Day 4-8 Outlook

Day 4-8 Convective Outlook  
NWS Storm Prediction Center Norman OK
0300 AM CST Thu Nov 26 2020

Valid 291200Z - 041200Z

...DISCUSSION...
It appears increasingly probable that a closed upper low over the
southern Plains will merge with a northern-stream upper trough over
the eastern CONUS on Day 4/Sunday, likely forming a highly amplified
upper trough/low by Day 5/Monday. Medium-range guidance is in
reasonably good agreement in depicting a deepening surface low
developing from coastal LA Sunday morning northeastward to the
Mid-Atlantic vicinity by Day 5/Monday.

As greater low-level Gulf moisture advances inland across parts of
the Southeast and Mid-Atlantic in tandem with the deepening surface
low, weak instability may develop across the warm sector of this
cyclone. Rapidly strengthening low and mid-level wind fields suggest
that organized severe storms capable of producing at least isolated
damaging winds may occur over parts of the Deep South into the
Carolinas on Day 4/Sunday, and from the Carolinas into eastern
portions of the Mid-Atlantic on Day 5/Monday.

At this point, it remains very uncertain how much surface-based
instability will ultimately develop across these regions, which will
have a large impact on overall severe potential. This uncertainty
precludes the introduction of 15% severe probabilities for now.
However, the severe potential for this system will be reevaluated in
later outlook updates. Once the cold front associated with this
cyclone clears the East Coast, severe thunderstorm potential appears
minimal across the CONUS on Day 6/Tuesday and Day 7/Wednesday.

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