Mesoscale Discussion 0656
NWS Storm Prediction Center Norman OK
1139 AM CDT Thu May 21 2020
Areas affected...portions of the central and southern FL Peninsula
Concerning...Severe potential...Watch unlikely
Valid 211639Z - 211845Z
Probability of Watch Issuance...5 percent
SUMMARY...A couple of strong storms could briefly become severe this
afternoon across the central and southern Florida peninsula.
Sporadic hail and strong gusts are possible with the most intense
cells, however the overall threat will remain limited and a watch is
not expected.
DISCUSSION...Isolated thunderstorms are developing early this
afternoon in low level convergence as the seabreeze develops across
the southern FL Peninsula. A very moist airmass is in place, with
surface dewpoints generally from 70-75 F and PW values greater than
1.5 inches. Strong heating has resulted in temperatures warming into
the upper 80s to low 90s beneath steep midlevel lapse rates (7-7.5
C/km), leading to MLCAPE values greater than 2000 J/kg. 12z regional
RAOBS and a recent 15z RAOB from XMR show very weak vertical winds,
with effective shear values generally less than 15-20 kt. This is
not expected to change throughout the day. As a result, convection
will generally be disorganized, and intense updrafts short-lived.
Nevertheless, strong instability and moderate lapse rates could
result in a few instances of marginally severe hail. Furthermore,
steep low level lapse rates in this very moist low level environment
could lead to a couple of strong, locally damaging gusts. Overall,
convection will be pulse-like in nature and threat is expected to
remain limited.
..Leitman/Hart.. 05/21/2020
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MFL...MLB...TBW...
LAT...LON 28798120 28508085 28238072 28028065 26748017 25978028
25888040 25758062 25738077 25778098 26058127 26358147
26688169 27558183 27758183 28268168 28548157 28728147
28788135 28798120
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