SPC 2000Z Day 1 Outlook

Day 1 Outlook Image

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0138 PM CST Sun Jan 31 2021

Valid 312000Z - 011200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS SOUTH
GEORGIA INTO NORTH AND WEST FLORIDA THIS EVENING THROUGH TONIGHT...

...SUMMARY...
A brief tornado and locally damaging winds are possible this evening
into tonight across parts of south Georgia into north and west
Florida.

...20z Update - FL/GA...

The previous forecast remains on track and no changes have been made
with this update. Low-to-mid 60s surface dewpoints have spread
northeast across northwest FL into southern GA this afternoon. This
is aiding in weak destabilization ahead of deeper convection now
developing along the front from southwest GA into southeast AL. This
activity is expected to slowly increase toward evening as the front
approaches the Marginal risk area. Short-term CAMs and forecast
soundings continue to indicate and environment capable of supporting
low-end supercells, an a couple of strong-to-severe storms are still
expected. For more details, see previous outlook below.

..Leitman.. 01/31/2021

.PREV DISCUSSION... /ISSUED 1015 AM CST Sun Jan 31 2021/

...FL/GA...
A shortwave trough centered over the Midwest will amplify on
approach to the central and southern Appalachians as a mid-level
speed max over the south-central states ejects through the basal
portion of the trough across the Southeast. In response, an initial
surface cyclone will slowly decay across the OH Valley while
secondary cyclogenesis occurs across the Southeast and more
prominently off the NC/VA coast towards 12Z Monday. A cold front
will move southeast and reach southwest GA to the eastern FL
Panhandle by 00Z before progressing off most of the South Atlantic
coast and north/central FL tonight. 

Low-level moisture return will likely remain characterized by 62-64
F surface dew points across the north-central to northeast Gulf
coast regions. More pronounced boundary-layer heating is expected to
be confined east of the moisture plume across north and central FL.
The net result will be the presence of weak buoyancy given
relatively poor mid-level lapse rates. By this evening, modest
cooling aloft and strengthening convergence near the front should
support isolated thunderstorms from the FL Big Bend into south GA.
The combination of adequately enlarged low-level hodographs (amid
strong southwesterly deep-layer shear) and the limited buoyancy may
be sufficient for a couple lower-end supercells as convection
increases in coverage across north FL to the west coast of the
peninsula. Strengthening 700-mb winds may also foster a short-line
segment or two with a risk for locally damaging winds from strong
gusts along the northern periphery of scant surface-based buoyancy
into south GA. While it is plausible that severe storms may not
develop at all, enough signal exists to warrant a cat 1/MRGL risk
delineation.

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