ZCZC MIATCDAT4 ALL TTAA00 KNHC DDHHMM HURRICANE IVAN DISCUSSION NUMBER 24 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT WED SEP 08 2004 IVAN HAS CONTINUED TO STRENGTHEN THIS MORNING. THE MAXIMUM 700 MB FLIGHT-LEVEL WIND REPORTED WAS 133 KT IN THE NORTHEAST QUADRANT... WHICH EQUALS A 120-KT SURFACE WIND. THE HIGHEST WIND OBSERVED BY DROPSONDES WAS 150 KT AT 923 MB IN THE NORTHEAST EYEWALL. THE CENTRAL HAS ALSO BEEN AS LOW AS 947 MB...BUT THE DROPSONDE MEASURED A SURFACE WIND OF 57 KT...SO THE CENTRAL PRESSURE WAS LIKELY LOWER. BASED ON THIS INFORMATION...THE INTENSITY IS INCREASED TO 120 KT. THE INITIAL MOTION IS 280/14. IVAN HAS CONTINUED TO MOVE NORTH OF DUE WEST ON THE SOUTH SIDE OF A STRONG SUBTROPICAL HIGH THAT IS ORIENTED NORTHEAST-SOUTHWEST OVER THE WESTERN ATLANTIC AND INTO THE NORTHWESTERN CARIBBEAN SEA. THE HIGH IS SEPARATING FRANCES TO THE NORTH OVER THE SOUTHEASTERN U.S. FROM IVAN OVER THE SOUTHEASTERN CARIBBEAN. DURING THE NEXT 2 DAYS...THE HIGH/RIDGE IS FORECAST BY ALL THE MODELS THE GRADUALLY LIFT NORTHWARD OVER FLORIDA AND THE EASTERN GULF OF MEXICO AS FRANCES LIFTS OUT TO THE NORTHEAST. BY DAY 3...A STRONG MID-LEVEL TROUGH CURRENTLY OFF THE U.S. WEST COAST IS FORECAST TO DIG INTO THE WEST COAST AND AMPLIFY THE DOWNSTREAM RIDGE OVER THE CENTRAL U.S. AND NORTHERN MEXICO. THIS PATTERN RESULTS IN A TROUGH CURRENTLY OVER THE NORTHERN PLAINS TO DIG SOUTHWARD AND ERODE/WEAKEN THE RIDGE EASTWARD ACROSS THE CENTRAL AND EASTERN GULF OF MEXICO AND FLORIDA. THE MAIN DIFFERENCE IN THE MODELS IS HOW THEY HANDLE A YET-TO-DEVELOP MID-/UPPER-LEVEL LOW OVER THE CENTRAL ATLANTIC. THE MAJORITY OF THE MODELS DEVELOP THE LOW AND THEN QUICKLY WEAKEN IT AS IT MOVES WESTWARD TO THE NORTHEAST OF THE BAHAMAS BY DAY 4. THE GFS...HOWEVER...HANGS ONTO THE LOW LONGER AND KEEPS IT FARTHER SOUTH...WHICH ERODES THE WESTERN PORTION OF THE RIDGE SOONER AND ALLOWS IVAN TO TURN NORTHWARD BY 72 HOURS WHEN THE HURRICANE IS NEAR JAMAICA. FOR THE TIME BEING...THE GFS AND THE BAM MODELS ARE CONSIDERED TO BE STRONG EASTERN OUTLIERS AND THE OFFICIAL TRACK IS CLOSE TO THE PREVIOUS TRACK AND A LITTLE TO THE LEFT OF THE GUNA MODEL CONSENSUS. UPPER-LEVEL WINDS ARE FORECAST TO REMAIN FAVORABLE THROUGHOUT THE FORECAST PERIOD. HOWEVER...TIMING CONCENTRIC EYEWALL CYCLES IS IMPOSSIBLE...EXCEPT IN THE SHORT TERM...WHICH IVAN APPEARS TO BE STARTING TO GO THROUGH NOW. ONCE THAT CYCLE ENDS...IVAN SHOULD BEGIN TO INTENSIFY AGAIN AS IT MOVES AWAY FROM THE NEGATIVE INFLUENCE OF THE NORTH COAST OF SOUTH AMERICA. INTENSITY DECREASES AT 72HR AND 120HR REFLECT POSSIBLE PASSAGES OVER JAMAICA AND CUBA. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 08/0900Z 12.4N 64.8W 120 KT 12HR VT 08/1800Z 13.1N 67.2W 120 KT 24HR VT 09/0600Z 14.2N 70.1W 125 KT 36HR VT 09/1800Z 15.5N 72.5W 130 KT 48HR VT 10/0600Z 16.8N 75.0W 130 KT 72HR VT 11/0600Z 19.1N 78.7W 120 KT 96HR VT 12/0600Z 21.5N 81.5W 130 KT 120HR VT 13/0600Z 25.0N 82.5W 120 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: Wednesday, 08-Sep-2004 09:02:54 UTC