SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1246 AM CDT Fri Oct 09 2020 Valid 101200Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL GULF COAST STATES AND FROM NEW YORK INTO NEW ENGLAND... ...SUMMARY... Tropical Cyclone Delta should continue to pose a risk for a couple of tornadoes and strong wind gusts across parts of the central Gulf Coast states on Saturday. Thunderstorms may also impact Upstate New York into portions of New England, posing an isolated risk for damaging wind gusts. ...Southeast... The latest forecast from the National Hurricane Center regarding Delta indicates that the tropical cyclone will continue to move northeastward over the lower MS Valley on Saturday while steadily weakening. Still, strong low-level south-southeasterly flow of 40-50+ kt will likely persist over parts of MS/AL and vicinity to the east of Delta's circulation through the day. Related strong low-level shear and curved hodographs suggest rotating updrafts will be a possibility. However, widespread cloudiness, poor low/mid-level lapse rates, and modest diurnal heating will tend to limit destabilization Saturday afternoon, with MLCAPE around 250-750 J/kg possible. Dry mid-level air is also forecast to overspread parts of the warm sector through the period, which may further temper updraft intensities. Even so, most guidance suggests that an outer rain band will be ongoing Saturday morning from parts of coastal MS/AL northward into central MS. This band of low-topped storms should shift east-northeastward across central/eastern MS into AL and the western FL Panhandle through Saturday evening, while posing a threat for isolated strong straight-line wind gusts and perhaps a couple tornadoes. Have opted to expand the Marginal Risk to include more of southern AL and the western FL Panhandle based on trends in latest guidance. An upgrade to Slight Risk remains possible across some part of the central Gulf Coast states in a later outlook update. However, confidence would need to increase that stronger diurnal heating and related instability will be realized. ...Northeast... An upper trough is forecast to amplify across Quebec, with strong low to mid-level west-southwesterly flow overspreading much of the Northeast by Saturday afternoon. At the surface, a cold front should shift east-southeastward across New England and Upstate NY by early Saturday evening. Limited low-level moisture is forecast to advance northeastward ahead of the cold front, with most guidance suggesting surface dewpoints will reach only into the 50s. MLCAPE may modestly increase to around 250-500 J/kg with diurnal heating and cooling mid-level temperatures with the amplifying upper trough. A broken line of low-topped storms may develop along/ahead of the cold front from parts of western NY to ME, and subsequently move eastward in tandem with the cold front. The forecast combination of weak instability and enhanced low/mid-level winds suggest some potential for isolated strong to damaging winds to reach the surface through boundary-layer mixing and downdraft accelerations. At this point, confidence remains too low regarding the degree of instability to include greater severe wind probabilities. ..Gleason.. 10/09/2020
There’s more click here.