MESO: Mesoscale Discussion 0864

ACUS11 KWNS 221710
SWOMCD
SPC MCD 221710
FLZ000-221915-

MESOSCALE DISCUSSION 0864
NWS STORM PREDICTION CENTER NORMAN OK
1210 PM CDT TUE MAY 22 2012

AREAS AFFECTED...S THROUGH PARTS OF EAST CENTRAL FL

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 221710Z - 221915Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...ISOLATED STRONG WIND GUSTS AND/OR MARGINALLY SEVERE HAIL
WILL BE POSSIBLE THROUGH THE AFTERNOON ACROSS S THROUGH EAST CENTRAL
FL. IN ADDITION...PW VALUES AROUND 1.8 INCH AND HIGHER FREEZING
LEVELS RESULTING IN WARM CLOUD PROCESSES WILL SUPPORT HEAVY RAINFALL
RATES UP TO 1.5-2 INCH PER HOUR...ESPECIALLY WITH SUSTAINED
ACTIVITY.

DISCUSSION...AT 1645Z...REGIONAL RADAR IMAGERY SHOWED SHOWERS AND A
FEW TSTMS HAVE ALREADY DEVELOPED ACROSS S FL...PRIMARILY INVOF TWO
E-W ZONES OF LOW LEVEL CONVERGENCE...AND THE INTERSECTIONS OF THESE
BOUNDARIES WITH SEA/LAKE BREEZE BOUNDARIES PER VISIBLE SATELLITE
IMAGERY. SURFACE ANALYSES INDICATED ONE OF THE E-W BOUNDARIES WAS
LOCATED S OF LAKE OKEECHOBEE FROM SRN PALM BEACH COUNTY THROUGH
CENTRAL COLLIER COUNTY...WHILE THE SECOND ONE WAS OVER FAR S FL.
DESPITE WEAK MIDLEVEL LAPSE RATES PER THE 12Z MIA SOUNDING...SURFACE
HEATING WITHIN A MOIST ENVIRONMENT WILL MAINTAIN MODERATE
INSTABILITY. HOWEVER...THESE WEAK MIDLEVEL LAPSE RATES SUGGEST
VERTICAL PARCEL ACCELERATIONS WILL TEND TO BE WEAKER AND THUS LIMIT
UPDRAFT STRENGTH/DURATION.

MIA WSR-88D VWP DATA SHOWED WEAK VERTICALLY VEERING WINDS IN THE
LOWEST 2-3 KM AGL...BUT STRONGER SWLY MIDLEVEL WINDS ATOP SELY LOW
LEVEL WINDS WILL SUPPORT EFFECTIVE BULK SHEAR OF 25-35 KT THROUGH
THE AFTERNOON. THIS WILL AID IN SOME ORGANIZATION WITH THE
POTENTIAL FOR ISOLATED STRONGER WIND GUSTS AS THE PRIMARY THREAT.

..PETERS/WEISS.. 05/22/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

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

LAT...LON 25988200 26358126 26968120 27508083 27488031 26768012
25918012 25308040 25218082 25258115 25628119 25878145
25878176 25988200

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