[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT44 KNHC 090235
TCDAT4
TROPICAL DEPRESSION IRENE DISCUSSION NUMBER  18
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT MON AUG 08 2005

IRENE CONTINUES TO LOOK INSIGNIFICANT ON SATELLITE IMAGES...AND
SHOWS NO INDICATIONS OF RESTRENGTHENING ANY TIME SOON.  THE
LOW-CLOUD CENTER IS NEAR THE WESTERN EDGE OF A SMALL AREA OF DEEP
CONVECTION...AND THERE ARE NO OBVIOUS BANDING FEATURES.  THE
DEPRESSION IS BEING SHEARED BY WESTERLY FLOW ASSOCIATED WITH THE
MID-ATLANTIC UPPER-LEVEL TROUGH.  ALSO...DROPSONDE DATA FROM A
SAHARAN AIR LAYER RESEARCH MISSION WITH THE NOAA G-IV JET CONFIRM
THAT IRENE IS IN AN ENVIRONMENT OF VERY DRY MID- TO UPPER-
TROPOSPHERIC AIR.  AS THE CYCLONE MOVES FARTHER TO THE WEST-
NORTHWEST OVER THE NEXT COUPLE OF DAYS...IT IS LIKELY TO ENTER A
WEAKER WIND SHEAR ENVIRONMENT SINCE THE UPPER FLOW IS EXPECTED TO
BECOME MORE SOUTHEASTERLY.  SOME RESTRENGTHENING IS THEREFORE SHOWN
IN THE FORECAST.

INITIAL MOTION IS 285/11.  IRENE IS EXPECTED TO EVENTUALLY TURN MORE
NORTHWARD LATER IN THE FORECAST PERIOD...IN RESPONSE TO A WEAKNESS
IN THE SUBTROPICAL RIDGE NEAR BERMUDA.  HOWEVER THERE ARE
SIGNIFICANT DIFFERENCES OF OPINION AMONG THE GLOBAL MODELS AS TO
THE CONFIGURATION OF THE SUBTROPICAL RIDGE OVER THE WESTERN
ATLANTIC AT DAYS 4-5.  BY THAT TIME IT DOES APPEAR THAT THE
STEERING CURRENTS WILL BECOME QUITE WEAK...SO THE FORWARD SPEED IS
FORECAST TO SLOW CONSIDERABLY LATE IN THE PERIOD.  THE OFFICIAL
FORECAST FOR THIS ADVISORY IS SIMILAR TO THE PREVIOUS ONE THROUGH
DAY 3 AND SHIFTED A LITTLE TO THE EAST AFTERWARDS...BUT NOT AS FAR
EAST AS THE DYNAMICAL CONSENSUS.

FORECASTER PASCH


FORECAST POSITIONS AND MAX WINDS

INITIAL      09/0300Z 22.6N  52.7W    30 KT
 12HR VT     09/1200Z 23.0N  54.4W    30 KT
 24HR VT     10/0000Z 23.7N  56.7W    35 KT
 36HR VT     10/1200Z 24.5N  59.0W    35 KT
 48HR VT     11/0000Z 25.5N  61.2W    40 KT
 72HR VT     12/0000Z 28.0N  64.5W    40 KT
 96HR VT     13/0000Z 30.0N  65.0W    45 KT
120HR VT     14/0000Z 32.0N  65.0W    45 KT


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