Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 AM EDT Thu Aug 05 2021 Valid 12Z Thu Aug 05 2021 - 12Z Sat Aug 07 2021 ...Heavy rain and scattered flash flooding possible this morning across southeastern New England, and across parts of northern Florida today... ...Excessive heat across the Desert Southwest as hot and dry conditions with fire weather threat and poor air quality across the interior Northwest... A mid- to upper-level ridge extending northward into the Pacific Northwest will continue to sustain the hot and and dry conditions one more day across interior western U.S. before a noticeable change in the weather pattern arrives. High temperatures in the 110s will be common in the Desert Southwest for the next couple of days while upper 90s are forecast for the interior Pacific Northwest this afternoon. As a result, Excessive Heat Warnings are in effect for the Desert Southwest. In addition, fire weather danger is forecast to be most prominent today over the Great Basin. Meanwhile, an upper-level low off the coast of California today is forecast to move onshore and head towards the northern Rockies on Friday. This will signal the beginning of a noticeable change in the general weather pattern across the western U.S., bringing cooler air into the Pacific Northwest during the next couple of days, together with a round of rain/thunderstorms pushing across the Intermountain region into the northern Rockies. The rain/storms are expected to continue spread eastward across the northern Plains on Friday as a complex low pressure system is forecast to develop over the northern High Plains. Heat is expected to build across the central High Plains today and especially on Friday where high temperatures are forecast to reach into the upper-90s. Elsewhere, a frontal boundary is forecast to remain nearly stationary near the Gulf Coast as well as along and just off the East Coast through the end of the week. An axis of heavy rain is forecast to extend along the boundary and associated waves of low pressure. The heaviest rainfall should stay just off the coast; however, a modest influx of moisture is expected to enter southeastern New England tonight and could produce around 1-2 inches of rainfall. Much of this region (besides Cape Cod) has experienced a very wet summer thus far, therefore isolated to scattered flash flooding is possible from eastern Connecticut to coastal Maine. Some heavy rainfall is also possible across northern Florida and the Big Bend region, as well as across southern Texas for the next couple of days. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php