Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 303 PM EDT Mon Apr 08 2024 Valid 00Z Tue Apr 09 2024 - 00Z Thu Apr 11 2024 ...Heavy rain, flash flooding and severe weather threat emerging across the Southern Plains into the Lower Mississippi Valley tonight and through Tuesday & Wednesday... ...Critical fire danger shifts into Texas Big Bend by Tuesday... At the writing of this discussion, the 2024 Great American Eclipse was well underway with the culprit for reduced visibility over the southern portion of the United States from Texas to the Lower Mississippi Valley is an anomalous deep upper level low starting to dig into northern Old Mexico. This has resulted in increased low level moisture, cloud cover but will become much more dangerous evolving into a very strong Southern Plains surface low bringing a cornucopia of severe weather hazards starting this evening across much of the southern Plains eventually sliding eastward into the lower Mississippi Valley. After eclipse parties may come with unwanted crashers in the form of: fireworks, potential spinners, wind machines, water sprayers and ice makers, as much of Texas has a broad Slight Risk (2 of 5) of severe weather over much of Texas, with an Enhanced Risk (3 of 5) across much of Northwest and Northeast Texas south of the Red River. Significant hail appears to be the greatest threat, but overlapped are isolated tornadoes and severe winds. As the severe party is going, heavy rainfall potential with possible flash flooding conditions will continue to the party into the later hours of Monday evening into Tuesday morning; with the Weather Prediction Center issuing a Slight Risk (level 2 of 4) much of northeast Texas and into southern Arkansas, northern Louisiana and western Mississippi into the early morning hours of Tuesday. On the western side of the system over the mid Rio Grande Valley and Big Bend of Texas, increased fire danger will exist with very low humidity values (single digit dewpoints) and increasing winds. Today, the Storm Prediction Center (SPC) has an Elevated (level 1 of 3) risk of fire danger, but as the surface low really takes shape tomorrow (Tuesday) and winds further increase, a Critical Fire (2 of 3) is forecast over the Big Bend to Lower Pecos River. Tuesday will fair little better across the Southern Plains as the upper-level low brings cooling aloft and with continued warm, moist air off the Gulf and dry air from the Mexican Plateau in the low to mid-levels; very unstable weather conditions will exist again across much of Texas; though the axis of concern will shift ever so southward, from the Permian Basin/Edwards Plateau across to the Piney Woods of E Texas and into Louisiana. Low level wind profiles become a bit more conducive for tornadoes with similar wind and hail risks. SPC has an Enhanced Risk (3 of 5) across central Texas to west-central Louisiana which also aligns with the hatched area indicating an increased potential for strong tornadoes. Similarly, with an overlap of additional round and increased overall moisture to the area, WPC has a Moderate Risk of Excessive Rainfall (3 of 4) is up for downstream areas of far E Texas, northern half of Louisiana, southern Arkansas into western Mississippi indicating broader areal coverage for potential flash flooding conditions. By Wednesday, the surface low is deepening in earnest across southern Texas and starting to lift into the Sabine River Valley by early Wednesday; so once again, a similar environment for severe weather and flash flooding will exist but start shifting east with the core of the Enhanced Risk from SPC over the Lower Mississippi Valley of LA/MS with a Slight Risk covering much of N MS and into AL and far western FL Panhandle. A similar downstream Slight Risk of Excessive Rainfall from WPC extends a bit further north and east into Western Kentucky and eastern Georgia, as multiple days/rounds of rainfall likely have saturated the ground making them more susceptible into Wednesday. A Moderate Risk of Excessive Rainfall is located from E MS, across central AL to the Chattahoochee River and western Georgia likely for stronger thunderstorms with rates of 2-3"/hr and potential training/repeating to induce higher risk of flash flooding as well. Elsewhere, cloud cover remains across the Northern Plains into the Upper Great Lakes with the rapidly filling cyclone. The warm frontal band of clouds and weak showers are/have ruined eclipse viewing in much of New York. Weak showers will slide downstream into the Northeast later today, with a secondary surge of light rain showers for the central Great Lakes into New York for Tuesday into Wednesday. Behind the front, clear skies will allow for increased heating across the Upper Midwest with the only area of above average temperatures (about 10-15 degrees) as places reach the mid to upper 60s on Wednesday. The Pacific Northwest will see a clipping frontal zone with some moisture and high elevation light snows into the northern Cascades and eventually Rockies Tuesday, drying out for Wednesday. Gallina Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php