and southern portions of the Northeast into this evening. The risk shifts southward tomorrow over parts of the Carolinas and southern Mid-Atlantic. Meanwhile, the western end of the front is expected to stall in the Midwest and then lift slowly northward through the weekend. A Slight Risk of flash flooding is in effect today across parts of the Middle Mississippi Valley and Ohio Valley, where the stalling front could lead to training storms causing locally heavy rainfall totals. Then on Sunday, Slight Risks of flash flooding are outlooked for portions of the Upper Mississippi Valley and the Ohio/Tennessee Valleys. Surface high pressure is expected over the Southeast, influenced by the western edge of the Bermuda High. This flow pattern will lead to continued inflow of Saharan dust into the southeastern part of the country. The main impacts of the Saharan dust will be hazy skies during the day, locally reduced visibility, and degraded air quality. However, this could also make for some very colorful sunrises and sunsets with deeper oranges and reds compared to normal. On Sunday, the highest concentration of dust looks to focus mainly over Florida. Additionally, temperatures over Florida should be hotter than normal, and could even set records with highs in the upper 90s through Sunday. A cold upper-level trough is forecast to deepen further as it pushes through the Pacific Northwest toward the Great Basin through the weekend. Much cooler air behind a sharp cold front will drop temperatures to more than 20 degrees below normal for many places across the Pacific Northwest on Sunday, reaching the Great Basin on Monday. The heat across interior California will moderate on Sunday as the upper trough edges closer. The cold upper trough will be accompanied with widespread precipitation, with rain totals locally exceeding 2 inches over the northern Rockies through the weekend. Some wet snow is even possible for higher elevations of the Cascades and northern Rockies as temperatures drop to near freezing. Meanwhile, elevated to critical fire risks are forecast to persist from the Great Basin to the Four Corners through the weekend due to gusty winds and low humidity ahead of the cold front. Kong/Tate Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php