[Tropical] Tropical Cyclone Discussion

EMWIN Server emwin at nashvilleweather.net
Wed Aug 3 21:33:12 CDT 2005


WTNT43 KNHC 040232
TCDAT3
TROPICAL STORM HARVEY DISCUSSION NUMBER   7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT WED AUG 03 2005

SATELLITE PRESENTATION HAS NOT IMPROVED DURING THE PAST FEW
HOURS...IN FACT...WITH LITTLE CONVECTION IT LOOKS LIKE A SKELETON.
DVORAK T-NUMBERS SUGGEST THAT MAXIMUM WINDS ARE ONLY BETWEEN 35 AND
45 KNOTS. THIS SYSTEM DOES NOT HAVE THE TYPICAL PATTERN OF A
TROPICAL CYCLONE...BUT DESPITE SUCH POOR SATELLITE PRESENTATION...
RECON MEASURED 62 KNOTS AT FLIGHT LEVEL AND A MINIMUM PRESSURE OF
998 MB EARLIER TODAY.  THE INITIAL INTENSITY IS THEN KEPT AT 50
KNOTS UNTIL THE NEXT PLANE REACHES THE AREA EARLY THURSDAY. THERE
IS A SMALL WINDOW OF OPPORTUNITY DURING THE NEXT 12 TO 24 HOURS FOR
HARVEY TO STRENGTHEN A LITTLE SINCE SHEAR IS NOT NORMALLY A
DETRIMENT TO NON-PURE TROPICAL CYCLONES LIKE HARVEY. THE CHANCES OF
BECOMING A HURRICANE BEFORE PASSING NEAR OR OVER BERMUDA ARE VERY
SMALL.  AS A PRECAUTION...THE HURRICANE WATCH IS KEPT FOR
BERMUDA...TAKING INTO CONSIDERATION HISTORICAL ERRORS IN INTENSITY
FORECASTS. HARVEY SHOULD BEGIN TO WEAKEN IN 36 HOURS OR SO.

HARVEY IS MOVING TOWARD THE EAST-NORTHEAST ABOUT 11 KNOTS. THE
CYCLONE IS EMBEDDED WITHIN THE GENERAL WESTERLY FLOW WHICH IS
FORECAST TO PERSIST...BUT THE STEERING WILL LIKELY VARY IN SPEED AS
SHORTWAVES MOVE BY THE AREA. HARVEY IS FORECAST TO SLOW DOWN AGAIN
AS SOON AS THE FIRST SHORTWAVE MOVES OUT OF THE AREA IN A DAY OR
SO. THEN...ANOTHER APPROACHING SHORTWAVE WILL ACCELERATE THE
WESTERLY FLOW AND HARVEY WILL INCREASE ITS FORWARD SPEED IN ABOUT 3
DAYS. THE OFFICIAL FORECAST IS VERY CLOSE TO THE MODEL CONSENSUS.

NOTE: A QUIKSCAT PASS OVER HARVEY...JUST RECEIVED...SUGGESTS THAT
WINDS MAY BE A LITTLE LESS THAN CURRENTLY INDICATED. WE WOULD
RATHER WAIT FOR THE RECONNAISSANCE PLANE BEFORE WE LOWER THE
INTENSITY...IF NECESSARY.

FORECASTER AVILA/BERG

FORECAST POSITIONS AND MAX WINDS

INITIAL      04/0300Z 31.5N  65.8W    50 KT
 12HR VT     04/1200Z 32.1N  64.1W    55 KT
 24HR VT     05/0000Z 32.8N  62.0W    55 KT
 36HR VT     05/1200Z 33.0N  60.0W    50 KT
 48HR VT     06/0000Z 33.5N  58.5W    45 KT
 72HR VT     07/0000Z 35.0N  55.5W    40 KT
 96HR VT     08/0000Z 38.0N  51.0W    35 KT
120HR VT     09/0000Z 41.0N  45.0W    30 KT


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