A weak shear in western Gulf may keep Ike to a 2 before landfall

HURRICANE IKE DISCUSSION NUMBER 34

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092008

1100 AM EDT TUE SEP 09 2008

RADAR AND RECONNAISSANCE OBSERVATIONS SHOW THAT IKE IS MAINTAINING A

SMALL AND WELL-DEFINED EYEWALL...AND THE SATELLITE PRESENTION IS

THAT OF A STRONGER STORM THAN THE RECONNAISSANCE WIND DATA SUPPORT.

THE CENTRAL PRESSURE WAS 965 MB ON THE LAST PASS...BUT THE PEAK

FLIGHT LEVEL WINDS WERE NO HIGHER THAN 66 KT. SFMR DATA SEEM TO

SUPPORT A 65 KT INTENSITY...BUT SINCE THERE WAS LIMITED SAMPLING IN

THE NORTHEAST QUADRANT THE ADVISORY ESTIMATE WILL REMAIN 70 KT.

THE INITIAL MOTION IS 290/11. IKE IS EXPECTED TO MOVE GENERALLY

WEST-NORTHWESTWARD FOR THE NEXT DAY OR TWO IN RESPONSE TO A

WEAKNESS IN THE SUBTROPICAL RIDGE OVER THE NORTHEASTERN GULF OF

MEXICO. AFTER THAT...RIDGING OVER THE SOUTHEASTERN STATES IS

EXPECTED TO BEND THE TRACK SLIGHTLY TO THE LEFT IN THE CENTRAL

GULF...AND THE GUIDANCE IS IN PRETTY GOOD AGREEMENT THROUGH 72

HOURS. THERE IS CONSIDERABLE UNCERTAINTY NEAR THE END OF THE

FORECAST PERIOD...WITH THE ECMWF AND UKMET MODELS SHOWING A

SHORT-WAVE TROUGH COMING OUT OF THE ROCKIES THAT INDUCES A RIGHT

TURN ON DAY 4. THE GFS AND NOGAPS HAVE A DIFFERENT PATTERN...WITH

MORE RIDGING EXTENDING WESTWARD TO THE NORTH OF IKE THAT KEEPS THE

HURRICANE MOVING BASICALLY WESTWARD. THE ECMWF HAS DONE VERY WELL

WITH IKE THUS FAR...AND HAS RELATIVELY HIGH SKILL IN FORECASTING

THE LARGE SCALE PATTERNS AT THE LONGER RANGES. OUT OF RESPECT FOR

THIS MODEL THE OFFICIAL FORECAST IS SHIFTED SLIGHTLY SLOWER AND TO

THE RIGHT OF THE PREVIOUS FORECAST...AND IS PRETTY CLOSE TO THE

DYNAMICAL MODEL CONSENSUS. BEGINNING TOMORROW AT 12Z THE NOAA G-IV

JET AIRCRAFT WILL BE SAMPLING THE ENVIRONMENT OF IKE TO ASSIST IN

THE DETERMINATION OF WATCHES AND WARNINGS.

WHEN IKE IS IN THE SOUTHEASTERN GULF OF MEXICO IT WILL BE IN A VERY

DIFLUENT AND FAVORABLE ENVIRONMENT FOR RESTRENGTHENING...AND IKE IS

EXPECTED TO REGAIN MAJOR HURRICANE STATUS. THE PATTERN LOOKS A

LITTLE LESS CONDUCIVE IN THE WESTERN GULF...WITH SOME NORTHEASTERLY

SHEAR...SO THE OFFICIAL FORECAST SHOWS NO FURTHER STRENGTHENING

THERE. THE OFFICIAL FORECAST IS A BLEND OF THE STATISTICAL

GUIDANCE...WHICH IS BASICALLY CATEGORY 2...AND THE DYNAMICAL

GFDL/HWRF WHICH SHOW CAT 3/4 STRENGTH IN THE WESTERN GULF.

FORECAST POSITIONS AND MAX WINDS

INITIAL 09/1500Z 22.6N 83.0W 70 KT

12HR VT 10/0000Z 23.2N 84.2W 70 KT

24HR VT 10/1200Z 24.0N 85.8W 85 KT

36HR VT 11/0000Z 24.7N 87.4W 95 KT

48HR VT 11/1200Z 25.2N 89.2W 100 KT

72HR VT 12/1200Z 26.0N 93.5W 100 KT

96HR VT 13/1200Z 27.5N 97.0W 100 KT

120HR VT 14/1200Z 29.0N 99.5W 40 KT...INLAND

$$

FORECASTER FRANKLIN