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 Depression TWELVE


ZCZC MIATCDAT2 ALL
TTAA00 KNHC DDHHMM
 
TROPICAL DEPRESSION TWELVE DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122011
500 AM AST MON AUG 29 2011
 
THE AREA OF LOW PRESSURE IN THE FAR EASTERN ATLANTIC TO THE SOUTH OF
THE CAPE VERDE ISLANDS HAS GAINED SUFFICIENT CONVECTIVE
ORGANIZATION TO BE CLASSIFIED AS A TROPICAL DEPRESSION. A CURVED
CONVECTIVE BAND WRAPS AROUND THE WESTERN AND SOUTHERN SIDE OF THE
SYSTEM AND THE INITIAL INTENSITY IS SET TO 30 KT BASED ON THE 06Z
DVORAK CLASSIFICATION FROM TAFB. THE DEPRESSION IS CURRENTLY IN AN
EASTERLY SHEAR ENVIRONMENT SITUATED TO THE SOUTH OF AN UPPER-LEVEL
RIDGE OVER THE EASTERN ATLANTIC. SOME EASTERLY SHEAR IS EXPECTED TO
PERSIST...BUT OTHERWISE THE ENVIRONMENT SHOULD BE CONDUCIVE FOR
STRENGTHENING THROUGH THE PERIOD. THE OFFICIAL INTENSITY FORECAST
SHOWS SLOW STRENGTHENING IN GOOD AGREEMENT WITH THE SHIPS...GFDL...
AND HWRF MODELS THROUGH 48 HOURS. AFTER THAT TIME THE CYCLONE SHOULD
STRENGTHEN A LITTLE MORE QUICKLY AS IT MOVES OVER PROGRESSIVELY
HIGHER OCEAN HEAT CONTENT. AT DAYS 3 THROUGH 5 THE NHC FORECAST IS
CLOSEST TO BUT A LITTLE BELOW THE HWRF MODEL. THE SHIPS FORECAST
LATE IN THE PERIOD APPEARS TOO LOW DUE TO STRONG SOUTHERLY SHEAR
IMPARTED BY THE TROPICAL CYCLONE VORTEX IN THE GFS MODEL FIELDS...
WHICH IS DISPLACED TO THE SOUTH AND EAST OF THE OFFICIAL TRACK.
 
THE INITIAL MOTION ESTIMATE IS TOWARD THE WEST OR 270 DEGREES AT 13
KNOTS. THE DEPRESSION IS CURRENTLY SITUATED TO THE SOUTH OF THE
SUBTROPICAL RIDGE...BUT THE WESTERN EDGE OF THE RIDGE WILL WEAKEN
OVER THE NEXT DAY OR TWO AS A MID/UPPER-LEVEL LOW CUTS OFF AND
RETROGRADES ACROSS THE CENTRAL ATLANTIC. THIS WILL ALLOW THE
DEPRESSION TO TURN TOWARD THE WEST-NORTHWEST DURING THE NEXT DAY OR
SO. AFTER 48 HOURS...THE MID/UPPER-LEVEL-LOW WEAKENS AND THE RIDGE
RE-STRENGTHENS TO THE NORTHEAST OF THE CYCLONE...WHICH SHOULD
RESULT IN A CONTINUED WEST-NORTHWESTWARD MOTION THROUGH THE END OF
THE PERIOD. THE OFFICIAL NHC TRACK FORECAST IS SOUTH OF AND FASTER
THAN MOST OF THE GUIDANCE FOR THE FIRST 48 HOURS...AS MOST OF THE
DYNAMICAL MODELS SHOW A MORE POLEWARD AND SLOWER MOTION THAN IS
CURRENTLY OBSERVED. DURING THIS TIME THE NHC TRACK IS BETWEEN THE
DYNAMICAL MODEL CONSENSUS AND THE LBAR...WHICH TYPICALLY PERFORMS
WELL IN THE DEEP TROPICS. AT 72 HOURS AND BEYOND THE NHC FORECAST
IS CLOSE TO A BLEND OF THE HWRF...GFDL...AND ECMWF MODELS AND IS
MUCH FASTER THAN THE LATEST RUN OF THE GFS.
  
FORECAST POSITIONS AND MAX WINDS
 
INIT  29/0900Z  9.4N  26.3W   30 KT  35 MPH
 12H  29/1800Z  9.8N  28.3W   35 KT  40 MPH
 24H  30/0600Z 10.7N  30.9W   40 KT  45 MPH
 36H  30/1800Z 11.9N  33.5W   45 KT  50 MPH
 48H  31/0600Z 13.1N  36.3W   50 KT  60 MPH
 72H  01/0600Z 15.0N  42.5W   65 KT  75 MPH
 96H  02/0600Z 16.5N  48.0W   75 KT  85 MPH
120H  03/0600Z 18.0N  52.0W   85 KT 100 MPH
 
$$
FORECASTER BRENNAN
 
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 USA
nhcwebmaster@noaa.gov
Disclaimer
Credits
Information Quality
Glossary
Privacy Policy
Freedom of Information Act (FOIA)
About Us
Career Opportunities
Page last modified: Tuesday, 17-Jul-2012 13:43:55 UTC