SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0648 AM CST Wed Nov 06 2024
Valid 061300Z - 071200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN THE LOWER
FLORIDA KEYS...
...SUMMARY...
A couple of brief tornadoes will be possible within outermost
fringes of the circulation of Hurricane Rafael, from late morning
into the evening, across the Keys and the far southwestern Florida
Peninsula.
...Synopsis...
In mid/upper levels, mean troughing will remain over the Rocky
Mountain States as a strong subsynoptic trough -- now evident in
moisture-channel imagery over the Four Corners region -- strengthens
to a closed cyclone. The associate 500-mb low is expected to become
better-developed throughout the period as it closes off and
retrogrades south-southwestward across AZ. In response to these
developments, height rises are forecast across the southern Plains
and Gulf Coast region, while ridging also builds westward from the
Bermuda high. In turn, this should shift Hurricane Rafael westward
toward the central Gulf, following today's crossing of western Cuba,
per NHC forecast.
At the surface, 11Z analysis showed a frontal-wave low over ON north
of Lake Huron, with cold front across Lower MI, IN, western parts of
KY/TN/MS, central LA, and the shelf waters off the TX Gulf Coast.
Under height rises and weakening/largely parallel flow aloft, the
frontal segment south of about I-40 should become quasistationary
through the remainder of the period. Given those factors, weak
midlevel lapse rates, and negligible mid/upper support, associated
thunderstorms should have an unconditional severe potential below 5%
for gusts and less than 2% for tornado, with no large-hail threat.
...FL Keys and vicinity...
Although Rafael will be pivoting more westward away from the region
than previous forecast cycles suggested, and is a relatively small
hurricane, the influence of ambient shear imparts a northeastward
tilt to the overall convective pattern. This will lead to the
passage of peripheral cells and perhaps (over the Lower Keys)
banding features. The track forecast also should result in the
largest low-level shear remaining west and south of EYW, but
still-favorable hodographs passing across the outlook area from this
afternoon into tonight. As such, the outlook lines are shifted
slightly westward, in keeping with NHC track-forecast trends, but
still kept at 5% "slight" levels over the Lower Keys for this cycle.
See latest NHC advisories for forecast track/intensity of Rafael,
and tropical-related watches/warnings.
..Edwards/Mosier.. 11/06/2024
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