####018004850#### ACUS01 KWNS 080551 SWODY1 SPC AC 080550 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1250 AM CDT Mon Apr 08 2024 Valid 081200Z - 091200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF NORTHWEST TEXAS INTO NORTH-CENTRAL TEXAS... ...SUMMARY... Multiple rounds of severe thunderstorms should develop from early afternoon today through Tuesday morning across a large portion of the southern Plains into the Mississippi Delta region. Large to very large hail is the main threat (potentially up to 4 inches), especially over northwest Texas, though a few tornadoes and severe wind gusts will also be possible. ...Synopsis... A positively-tilted mid-level trough will amplify as it moves across the Southwest and northern Mexico today. Ahead of this trough, a broad region of moderate mid-level southwesterly flow will overspread the southern Plains and into the lower-Mississippi Valley. A weak surface cyclone will develop in West Texas and deepen through the period. As this occurs, the remnant front across southeast Texas early this morning will start to lift north as a warm front through the day. Mid-60s dewpoints are expected as far north as the Red River by 00Z. A cold front moving south through the central Plains this morning will meet this warm front near the Red River by late afternoon/early evening and become mostly stationary and mark the northward extent of significant destabilization and thus severe risk. ...Northwest Texas into north-central Texas... Storms are expected to rapidly form on the northwestern periphery of moisture return in a region of pressure falls across northwest Texas this afternoon. 40 to 45 knots of effective shear should support supercell organization. These storms will initially be high-based with limited moisture with large to very large hail as the primary threat. Low-level flow is forecast to be mostly weak, but there will be strong low-level veering which may be sufficient for some low-level updraft organization. Storms will move into better low-level moisture late in the afternoon and into the evening, which may increase the potential for a tornado or two. ...East Texas into the ArkLaTex... Moderate to strong instability is expected to develop across east Texas and into western Louisiana this afternoon as upper 60s to near 70s dewpoints advect northward. Despite a rare total solar eclipse across this region, its impact on the overall severe weather threat will likely remain minimal. Only moderate warming will be sufficient to erode inhibition across the region with the strengthening low-level jet and isentropic ascent as the primary focus for storm development later in the afternoon. Therefore, most guidance shows storms developing between 20Z and 22Z as the low-level jet strengthens, even the RAP/HRRR which account for eclipse-related radiation effects. Strong instability and shear is expected which will support supercells capable of large to very large hail. However, there are some concerns about storm interference and updraft longevity. Initially, a warm nose around 700mb is evident on NAM/RAP forecast soundings which may limit more robust updraft development. This warm nose is forecast to erode by 23/00Z. However, by that time, widespread shower/thunderstorm development may be underway which could be a limiting factor to updraft longevity and a greater tornado/large hail threat. Some guidance suggests a MCS may develop out of the northwest/north-central Texas convection and move through northeast Texas during the overnight hours. This solution will greatly depend on the evolution of earlier convection and position of the convectively enhanced warm front by late evening. ...Texas Hill Country overnight... Monday night, height falls will overspread much of Texas with a secondary low-level jet max strengthening into portions of central Texas. After 06Z, a very favorable environment will be present with NAM/RAP forecast soundings showing 2500 to 3000 J/kg MUCAPE and over 60 knots of effective shear. Therefore, there is a conditional threat for strong supercells with a threat for large to very large hail if isentropic ascent is sufficient for storm development into central Texas. ...West Texas early Tuesday... The dryline is expected to retreat into West Texas overnight with strong instability building back to near Midland early Tuesday morning. As forcing overspreads this region Tuesday morning, storms are expected to develop in a very unstable and strongly sheared environment. Therefore, supercells are possible with large to very large hail as the primary threat. ..Bentley.. 04/08/2024 $$ ####018004194#### ACUS02 KWNS 080554 SWODY2 SPC AC 080553 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1253 AM CDT Mon Apr 08 2024 Valid 091200Z - 101200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS IN SOUTHEAST TX TO WEST LA... ...SUMMARY... Severe thunderstorms are expected from Tuesday into early morning Wednesday across most of Texas towards the Lower Mississippi River Valley. Several tornadoes, a couple of which should be strong, significant large hail, and damaging winds are likely. ...Synopsis... A shortwave trough centered near the AZ/NM/northwest Mexico border area at 12Z Tuesday will progress steadily eastward into west TX by early Wednesday. Two separate mid-level speed maxes, one curling through the base of the trough and another farther east closer to the northwest Gulf Coastal Plain will gradually translate eastward, likely phasing by 12Z Wednesday. As this occurs, multiple surface lows should consolidate into a primary cyclone in the southeast TX vicinity early Wednesday. ...TX/LA... Several rounds of deep convection are expected across a large portion of TX towards the Ark-La-Tex and Lower MS Valley vicinity during the period. A corridor of enhanced severe potential is evident across a part of southeast TX into west LA, where the environment should be most favorable for regenerative supercells and organized clustering. An MCS will likely be ongoing at 12Z Tuesday in the Ark-La-Tex to Ark-La-Miss vicinity with scattered to widespread convection trailing westward into west TX. An isolated supercell or two may be ongoing in the south-central TX area as well. Primary convective coverage during the day will be tied to the persistent low-level warm theta-e advection regime, with regenerative periods of convection expected across at least east TX to the Ark-La-Miss. Surface heating of a richly moist Gulf air mass to the south of the convective plume, coupled with steep mid-level lapse rates from 8-9 C/km should support a broad swath of moderate to large buoyancy by afternoon. This will yield an uptick in severe storms in a portion of southeast TX to west LA. Although convective mode should predominately consist of clusters, embedded supercells are expected within a favorable low-level hodograph and deep-layer shear, supporting all severe hazards. Farther west, isolated convective redevelopment should occur during the early evening along the trailing outflow boundary intersection with the dryline/surface trough in the central TX vicinity. Low-level shear should be substantially weaker relative to the Sabine Valley, but the favorable deep shear/thermodynamic environment should yield a threat for significant severe hail. An increase in storm coverage is expected Tuesday night across south-central TX to southwest LA. Overall tornado potential should be centered on the Sabine Valley, with potential for discrete warm-sector supercells merging into the residual large-scale outflow boundary. A couple strong tornadoes will be possible. Finally, in west TX, early-day large hail potential should subside for a time, before additional storms refire later into the afternoon near the mid-level trough. While surface winds should largely be northerly by this time, adequate buoyancy within the approaching mid-level cold pocket will yield a renewed threat for large hail. This should wane after dusk. ...Lower Great Lakes... The drifting mid/upper low over the Upper Great Lakes/northern Ontario will aid in scattered showers and lower-topped thunderstorms across the Lower Great Lakes vicinity on Tuesday afternoon. A plume of low-level moisture being advected northeast from the Lower MS Valley, coupled with differential boundary-layer heating south of the stratocu field attendant to the northwest Ontario surface cyclone, should yield a plume of MLCAPE around 500 J/kg. Adequate speed shear within the deep-layer southwesterly flow regime should support a threat for isolated severe hail and locally strong gusts. ..Grams.. 04/08/2024 $$