Subj : DAY1SVR: Day 1 Convective To : All From : Mike Powell Date : Sat Jan 27 2024 09:47:00 ACUS01 KWNS 271256 SWODY1 SPC AC 271255 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0655 AM CST Sat Jan 27 2024 Valid 271300Z - 281200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF SOUTHERN ALABAMA AND THE WESTERN/CENTRAL FLORIDA PANHANDLE... ....SUMMARY... Scattered severe storms are possible today mainly over parts of Alabama, the Florida Panhandle and coastal Mississippi. Isolated severe storms may extend into southern Tennessee and the western Carolinas. ....Synopsis... The mid/upper-level pattern will remain fairly highly amplified yet progressive through the period, dominated by strong ridging moving eastward across western North America, and a downstream trough now over the southern Plains. The trough -- with an embedded, intermittently closed 500-mb low over OK -- is forecast to phase with an initially separate, weaker, northern-stream perturbation over the Dakotas and northwestern MN. The result should be the 500-mb low's reaching the PAH area by 00Z, along a trough extending very nearly the length of the Mississippi Valley. Overnight, the low will move up the lower Ohio Valley, reaching near CVG by the end of the period, with trough southwestward across MS. At the surface, the associated low was analyzed at 11Z over northwestern MS, with cold front arching through central/ southwestern LA and waters offshore from the TX coast. By 00Z, the low should enter southern KY and approach the position of the mid/ upper-level cyclone center, with cold front across middle TN, central/southern AL, and the western FL Panhandle. A marine warm front initially over the northern Gulf will move northeastward over parts of southern AL and the FL Panhandle today before being overtaken by convection ahead of the cold front. A slow-moving synoptic warm front initially was located from the low eastward over northern parts of MS/AL/GA, and should drift-develop to a 00Z position across northern GA and the western Carolinas. The front then should extend near and offshore from the ILM area, with a weak wave low possible west of CLT. By 12Z, that wave low may be the occlusion triple point near RDU, with warm front eastward past the ECG area, and cold front across coastal SC to near a JAX-SRQ line. ....Southeastern CONUS... Two primary convective episodes with somewhat conditional severe threats appear plausible today, having some spatial overlap possible over parts of AL. In chronological order, they are: 1. A prefrontal belt of thunderstorms should move eastward along the Gulf Coast, likely as an eastward shift of initially poorly organized activity now located from western AL and southeastern MS southwestward across southeastern LA. Damaging gusts and a slight tornado threat may accompany this convection later this morning into afternoon before it outruns a narrowing sector of favorable destabilization near the Chattahoochee/Apalachicola Rivers. In the meantime, some inland expansion/intensification of the convection is possible today ahead of its downshear precip shield (mainly southeast of the I-65 corridor in southern AL) as the preceding warm sector continues to recover from yesterday's MCS across the north- central/northeastern Gulf. Surface dewpoints across much of the shelf waters have risen into the upper 60s, with low/mid 70s detected over open waters of the central Gulf, south of the decaying/residual outflow boundary. MLCAPE may reach 500-1000 J/kg in the western FL Panhandle, decreasing considerably northward into southern AL and eastward toward the coastal bend, amidst 35-45-kt effective-shear magnitudes. 2. Some severe potential may develop with a low-topped round of convection forming closer to or along the cold front, this afternoon over portions of AL and southern/southeastern TN, then moving eastward across parts of the southern Appalachians. This activity would occur in a regime of strongly convectively modified boundary- layer air with marginal moisture (upper 50s to near 60 F surface dewpoints), thanks mainly to the earlier activity near the coast. However, midlevel cooling/destabilization, frontal lift, and strong deep shear (effective-shear magnitudes 50-60 kt) should be present. Sufficiency of diurnal boundary-layer destabilization behind the ongoing precip shield remains the greatest uncertainty and potential limiting factor. Given enough warm advection and/or insolation to support a few hundred kg of SBCAPE, any sustained cells may rotate, with damaging gusts and a marginal tornado threat. ...Edwards/Gleason.. 01/27/2024 $$ --- SBBSecho 3.14-Linux * Origin: Ilink: CCO - capitolcityonline.net (454:1/105) .