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SPC Mar 25, 2024 2000 UTC Day 1 Convective Outlook

1 year 3 months ago

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0253 PM CDT Mon Mar 25 2024 Valid 252000Z - 261200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING OVER PORTIONS OF NORTHEAST LOUISIANA...SOUTHEAST ARKANSAS...AND CENTRAL MISSISSIPPI... ...SUMMARY... Tornadoes and damaging thunderstorm gusts are possible today through tonight from east Texas to Alabama. ...20Z Update... ...ArkLaMiss Region... Recent surface analysis places a low east of TXK, with a cold front extending southward through far northwest LA and then back southwestward to 30 miles east of HOU. Storms along this boundary have weakened, while strengthening within a pre-frontal confluence band extending from north-central LA into the TX Golden Triangle. As noted by the 18Z LCH sounding and recent mesoanalysis, much of the earlier convective inhibition has eroded, although overall buoyancy and EL heights still remain limited. Overall forecast remains unchanged, with the ongoing line of storms expected to intensify later this afternoon under the influence of increasing ascent (both from the front as well as large-scale attendant to the approaching upper trough). Limited buoyancy and storm depth will remain limiting factors, but very strong low-level shear will support embedded supercells and bowing segments with any more mature convection. Potential for damaging winds and a few tornadoes (possibly strong) will continues within this line this afternoon and evening. Tornado Watch #61 was recently issued across southeast Arkansas, western and northern Louisiana, and southeast Texas to address this near-term threat. ...Mid/Lower MO Valley... As discussed in recently issued MCD #301, though the thermal profile is marginal (around 500 J/kg MUCAPE), steep low-level lapse rates around 7-8 C/km will continue to nose into southern Iowa through the afternoon. Given the proximity of the low, steep lapse rates, and modest low-level curvature of hodographs, a funnel cloud or isolated tornado could be possible. ..Mosier.. 03/25/2024 .PREV DISCUSSION... /ISSUED 1105 AM CDT Mon Mar 25 2024/ ...ArkLaMiss Region... Few changes have been made to the ongoing forecast. A large upper trough is present today over the western states, with the primary cold front sagging southward from east TX into western AR. Low-level moisture return has been slow ahead of the front over much of the lower MS Valley due to easterly trajectories. However, mid/upper 60s dewpoints are finally spreading inland into southern LA. This trend will continue through the afternoon with ample moisture expected into the southern half of MS by evening. Increasing moisture and at least broken sunshine should lead to sufficient destabilization for thunderstorm intensification by mid-afternoon along/ahead of the front over central LA. These storms will track northeastward toward central MS by early evening, then into western AL after dark. Forecast soundings suggest poor lapse rates in the lower troposphere which may limit updraft strength and overall severe risk. However, very strong low-level shear will promote supercell/bowing structures. Damaging winds and a few tornadoes (possibly strong) continue to be the concern this afternoon and evening. ...IA/MO/KS... The primary surface low is currently over eastern KS and will track into western IA this afternoon. Visible satellite imagery shows a region of mostly clear skies in the warm sector of the low, leading to steepening low-level lapse rates and marginal CAPE. Most 12z CAM guidance develops a few low-topped showers or perhaps thunderstorms late today along the front as it moves into this area. The most robust cells might produce gusty winds, funnel clouds, or perhaps a tornado for a few hours this afternoon. Read more