Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Feb 22 2024 12:56:24 ACUS01 KWNS 221256 SWODY1 SPC AC 221254 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0654 AM CST Thu Feb 22 2024 Valid 221300Z - 231200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE MID-SOUTH REGION... ....SUMMARY... Thunderstorms may produce marginally severe gusts or hail this afternoon and evening over parts of the Mid-South region. ....Synopsis... In the mean, mid/upper-level pattern amplification should begin again during this period, as ridging builds over NV, the Pacific Coast States and interior Northwest. Downstream, a series of shortwaves will contribute to substantial synoptic-scale height falls over much of the Mississippi and Ohio Valleys to the central Gulf Coast. None of those perturbations -- including some apparent in moisture-channel imagery over OK, northern KS/NE, and western CO -- are (or will become) particularly intense, but should contribute to at least weak large-scale destabilization aloft and maintenance or strengthening of cyclonic flow. At the surface, 11Z analysis showed a cold front extending from a low over southeastern ON across northern IN, through weak lows over central MO and near TUL, then across northwest TX to southern NM. The front should move eastward and southeastward today, to a 00Z position over eastern/southern OH, the lowest Ohio Valley, eastern/ southern AR, and northeast to south-central TX. By 12Z, the front should reach central NY, eastern PA, the southern Appalachians, central parts of MS/LA, and shelf waters of the northwestern Gulf. ....Mid-South region... Isolated to widely scattered thunderstorms are expected to develop by late this afternoon along/ahead of the cold front, over central/ eastern AR and perhaps western TN. Activity should strengthen and increase in coverage through evening as it encounters greater moisture across the Mississippi Valley and into northern portions of MS tonight. Some upscale organization into a short QLCS is possible from early multicell to supercell modes. Marginally severe hail and damaging gusts will be the main concerns. The outlook area will reside on the southwestern rim of a far larger swath of general thunderstorm potential, but with access to sustained, effectively surface-based and at least marginally moist inflow parcels beginning mid/late afternoon in AR and shifting east- southeastward with time. Progs that generate little substantial convection generally are too cool at the surface. Forecast max surface temperatures in the mid/upper 60s F over much of the area will support favorable low-level lapse rates, as well as some boundary-layer mixing, amidst potential for localized downward momentum transfer from stronger flow aloft, for gust support. Midlevel lapse rates are not expected to be very strong, limiting MLCAPE to around 250-750 J/kg, and likely keeping the hail potential isolated, marginal and conditional to supercell maturation. Sufficient deep shear will exist for that, however, with modified forecast soundings indicating around 40-450-kt effective-shear magnitudes and 150-250 J/kg effective SRH -- despite prefrontal veering with time of surface winds toward southwesterly. Greater diurnal boundary-layer mixing/drying, EML-related CINH and weaker CAPE will likely restrict severe potential around western parts of the outlook, while instability decreases northward, moisture decreases eastward, and lift weakens southward. ...Edwards/Mosier.. 02/22/2024 $$ = = = 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) .