SPC AC 051205 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0705 AM CDT Fri May 05 2023 Valid 051300Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF CENTRAL TX AND THE CENTRAL GREAT PLAINS... ...SUMMARY... Isolated to scattered severe thunderstorms are most likely across a portion of central Texas and in the central Great Plains, centered on 4 to 10 PM CDT. Large hail should be the primary hazard in terms of coverage. ...Central TX vicinity... In the wake of a low-amplitude shortwave impulse over the Lower MS Valley, a low-amplitude mid-level ridge axis should become centered over east TX through central NE at 21Z. Compared to yesterday, full insolation will allow the dryline to mix farther east into central OK, arcing south-southwest to the Edwards Plateau. Above-normal agreement appears within guidance in indicating high-based convection likely forming as surface temperatures approach the mid to upper 90s across the Big Country vicinity. This activity will deepen into at least isolated thunderstorms during the late afternoon as it impinges on large warm-sector buoyancy over central TX. Despite weak low-level flow, 30-40 kt effective bulk shear will support a few slow-moving supercells with mid-level rotation capable of producing very large hail. More prominent MLCIN deeper into the warm sector and especially in time after sunset, along with a lack of synoptic-scale ascent suggests that the spatiotemporal extent of the threat will likely be limited. Thus, large hail should be the primary hazard, but locally damaging severe wind gusts will be possible given the ample CAPE/steep lapse rate environment. ...Central Great Plains... A low-amplitude shortwave impulse embedded within the broader trough across the West should track from the Lower CO Valley to the central High Plains, impinging on a low-amplitude mid-level ridge that should gradually progress east from the High Plains towards IA/MO through early Saturday. This will encourage diurnal sharpening of the lee trough with a cyclone becoming established over eastern CO. This low will track east and weaken across northern KS tonight. Scattered high-based thunderstorms will initially develop along the lee trough across eastern WY into northeast CO during the mid to late afternoon. The most concentrated corridor of sustained thunderstorms into the evening should spread across western to central NE and northwest KS, as activity impinges on the plume of mainly 50s surface dew points over the central Great Plains. Lower-level wind profiles will be weak initially, but some elongation to a nearly straight-line hodograph should favor a few sustained supercells. An increase in low-level southeasterlies is expected during the evening, but this orientation will yield increasing MLCIN spreading northwest from central/eastern KS and modulate the severe threat tonight. As such, large hail should be the main hazard with strong to locally severe wind gusts also possible. ...Lower MS Valley... A convectively aided low-amplitude shortwave impulse has been coincident with an eastward-moving non-severe MCS across MS and southeast LA. The stronger convection has been confined to the far southern portion near the surface warm front. There will be a small temporal window for intensification in a narrow swath before it largely pushes off the central Gulf Coast later this morning. Guidance is insistent that composite outflow/warm front trailing in its wake to the northwest will serve as a focus for regenerative thunderstorm development through early evening along and to the cool side of the boundary, despite the shortwave impulse shifting east and the elevated mixed layer impinging from TX. The first round of this scenario appears to be underway with elevated convection developing near the Ark-La-Tex, which may spread southeast through the day. This type of setup should largely favor a cluster type mode. With weakening low-level winds through the day, the sustenance of embedded supercells is uncertain. A mix of isolated large hail and damaging winds appears plausible, most likely centered on the late afternoon. ..Grams/Kerr.. 05/05/2023 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z CURRENT UTC TIME: 1530Z (11:30AM), RELOAD THIS PAGE TO UPDATE THE TIME
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