SPC AC 151630 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1030 AM CST Sun Dec 15 2024 Valid 151630Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF NORTH TEXAS TO THE OZARKS... ...SUMMARY... Isolated severe hail, strong/gusty winds, and perhaps a tornado may occur tonight through early Monday morning from parts of north Texas to the Ozarks. ...Synopsis... Gradual amplification and consolidation of upper troughing will occur through the period across parts of the northern Plains and Upper Midwest. The southern fringe of this upper trough will begin to influence and overspread portions of the central/southern Plains late this evening and overnight. The primary surface low will develop towards the international border region of northern MN/southern Canada, while partially modified Gulf moisture continues to gradually stream northward over portions of the southern Plains into the Ozarks ahead of a cold front. ...Eastern Oklahoma into Western Arkansas and Southwest Missouri... Convective initiation will likely be delayed until 03Z or later this evening across eastern OK/western AR vicinity, as low-level warm/moist advection aids in the northward transport of a moist low-level airmass. Once convection develops as glancing ascent from the approaching upper trough overspreads the warm sector, convective mode may quickly become messy, as generally southwesterly low/mid-level flow encourages updraft interactions and mergers. Even so, around 1000-2000 J/kg of MUCAPE, aided by modestly steepened mid-level lapse rates, should support robust updrafts. Coupled with sufficient (around 30-40 kt) deep-layer shear, some of this initial development could produce marginally severe hail on an isolated basis. Based on latest guidance trends showing convective initiation farther north across parts of northern OK into southwest MO, the Marginal Risk has been expanded northward to account for this initial hail threat. Poor/neutral low-level lapse rates and a generally saturated boundary-layer shown in various NAM/RAP forecast soundings limit confidence to some extent in the potential for truly surface-based thunderstorms tonight across the warm sector. Still, the presence of a 35-45 kt southwesterly low-level jet, with associated 0-1 km SRH sufficient for low-level updraft rotation, suggests a non-zero threat for a tornado along with some potential for occasional strong/gusty winds as convection spreads eastward across eastern OK into western AR and the Ozarks through early Monday morning. The potential for sustained supercells appears limited by a weakness in the flow/hodograph forecast around 700 mb, with the southward-moving cold front also encouraging a more linear/cluster mode with time. Overall, the severe threat with any convection that develops should remain rather isolated, but within a conditionally somewhat favorable environment. ..Gleason/Squitieri.. 12/15/2024 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
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2024-12-15 16:34:30