Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 359 PM EDT Fri Jul 12 2024 Valid 00Z Sat Jul 13 2024 - 00Z Mon Jul 15 2024 ...Dangerous and record-breaking heat will continue for much of the West through Saturday, while sizzling temperatures will also begin to build across portions of the central and eastern U.S.... ...Showers and storms will continue along portions of the East Coast from the Carolinas to the New England, with flash flooding possible... ...Several rounds of thunderstorms will bring the threat of large hail and damaging winds to the Northern Plains and Upper Midwest this weekend... ...Monsoon showers expected for the Four Corners Region with locally heavy rainfall and isolated flash flooding possible... Temperatures will remain dangerously hot through at least Saturday across much of the West as a stubborn upper-level ridge remains overhead. The most intense heat Friday and Saturday will focus over portions of the Desert Southwest Friday and the Great Basin and central California Valleys Friday into Saturday. Many near daily record-tying/breaking high temperatures are expected with highs generally in the low 100s, and into the 110s for the Desert Southwest. Widespread heat-related advisories and warnings remain in place due to the threat from this heat, which remains dangerous given the longevity and the intensity of this heat wave. The ridge is expected to begin shifting a bit eastward by Sunday, which will finally bring a little relief to the region. Pockets of hotter temperatures will remain, particularly in the northern Great Basin, but highs overall will be cooler by a few degrees, reducing the intensity of the heat and heat-related illnesses. Unfortunately, as the ridge begins to shift eastward and heights build in over the southern U.S., areas of hazardous heat will expand over central and eastern portions of the country through this weekend. Portions of the northern and central Plains, already hot this week, will continue to see intense heat in the upper 90s to low 100s into the weekend, with some daily record-tying/breaking highs possible. Hotter temperatures into the upper 90s will also begin to expand over the Southeast Saturday, and then in the low to mid-90s across the Midwest on Sunday. The threat from this heat will only expand and intensify across the central/eastern U.S. heading into early next week, and it will be important to monitor the latest forecast and watches/warnings for your area as confidence is increasing in extremely dangerous, potentially deadly heat for many of the urban areas across the Southeast and along the East Coast. A quasi-stationary frontal boundary draped along the East Coast will continue to remain a focus for numerous showers and thunderstorms through Friday evening. Plentiful moisture pooling along the eastern side of the boundary as air flows in from the Atlantic will lead to heavy rainfall rates, and with flow along the boundary leading to repeated rounds of storms increasing the chance for accumulating rainfall. A Slight Risk of Excessive Rainfall (level 2/5) remains in effect from the coastal Carolinas north through the coastal Mid-Atlantic as some instances of flash flooding can be expected. A similar scenario will be in place Saturday, though the boundary is expected to shift slightly eastward, limiting the threat for locally heavy rainfall and flash flooding closer to the coast. An incoming upper-level shortwave will help to reinvigorate storm development, with the greatest potential for storm coverage and heavier rainfall currently forecast over portions of southeastern Pennsylvania/southern New Jersey into the northern DelMarVa Peninsula, where another Slight Risk is in effect. The front is forecast to shift even further eastward on Sunday, keeping the showers and storms mostly offshore and leading to a much more drier day along the East Coast. Another area of active weather will set up over portions of the Northern Plains and Upper Midwest under west-northwesterly flow on the northern side of the upper-level ridge. A cold front pushing slowly southward into the region from Canada as well as embedded upper-level waves in the flow will help to trigger periods of showers and thunderstorms through the weekend. The presence of sufficient moisture, moderate instability, and the strong flow aloft will lead to the threat of severe weather with these rounds of thunderstorms. On Saturday, the Storm Prediction Center has issued a Slight Risk for severe weather (level 2/4) for the threat of large hail as well as damaging winds, particularly with any storms in the evening that grow upscale into more organized convective systems. Additional storms are expected north of the frontal boundary Sunday with a Slight Risk for large hail and damaging winds over eastern North Dakota and northwestern Minnesota. Any clusters of storms continuing southeastward in the flow, particularly across the Upper Midwest Saturday, and the Upper Midwest into the Great Lakes on Sunday, will also pose a threat for some locally heavy rainfall and isolated flash flooding. A monsoonal pattern will set-up over the Four Corners region this weekend as southerly moisture flows in under the influence of the upper-level ridge. Scattered thunderstorms with the potential for some locally heavy downpours are forecast, with an isolated threat of flash flooding, particularly in vicinity of any burn scars. Elsewhere, daily showers and thunderstorms are expected over Florida and westward along the Gulf Coast, particularly on Saturday. An isolated threat of flash flooding will remain in the Houston vicinity given more sensitive soils following rainfall from Beryl. Putnam Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php