SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1241 AM CDT Wed Oct 07 2020 Valid 071200Z - 081200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM NEW YORK TO NEW ENGLAND... ...SUMMARY... Gusty winds are possible with thunderstorms later today from New York into New England. ...NY to New England... Strong mid-level short-wave trough is currently digging southeast across the Great Lakes. This feature is forecast to progress into NY early in the period before ejecting off the New England coast by 08/00z. Latest model guidance suggests 120-150m mid-level height falls and pronounced high-level difluence will spread across the northeastern US during daylight hours. This strongly-forced system will encourage scattered low-topped convection along/ahead of a cold front as it surges across NY during the late morning hours. While boundary-layer moisture is not forecast to be that significant, and overall moisture is somewhat meager, steep low-level lapse rates and cooling profiles strongly favor surface-based convection, especially along the front where convergence will be maximized. Latest CAMs support this scenario with a band of weak elevated convection expected to spread ahead of the front early, then isolated-scattered convection developing ahead of the front where partial sunshine and surface thermals will be maximized. Given the increasing westerly flow in the cloud-bearing layer, there is some concern for stronger winds mixing to the surface; however, weak buoyancy could limit this mixing. Will maintain 5 percent severe probabilities for gusty winds primarily due to buoyancy/updraft concerns. If it becomes more clear that robust convection will be more concentrated then severe probabilities may be adjusted accordingly. Severe threat should spread across New England during the afternoon and off the Atlantic Coast by early evening. ..Darrow/Squitieri.. 10/07/2020
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