Post-Tropical Cyclone IRENE

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POST-TROPICAL CYCLONE IRENE DISCUSSION NUMBER  35
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL092011
1100 PM EDT SUN AUG 28 2011
 
SATELLITE IMAGERY...RADAR DATA...AND SURFACE OBSERVATIONS INDICATE
THAT IRENE HAS LOST TROPICAL CHARACTERISTICS.  ALSO...SURFACE
OBSERVATIONS FROM NORTHERN NEW ENGLAND INDICATE THAT THE LOW-LEVEL
CENTER HAS BECOME ELONGATED NOW THAT IT IS EMBEDDED WITHIN A
FRONTAL ZONE...AND IRENE IS BEING DECLARED A POST-TROPICAL CYCLONE
AT THIS TIME.  GLOBAL MODELS SUGGEST THAT THERE WILL NOT BE ENOUGH
BAROCLINIC FORCING FOR THE POST-TROPICAL CYCLONE TO STRENGTHEN...
AND LITTLE CHANGE IN INTENSITY IS THEREFORE INDICATED IN THE
OFFICIAL FORECAST FOR THE NEXT 5 DAYS.

THE INITIAL MOTION IS 025/23...AND THE CYCLONE IS EXPECTED TO TURN
TOWARD THE NORTHEAST AND EAST-NORTHEAST OVER THE NEXT COUPLE OF
DAYS WHILE BEING STEERED BY A BROAD MID-LEVEL TROUGH LOCATED OVER
EXTREME NORTHEASTERN CANADA.  THE OFFICIAL FORECAST IS A BLEND OF
THE PREVIOUS FORECAST...THE MULTI-MODEL CONSENSUS TVCA...AND
GUIDANCE FROM THE NOAA OCEAN PREDICTION CENTER.

FUTURE INFORMATION ON THIS SYSTEM...INCLUDING TOTAL RAINFALL
ACCUMULATIONS FROM IRENE...CAN BE FOUND IN PUBLIC ADVISORIES ISSUED
BY THE NOAA HYDROMETEOROLOGICAL PREDICTION CENTER...UNDER AWIPS
HEADER TCPAT4 AND WMO HEADER WTNT34 KWNH...BEGINNING AT 5 AM EDT.
FOR MARINE INTERESTS...ADDITIONAL INFORMATION CAN BE FOUND IN HIGH
SEAS FORECASTS ISSUED BY THE NATIONAL WEATHER SERVICE...UNDER AWIPS
HEADER NFDHSFAT1 AND WMO HEADER FZNT01 KWBC.

THE NATIONAL HURRICANE CENTER WOULD LIKE TO THANK THE AIR FORCE
RESERVE AND NOAA HURRICANE HUNTERS FOR ALL THE RECONNAISSANCE AND
SURVEILLANCE DATA COLLECTED DURING IRENE...AS WELL AS ALL THE LOCAL
WEATHER SERVICE OFFICES THAT CONDUCTED SPECIAL RADIOSONDE RELEASES
DURING THE PAST WEEK.

FORECAST POSITIONS AND MAX WINDS
 
INIT  29/0300Z 45.3N  71.3W   45 KT  50 MPH...POST-TROP/EXTRATROP
 12H  29/1200Z 48.4N  68.7W   40 KT  45 MPH...POST-TROP/EXTRATROP
 24H  30/0000Z 52.7N  63.4W   40 KT  45 MPH...POST-TROP/EXTRATROP
 36H  30/1200Z 56.0N  57.1W   40 KT  45 MPH...POST-TROP/EXTRATROP
 48H  31/0000Z 57.8N  49.3W   40 KT  45 MPH...POST-TROP/EXTRATROP
 72H  01/0000Z 60.0N  34.5W   40 KT  45 MPH...POST-TROP/EXTRATROP
 96H  02/0000Z 62.5N  26.5W   35 KT  40 MPH...POST-TROP/EXTRATROP
120H  03/0000Z 64.0N  27.5W   35 KT  40 MPH...POST-TROP/EXTRATROP
 
$$
FORECASTER BERG/STEWART
 
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