Monday, October 31, 2011

MESO: Mesoscale Discussion 2281

ACUS11 KWNS 310435
SWOMCD
SPC MCD 310435
FLZ000-310630-

MESOSCALE DISCUSSION 2281
NWS STORM PREDICTION CENTER NORMAN OK
1135 PM CDT SUN OCT 30 2011

AREAS AFFECTED...PARTS OF THE SERN FL PENINSULA...INCLUDING THE
MIAMI AREA

CONCERNING...HEAVY RAINFALL

VALID 310435Z - 310630Z

RAINFALL RATES OF 2-4 IN/HR WILL BE POSSIBLE FROM CONVECTION OVER
PARTS OF THE SERN FL PENINSULA INTO THE OVERNIGHT HOURS. THE
GREATEST THREAT WILL OCCUR OVER PARTS OF THE MIAMI
AREA...PARTICULARLY FROM CORAL GABLES AND COCONUT GROVE TOWARD
DOWNTOWN MIAMI AND MIAMI BEACH...AS WELL AS KEY BISCAYNE.

TERMINAL DOPPLER RADAR FROM MIAMI INDICATES A VERY
PERSISTENT...10-15-MILE-WIDE AREA OF CONVECTION OVER BISCAYNE BAY
NEAR CORAL GABLES AND COCONUT GROVE. THE BULK OF THIS CONVECTION HAS
MOVED LITTLE DURING THE PAST SEVERAL HOURS...WITH ONLY A SLIGHT EWD
NUDGE AFTER HAVING DEVELOPED A BROAD MID-LEVEL STORM-SCALE
CIRCULATION /FURTHER SUSTAINING CONVECTION/. SFC MESOANALYSIS AT 04Z
INDICATES THAT THIS CONVECTION REMAINS ANCHORED TO A
QUASI-STATIONARY BAROCLINIC ZONE ORIENTED WSW-ENE ACROSS THE SRN FL
PENINSULA. PER MIAMI 00Z RAOB...ELY INFLOW OF 20-25 KT WITHIN THE
925-850-MB LAYER OPPOSING THE WLY COMPONENT OF FLOW DEEPER IN THE
CLOUD-BEARING LAYER IS CURRENTLY LIMITING STORM MOTION.
HOWEVER...NAM/RUC FORECAST SOUNDINGS SUGGEST THAT THE 925-850-MB
FLOW WILL GRADUALLY VEER TOWARD THE SE/S DURING THE NEXT SEVERAL
HOURS...ALLOWING THE CONVECTION TO CONTINUE TO SLOWLY TRANSLATE
TOWARD PARTS OF DOWNTOWN MIAMI...MIAMI BEACH...AND KEY BISCAYNE.
WITH THE 00Z MIAMI RAOB INDICATING A NEARLY 4.5-KM DEEP WARM-CLOUD
LAYER...COLLISION-COALESCENCE PROCESSES WITHIN ABUNDANT DEEP-LAYER
MOISTURE /PW VALUES AOA 2 INCHES PER GPS DATA/ WILL SUPPORT HEAVY
RAINFALL RATES OF 2-4 IN/HR. FARTHER NORTH INTO BROWARD
COUNTY...HEAVY RAINFALL WITH RATES TO 2 IN/HR WILL BE POSSIBLE WITH
CONVECTION NEAR WESTON AND FORT LAUDERDALE. HOWEVER...THE LACK OF
CONVECTIVE ORGANIZATION AND STRONGER MID-LEVEL FLOW YIELDING FASTER
STORM MOTIONS WILL LIMIT THE HEAVY RAIN THREAT. WHILE CONVECTION MAY
OCCASIONALLY EXHIBIT MID-LEVEL CIRCULATIONS...WEAK LOW/MID-LEVEL
LAPSE RATES AND WEAK LOW-LEVEL SHEAR WILL GREATLY MITIGATE THE SVR
POTENTIAL.

..COHEN.. 10/31/2011

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

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

LAT...LON 25518015 25598033 25898041 26018060 26228054 26258027
26168006 25648003 25518015

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