Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
507 ACUS02 KWNS 231730 SWODY2 SPC AC 231729 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1229 PM CDT Mon Sep 23 2024 Valid 241200Z - 251200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF CENTRAL AND EASTERN KENTUCKY... ...SUMMARY... Isolated to scattered severe thunderstorms are possible on Tuesday across portions of the Ohio and Tennessee Valleys into the central/southern Appalachians. ...Synopsis... A lead shortwave trough will be moving through parts of the Ohio Valley Tuesday morning with a stronger mid-level jet digging southward through the central Plains. Trends in model guidance have suggested a stronger large-scale trough across the Midwest over the last few cycles. However, the surface pattern still remains a point of uncertainty. At least a weak surface low is expected to be positioned near the Illinois/Indiana border Tuesday morning. The exact position and evolution are not clear, but a general movement to the north-northeast is expected. This will aid in slowly pushing an effective warm front north in Indiana/Ohio/western Pennsylvania. Farther to the west, a secondary, weak surface low is forecast to develop in the Texas Panhandle/western Oklahoma. A weak cold front will push southward as mid-level jet/trough moves south and eastward, respectively. ...Central/Eastern Kentucky... Confidence in scattered storm coverage has increased. While some activity may be ongoing early Tuesday, model guidance generally suggested that at least broken heating is possible. Additional storms are expected along/ahead of the cold front during the afternoon. While mid-level lapse rates will not be overly steep, 40-50 kts of effective shear should lead to organized storms capable of wind damage and isolated large hail. 15% wind probabilities have been limited to where the highest confidence in scattered storm coverage is. Some adjustments are still possible as details regarding low-level destabilization becomes more apparent. ...Mid-South into southern Appalachians... While low/mid-level forcing will be weaker in these areas, shear will still be strong enough to support organized convection along the cold front and within the higher terrain. Mid-level lapse rates will be modest, but a moist airmass (dewpoints in the upper 60s to perhaps low 70s F) will support 1500-2000 J/kg MLCAPE where heating occurs. Damaging winds are likely the primary threat, but effective shear of 40-45 kts will also support some risk of large hail with the strongest storms. ...Lower Great Lakes Vicinity... Uncertainty in the track of the surface low and effective warm front complicate the forecast for this region. Some guidance is more aggressive in destabilizing the boundary layer in the wake of early day activity. Wind profiles will support supercells capable of damaging winds and large hail. Forecast soundings show enlarged low-level hodographs near the effective warm front. While the tornado threat will be conditional on the degree of destabilization and overall storm evolution, a supercell interacting with the boundary could produce a brief tornado. ...Western Oklahoma Vicinity... Some model guidance develops convection along the cold front and moves it southward through western Oklahoma. Moisture will likely be limited which will likely limit storm intensity if any form at all. Gusty winds and small hail could occur with strong northwesterly flow and cold temperatures aloft. Uncertainty is too high to introduce probabilities at this time. ..Wendt.. 09/23/2024 $$