Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 PM EDT Mon Jun 14 2021 Valid 00Z Tue Jun 15 2021 - 00Z Thu Jun 17 2021 ...Thunderstorms could be severe in the Mid-Atlantic into this evening... ...Heat will continue across the interior West into the northern High Plains with record-breaking temperatures and fire danger in some areas... An upper-level trough combining with multiple frontal boundaries pushing into the Great Lakes region into the Northeast will provide the ingredients for the thunderstorms to become severe across the Mid-Atlantic region for the remainder of this afternoon into tonight. Thunderstorms that organize into a squall line would increase the chance for high winds and heavy downpours in its track, where isolated flash flooding is also possible. The chance of severe storms should decrease on Tuesday but widely scattered thunderstorms will again be possible by Tuesday afternoon as the final reinforcing shot of cooler air pushes across the central Appalachians into the Mid-Atlantic. The cool air mass will then dominate the Northeast on Wednesday as it continues push southward through the rest of the East Coast. Farther south, scattered thunderstorms will be the rule over the next couple of days near the Gulf Coast into much of the Florida peninsula locally heavy downpours and isolated flash flooding are possible into this evening. Some thunderstorms over west-central Texas could result in locally heavy downpours into this evening as well. Meanwhile, a strong upper-level ridge across western and central parts of the U.S. will sustain a heat wave for the next several days. Temperatures well into the 110s are forecast for the next few days in the Desert Southwest, and temperatures exceeding 100 as far north as Montana especially tomorrow will be 25+ degrees above average. Dozens (possibly hundreds) of daily record high maximum and minimum temperatures are likely to be set over the next few days in California, the Intermountain West, Desert Southwest, Rockies, and High Plains. Excessive Heat Warnings and Watches as well as Heat Advisories are in effect. Given the heat, dry conditions, and gusty winds, Elevated to Critical Risks of fire weather are in place across the Great Basin and portions of southern California through at least Tuesday. The exception to the Western heat will be in the Pacific Northwest, where a cold front is expected to cause cooler temperatures and rain chances that could shift into the Northern Great Basin as well by Tuesday. Kong/Tate Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php