SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook CORR 1 NWS Storm Prediction Center Norman OK 0322 PM CDT Wed Nov 03 2021 Valid 032000Z - 041200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE THIS AFTERNOON AND EVENING ACROSS PARTS OF SOUTHERN TEXAS... CORRECTED UPDATE TIME ...SUMMARY... Strong thunderstorms may impact parts of the lower Rio Grande Valley and adjacent portions of Deep South Texas late this afternoon into tonight, accompanied by at least some risk for severe hail and wind. ...20Z Outlook Update... In the presence of modestly steep lower/mid tropospheric lapse rates, daytime heating within a moistening boundary-layer appears to be contributing to moderately large mixed-layer CAPE (up to around 1500 J/kg) to the south of a front advancing southward into middle Texas coastal areas and Deep South Texas. This is occurring as one short wave impulse, within digging larger-scale mid-level troughing, slowly approaches the lower Rio Grande Valley. The front might provide one focus for intensifying thunderstorm development late this afternoon and evening, while additional thunderstorms form and propagate southeastward off the higher terrain to the west of the Rio Grande River. Given the available instability, and increasing forcing for ascent with the approaching short wave, there appears potential for considerable upscale convective growth across the lower Rio Grande Valley and adjacent portions of Deep South Texas through mid/late evening. Although low-level wind fields are weak, and deep-layer shear may remain fairly modest at best, it is possible that the overall environment this evening may gradually become conducive to organizing convection with the potential to produce strong wind gusts, particularly near and south of the Rio Grande River. Otherwise, profiles may be marginally conducive to a risk for severe hail in initially stronger storm development late this afternoon and evening. ..Kerr.. 11/03/2021 .PREV DISCUSSION... /ISSUED 1057 AM CDT Wed Nov 03 2021/ ...TX/LA... Morning water vapor loop shows a broad upper trough over the eastern US, with a shortwave trough digging southeastward across NM into TX. Lift ahead of this feature has been resulting in rather widespread showers and scattered thunderstorms over much of central and east TX. This activity is along and north of a southward moving cold front. The air mass ahead of the front is relatively moist and unstable, with a corridor of moderate afternoon CAPE values expected from the Houston area southwestward into south TX. Morning CAM solutions indicate that scattered elevated convection will remain atop the stable post-frontal air. However, one or two solutions do show the possibility of a strong storm forming along the front later today. If this can occur, gusty winds and hail would be possible. However, given the considerable uncertainty of this outcome, will maintain less-than-5% severe probabilities in the forecast. Elsewhere, isolated thunderstorms are possible over parts of FL this afternoon, and along the OR coast this evening and tonight. No severe storms are anticipated with this activity. Read more LIVE: spc.noaa.gov
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