Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 AM EDT Tue May 06 2025 Valid 12Z Tue May 06 2025 - 12Z Thu May 08 2025 ...Widespread showers and storms to bring scattered to numerous instances of flash flooding and severe weather to portions of Texas and the Lower Mississippi Valley Tuesday... ...Showers and storms continue to linger across much of the Ohio Valley/Lower Great Lakes and Northeast through Tuesday... ...Cooler, well below average temperatures persist across much of the Interior West and central/southern Plains as the northern Plains/Upper Midwest remain much above average through mid-week... A stagnant, omega block pattern over the CONUS with an upper-low over the Ohio Valley and another upper-low over the Southwest will begin to break down over the next couple of days as both lows begin to make some eastward progress, but not before another couple days of associated unsettled weather with a threat for flash flooding and severe storms. The upper-low over the Southwest and an accompanying surface low pressure/frontal system emerging across the Plains this morning will provide the focus for continued widespread showers and thunderstorms across much of the central/southern Plains and Lower Mississippi Valley. An influx of anomalously high Gulf moisture northwestward along a quasi-stationary front stretching across Texas and Louisiana will lead to locally heavy downpours with repeated rounds of rainfall expected as a complex of storms moves roughly parallel to the boundary. A Moderate Risk of Excessive Rainfall (ERO) is in effect from eastern Texas eastward through the Lower Mississippi Valley as scattered to numerous instances of flash flooding are expected. A broader Slight Risk (level 2/4) extends northwestward as additional storms are expected north of the boundary across Oklahoma and in upslope flow through the Texas Panhandle into southeastern Colorado/northeastern New Mexico, with additional scattered instances of flash flooding possible. In addition, cooler air aloft and increasing winds with the approaching upper-low will lead to very strong instability and both deep and low-level shear more than sufficient for some intense, supercell thunderstorms along and south of the front across southeastern Texas. The Storm Prediction Center has issued an Enhanced Risk of severe weather (level 3/5) for the threat of a few tornadoes, some of which could be strong, as well as large hail and damaging winds. More scattered severe storms are expected broadly from the Lower Mississippi Valley west through central and northwest Texas, with large hail, especially for northwest/central Texas, damaging winds, and a few tornadoes possible. The upper-low will make slow eastward progress on Tuesday, with the aforementioned frontal boundary sagging southward towards the Gulf Coast but generally remaining quasi-stationary. Another round of widespread storms is expected along the boundary, particularly along the central Gulf Coast. Locally heavy downpours and repeated rounds of rainfall as storms cluster along the boundary have prompted a Slight Risk ERO for scattered flash flooding. More scattered storms with moderate rainfall are expected across the Southeast, as well as in the central Plains ahead of a secondary frontal boundary pushing southward through the region. Lingering showers and storms will also continue under the upper-low over the Four Corners region Monday. Snow is ongoing for higher elevations of the Rockies in Colorado and north-central New Mexico, with some heavy snow totals of 1-2'+ forecast Tuesday for the Front Range of the Rockies given the focused moist upslope flow from the east. Most of this precipitation will come to an end by Tuesday as the upper-low continues east. Showers and storms also continue this morning under the eastern upper-low over the Ohio Valley and ahead of an accompanying surface frontal system through the Northeast/Mid-Atlantic. Moderate to locally heavy rainfall is most likely from the Lower Great Lakes/Upper Ohio Valley east through the northern Mid-Atlantic and into New England, with some isolated flash flooding possible. Conditions should begin to dry out from west to east overnight Tuesday as the upper-low opens into a wave and finally begins to move eastward, with some lingering lighter rain chances Wednesday mainly for the interior Northeast and New England. Elsewhere, scattered daily thunderstorm chances are expected for Florida ahead of a frontal boundary lingering through the region. A Pacific system moving into the Pacific Northwest will bring some light rain chances Wednesday afternoon/evening. Persistent well below average and well above average temperatures are forecast through mid-week as the omega block pattern lingers for a couple more days. The most anomalously cooler temperatures stretch across much of the Interior West and into the central/southern Plains under the western upper-low. Forecast highs Tuesday and Wednesday are mainly in the 50s and 60s, with 60s and 70s for the Desert Southwest and portions of the Southern Plains. Below average temperatures are also expected through the Ohio Valley/Lower Great Lakes, with highs in the 50s and 60s, and into the Southeast, with highs in the 60s and 70s. The East Coast will be closer to average for most locations, with some cooler temperatures across New England in the 50s and 60s, but some warmer temperatures south with 60s and 70s in the Mid-Atlantic and 80s from the Carolinas south to Florida. In contrast, highs over the northern Plains and Upper Midwest remain well-above average and into the 70s and 80s for many locations. The West Coast will also be well above average as a ridge builds northward in the wake of the upper-low, with highs in the 70s and 80s. These warmer temperatures will spread inland for northern portions of the Interior West by Wednesday. Putnam Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php