Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Feb 11 2023 20:16:30 ACUS01 KWNS 112016 SWODY1 SPC AC 112014 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0214 PM CST Sat Feb 11 2023 Valid 112000Z - 121200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATE THIS AFTERNOON INTO EARLY EVENING ACROSS PARTS OF NORTHERN FLORIDA... ....SUMMARY... Strong thunderstorm development is still possible across parts of northern Florida late this afternoon and evening. A couple of these could become severe and pose a risk for producing locally damaging wind gusts and perhaps a tornado or two. ....20Z Update... Latest model output suggests that the modest surface cyclone over the northeastern Gulf of Mexico (and approaching the Panama City/Apalachicola vicinity at 20Z) may deepen a bit further, while occluding and migrating inland across the Florida Panhandle into southwestern Georgia and adjacent portions of Alabama late this afternoon and evening. It is possible that the point of occlusion could provide a focus for intensifying thunderstorm development near/north of Gainesville toward the Jacksonville vicinity by early evening. However, cloud cover and precipitation from the remnants of weakening convection spreading off the northeastern Gulf of Mexico continues to inhibit boundary-layer destabilization across much of northern Florida into southern Georgia, where vertical shear profiles near a strengthening southerly 850 mb jet (40-50+ kt) are becoming potentially conducive to supercells. Otherwise, a pre-cold frontal convective band offshore of coastal areas to the north of Tampa might still intensify a bit during the next couple of hours as it approaches the coastal waters. This activity could pose a risk for strong wind gusts, but the lingering more stable boundary-layer over the coastal waters probably will tend to weaken the stronger storms embedded within the band, as they migrate inland by early this evening. Thereafter, secondary frontal wave development near and east-northeast of Georgia coastal areas probably will become the primary focus for convective development by the 01-03Z. Strong storms are still expected to remain confined to the better boundary-layer instability over the offshore waters. ...Kerr.. 02/11/2023 ..PREV DISCUSSION... /ISSUED 1028 AM CST Sat Feb 11 2023/ ....Synopsis... An active mid-level flow regime is expected to continue across the CONUS through the forecast period with several large-scale features of interest. Morning water-vapor imagery showed two deepening upper lows; one over the central CA Coast, with a second over eastern TX and southwestern LA moving southeastward into the northern Gulf Of Mexico. Associated height falls and diffluent flow aloft already are underway over the northern Gulf and most of the mainland Southeast, and will spread eastward, with the upper low, to the southern Atlantic Coast this evening/overnight. At the surface, a frontal wave tied to a cold front over the Gulf will translate northeastward, deepening into an established surface cyclone across the western FL panhandle and southern AL tonight. A warm front observed over the central Peninsula should gradually lift north with the surface low drawing mid 60s F surface dewpoints north through this afternoon. ....Northern FL into far southern GA... Morning radar and visible imagery showed widespread cloud debris and precipitation ongoing north of the surface warm front analyzed north of Tampa to near KEVB. Additional convection over the eastern Gulf should spread northeastward toward the FL Panhandle and western coast as the low deepens. Some uncertainty with diurnal destabilization remains given the extent of cloud debris over FL and additional storms farther west. However, clear skies and surface dewpoints in the mid to upper 60s F should gradually expand northward as evidence by wind gradually veering near the front over the last couple of hours. Though lapse rates from the 12z RAOBS remain weak, around 6 C/km, adequate heating and moistening should support 500-1500 J/kg of MLCAPE development through the afternoon along with weak MLCINH. Strong mid-level flow ahead of the deepening upper low should also support 40-50 kt of effective shear across the northern third of FL as evidence by area RAP soundings. Enlarging low-level hodographs with backed low-level flow may also support storm scale rotation with 100-250 m2/s2 of effective SRH. Should sufficient destabilization continue this afternoon, the favorable CAPE/shear space may support organized storms including a few supercells and short line segments capable of damaging wind gusts and a couple tornadoes. Given the weak MLCINH environment, CAMs show numerous potential storm interactions which may limit the duration of any sustained organized storms. Confidence in severe potential decreases with southern extent as the main synoptic forcing for ascent is expected to pass farther north, focused near the FL/GA line later this evening. However, at least isolated severe potential may develop within the unstable but more modestly sheared airmass farther south near the Atlantic Coast. Here, more isolated convection may develop along remnant outflow and seabreaze boundaries, with some potential for damaging gusts and perhaps a brief tornado. $$ = = = To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. 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