Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
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213 ACUS01 KWNS 051952 SWODY1 SPC AC 051951 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0251 PM CDT Sun May 05 2024 Valid 052000Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM SOUTH TEXAS INTO THE MIDDLE TEXAS COASTAL PLAIN... ...SUMMARY... Scattered severe thunderstorms are possible across parts of south-central Texas eastward into parts of southeast Texas, mainly this afternoon and early evening. ...20Z Update... Primary change with this update was to increase severe probabilities across the Arklatex region. ..Arklatex.. Low-level moisture continues to quickly advect northward into the region, with a resulting increase in buoyancy as well. Recent surface analysis places a weak low over far southeast OK, with modest troughing extending southwestward from this low. An effective warm front also extends southeastward from this low, coincident with the leading edge of the better low-level moisture. Interaction of these surface features with the destabilizing airmass could result in thunderstorm development. Vertical shear is strong enough to support organized storm structures, and a few storms may be able to produce hail and/or damaging as well as a brief tornado. ...Elsewhere... Forecast outlined in the previous outlook (appended below) remains valid for South TX, where supercells capable of large to very large hail and damaging gusts are ongoing. These will likely continue for the next few hours while slowly progressing southward. Also, as discussed in the previous outlook and recently issued MD #640, the potential for isolated damaging gust will persist across the Upper OH Valley into the early evening. ..Mosier.. 05/05/2024 .PREV DISCUSSION... /ISSUED 1129 AM CDT Sun May 05 2024/ ...South TX to Mid-South/lower Mississippi Valley... An ongoing linear sub-severe MCS over AR moving north-northeast will likely continue into portions of northeast AR/southeast MO and adjacent parts of KY/TN through mid afternoon. Some additional heating may lead to some invigoration of storms along the leading edge of outflow with a localized strong/severe risk. Farther southwest across south-central into southeast TX, an earlier MCV over western LA and convective overturning from overnight thunderstorm activity has left a remnant outflow boundary draped across southeast TX. South of the boundary, a very moisture-rich airmass (16 g/kg lowest 100mb mean mixing ratios) beneath a residual plume of steep 700-500 mb lapse rates, are contributing to moderate to strong buoyancy. Water-vapor imagery shows a mid- to upper-level impulse moving east over northern Mexico and into south-central TX late this morning. Recent thunderstorm development over south-central TX to the middle TX coast may be in part due to ascent related to this upper feature. Isolated to scattered thunderstorms will probably continue to intensify with severe multicells or supercells with large hail, damaging gusts and at least marginal tornado potential this afternoon. In the absence of notable mid/upper support behind the shortwave trough, convection may diminish rapidly through the evening, as the boundary layer stabilizes from both nocturnal cooling and spreading outflow air. ...Upper Ohio Valley vicinity... As a mid-level trough glances the region to the north over mainly southeast Canada, a surface front will provide a focus for lift and thunderstorm development this afternoon. A plume of richer low-level moisture, characterized by lower 60s deg F surface dewpoints, is located ahead of the cold front and west of a north-south oriented warm front over western PA. Continued heating will result in moderate buoyancy and favor the development of scattered thunderstorms. Modest low to mid-level flow will limit overall storm intensity, but some multicellular organization is possible. Isolated hail/damaging gusts will be the primary hazards with the stronger storms before this activity weakens by early evening. $$