SWOMCD
SPC MCD 282235
FLZ000-290100-
MESOSCALE DISCUSSION 2275
NWS STORM PREDICTION CENTER NORMAN OK
0535 PM CDT FRI OCT 28 2011
AREAS AFFECTED...SOUTH FL...FL KEYS
CONCERNING...HEAVY RAINFALL
VALID 282235Z - 290100Z
SHOWERS AND THUNDERSTORMS WITH HEAVY RAIN WILL CONTINUE INTO THE
EVENING AND OVERNIGHT HOURS...WITH RAINFALL RATES OF 2 IN/HR
POSSIBLE. THE THREAT FOR SEVERE WEATHER WILL REMAIN MINIMAL.
...HEAVY RAINFALL...
MASSES OF CONVECTION CONTINUE MOVING EWD/NEWD OVER THE SERN GULF OF
MEXICO...POSSIBLY IN ASSOCIATION WITH DOWNSTREAM-SHEARED MID-LEVEL
VORTICITY EMANATING FROM POST-TROPICAL CYCLONE RINA /REFERENCE FINAL
NHC ADVISORY ON RINA FOR FURTHER DETAILS/. LATE AFTERNOON
MESOANALYSIS INDICATES A SFC TROUGH EXTENDING NEWD OF THE ATTENDANT
SFC CIRCULATION TOWARD MAINLAND MONROE COUNTY INTO ERN PALM BEACH
COUNTY. CONVERGENCE ALONG THIS FEATURE...ALONG WITH MID-LEVEL ASCENT
IN ASSOCIATION WITH THE AFOREMENTIONED VORTICITY...AND MLCAPE VALUES
OF 1000-1500 J/KG...WILL FOSTER SCATTERED/NUMEROUS SHOWERS AND
THUNDERSTORMS INTO THE EVENING AND OVERNIGHT HOURS. GPS DATA SUGGEST
AN INFLUX OF ABUNDANT DEEP-LAYER MOISTURE INTO THE REGION...WITH PW
VALUES OF 2.0 TO 2.3 INCHES. THE MAIN HAZARD WITH THIS ACTIVITY WILL
BE HEAVY RAINFALL...WITH RATES OF 2 IN/HR POSSIBLE. WHILE KEY WEST
VWP DATA DEPICT WSWLY FLOW OF 25-35 KT AOA 5 KM AGL YIELDING MODEST
STORM MOTIONS...THIS FLOW IS ORIENTED NEARLY PARALLEL TO THE
AFOREMENTIONED SFC TROUGH TO SUPPORT TRAINING CONVECTION.
FURTHERMORE...SELY TO SLY FLOW OF 10-20 KT BELOW 3 KM AGL WILL
CONTINUE TO TRANSPORT COPIOUS AMOUNTS OF LOW-LEVEL...CARIBBEAN
MOISTURE INTO THE AREA. WARM-CLOUD-LAYER DEPTHS EXCEEDING 4 KM PER
RUC FORECAST SOUNDINGS SUGGEST COLLISION-COALESCENCE PROCESS WILL
FAVOR EFFICIENT RAINFALL RATES...AS WELL.
...SEVERE POTENTIAL...
THE SEVERE WEATHER THREAT IS FORECAST TO REMAIN MINIMAL THROUGH THE
EVENING HOURS. EFFECTIVE SHEAR MAGNITUDES OF 30-35 KT MAY SUPPORT
OCCASIONALLY ORGANIZED STORM STRUCTURES. GUSTY WINDS...A COUPLE OF
BRIEF FUNNEL CLOUDS...AND MARINE WATERSPOUTS CANNOT BE RULED OUT
WITH THE STRONGEST STORMS IN THIS TROPICAL-LIKE ENVIRONMENT.
HOWEVER...WEAK LOW-LEVEL SHEAR COUPLED WITH WEAK LOW/MID-LEVEL LAPSE
RATES WILL GREATLY MINIMIZE THE THREAT FOR SEVERE STORMS. THIS IS
AFFIRMED BY THE ABSENCE OF ANY SUBSTANTIAL LOW-LEVEL ROTATION OR
CONVERGENCE NOTED WITH DISCRETE CONVECTION CROSSING PARTS OF NRN
MIAMI-DADE AND BROWARD COUNTIES.
..COHEN.. 10/28/2011
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...MFL...MLB...KEY...TBW...
LAT...LON 27288034 26677993 25738006 25088033 24568103 24428180
24518205 24698203 24818163 25088136 25348130 25648148
26108185 26848178 27328118 27288034
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