AWUS01 KWNH 090713
FFGMPD
FLZ000-091230-

Mesoscale Precipitation Discussion 1096...Corrected
NWS Weather Prediction Center College Park MD
311 AM EDT Wed Oct 09 2024

Corrected for Summary statement

Areas affected...Southwest Florida....

Concerning...Heavy rainfall...Flash flooding possible

Valid 090700Z - 091230Z

SUMMARY...Potential for coastal training rotating thunderstorms
capable of 2.5"/hr rates and spots of 2-5" possible through
morning.

DISCUSSION...06z surface analysis along with BYX VWP and RADAR
animation shows winds have veered to more southerly and starting
to increase WAA, lifting the stalled boundary across southeast
Gulf/Florida Bay northward.  Upper 70s to lower 80s temp/dewpoints
along the Florida Straits and the strengthening speed convergence
with this warm air advection is allowing for increased instability
advection northward expanding 2500+ J/kg SBCAPE values northward
along the coastal boundary.

SPC MCD and bulk shear values suggest main mode of shallow
rotating thunderstorms along this band.  While mean steering flow
and approaching isallobaric influence would press cell motions
further west, rotation and right movement is generally
counteracting this influence and supporting a generally north or
north-northeast cell motion for these thunderstorms allowing for a
solid potential for training development given upstream moisture
convergence in proximity of the lifting boundary and coastal
frictional convergence may allow for this.

While updrafts are narrow, the rotational flow increases speed and
directional moisture flux into the updrafts allowing for intense
low level moisture loading and therefore intense rainfall
production. Overall moisture of 2.25-2.5", though clearly loaded
in the sfc to 700mb layer will support efficient production with
hourly rates of 2-3"/hr though inner cores will likely drive the
majority of that rain in sub-hourly time frames (15-30 minutes)
further increasing the potential for rapid inundation flooding
across the flat/urban ground conditions.  This is further
compounding potential issues given recent moderate to heavy
rainfall.  NASA SPoRT 0-40cm soil moisture is well above normal at
70-80% capacity and generally above 95th percentile for the time
period.=20

Much of the Hi-Res guidance suite does not place this warm
advective training band ashore, but most have assimilated this
band much further west than current trends would suggestion, with
recent HRRR solutions slowly adjusting to RADAR with the 05z run
getting closest, so far.  So, while the band still may align
along/just offshore with the most intense cores/training axis, the
risk for this training band crossing the urban coastal zones has
increased enough to suggest spots of 2-5", resulting in possible
localized inundation flooding through early morning.

Gallina

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!616dJne68gZ0FK_N9zgLgg56Pwl21KkvT_oB9F_yiRk3kKVe4nDWG2nubPu104knwJLI=
a-9Y3lAxgViYxvDHe-_P0fk$  for graphic product...

ATTN...WFO...MFL...TBW...

ATTN...RFC...SERFC...NWC...

LAT...LON   27488254 27148203 26648165 26078099 25338037=20
            25178105 25848176 26328196 26478225 27108255=20
            27348270=20

=3D =3D =3D
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