Skip Navigation Links weather.gov   
NOAA logo - Click to go to the NOAA homepage National Weather Service   NWS logo - Click to go to the NWS homepage
National Hurricane Center
Local forecast by
"City, St" or "ZIP"

 
Alternate Formats
   Text     |   Mobile
   Email   |   RSS XML/RSS logo
   About Alternates
Cyclone Forecasts
   Latest Advisory
   Past Advisories
   Audio/Podcasts
   About Advisories
Marine Forecasts
   Atlantic & E Pacific
   Gridded Marine
   About Marine
Tools & Data
   Satellite | Radar
   Analysis Tools
   Aircraft Recon
   GIS Datasets
   Data Archive
Development
   Experimental
   Research
   Forecast Accuracy
Outreach & Education
   Prepare
   Storm Surge
   About Cyclones
   Cyclone Names
   Wind Scale
   Most Extreme
   Forecast Models
   Breakpoints
   Resources
   Glossary | Acronyms
   Frequent Questions
Our Organization
   About NHC
   Mission & Vision
   Staff | Q&A
   Visitors | Virtual Tour
   Library Branch
   NCEP | Newsletter
Contact Us
   Comments
Follow the National Hurricane Center on Facebook Follow the National Hurricane Center on Twitter
Subscribe the National Hurricane Center on YouTube Read the National Hurricane Center Inside the Eye blog on WordPress
FirstGov.gov is the U.S. Government's official Web portal to all Federal, state and local government Web resources and services.
 
 

Tropical Storm ISAAC


ZCZC MIATCDAT4 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM ISAAC DISCUSSION NUMBER   9
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL092006
500 PM EDT FRI SEP 29 2006
 
CONVECTION HAS BEEN INTENSIFYING AND ATTEMPTING TO FORM A RING
AROUND THE CENTER OF ISAAC. IN ADDITION THE OUTFLOW HAS BEEN
EXPANDING AND BECOMING MORE SYMMETRIC. THESE ARE ALL SIGNS OF AN
INTENSIFYING SYSTEM. DVORAK T-NUMBERS HAVE INCREASED MARKEDLY...
AND SINCE AN EARLIER QUIKSCAT PASS SUPPORTED WINDS OF 40-45 KT
TWELVE HOURS AGO... THE INITIAL INTENSITY IS RAISED TO 50 KT. ISAAC
IS LEAVING THE COOLER WATERS PREVIOUSLY UPWELLED BY GORDON AND
HELENE AND MOVING INTO WARMER SSTS. IN ADDITION... THE DRY AIR IN
THE MIDDLE TO UPPER LEVELS NEAR THE SYSTEM'S CORE HAS BEEN REDUCED
AND THERE IS LITTLE SHEAR APPARENT ON SATELLITE IMAGES. THESE
FACTORS SUPPORT INTENSIFICATION FOR THE NEXT 36 HOURS OR SO. THUS
THE INTENSITY FORECAST IS RAISED FROM THE PREVIOUS ONE AND SHOWS
ISAAC BECOMING A HURRICANE. THE FORECAST IS HIGHER THAN THE
PREVIOUS ONE AND IN BEST AGREEMENT WITH A BLEND OF THE SHIPS/FSSE. 
 
THE INITIAL MOTION IS VIRTUALLY UNCHANGED FROM EARLIER AND IS ABOUT
295/6. MIDDLE-LEVEL RIDGING OVER THE CENTRAL ATLANTIC SHOULD BE THE
PRIMARY STEERING MECHANISM FOR THE NEXT ONE OR TWO DAYS... SENDING
THE STORM ON A WEST-NORTHWEST TO NORTHWESTWARD HEADING. THEREAFTER
ISSAC WILL REACH THE WESTERN PERIPHERY OF THE RIDGE AND LIKELY
ACCELERATE TO THE NORTH IN FRONT OF A MASSIVE TROUGH FORECAST TO
PROGRESS EASTWARD ACROSS THE WESTERN ATLANTIC. THE UKMET HAS
SHIFTED ITS TRACK WESTWARD FROM EARLIER BUT IS STILL ON THE EASTERN
SIDE OF THE MODEL ENVELOPE. OTHER MODELS ARE MOSTLY UNCHANGED OR
SLIGHTLY FARTHER WEST OF THE PREVIOUS GUIDANCE. THE OFFICIAL
FORECAST IS NUDGED WESTWARD BUT STILL LIES JUST EAST OF THE MODEL
CONSENSUS. GLOBAL MODELS SUGGEST THAT ISAAC WILL BECOME RAPIDLY
EXTRATROPICAL BETWEEN 48 AND 72 HOURS FOLLOWED BY ABSORPTION INTO A
LARGER EXTRATROPICAL LOW IN 4 TO 5 DAYS. 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      29/2100Z 29.7N  56.8W    50 KT
 12HR VT     30/0600Z 30.1N  57.8W    55 KT
 24HR VT     30/1800Z 31.1N  59.1W    60 KT
 36HR VT     01/0600Z 32.5N  60.3W    65 KT
 48HR VT     01/1800Z 34.7N  61.0W    60 KT
 72HR VT     02/1800Z 43.5N  57.0W    55 KT...EXTRATROPICAL
 96HR VT     03/1800Z 50.0N  48.0W    50 KT...EXTRATROPICAL
120HR VT     04/1800Z...ABSORBED
 
$$
FORECASTER BLAKE/STEWART
 
NNNN


Quick Navigation Links:
Tropical Cyclone Forecasts  -  Tropical Marine Forecasts  -  Data Archive
Outreach  -  Prepare  -  About Cyclones  -  About NHC  -  Contact Us

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
Credits
Information Quality
Glossary
Privacy Policy
Freedom of Information Act (FOIA)
About Us
Career Opportunities
Page last modified: Friday, 29-Sep-2006 20:35:01 UTC