[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 072036
TCDAT4
TROPICAL STORM IRENE DISCUSSION NUMBER  13
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT SUN AUG 07 2005

THE DEEP CONVECTION THAT WAS NEAR THE CENTER OF IRENE THIS MORNING
HAS DISSIPATED OR BEEN LEFT BEHIND BY WESTERLY SHEAR.  THE INITIAL
INTENSITY WILL BE HELD AT 35 KT FOR NOW...BUT IF CONVECTION DOES
NOT RETURN THE CIRCULATION WILL GRADUALLY SPIN DOWN.  FOR THE NEXT
DAY OR TWO IRENE WILL BE MOVING THROUGH AN ENVIRONMENT
CHARACTERIZED BY DRY AIR AND NORTHWESTERLY SHEAR.  THE CYCLONE MAY
WELL NOT SURVIVE THIS TRIP BUT IF IT DOES...GLOBAL MODELS INDICATE
THAT A MORE FAVORABLE UPPER PATTERN MAY EXIST AFTER 48 HOURS.
WATER TEMPERATURES WILL ALSO BE GRADUALLY INCREASING ALONG THE PATH
OF IRENE SO THE OFFICIAL FORECAST STILL SHOWS SOME STRENGTHENING
LATE IN THE FORECAST PERIOD.  THIS INTENSITY FORECAST IS A LITTLE
BELOW THE SHIPS GUIDANCE.  THE GFDL MODEL DISSIPATES IRENE WITHIN
48 HOURS.

THE INITIAL MOTION IS 300/9...AND THERE HAS BEEN NO SIGNIFICANT
CHANGE TO THE TRACK FORECAST REASONING. A MID-LEVEL HIGH PRESSURE
RIDGE CURRENTLY LIES TO THE NORTHWEST OF IRENE. WITH THE EXCEPTION
OF THE CANADIAN MODEL...GUIDANCE AGREES THAT THIS RIDGE WILL MOVE
WESTWARD AND WEAKEN OVER THE NEXT 5 DAYS. IRENE IS EXPECTED TO
CONTINUE A GENERAL WEST-NORTHWESTWARD TRACK AND THEN TURN NORTHWARD
INTO A WEAKNESS TO THE EAST OF THIS RIDGE. THE OFFICIAL FORECAST IS
ADJUSTED SLIGHTLY NORTHWARD OF THE PREVIOUS ADVISORY AND IS NEAR
THE DYNAMICAL MODEL CONSENSUS.

FORECASTER FRANKLIN


FORECAST POSITIONS AND MAX WINDS

INITIAL      07/2100Z 21.1N  46.5W    35 KT
 12HR VT     08/0600Z 21.7N  47.8W    35 KT
 24HR VT     08/1800Z 22.4N  49.6W    35 KT
 36HR VT     09/0600Z 23.0N  51.3W    35 KT
 48HR VT     09/1800Z 23.8N  53.0W    40 KT
 72HR VT     10/1800Z 26.0N  55.5W    45 KT
 96HR VT     11/1800Z 29.0N  58.0W    50 KT
120HR VT     12/1800Z 32.5N  58.0W    50 KT


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