MD 1832 CONCERNING SEVERE POTENTIAL…TORNADO WATCH LIKELY FOR PORTIONS OF THE FL KEYS AND THE SOUTHERN FL PENINSULA
Mesoscale Discussion 1832
NWS Storm Prediction Center Norman OK
0524 AM CDT Tue Sep 27 2022
Areas affected...Portions of the FL Keys and the southern FL
Peninsula
Concerning...Severe potential...Tornado Watch likely
Valid 271024Z - 271300Z
Probability of Watch Issuance...80 percent
SUMMARY...The threat for a few tornadoes will gradually increase
this morning in association with Hurricane Ian. A Tornado Watch will
likely be issued before 13Z (9 AM EDT) for the Florida Keys and much
of south Florida.
DISCUSSION...Recent radar and satellite imagery show the core of
Hurricane Ian moving northward across western Cuba. Transport of
very rich low-level moisture, with mid to upper 70s surface
dewpoints noted across the Keys into parts of south FL, will
continue through the morning hours. Modifying the 06Z observed
soundings from KEY/MFL for current conditions shows a weakly
unstable airmass present, with latest mesoanalysis estimating MLCAPE
generally ranging from 500-1000 J/kg across this area. Surface-based
convection will be possible wherever even modest daytime heating can
occur later this morning given the very moist low-level airmass.
Radar reflectivity/velocity trends from KBYX/KAMX over the past few
hours have shown low-topped cells over the FL Straits occasionally
approaching the Keys. Some of this activity had modest low-level
rotation. VWPs from KBYX show the low/mid-level east-southeasterly
flow has gradually strengthened this morning as Hurricane Ian
approaches. A corresponding increase in the low-level hodograph and
effective SRH has also occurred, especially with any cells that
maintain a more northward motion compared to northwestward. With
further strengthening of the low-level wind field expected this
morning, current expectations are for the tornado threat to
gradually become greater with any low-topped supercells that can
develop and be sustained in Ian's outer rain bands. Accordingly, a
Tornado Watch will likely be needed for the FL Keys and much of
south FL before 13Z (9 AM EDT).
..Gleason/Guyer.. 09/27/2022
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MFL...KEY...
LAT...LON 24608221 24908158 25658168 26108184 26488147 26608093
26568039 26478002 25678010 25288021 24728074 24498152
24448199 24488223 24608221
