[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 122041
TCDAT4
TROPICAL STORM IRENE DISCUSSION NUMBER  33
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT FRI AUG 12 2005

AN AIR FORCE PLANE INVESTIGATING IRENE CONFIRMED EARLIER SATELLITE
INTENSITY ESTIMATES AT 1800 UTC. THE RECON MEASURED 64 KNOTS AT
FLIGHT LEVEL AND A MINIMUM PRESSURE OF 997 MB. IT ALSO REPORTED A
WELL-DEFINED CIRCULATION WITH GOOD RADAR PRESENTATION. BOTH SHEAR
AND SST ARE FAVORABLE FOR STRENGTHENING BUT SINCE NO GUIDANCE
BRINGS IRENE ABOVE A CATEGORY ONE HURRICANE...ONLY SLIGHT
INTENSIFICATION IS INDICATED.

IRENE HAS DECREASED ITS FORWARD SPEED AND IS MOVING TOWARD THE
NORTHWEST OR 310 DEGREES AT 9 KNOTS. THE CYCLONE HAS BEEN STEERED
BY THE FLOW AROUND A STRONG MID-LEVEL SUBTROPICAL RIDGE. AS THE
RIDGE MOVES EASTWARD...IRENE SHOULD TURN MORE TOWARD THE
NORTH-NORTHWEST AND NORTH AROUND THE RIDGE INTO AN AREA OF LIGHT
STEERING CURRENTS. THIS WOULD RESULT IN A SIGNIFICANT DECREASE IN
FORWARD SPEED DURING THE NEXT 2 TO 4 DAYS. IN FACT...IRENE COULD
BEGIN TO MEANDER FOR A WHILE. THEREAFTER...THE WESTERLIES ARE
EXPECTED TO BECOME ESTABLISHED AND THIS FLOW SHOULD TAKE IRENE
NORTHEASTWARD AWAY FROM THE U.S. COAST.

THE OFFICIAL TRACK FORECAST HAS BEEN GRADUALLY SHIFTING EASTWARD IN
AGREEMENT WITH GUIDANCE. THIS LESSENS THE POTENTIAL THREAT TO THE
UNITED STATES EAST COAST. A HIGH ALTITUDE NOAA JET IS CURRENTLY
SAMPLING THE ENVIRONMENT. THE DATA WILL GO INTO  TONIGHT'S MODEL
RUNS.

NOTE: JUST AFTER THE COORDINATION CALL THE PLANE REPORTED A PEAK
WIND OF 75 KNOTS AT 850 MB. THE INITIAL INTENSITY HAS BEEN ADJUSTED
TO 60 KNOTS.

FORECASTER AVILA


FORECAST POSITIONS AND MAX WINDS

INITIAL      12/2100Z 28.7N  67.5W    60 KT
 12HR VT     13/0600Z 29.4N  68.8W    65 KT
 24HR VT     13/1800Z 30.8N  70.0W    75 KT
 36HR VT     14/0600Z 32.5N  70.5W    75 KT
 48HR VT     14/1800Z 34.0N  70.5W    75 KT
 72HR VT     15/1800Z 36.0N  70.4W    75 KT
 96HR VT     16/1800Z 37.1N  70.0W    75 KT
120HR VT     17/1800Z 39.0N  64.0W    75 KT


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