ZCZC MIATCDAT3 ALL TTAA00 KNHC DDHHMM HURRICANE ISABEL DISCUSSION NUMBER 16 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 PM EDT TUE SEP 09 2003 THERE HAS BEEN SOME EROSION OF THE EYEWALL CONVECTION IN THE EASTERN SEMICIRCLE AND THE EYE HAS BECOME LESS DISTINCT OVER THE PAST FEW HOURS. WATER VAPOR IMAGERY ALSO INDICATES THAT THE OUTFLOW TO THE NORTHEAST OF ISABEL IS BECOMING SLIGHTLY RESTRICTED. DVORAK T NUMBERS ARE 5.5 FROM TAFB AND SAB...AND THE 3-HR AVERAGE RAW ODT IS ALSO DOWN TO 5.4. THE INITIAL INTENSITY WILL BE HELD AT 115 KT FOR THIS ADVISORY. THE INITIAL MOTION ESTIMATE...BASED ON THE LAST 12 HOURS...IS 295/12...ALTHOUGH OVER THE PAST THREE HOURS THE MOTION HAS BEEN TOWARD THE WEST. THIS IS QUITE POSSIBLY THE BEGINNING OF THE EXPECTED WESTWARD TURN...BUT THREE HOURS OF MOTION IS NOT ENOUGH TO BE SURE...ESPECIALLY GIVEN THE DEGRADATION OF THE EYE OBSERVED DURING THIS PERIOD. REGARDLESS...ISABEL IS SOUTH OF A MID-LEVEL RIDGE OF HIGH PRESSURE THAT SHOULD FORCE THE HURRICANE ON A GENERALLY WESTWARD TRACK OVER THE NEXT THREE DAYS. AFTER THAT... GLOBAL MODELS GENERALLY SHOW A BREAK IN THE RIDGE BETWEEN 75 AND 80W THAT WOULD ALLOW A TURN BACK TO THE WEST-NORTHWEST ON DAYS 4 AND 5 OF THE FORECAST. FOR THE LAST COUPLE OF DAYS...THE GUIDANCE ENVELOPE HAS BEEN CONSISTENTLY DEFINED BY THE UKMET ON THE NORTH AND THE GFS/NOGAPS ON THE SOUTH. AMONG THE GLOBAL MODELS...THE UKMET HAS BEEN THE BEST PERFORMER SO FAR WITH ISABEL AND THE GFS HAS BEEN THE WORST. THE UKMET ALSO WAS THE BEST OF THE GLOBAL MODELS FOR FABIAN. THE INITIAL VORTEX FOR ISABEL IN THE GFS HAS BEEN CONSISTENTLY MUCH WEAKER THAN THE INITIALIZATION IN THE UKMET...ALTHOUGH I AM NOT CERTAIN THAT THIS EXPLAINS THE DIFFERENCES BETWEEN THE TWO MODELS. GIVEN THE RECENT MOTION...I HAVE NUDGED THE OFFICIAL FORECAST TRACK A LITTLE SOUTH OF THE PREVIOUS ADVISORY. THE NEW TRACK IS IN BEST AGREEMENT WITH THE GFDL...AND SLIGHTLY ON THE UKMET SIDE OF THE GLOBAL MODEL CONSENSUS. ENVIRONMENTAL CONDITIONS SHOULD BE GENERALLY FAVORABLE FOR THE NEXT SEVERAL DAYS...SO LITTLE OVERALL CHANGE IN STRENGTH IS FORECAST. HOWEVER...FLUCTUATIONS IN INTENSITY ARE COMMON IN MAJOR HURRICANES AND THESE ARE GENERALLY VERY DIFFICULT TO FORECAST. FORECASTER FRANKLIN FORECAST POSITIONS AND MAX WINDS INITIAL 10/0300Z 20.6N 48.8W 115 KT 12HR VT 10/1200Z 21.3N 50.4W 115 KT 24HR VT 11/0000Z 21.5N 52.3W 115 KT 36HR VT 11/1200Z 21.5N 53.9W 115 KT 48HR VT 12/0000Z 21.5N 55.5W 115 KT 72HR VT 13/0000Z 21.5N 58.5W 115 KT 96HR VT 14/0000Z 22.0N 61.5W 110 KT 120HR VT 15/0000Z 23.0N 65.0W 110 KT NNNN
Alternate Formats
About Alternates -
E-Mail Advisories -
RSS Feeds
Cyclone Forecasts
Latest Advisory -
Past Advisories -
About Advisories
Marine Forecasts
Latest Products -
About Marine Products
Tools & Data
Satellite Imagery -
US Weather Radar -
Aircraft Recon -
Local Data Archive -
Forecast Verification -
Deadliest/Costliest/Most Intense
Learn About Hurricanes
Storm Names
Wind Scale -
Prepare -
Climatology -
NHC Glossary -
NHC Acronyms -
Frequently Asked Questions -
AOML Hurricane-Research Division
About Us
About NHC -
Mission/Vision -
Other NCEP Centers -
NHC Staff -
Visitor Information -
NHC Library
NOAA/
National Weather Service
National Centers for Environmental Prediction
National Hurricane Center
11691 SW 17th Street
Miami, Florida, 33165-2149 USA
nhcwebmaster@noaa.gov
Disclaimer
Privacy Policy
Credits
About Us
Glossary
Career Opportunities
Page last modified: Monday, 07-Feb-2005 16:49:58 UTC