WTNT44 KNHC 062035
TCDAT4
 
TROPICAL DEPRESSION FOURTEEN DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142011
500 PM EDT TUE SEP 06 2011
 
SATELLITE IMAGES INDICATE THAT A TROPICAL DEPRESSION HAS FORMED
WITHIN THE AREA OF DISTURBED WEATHER IN THE FAR EASTERN ATLANTIC.
THERE HAS BEEN AN INCREASE IN THE ORGANIZED CONVECTION PRIMARILY IN
BANDS TO THE NORTH AND WEST OF THE CENTER...AND THE UPPER-LEVEL
OUTFLOW IS WELL ESTABLISHED PRIMARILY IN THE WESTERN SEMICIRCLE.
DVORAK T-NUMBERS FROM TAFB AND SAB HAVE INCREASED TO 2.0 ON THE
DVORAK SCALE LEADING TO AN INITIAL INTENSITY OF 30 KNOTS. SATELLITE
IMAGES SHOW THAT THE DEPRESSION IS CURRENTLY ON A DEVELOPING
TREND...BUT GLOBAL MODELS INDICATE THAT THE UPPER-LEVEL WINDS ARE
ONLY MARGINALLY FAVORABLE FOR STRENGTHENING ALONG THE PATH OF THE
CYCLONE. THE OFFICIAL FORECAST CALLS FOR GRADUAL INTENSIFICATION...
FOLLOWING THE LGEM MODEL. NONE OF THE GUIDANCE SUGGEST SIGNIFICANT
STRENGTHENING...BUT THE DEPRESSION IS EXPECTED TO BE A HURRICANE AS
IT NEARS THE LEEWARD ISLANDS. 
 
SINCE THE DEPRESSION HAS JUST FORMED AND WE DID NOT HAVE A WELL
DEFINED CENTER BEFORE...THE INITIAL MOTION IS UNCERTAIN. IT APPEARS
THAT THE DEPRESSION IS MOVING TOWARD THE WEST-NORTHWEST AT 16 KNOTS
ON THE SOUTH SIDE OF THE ATLANTIC SUBTROPICAL RIDGE. THIS PATTERN
IS FORECAST TO PERSIST...SO THIS GENERAL MOTION WITH A GRADUAL
DECREASE IN FORWARD SPEED IS EXPECTED THROUGH FIVE DAYS. THE TRACK
GUIDANCE IS UNCERTAIN WITH THE GFS MOVING THE CYCLONE VERY FAST ON
A WEST-NORTHWEST TO NORTHWESTWARD TRACK...AND THE ECMWF A LITTLE
SLOWER AND FARTHER TO THE SOUTH. HOWEVER...IT APPEARS THAT THESE
TWO RELIABLE MODELS ARE GRADUALLY COMING INTO BETTER AGREEMENT. 
THE OFFICIAL FORECAST TRACK IS BIASED A LITTLE SLOWER TOWARD THE
ECMWF.
  
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  06/2100Z 11.8N  37.0W   30 KT  35 MPH
 12H  07/0600Z 12.3N  39.6W   35 KT  40 MPH
 24H  07/1800Z 12.9N  43.8W   40 KT  45 MPH
 36H  08/0600Z 13.7N  47.5W   45 KT  50 MPH
 48H  08/1800Z 14.5N  50.7W   50 KT  60 MPH
 72H  09/1800Z 16.0N  57.0W   55 KT  65 MPH
 96H  10/1800Z 17.0N  62.0W   60 KT  70 MPH
120H  11/1800Z 19.5N  66.5W   65 KT  75 MPH
 
$$
FORECASTER AVILA
 

WTNT44 KNHC 070243
TCDAT4
 
TROPICAL DEPRESSION FOURTEEN DISCUSSION NUMBER   2
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142011
1100 PM AST TUE SEP 06 2011

THE CLOUD PATTERN OF THE DEPRESSION HAS NOT BECOME ANY BETTER
ORGANIZED OVER THE PAST FEW HOURS. DVORAK INTENSITY ESTIMATES
WERE 2.0/30 KT FROM TAFB AND SAB AT 00Z...AND THAT REMAINS THE
INTENSITY FOR THIS ADVISORY. THE CYCLONE APPEARS TO BE MOVING
THROUGH AN ENVIRONMENT THAT SHOULD SUPPORT STRENGTHENING THROUGH
NEXT 5 DAYS...WITH GENERALLY LOW SHEAR AND A GRADUAL INCREASE IN
SSTS. HOWEVER...MOST OF THE INTENSITY GUIDANCE IS NOT TERRIBLY
ENTHUSIASTIC AND SHOWS ONLY SLOW STRENGTHENING. THE OFFICIAL
FORECAST IS UNCHANGED FROM THE PREVIOUS ADVISORY AND IS NEAR OR A
LITTLE ABOVE THE SHIPS MODEL...SHOWING THE CYCLONE BECOMING A
TROPICAL STORM IN 12 HOURS AND APPROACHING HURRICANE INTENSITY BY
THE END OF THE PERIOD. 

