SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0132 PM CST Thu Nov 26 2020 Valid 262000Z - 271200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE THIS AFTERNOON ACROSS PARTS OF THE FLORIDA PANHANDLE...SOUTHERN GEORGIA AND SOUTH CAROLINA...AND TONIGHT ACROSS PARTS OF SOUTHEASTERN TEXAS AND SOUTHERN LOUISIANA... ...SUMMARY... Isolated damaging winds with thunderstorms remain possible in narrow corridor across parts of the Florida Panhandle through southern Georgia and far southern South Carolina this afternoon. Isolated large hail will be possible, mainly overnight, near the northwest Gulf coast. ...20Z Outlook Update... Some adjustments to the categorical and probabilistic lines have been made, mainly to account for the ongoing progression of the synoptic and sub-synoptic features. As expressed in the prior discussion appended below, support for severe storms across the Southeast remains quite marginal. However, 5 percent severe wind probabilities have been extended along a narrow corridor of modest prefrontal boundary-layer destabilization, from parts of the western Florida Panhandle into far southern South Carolina. ..Kerr.. 11/26/2020 .PREV DISCUSSION... /ISSUED 1028 AM CST Thu Nov 26 2020/ ...Southeast AL/southwest GA this afternoon... Occasional weak supercell structures will remain possible within a band of convection drifting southeastward along a surface cold front. Ascent along the front will be aided by weak embedded speed maxima aloft moving over the lower MS/TN Valley regions, in concert with the diurnal heating cycle. However, low-level shear will be weak and deep-layer shear will be on the lower margins for supercells, in an environment with MLCAPE near 1000 J/kg. Thus, any severe threat should be confined to isolated wind damage this afternoon, prior to the storms weakening this evening. ...Southwest LA coast this afternoon into southeast TX overnight... Low-level moisture is beginning to return northward toward the northwest Gulf coast, and a few thunderstorms are ongoing across the northwest Gulf along the warm front/buoyancy gradient. Moisture will spread inland this afternoon into tonight in a weak warm advection regime, with the potential additional influence of a subtle speed max aloft moving east-northeastward from northwest Mexico. A few thunderstorms will develop inland over southwest LA this afternoon, with more substantial storm development expected farther west and north in southeast TX after 06z tonight. Low-level shear will not be particularly strong, but effective bulk shear of 40-50 kt, midlevel lapse rates of 7-8 C/km, and MUCAPE near 1500 J/kg could support isolated hail near 1" with slightly elevated convection.
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