####018003427#### ACUS03 KWNS 240729 SWODY3 SPC AC 240728 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0228 AM CDT Sun Mar 24 2024 Valid 261200Z - 271200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL GULF COAST...AND PORTIONS OF THE OHIO VALLEY... ...SUMMARY... An isolated severe threat may persist Tuesday along/near the central Gulf Coast, with a separate area of isolated severe potential also developing by Tuesday afternoon across parts of the Ohio Valley. ...Central Gulf Coast... A line of thunderstorms will likely be ongoing at the start of the period Tuesday morning across far southeastern MS/LA into southern AL. The airmass ahead of this convection should be only weakly unstable, as low-level moisture will struggle to advance quickly enough northward ahead of the line. Still, various NAM/GFS forecast soundings across southern AL and the FL Panhandle show strong deep-layer shear associated with a 50-70 kt southwesterly mid-level jet over the Southeast. This shear, coupled with weak but potentially sufficient boundary-layer instability, should be enough for an isolated threat for damaging winds to continue through at least Tuesday morning as the line moves eastward. Any tornado threat will probably remain confined along and very near the coast, where greater low-level moisture is forecast, in the presence of sufficient but weakening low-level shear through the day. Some guidance suggests that an isolated severe threat may also persist Tuesday evening/night farther east across parts of the FL Panhandle and far southwestern GA, although this potential is more uncertain and dependent on mid to upper 60s surface dewpoints advancing inland across these areas. ...Ohio Valley... A very strong mid/upper-level jet, with winds around 100 kt at 500 mb, will be present over parts of the mid MS into OH Valleys Tuesday morning. This jet will be embedded within a large-scale upper trough encompassing much of the western/central CONUS, and associated with a mid-level shortwave trough that is forecast to continue east-northeastward across the OH Valley and Great Lakes through the period. The primary surface low should be over the Upper Midwest Tuesday morning, with a trailing cold front extending southward over the mid/lower MS Valley. Moisture ahead of this front will likely remain quite limited, especially with northward extent into the OH Valley. Still, most guidance indicates that low 50s surface dewpoints should be present late Tuesday morning into the afternoon, potentially as far north as the IN/MI border vicinity. Cold mid-level temperatures with somewhat steepened lapse rates aloft, coupled with modest daytime heating, should support the development of weak instability by early Tuesday afternoon (MLCAPE generally 500 J/kg or less). Strong deep-layer shear should foster convective organization with any low-topped thunderstorms that can form. Isolated severe/damaging winds appear to be the main threat with this activity given the forecast strength of the low/mid-level winds. But, some hail may also occur with the more robust cores. This convection is expected to quickly weaken by early Tuesday evening across western OH and central KY with the loss of daytime heating. ..Gleason.. 03/24/2024 $$