Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Feb 16 2023 13:01:39 ACUS01 KWNS 161301 SWODY1 SPC AC 161300 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0700 AM CST Thu Feb 16 2023 Valid 161300Z - 171200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM SOUTHERN MISSISSIPPI TO CENTRAL KENTUCKY... ....SUMMARY... Widely scattered severe thunderstorms are likely from the central Gulf Coast states northward into the Ohio Valley. Strong tornadoes are most likely over Mississippi, Alabama and middle Tennessee. ....Synopsis... In mid/upper levels, the most important feature for this convective cycle will be a positively tilted synoptic trough, initially apparent in moisture-channel imagery from near OMA southwestward through a small closed cyclone over northwestern KS/south-central NE, to the northern TX Panhandle, south-central NM and southern AZ. An initially separate, northern-stream perturbation over MB and the Dakotas will move southeastward and amplify through the day, gradually phasing with the southern trough. By 00Z, the result should be a lengthy trough from Lake Superior southwestward to the southern High Plains and over the ELP/DMN corridor. By 12Z, the trough should extend from Lower MI across the Ozarks to central TX. At the surface, 11Z analysis showed a surface low over the east- central Ozarks near the AR/MO border, with cold front southwestward across the Arklatex to the middle TX Coastal Plain and deep south TX. Through the day, as the surface low moves toward southern IN, the cold front should sweep southeastward across the lower/mid Mississippi Valley, and the remainder of south/southeast TX into the Gulf and northeastern MX. By 00Z, the low should be near the IN/OH border, with cold front across central KY, middle TN, southern MS, and southeastern LA. By 12Z, the low should be over eastern/central NY near UCA, with cold front from there across central PA, western parts of VA/NC, central/southwestern GA, the central/western FL Panhandle, and the central/southwestern Gulf. ....Central Gulf States to Ohio Valley... Ongoing strong/isolated severe thunderstorms are noted in two main corridors -- one over western parts of TN/KY, another near the cold front over AR. See SPC tornado watch 37 and related mesoscale discussions for near-term concerns. An additional round of convection is expected to develop ahead of the surface cold front as diurnal heating destabilizes a favorably moist warm sector, amidst weakening MLCINH. The most probable area and timing for this development appears to be late morning into early afternoon across southeastern LA and southern MS, moving/ building northeastward into more of MS/AL into the afternoon. Surface dewpoints in the mid 60s to near 70 F, at the bottom of a deep boundary layer with up to about 1.5-inch PW, will contribute to MLCAPE commonly around 1500 J/kg, locally near 2000 J/kg. Kinematically, a period of strengthening shear is expected into the afternoon, followed by leveling off and perhaps some lessening of shear due to veering surface winds. This will lead to varying but generally large hodograph sizes and shapes, but with effective SRH generally remaining in the 250-400 J/kg range over much of the area. The wind profiles throughout that cycle will be favorable for supercells, with effective-shear magnitudes in the 45-55-kt range over southern areas, to 50-60 kt across the Tennessee Valley region. A northward extension of significant-tornado probabilities is being made accordingly, and some parts of this region may need a further, tactically focused, tornado-driven upgrade today, as mesoscale trends and later objective guidance warrant. The strongest unconditional parameter space for significant-tornado potential this afternoon and evening still appears to be in the corridor from southern MS to middle TN and western/central/northern AL, but that doesn't preclude one farther north into a much more conditional regime as well. Deep shear and SRH will remain favorable northward into the Ohio Valley, but instability at all depths should diminish due to a combination of antecedent precip and less-mature, lower-theta-e return flow. As frontal/prefrontal convection moves over the region, a blend of linear and precursory supercell modes is possible, with damaging to severe wind being the most common event, and a few tornadoes also possible. Severe potential also should diminish in the Ohio Valley corridor sooner than the Gulf Coast States, as the frontal/prefrontal convection outruns a narrower warm sector. ...Edwards/Lyons.. 02/16/2023 $$ = = = To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .