[MCD] SWOMCD

[MCD at goshenarc.org]

ACUS11 KWNS 201843
SWOMCD
SPC MCD 201842 
FLZ000-202045-

MESOSCALE DISCUSSION 2240
NWS STORM PREDICTION CENTER NORMAN OK
0142 PM CDT TUE SEP 20 2005

AREAS AFFECTED...SOUTH FLA/FLA KEYS

CONCERNING...TORNADO WATCH 803...

VALID 201842Z - 202045Z

THREAT FOR ISOLATED TORNADOES WILL GRADUALLY INCREASE THROUGH THE
AFTERNOON HRS...AS NE QUADRANT CONVECTIVE BANDS OF HURRICANE RITA
ROTATE THROUGH SOUTH FLA. THUS A REPLACEMENT WW WILL BE NEEDED BY
21Z /WW 803 EXPIRATION TIME/ FOR ROUGHLY THE SAME AREA AS WW 803.

CONVECTIVE BANDS ON THE NE QUADRANT OF HURRICANE RITA WILL CONTINUE
TO ROTATE WWD INTO SOUTH FLA OVER THE NEXT 6+ HRS. RECENT MODIFIED
VWP DATA FROM MIA INDICATES 150-200 M2/S2 OF 0-1 KM SRH GIVEN
OBSERVED STORM MOTIONS FROM 120 DEG AROUND 40 KTS.
ADDITIONALLY...THE 18Z EYW SOUNDING INDICATED AROUND 50 KTS OF 0-1
KM VECTOR SHEAR. BOTH OF THESE PARAMETERS ARE SUFFICIENT FOR
MODERATE TO STRONG LOW LEVEL ROTATIONAL POTENTIAL WITH THE STRONGEST
STORMS. 18Z EYW SOUNDING INDICATES A NEARLY MOIST-ADIABATIC LAYER
FROM THE SFC TO 700 MB THAT OVERALL UPDRAFT STRENGTH IN THE LOW
LEVELS MAY BE SOMEWHAT LIMITED FOR TORNADO POTENTIAL. HOWEVER
FARTHER NORTH...FROM THE UPPER KEYS NWD TO THE NRN MIAMI METRO
SUBURBS...SLIGHTLY HIGHER INSOLATION AND WARMER TEMPERATURES WILL
SUPPORT STEEPER LOW LEVEL LAPSE RATES/PARCEL ACCELERATION AND HIGHER
PROBABILITY OF ISOLATED TORNADO POTENTIAL.

..CROSBIE.. 09/20/2005

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

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

26838144 24488249 24478058 26807951 

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