MIL-OSI USA: SPC MD 1921

1

Source: US National Oceanic and Atmospheric Administration

Mesoscale Discussion 1921
NWS Storm Prediction Center Norman OK
0712 AM CDT Thu Oct 28 2021

Areas affected…Parts of northern and central Florida

Concerning…Severe potential…Watch possible

Valid 281212Z – 281415Z

Probability of Watch Issuance…60 percent

SUMMARY…Intensifying thunderstorm development may pose increasing
potential to produce tornadoes inland of coastal areas, across much
of northern and central Florida, perhaps as far west as Tallahassee,
by 10 AM to Noon EDT. Trends are being monitored for the
possibility of a watch issuance.

DISCUSSION…To the southeast of a broad, deep occluded lower/mid
tropospheric cyclone centered over the Ozark Plateau vicinity, the
surface cold front is advancing eastward through the Florida
Panhandle. The front is preceded by the weak northern flank of a
more extensive squall line (now extending across the northeast into
south central Gulf of Mexico), which is advancing through Big Bend
vicinity. As the front and convective boundary continue eastward,
beneath difluent and increasingly cyclonic mid/upper flow, latest
model output suggests that the moist warm sector will begin
advancing inland of Gulf coast areas through much of northern into
central Florida by 14-16Z.

It appears that boundary-layer dew points will increase through the
lower 70s and possibly contribute to mixed-layer CAPE in excess of
1000 J/kg, despite the continuing presence of weak lapse rates
associated with warm layer aloft. Boundary-layer warming may also
be inhibited by considerable cloud cover, but clockwise-curved
low-level hodographs are forecast to enlarge beneath southerly 850
mb flow strengthening to 30-40+ kt.

This environment may become increasingly conducive to the inland
development of discrete thunderstorm development, as well as
intensification of thunderstorms along the pre-frontal convective
line, including evolving supercell structures which may pose a risk
for tornadoes and locally strong surface gusts.

..Kerr/Guyer.. 10/28/2021

…Please see www.spc.noaa.gov for graphic product…

ATTN…WFO…MLB…TBW…JAX…TAE…

LAT…LON 29898412 30418390 30108214 29458137 28368273 28888284
29658379 29898412

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