SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Sat Oct 10 2020 Valid 101630Z - 111200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO THIS EVENING FOR PARTS OF AL/WESTERN GA/FL PANHANDLE...AS WELL AS UPSTATE NY INTO NORTHERN NEW ENGLAND... ...SUMMARY... A few tornadoes are possible into this evening across parts of Alabama, western Georgia, and the Florida Panhandle. Damaging thunderstorm winds are possible across parts of northern New York and northern New England from mid afternoon into this evening. ...AL/FL Panhandle/western GA through late evening... The weakening remnants of tropical cyclone Delta will move generally eastward across northern MS today to northern AL tonight. The system has a more baroclinic structure now with a warm front extending eastward from roughly Birmingham to Atlanta, and the primary surface trough near the MS/AL border. Most of the convection is focused in a north-south band across central/southern AL and the western FL Panhandle in the zone of strongest low-level confluence/convergence. Expect the main threat for embedded rotating storms to be focused within this band this afternoon as the stronger forcing for ascent spreads northeastward, and along the warm front as more isolated storms form in response to daytime heating in cloud breaks. The combination of boundary-layer dewpoints in the low-mid 70s, weak buoyancy (MLCAPE of 500-1000 J/kg), and sufficiently strong flow/shear east of the center of Delta will support a threat for occasional supercells and tornadoes this afternoon through late evening. ...Upstate NY into northern New England this afternoon/evening... A midlevel shortwave trough over the upper Great Lakes and ON will progress eastward over upstate NY and northern New England this afternoon through early tonight. The midlevel trough will be accompanied by a surface cold front, with a narrow corridor of low-level moistening and modest destabilization expected along and just ahead of the front. Though boundary-layer dewpoints will remain in the 50s, daytime heating and midlevel lapse rates of 7-8 C/km will support MLCAPE of 500-1000 J/kg. Deep-layer vertical shear will increase in this same corridor this afternoon, with effective bulk shear increasing to 50-60 kt with 50 kt flow within 1-2 km of the ground. Scattered thunderstorm development is expected along and just ahead of the front by mid afternoon across upstate NY, and storms will subsequently spread eastward across northern New England through this evening. Storms will consist of a mix of supercells and line segments, with the primary threat for damaging winds. ..Thompson/Bentley.. 10/10/2020
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