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 Cent
er on Facebook Follow the National Hurricane Center on Twitter
FirstGov.gov is the U.S. Government's official Web portal to all Federal, state and local government Web resources and services.
 
 

Tropical Storm BILL


ZCZC MIATCDAT3 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM BILL DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032009
500 PM AST SUN AUG 16 2009
 
SATELLITE IMAGES SHOW THAT BILL HAS DEVELOPED A CENTRAL DENSE
OVERCAST ALONG WITH IMPRESSIVE BANDING AND OUTFLOW.  THESE FEATURES
SUGGEST THAT THE STORM CONTINUES TO INTENSIFY.  SATELLITE INTENSITY
ESTIMATES FROM TAFB/SAB HAVE INCREASED TO T3.5...55 KT ON THE
DVORAK SCALE AND THIS VALUE WILL BE USED FOR THE INITIAL WIND
SPEED.

BILL IS MOVING TOWARD THE WEST-NORTHWEST OR 285/14.  THIS GENERAL
MOTION IS EXPECTED FOR THE NEXT COUPLE OF DAYS AS A SUBTROPICAL
RIDGE SHOULD REMAIN FIRM TO THE NORTH OF THE TROPICAL CYCLONE. 
THEREAFTER...A COUPLE OF EVOLUTIONS TO THE SYNOPTIC PATTERN SEEM
POSSIBLE.  THE FIRST...FAVORED BY THE GFS/ECMWF/GFDL/HWRF...SHOWS A
MID-LATITUDE SHORTWAVE DIVING INTO THE SUBTROPICAL RIDGE...CAUSING
IT TO BREAK AROUND 65W.  THIS LEADS TO A NORTHWEST MOTION OF BILL
IN ABOUT THREE DAYS.  THE OTHER SOLUTION...SHOWN BY THE
NOGAPS/UKMET...IS THAT THE HURRICANE BYPASSES THE FIRST BREAK AND
CONTINUES MOVING TOWARD THE WEST-NORTHWEST...EVENTUALLY TURNING
NORTHWEST AT THE END OF THE FORECAST DUE TO A LARGE MID-LATITUDE
TROUGH APPROACHING THE EASTERN UNITED STATES.  THE OFFICIAL
FORECAST IS SHIFTED A LITTLE BIT TO THE RIGHT AT THE END...IN
DEFERENCE TO THE HIGHLY-SKILLED MODELS IN THE FORMER SOLUTION.

WATER VAPOR IMAGES SHOW THAT THE HURRICANE IS ON THE SOUTH SIDE OF
AN UPPER HIGH WITH LITTLE SHEAR LIKELY FOR THE NEXT SEVERAL DAYS. 
IN COMBINATION WITH WARM SSTS...THERE IS NO REASON NOT TO FORECAST
CONTINUED STRENGTHENING OF BILL.  IN FACT...THE SHIPS RAPID
INTENSIFICATION INDEX SHOWS A 38 PERCENT CHANCE OF A 30 KT INCREASE
IN WINDS DURING THE NEXT 24 HOURS.  ALL RELIABLE MODELS CONTINUE TO
SHOW THIS SYSTEM BECOMING A MAJOR HURRICANE...WITH THE
GFDL/HWRF/GFDN MODELS FORECASTING BILL TO REACH CATEGORY FOUR
STRENGTH BY DAY 5.  HOWEVER...THERE IS SOME EVIDENCE IN THE GLOBAL
MODEL FIELDS THAT THE UPPER-LEVEL WINDS WILL BECOME LESS FAVORABLE
AFTER 72 HOURS WITH SOME SOUTHWESTERLY SHEAR DEVELOPING AS BILL
BECOMES DISPLACED FROM AN UPPER-LEVEL HIGH.  THE OFFICIAL FORECAST
WILL SHOW THE INTENSITY LEVELING OFF AFTER THAT TIME DUE TO THAT
POSSIBILITY. THE NHC INTENSITY FORECAST IS CLOSE TO THE PREVIOUS
FORECAST AND IS SIMILAR TO THE SHIPS MODEL.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      16/2100Z 12.8N  40.0W    55 KT
 12HR VT     17/0600Z 13.4N  42.1W    65 KT
 24HR VT     17/1800Z 14.2N  45.0W    75 KT
 36HR VT     18/0600Z 15.0N  47.7W    85 KT
 48HR VT     18/1800Z 16.0N  50.4W    95 KT
 72HR VT     19/1800Z 18.5N  55.5W   105 KT
 96HR VT     20/1800Z 22.0N  60.5W   105 KT
120HR VT     21/1800Z 26.5N  65.0W   105 KT
 
$$
FORECASTER BLAKE
 
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: Thursday, 31-Dec-2009 12:09:05 UTC