SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0744 AM CDT Thu Nov 04 2021 Valid 041300Z - 051200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are unlikely across the U.S. today. ...Synopsis/Discussion... In a progressive mid/upper-level pattern, broadly cyclonic flow is evident around troughing that extends from eastern Canada across the Upper Great Lakes to deep south TX and northeastern MX. The southwestern portion of that troughing is a basal southern-stream shortwave perturbation quite evident in moisture-channel imagery over northeastern MX and the lower Rio Grande Valley -- convectively augmented by a prior/overnight MCS now located over the extreme western Gulf. The trough should move eastward to the north-central/ west-central Gulf by the end of the period. Assorted small perturbations/vorticity maxima are possible in the downstream southwest flow aloft, from the central Gulf across FL. A wavy surface frontal zone was analyzed at 11Z under and ahead of the trough aloft, from northeastern MX across the northwestern Gulf (south and east of BRO), north-central/northeastern Gulf, central FL, to a low over Atlantic waters southeast of eastern NC. Isolated to scattered thunderstorms are possible episodically and mainly this afternoon south of the front across the southern FL Peninsula, then area-wide overnight on both sides of the boundary. Given the presence of roughly 35-40 kt effective-shear magnitudes in forecast soundings this afternoon over south FL, a few organized multicells are possible, with strong downdraft gusts. At this time, unconditional severe potential appears too isolated and low to warrant a categorical outlook. Elsewhere, a strong shortwave trough is apparent just offshore from the pacific Northwest. This feature should deamplify gradually as it eject east-northeastward to northeastward today, reaching western MT and central ID by 00Z. The trough then should reach eastern MT and southwestern SK by 12Z. Isolated thunder may occur today over parts of the northern Rockies and interior Northwest, associated with frontal and post-frontal/large-scale lift preceding the Pacific perturbation. ..Edwards.. 11/04/2021 Read more LIVE: spc.noaa.gov
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