SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0200 AM CST Tue Nov 16 2021 Valid 181200Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast across the contiguous United States on Thursday. ...Synopsis and Discussion... Isolated thunderstorms may be ongoing at the start of the period Thursday morning along/near a cold front across parts of Deep South TX and coastal LA/MS. This front is expected to continue advancing southward over the Gulf of Mexico through the day, which should quickly end thunderstorm chances across both areas. Farther north, a large-scale upper trough/low should move from Ontario into Quebec through the period, while the southern portion of the trough develops eastward from the Great Lakes/OH Valley across the Mid-Atlantic and Northeast. The primary surface low will remain displaced well to the north of these regions in Canada. A cold front arcing southward from this low is expected to sweep eastward across much of the eastern CONUS through the day, and north FL Thursday night. Boundary-layer moisture will probably remain rather modest ahead of the front along most of the East Coast, as a prior frontal passage should limit potential for more robust return flow from either the Gulf of Mexico or tropical Atlantic. This should hamper the development of sufficient instability to support thunderstorms along much of the front on Thursday, with the possible exception of coastal NC/SC where convection may develop late. Still, there will be strong flow at low/mid levels associated with the upper trough that will overspread much of the Mid-Atlantic. If even a small amount of boundary-layer instability can be realized, then strong/gusty winds could occur with low-topped convection along the front. At this point, latest guidance continues to suggest that instability will remain too meager to support storms, with the previously mentioned exception in coastal NC/SC. Otherwise, thunderstorms will be possible Thursday across much of central/south FL, where greater low-level moisture will reside. Poor mid-level lapse rates and the lack of stronger flow below 500 mb should greatly limit the severe threat across this area. ..Gleason.. 11/16/2021 Read more LIVE: spc.noaa.gov
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