SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0155 PM CST Tue Jan 26 2021 Valid 262000Z - 271200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE THIS AFTERNOON INTO TONIGHT ACROSS PARTS OF THE FLORIDA PANHANDLE...SOUTHERN GEORGIA...SOUTHERN SOUTH CAROLINA... ...SUMMARY... A couple of strong thunderstorms could still impact a narrow corridor across the Florida Panhandle and parts of southern Georgia into southern South Carolina late this afternoon into tonight, accompanied by some risk for severe weather. ...20Z Outlook Update... ...Southeast... Thunderstorms through this afternoon have been mostly confined to the vicinity of a narrow plume of higher precipitable water returning around the northern periphery of the subtropical ridge. Pre-frontal destabilization over land, aided by daytime heating, has been generally weak, but in the presence of strong deep-layer shear. While low severe weather probabilities are being maintained along this corridor into early evening, the Rapid Refresh, supported by area VWP data, suggests that low-level flow is in the process of weakening. An appreciable increase in severe weather potential seems unlikely, and strongest thunderstorms may tend to remain focused near the coastal waters south/west of Panama City through Pensacola, aided by inflow (albeit perhaps slightly elevated above a stable near surface layer) of higher moisture content/potential instability. Otherwise, in advance of the significant short wave trough accelerating northeast of the southern Rockies tonight, strengthening lower/mid tropospheric warm advection may support increasing thunderstorm activity, mostly to the cool side of the stalling surface frontal zone, across parts of southern Mississippi through north central Georgia. ...Southeast Arizona into southern Rockies... While convection capable of producing a flash or two of lightning might still be possible across southeastern Arizona through 20-22Z, the relatively compact mid-level cold core appears in the process of the shifting northeastward into southwestern New Mexico, with mid-level warming underway in its wake. As the larger-scale mid-level thermal trough continues overspreading the higher terrain of New Mexico this afternoon, forecast soundings suggest that thermodynamic profiles might become conducive for some convection capable of producing lightning. However, eastward into the high plains, this potential appears likely to become increasingly negligible. ...Northern California coast... Some lightning is evident in convection along the occluding surface front offshore, which might spread into northern California coastal areas by early evening. Otherwise, post-frontal cooling aloft may contribute to isolated thunderstorm activity approaching coastal areas toward 12Z Wednesday. ..Kerr.. 01/26/2021 .PREV DISCUSSION... /ISSUED 1025 AM CST Tue Jan 26 2021/ ...FL/AL/GA/SC... Deep southwesterly tropospheric flow is present today over much of the eastern CONUS, with the primary mid level jet extending from TX into the upper OH Valley. A surface boundary extends from southern SC southwestward into parts of southern GA, southeast AL, and the FL panhandle. A moist and marginally unstable air mass remains along and south of the boundary, with a few breaks in the clouds possible this afternoon. This will provide sufficient CAPE and forcing for scattered afternoon thunderstorms across the MRGL risk area. Flow fields are strong but veered. This would suggest that locally gusty/damaging winds are the main concern, although an isolated tornado is possible. Mid level heights will rise slightly this evening in between systems, before the next upper trough begins to approach AL/FL panhandle late tonight. Low level winds will strengthen before dawn in this area, with the potential for redevelopment of a few thunderstorms - with some risk of gusty/damaging wind or an isolated tornado.
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