Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 PM EDT Sat Aug 24 2024 Valid 00Z Sun Aug 25 2024 - 00Z Tue Aug 27 2024 ...Record heat relents over the Southern Plains as the heat shifts northward into the central/northern Plains and Midwest... ...Severe storms and isolated flash flooding possible for the Northern Plains/Upper Midwest Sunday-Monday... ...Daily Monsoonal thunderstorms continue across the Four Corners region, shifting eastward into the southern Rockies/High Plains... A relentless heatwave over portions of the Southern Plains will finally start to ease a bit Sunday following another day of possibly record-tying/breaking high temperatures into the mid-100s today (Saturday). Forecast highs in the mid-90s Sunday and Monday will still be hot but closer to average. Unfortunately, the upper-level ridge responsible for the hot weather will shift eastward and build northward, bringing dangerous heat into the central/northern Plains and Midwest the next couple of days. Highs will soar into the mid- to upper 90s, with some low 100s possible. When combined with high humidity values, heat indices will reach into the 105-110 degree range, with widespread heat-related advisories and warnings in effect, particularly for portions of the Middle/Upper Missouri and Upper Mississippi Valleys. Extra caution should be observed by those without effective air conditioning and anyone who must be outdoors should remain adequately hydrated. A cold front will bring relief to portions of the Northern Plains Monday. This cold front pushing through the Northern Plains/Upper Midwest will bring increasing storm chances Sunday and Monday. Plentiful moisture, strong instability, and increasing upper-level winds as a shortwave traverses the broader ridge aloft will lead to the threat of some severe thunderstorms, with the Storm Prediction Center highlighting the Red River Valley of the north on Sunday with a Slight Risk (level 2/5) of severe weather. Isolated large hail and damaging winds will be the main threats. Then, on Monday, another Slight Risk is in effect ahead of the front over portions of the Upper Mississippi and Missouri Valleys, with a chance for isolated but potentially larger hail and significant damaging winds. Some locally heavy rainfall and isolated flash flooding will also be possible. Some organized clusters of storms will also be possible for the Middle Mississippi Valley through Sunday morning ahead of separate frontal system lifting northeastward across the Plains, bringing locally heavy rainfall and isolated flash flooding. To the southwest, daily Monsoonal thunderstorm chances will continue, focusing over the Four Corners region through this evening before shifting eastward into the central and southern Rockies/High Plains Sunday/Monday. Deep moisture and moderate instability will lead to some more intense thunderstorms with locally heavy downpours, and some isolated flash flooding will be possible, especially for terrain sensitive areas such as burn scars. Besides the rainfall, the big story across the West the next few days will be the much below average temperatures expected behind a strong cold front pushing through the region. Widespread high temperatures in the 60s and 70s will be common today and tomorrow across the Pacific Northwest, northern Rockies, Great Basin, and northern California, near record low maximum values for some locations. Morning lows Sunday will dip into the 40s and even 30s for much of the interior Pacific Northwest and Great Basin, with a Frost Advisory in effect in northern Nevada. The focus for these mild temperatures will shift eastward over the northern Rockies/eastern Great Basin by Monday while conditions moderate to the west, with highs back into the 80s. Some post-frontal showers and storms will be possible over portions of the Great Basin this evening, becoming more widespread across the northern Rockies/High Plains Sunday into Monday. Elsewhere, some showers and storms with moderate to locally heavy rainfall will be possible Monday into Tuesday over New England as an upper-level wave passes over the region. Daily showers and thunderstorms will also be possible for Florida and along the Gulf Coast with a lingering frontal boundary in the region. Putnam Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php