Mesoscale Precipitation Discussion 0996
NWS Weather Prediction Center College Park MD
1141 AM EDT Thu Sep 12 2024
Areas affected...central/eastern FL Panhandle
Concerning...Heavy rainfall...Flash flooding possible
Valid 121538Z - 122000Z
SUMMARY...Slow moving and training axes of very heavy rain are
expected to continue to impact the FL Panhandle over the next few
hours with a gradual shift toward the east. Rainfall rates of 2-3
in/hr with highly localized hourly rainfall over 3 inches are
anticipated.
DISCUSSION...1515Z radar imagery showed a SW to NE oriented axis
of heavy rain slowly tracking east toward Apalachicola, FL while a
few cells to the east were observed to be slow moving and/or
training in and north of Apalachee Bay. These bands have had a
history of producing localized observed 4+ in/hr rainfall rates in
Walton County earlier this morning but MRMS estimates have come
down since then into the 2-3 in/hr range due to greater forward
propagation toward the east. At 1515Z, The highest rainfall rates
were estimated via MRMS to be just south of the coast and a
quasi-stationary front where 15Z SPC mesoanalysis data showed
MLCAPE of 1000 to 2000+ J/kg...versus 500 J/kg or less to the
north of the front. These areas of heavy rain were co-located with
low level convergent wind axes which were focused within the 0-1
km AGL layer beneath diffluent flow in the upper levels.
Recent runs of the RAP showed these convergence axes to be
co-located with the ongoing areas of heavy rain on radar, although
the most recent run of the RAP was slow and too weak with low
level wind fields. VAD wind data from KTLH showed 0-1 km winds of
20-30 kt, slightly weaker since 14Z. Nonetheless, a slow eastward
movement to the convergence axis is anticipated with continued
slow movement and training of heavy rain over the next 2-4 hours.
Additional rainfall totals into the FL Panhandle may exceed 4 to 5
inches through 20Z with areas of flash flooding considered likely,
though probably remaining localized.
Otto
ATTN...WFO...JAX...TAE...
ATTN...RFC...SERFC...NWC...
LAT...LON 30728509 30598416 30338320 29948308 29358329
29078378 29168466 29338540 29668554 30158549
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