SPC AC 041221 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0721 AM CDT Thu May 04 2023 Valid 041300Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF THE SOUTHERN GREAT PLAINS... ...SUMMARY... Isolated to scattered severe thunderstorms will be possible across the central to southern Great Plains, centered on 2 to 10 PM CDT. In terms of coverage, large hail should be the primary hazard. ...TX/OK/KS... The leading edge of rich western Gulf moisture, consisting of surface dew points of at least 65 F, remains confined south of a DRT-TPL-HOU line as of 12Z. As a lee trough sharpens over the High Plains this moisture will be transported north with a confined plume likely reaching the Red River vicinity of western north TX and southwest OK by early evening. Upper 50s to low 60s dew points will be more common surrounding this plume across most of OK into south KS. A wavy dryline should mix into the western Edwards Plateau through western north TX, and then arc northwest to north across the Panhandles and western KS. The warm-moist sector ahead of it will be increasingly narrow with northern extent owing to the aforementioned low-level moisture transport and lingering effects of a decaying MCS in central to eastern OK. It is possible that convective redevelopment is maintained on the backside of the remnant MCV in parts of OK as it drifts towards the Ozarks. In addition, widespread high clouds within the southern stream will modulate boundary-layer heating to some degree. The largest buoyancy is most likely to develop over south to central TX where MLCAPE should reach 1500-2000 J/kg. This corridor will also be where the strongest mid-level southwesterlies reside at around 50-60 kts, compensating for weak low-level winds and resulting in moderately elongated/nearly straight hodographs. Below-average confidence exists in the evolution of convective development today. Guidance lacks consistency in pre-dryline convective development with waves of low-amplitude lower-level isentropic ascent. Any of this activity will have the potential for large hail given initially steep mid-level lapse rates and adequate cloud-bearing shear. The relatively best conditional environment for large hail should be in the open warm sector from the Edwards Plateau to central TX during the late afternoon to early evening. Farther north, downstream of the dryline/remnant MCS outflow intersection in the western OK/eastern TX Panhandle vicinity, some low-level hodograph curvature will support a large hail and at least a brief tornado risk. But weaknesses in the hodograph aloft and above-normal spread in the degree of effective bulk shear lower confidence in highlighting a more intense supercell threat. ...Interior West... A shortwave trough over southern CA will move north-northeast across the Great Basin through this evening. Downstream, pockets of weak surface-based buoyancy with MLCAPE less than 1000 J/kg will develop this afternoon across lower elevations of ID and far western MT into OR/WA east of the Cascades. While the belt of stronger low to mid-level winds will remain confined over the southern Great Basin, modest enhancement of deep-layer southeasterlies is anticipated. In conjunction with steep lapse rates, the setup should support a threat for marginally severe wind/hail in the most robust storms. Farther south into a portion of the Great Basin, despite scant buoyancy, localized severe wind gusts will be possible where well-mixed thermodynamic profiles can develop and support high-based, low-topped convection. ..Grams/Wendt.. 05/04/2023 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z CURRENT UTC TIME: 1447Z (10:47AM), RELOAD THIS PAGE TO UPDATE THE TI
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