SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0758 AM CDT Sat Oct 10 2020 Valid 101300Z - 111200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE DEEP SOUTH AND NORTHEAST/NEW ENGLAND... ...SUMMARY... A few tornadoes are possible today into this evening across the Deep South including parts of Alabama, Georgia, and Florida Panhandle. Severe thunderstorms are also expected across parts of northern New York and northern New England. ...Deep South including Alabama/Georgia/Florida Panhandle... Tropical Cyclone Delta, which is centered over far west-central Mississippi around sunrise, will continue northeastward. Although the remnant circulation/low will tend to weaken, low-level winds on its eastern periphery will remain strong (40-55 kt), with the strongest core of south-southwesterly winds in the lowest 2-3 km AGL expected to transition east-northeastward across Alabama/Florida today, and toward Georgia and the nearby southern Appalachians by evening. Transient low-topped (including an absence of lightning flashes) low-level mesocyclones have been noted through the early morning hours within a zone of confluence across southwest Alabama and the western Florida Panhandle. Potentially aided by cloud breaks and the periphery of the eastward-advancing mid-level dry slot, a diurnal destabilization trend this morning into afternoon may modestly boost low-level parcel accelerations and updraft intensity (albeit still low-topped). Diurnal destabilization aside, a general northeastward flux of low-level moisture will coincide with the entrance region of the low-level jet, which should allow for a net east-northeastward transition of the tornado threat today across additional parts of Alabama toward western Georgia. ...Northeast/New England... An upper-level trough centered near the border vicinity of northern Ontario/northern Quebec early today will steadily amplify and progress eastward today toward northern New England. While surface dewpoints are only in the 40s F early today, a steady influx of modest moisture is expected into the region ahead of an east/southeastward-advancing cold front. Given the kinematic scenario, low-level moisture/buoyancy should be adequate for the development of stronger convection this afternoon. This should initially occur over northern portions of New York into northern Vermont/New Hampshire, while additional low-topped thunderstorms may develop across/move out of eastern Quebec into Maine a bit later this afternoon through early/mid evening. Very strong deep-layer west-southwesterly winds will support fast eastward-moving bands of storms capable of wind damage and possibly some line-embedded tornado risk. ...Western Washington... A locally severe storm, including the potential for convectively enhanced wind gusts, cannot be entirely ruled out early today in general association with an eastward-moving/inland-spreading shortwave trough and associated front. However, very limited buoyancy, as sampled by the 12Z observed KUIL/Quillayute sounding, suggests that any such severe potential should remain limited. ..Guyer/Goss.. 10/10/2020
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