[Tropical] Tropical Cyclone Discussion

EMWIN Server emwin at nashvilleweather.net
Thu Aug 21 09:42:05 CDT 2008


WTNT41 KNHC 211441
TCDAT1
TROPICAL STORM FAY DISCUSSION NUMBER  24
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL062008
1100 AM EDT THU AUG 21 2008

THERE IS BASICALLY NOTHING NEW TO REPORT. FAY HAS BEEN MEANDERING
FOR THE PAST 12 HOURS OR SO WITH LITTLE CHANGE IN INTENSITY. LATEST
MINIMUM PRESSURE REPORTED BY A RECONNAISSANCE PLANE WAS 994 MB AND
FLIGHT LEVEL WINDS SUPPORT AN INITIAL INTENSITY OF 50 KT.
SATELLITE IMAGES SHOW NUMEROUS RAINBANDS AND DEEP CONVECTION
MAINLY TO THE NORTHEAST OF THE CENTER WITH A WELL-DEFINED
UPPER-LEVEL OUTFLOW.  NWS DOPPLER RADAR CLEARLY SHOWS A SPINNING
RING OF CONVECTION WITH DOPPLER VELOCITIES OF UP TO 67 KNOTS AT
APPROXIMATELY 5000 FEET. HOWEVER...FAY DOES NOT HAVE AN INNER
CORE.  ALTHOUGH THE ATMOSPHERIC CONDITIONS ARE QUITE FAVORABLE FOR
STRENGTHENING...THE INTERACTION WITH LAND SHOULD IMPEDE IT. NO
SIGNIFICANT CHANGE IN STRENGTH IS FORECAST BEFORE THE CENTER MOVES
INLAND WITHIN THE NEXT 12 HOURS OR SO. THEREAFTER...FAY SHOULD
BEGIN TO WEAKEN BUT A TRACK FATHER SOUTH THAN INDICATED COULD BRING
THE CENTER OVER THE NORTHEAST GULF OF MEXICO. IN THIS CASE...FAY
SHOULD NOT WEAKEN AS MUCH AS FORECAST...AND DO NOT RULE OUT THE
POSSIBILITY OF SLIGHT STRENGTHENING IF THE CENTER OF FAY REMAINS
OVER WATER LONGER THAN ANTICIPATED.

STEERING CURRENTS HAVE REMAINED VERY LIGHT...CONSEQUENTLY FAY HAS
BARELY MOVED SINCE YESTERDAY. GLOBAL MODELS INSIST ON THE
DEVELOPMENT OF A HIGH PRESSURE SYSTEM NORTH OF FAY. THIS PATTERN
SHOULD FORCE THE CYCLONE TO MOVE SLOWLY TOWARD THE WEST-NORTHWEST
OR WEST...A MOTION WE HAVE BEEN FORECASTING BUT HAS NOT MATERIALIZED
YET. NEVERTHELESS...THE DEVELOPING STEERING PATTERN GIVES ME NO
OPTION BUT TO FORECAST A TURN TO THE LEFT WHICH SHOULD BEGIN SOON.
THIS IS CONSISTENT WITH ALL GLOBAL MODELS AND TRACK GUIDANCE.

REGARDLESS OF ITS EXACT TRACK...FAY WILL BE MOVING RATHER SLOWLY
DURING THE NEXT SEVERAL DAYS...POSING A SIGNIFICANT HEAVY RAINFALL
AND FLOOD HAZARD TO A VERY LARGE AREA.




FORECAST POSITIONS AND MAX WINDS

INITIAL      21/1500Z 29.3N  80.8W    50 KT
 12HR VT     22/0000Z 29.5N  81.6W    50 KT...INLAND
 24HR VT     22/1200Z 29.6N  82.7W    40 KT...INLAND
 36HR VT     23/0000Z 29.8N  84.0W    30 KT...OVER WATER
 48HR VT     23/1200Z 30.0N  85.5W    30 KT...INLAND
 72HR VT     24/1200Z 31.0N  88.0W    25 KT...INLAND
 96HR VT     25/1200Z 31.5N  89.5W    25 KT...INLAND
120HR VT     26/1200Z 32.0N  90.0W    20 KT...REMNANT LOW

$$
FORECASTER AVILA

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