[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT44 KNHC 261446
TCDAT4

HURRICANE IRENE DISCUSSION NUMBER  25
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL092011
1100 AM EDT FRI AUG 26 2011

DATA FROM NOAA AND AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT
SUGGEST THE INTENSITY OF IRENE IS SLIGHTLY LOWER.  ALTHOUGH PEAK
FLIGHT-LEVEL WINDS AT 700 MB WERE 111 KT...SFMR AND DROPSONDE
OBSERVATIONS INDICATED THAT A HIGHER-THAN-TYPICAL REDUCTION OF THE
WIND FROM FLIGHT-LEVEL TO THE SURFACE APPLIES...AND THE INITIAL
INTENSITY IS REDUCED TO 90 KT.  GIVEN THE CURRENT STORM STRUCTURE
AND PREDICTED ENVIRONMENTAL FACTORS...LITTLE CHANGE IN STRENGTH IS
EXPECTED DURING THE NEXT 12 TO 24 HOURS.  AFTER PASSING NORTH
CAROLINA...SOUTHWESTERLY SHEAR IS FORECAST TO INCREASE AND SEA
SURFACE TEMPERATURES WILL BE GRADUALLY DECREASING.  THIS SHOULD
RESULT IN GRADUAL WEAKENING OF THE CYCLONE AS IT MOVES NEAR THE
MID-ATLANTIC COAST.  HOWEVER...IRENE IS EXPECTED TO REMAIN A LARGE
AND DANGEROUS TROPICAL CYCLONE AND HAS THE POTENTIAL TO PRODUCE
DAMAGING WINDS...STORM SURGE FLOODING...AND EXTREMELY HEAVY RAINS
ALMOST ANYWHERE FROM EASTERN NORTH CAROLINA NORTHWARD THROUGH NEW
ENGLAND.

IRENE IS MOVING NORTHWARD OR 360/12 KT.  THERE HAS BEEN NO CHANGE
TO THE FORECAST PHILOSOPHY.  IRENE SHOULD MOVE NORTHWARD FOR ANOTHER
12 HOURS OR SO....FOLLOWED BY A GRADUAL TURN TO THE NORTH-NORTHEAST
AS IT MOVES ALONG THE EAST COAST OF THE UNITED STATES.  THE TRACK
GUIDANCE IS IN GOOD AGREEMENT ON THIS SCENARIO AND NO CHANGE WAS
REQUIRED FROM THE PREVIOUS NHC FORECAST THROUGH 72 HOURS.

ONLY A SMALL ADJUSTMENT WAS MADE TO THE HURRICANE WARNING ON THIS
ADVISORY.  IT IS ANTICIPATED THAT THE HURRICANE WARNING AND WATCH
AREAS WILL NEED TO BE EXTENDED NORTHWARD ALONG THE U.S. EAST COAST
THIS AFTERNOON.



FORECAST POSITIONS AND MAX WINDS

INIT  26/1500Z 30.7N  77.3W   90 KT 105 MPH
 12H  27/0000Z 32.2N  77.1W   90 KT 105 MPH
 24H  27/1200Z 34.4N  76.6W   90 KT 105 MPH
 36H  28/0000Z 36.7N  75.6W   85 KT 100 MPH
 48H  28/1200Z 39.5N  74.1W   75 KT  85 MPH
 72H  29/1200Z 47.5N  68.8W   55 KT  65 MPH...INLAND
 96H  30/1200Z 55.5N  57.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
120H  31/1200Z 59.0N  38.0W   40 KT  45 MPH...POST-TROP/EXTRATROP

$$
FORECASTER BROWN/BLAKE


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