SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1128 AM CDT Sun Jul 25 2021 Valid 251630Z - 261200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING IN A CORRIDOR FROM SOUTHEAST NY TO NORTHERN VA AND KY...ACROSS MUCH OF KS AND SD...AND NORTHWEST AZ/EXTREME SOUTHEAST NV/CA... ...SUMMARY... Isolated damaging winds are possible this afternoon/evening from parts of the Northeast to the Ohio Valley, across Kansas and South Dakota, and across northeast Arizona and extreme southeast Nevada/California. ...Northeast to Ohio Valley... The southern fringe of stronger westerly flow aloft extends across much of the OH Valley and Mid-Atlantic states today. A weak surface front extends from west of New York City into VA, then westward into KY. This boundary will be the focus for scattered afternoon thunderstorms. Forcing aloft and low-level convergence is weak along the boundary, suggesting that storms will be relatively isolated in most areas. Low and mid-level wind fields are also weak enough to limit convective organization. Nevertheless, moderate CAPE values, steep low-level lapse rates, and enough steering flow may result in a few strong storms capable of locally gusty/damaging winds. ...KS... A large area of weakening convection over northern KS has surged an outflow boundary southward. A hot/humid low-level air mass will develop today south of the boundary, where isolated afternoon thunderstorms may develop. Steep low-level lapse rates and ample CAPE suggest the potential for gusty/damaging winds in the strongest cells. ...SD/MN... A baroclinic zone will strengthen across SD and southwestern MN this afternoon and evening, with increasing low-level warm advection in the area. This combined with strong daytime heating will lead to scattered thunderstorm development - mainly after 00z. Northwest flow aloft may be sufficient to organize storms and pose a risk of hail or gusty/damaging wind gusts. ...NV/AZ/CA... The corridor of stronger northeasterly mid-level winds associated with a persistent upper low over the Southwest states extends across northwest AZ into southeast CA today. This corridor will see strong heating, and currently has dewpoints in the low/mid 60s. Most CAM guidance shows afternoon thunderstorms developing over the Grand Canyon region and spreading southwestward into the southern tip of NV and southeast CA this evening. If storm clusters can congeal, gusty/damaging winds will be possible with this activity. ..Hart/Wendt.. 07/25/2021 Read more LIVE: spc.noaa.gov
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