SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1125 AM CST Wed Jan 11 2023
Valid 121200Z - 131200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE OHIO
VALLEY SOUTHWARD ACROSS THE MID SOUTH AND PARTS OF THE SOUTHEAST...
...SUMMARY...
Isolated to scattered severe thunderstorms appear possible Thursday
across parts of the Tennessee/Ohio Valleys, and the Southeast.
Damaging winds should be the main threat, but a brief tornado or two
may also occur.
...Synopsis...
A strengthening upper trough is forecast to move eastward across the
eastern half of the U.S. Thursday. By the end of the period, a
highly amplified flow field aloft will prevail over the U.S., with a
Pacific trough approaching the West Coast, a ridge across the
Intermountain West and Canadian Rockies, and a trough over the East.
At the surface, a low initially progged to reside near the
confluence of the Ohio and Mississippi Rivers will deepen steadily
as it shifts northeastward, reaching the Pennsylvania/New York
vicinity late. South of the low, a trailing cold front will cross
the Mid South and central Gulf Coast states through the day,
reaching the Appalachians during the evening. Overnight, the front
will continue making steady eastward progress, likely reaching the
Atlantic Coast near the end of the period.
...Ohio and Tennessee Valleys into the Southeast...
Showers and scattered thunderstorms should be ongoing at the start
of the period, ahead of the advancing cold front, from the middle
Mississippi/lower Ohio Valleys southward into the central Gulf Coast
states. While instability should remain limited overall, due to
return of an incompletely modified Gulf boundary layer and
substantial cloud cover, storms should nonetheless increase
gradually in coverage through the day as a subtle increase in
warm-sector CAPE occurs.
Given antecedent stability, and a low-level capping inversion,
ascent near the front will likely be required to eliminate the
inversion and permit storm development -- which suggests largely
linear storm mode. Still, with deep-layer flow veering modestly and
speed increasing substantially with height, organized updrafts along
with locally rotating elements within the line are expected.
Damaging winds will likely be the primary risk, likely peaking
through the afternoon and then very gradually diminishing during the
evening -- in part due to a less favorable thermodynamic environment
expected to persist east of the southern Appalachians. A couple of
tornadoes will also be possible, across a broad area -- mainly of
the brief variety within the linear band of convection.
Severe risk will likely decrease more substantially overnight, as
frontal convection nears -- and eventually clears -- the Atlantic
coast. Convection lingering across Florida as the front slides
southward across the Peninsula overnight should remain sub-severe.
..Goss.. 01/11/2023
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