Day 1 Severe Weather Outlook

Valid 171200Z – 181200Z


A few strong to locally-severe storms will be possible from portions
of northern Florida to eastern North Carolina Tuesday.


Large-scale height falls will spread across the eastern portions of
the US during the day1 period as a pronounced positive-tilt trough
sags southeast to a position from OH – western TN – TX by late
afternoon. As this occurs, a weak surface low should translate
northeast along a cold front across the central Appalachians to off
the southern New England Coast at 18/00z.

Boundary-layer moisture is a bit meager across the warm sector over
the southeastern States late this evening and appreciable
instability will be limited early in the period, likely holding near
the coast prior to frontal passage. Farther south, upper 60s to near
70F surface dew points are expected to spread across northern FL
which should result in a more buoyant environment favorable for
potentially robust updrafts. Even so, low-level shear will weaken
through the period, though high-level flow will be more than
adequate for sustained, potentially rotating updrafts. Convection
should readily develop across low latitudes due to the expected
buoyancy and there is some concern that a few severe thunderstorms
may ultimately materialize along/ahead of the cold front. Will
maintain MRGL Risk across this region but some thought has been
given to higher severe probs where low-level moisture is forecast to
be in place prior to convection. This region will be monitored for
possible higher severe probs in later outlooks.

While stronger shear will be noted across the Carolinas, there is
some concern that instability will ultimately be too weak to justify
higher severe probs. This region, too, will be monitored for
possible SLGT Risk if buoyancy is greater than expected.

..Darrow/Bentley.. 12/17/2019


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