ZCZC MIATCDAT4 ALL TTAA00 KNHC DDHHMM HURRICANE ISAAC DISCUSSION NUMBER 16 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092006 1100 AM EDT SUN OCT 01 2006 THE EYE FEATURE OF ISAAC HAS BECOME MUCH LESS DEFINED OVER THE PAST SEVERAL HOURS. IT APPEARS THAT SOUTHWESTERLY SHEAR IS BEGINNING TO HAVE SOME EFFECT ON THE TROPICAL CYCLONE. DVORAK INTENSITY ESTIMATES ARE BETWEEN 65 AND 75 KT AND AN EARLIER QUIKSCAT PASS SUPPORTED MAXIMUM WINDS OF ABOUT 70 KT...WHICH IS THE ESTIMATED INITIAL INTENSITY. ISAAC IS EXPECTED TO GRADUALLY WEAKEN AS IT ENCOUNTERS INCREASING SHEAR AND MUCH COOLER SSTS DURING THE NEXT 24-36 HOURS. FSU PHASE SPACE DIAGRAMS BASED ON THE GLOBAL MODELS SHOW THAT ISAAC WILL TRANISITION INTO A EXTRATROPICAL CYCLONE IN NOT MORE THAN 24-36 HOURS. THE CURRENT MOTION IS 355/11. IT APPEARS THAT ISAAC IS BEGINNING TO ACCELERATE AND TURN NORTHWARD AHEAD OF THE LARGE DEEP-LAYER TROUGH THAT IS APPROACHING THE EAST COAST OF THE UNITED STATES. ALL OF THE GLOBAL MODELS INDICATE THAT THE CYCLONE WILL MOVE OVER OR VERY NEAR SOUTHEASTERN NEWFOUNDLAND IN ABOUT 36 HOURS. THE GFS AND UKMET MODELS REMAIN ON THE WESTERN SIDE OF THE GUIDANCE WHILE THE GFDL IS TO THE EAST AND KEEPS ISAAC OFFSHORE. THE OFFICIAL FORECAST LEANS TOWARDS THE GFS/UKMET SOLUTION AND IS A LITTLE WEST OF THE GUNA MODEL CONSENSUS. AFTER PASSING NEWFOUNDLAND...THE MODELS DIVERGE SIGNIFICANTLY ON WHICH LOW BECOMES DOMINANT...THE EXTRATROPICAL REMNANT OF ISAAC OR THE BAROCLINIC LOW MOVING OFF THE NORTHEAST UNITED STATES COAST. THIS FORECAST ASSUMES THE SMALLER ISAAC WILL BECOME ABSORBED BY THE LARGE BAROCLINIC LOW AND THE 72 HOUR FORECAST REFLECTS THIS SCENARIO. FORECAST POSITIONS AND MAX WINDS INITIAL 01/1500Z 34.4N 60.3W 70 KT 12HR VT 02/0000Z 37.2N 59.8W 70 KT 24HR VT 02/1200Z 42.0N 57.2W 65 KT 36HR VT 03/0000Z 47.0N 53.0W 60 KT...EXTRATROPICAL 48HR VT 03/1200Z 50.5N 48.7W 55 KT...EXTRATROPICAL 72HR VT 04/1200Z...ABSORBED $$ FORECASTER BROWN/FRANKLIN 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: Sunday, 01-Oct-2006 15:00:01 UTC