THE LATEST SATELLITE FIXES INDICATE THAT THE CENTER IS LOCATED A
LITTLE SOUTH AND EAST OF PREVIOUS ESTIMATES...YIELDING AN INITIAL
MOTION OF 280/16. THE CYCLONE SHOULD MOVE WESTWARD OR
WEST-NORTHWESTWARD FOR THE NEXT 3 DAYS TO THE SOUTH OF THE ATLANTIC
SUBTROPICAL RIDGE. LATE IN THE PERIOD THE CYCLONE REACHES THE
SOUTHWESTERN EDGE OF THE WEAKENING RIDGE...WHICH SHOULD RESULT IN A
TURN TOWARD THE NORTHWEST AND A GRADUAL DECREASE IN FORWARD SPEED.
WHILE THE GUIDANCE REMAINS IN OVERALL AGREEMENT ON THIS SCENARIO...
THERE CONTINUES TO BE SOME SPREAD IN THE FORWARD SPEED AMONG THE
MODELS. THE GFS AND GFDL ARE FASTEST THROUGH THE PERIOD...WITH THE
ECMWF AND UKMET ON THE SLOW SIDE OF THE ENVELOPE. OVERALL...THE NEW
NHC TRACK FORECAST IS A LITTLE FASTER THAN THE PREVIOUS ONE THROUGH
THE PERIOD...TRENDING TOWARD THE SPEED OF THE TVCA MULTI-MODEL
CONSENSUS. THROUGH 72 HOURS A SMALL SOUTHWARD ADJUSTMENT WAS MADE
TO THE TRACK FORECAST DUE TO THE MORE SOUTHERLY INITIAL POSITION.

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  07/0300Z 11.6N  38.1W   30 KT  35 MPH
 12H  07/1200Z 12.2N  40.8W   35 KT  40 MPH
 24H  08/0000Z 12.9N  44.6W   40 KT  45 MPH
 36H  08/1200Z 13.6N  48.5W   45 KT  50 MPH
 48H  09/0000Z 14.4N  52.0W   50 KT  60 MPH
 72H  10/0000Z 16.0N  58.5W   55 KT  65 MPH
 96H  11/0000Z 18.0N  63.5W   60 KT  70 MPH
120H  12/0000Z 21.0N  67.5W   65 KT  75 MPH
 
$$
FORECASTER BRENNAN
 

WTNT44 KNHC 070850
TCDAT4
 
TROPICAL DEPRESSION FOURTEEN DISCUSSION NUMBER   3
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142011
500 AM AST WED SEP 07 2011
 
DATA FROM AN EARLIER ASCAT PASS SUGGESTED THAT THE CYCLONE WAS NEAR
TROPICAL STORM STRENGTH.  HOWEVER...THE CLOUD PATTERN HAS NOT BECOME
SIGNIFICANTLY BETTER ORGANIZED AND DVORAK T-NUMBERS FROM BOTH
AGENCIES ARE 2.0...WHICH DO NOT SUPPORT NAMING THE SYSTEM AT THIS
TIME.  NORMALLY WE WOULD EXPECT SIGNIFICANT STRENGTHENING OF A
TROPICAL CYCLONE IN THIS LOCATION AT THIS TIME OF YEAR.  MOST OF THE
INTENSITY GUIDANCE...HOWEVER...DOES NOT CALL FOR MUCH OF AN INCREASE
IN STRENGTH FOR THE NEXT 72 HOURS OR SO.  THE REASONS FOR THIS ARE
NOT CLEAR...BUT WATER VAPOR IMAGERY DOES SHOW A WEAK UPPER-LEVEL
TROUGH OR SHEAR AXIS ABOUT 500 MILES TO THE NORTHWEST OF THE
DEPRESSION...AND THIS COULD BE AN INHIBITING FACTOR.  LATE
IN THE FORECAST PERIOD...THE GFDL MODEL SHOWS CONSIDERABLE
INTENSIFICATION...BUT IT IS ONE OF FEW MODELS TO DO SO. THE NHC
INTENSITY FORECAST IS ABOVE THE OPERATIONAL MODEL CONSENSUS BUT
QUITE CLOSE TO A CONSENSUS THAT INCLUDES THE HURRICANE FORECAST
IMPROVEMENT PROJECT...HFIP...MODELS.  THIS IS ALSO THE SAME AS THE
PREVIOUS OFFICIAL WIND SPEED FORECAST.  

THERE HAS BEEN SOME SCATTER IN THE CENTER FIXES...BUT A SMOOTHED
ESTIMATE OF THE INITIAL MOTION IS 280/17.  OVER THE NEXT DAY OR
TWO...THE TROPICAL CYCLONE WILL BE MOVING TO THE SOUTH OF A
STRENGTHENING SUBTROPICAL RIDGE WHICH IS LIKELY TO CAUSE SOME
ADDITIONAL INCREASE IN FORWARD SPEED.  BY DAYS 2-3...HOWEVER...THE
RIDGE BEGINS TO WEAKEN AND THE CYCLONE SHOULD BEGIN A GRADUAL TURN
TO THE RIGHT WITH DECREASING FORWARD SPEED.  THE TRACK GUIDANCE
CONTINUES TO SHOW QUITE A BIT OF SPREAD...WITH THE GFDL AND GFS
AMONG THE FASTEST OF THE MODELS AND THE ECMWF AND HWRF
SIGNIFICANTLY SLOWER.  THE OFFICIAL FORECAST FOR THIS PACKAGE IS
ONLY SLIGHTLY FASTER THAN THE PREVIOUS ONE AND NEAR OR A LITTLE TO
THE LEFT OF THE MULTI-MODEL CONSENSUS.

FORECAST POSITIONS AND MAX WINDS
 
INIT  07/0900Z 12.0N  39.9W   30 KT  35 MPH
 12H  07/1800Z 12.6N  42.7W   35 KT  40 MPH
 24H  08/0600Z 13.3N  46.8W   40 KT  45 MPH
 36H  08/1800Z 14.0N  51.0W   45 KT  50 MPH
 48H  09/0600Z 14.6N  54.5W   50 KT  60 MPH
 72H  10/0600Z 16.7N  60.5W   55 KT  65 MPH
 96H  11/0600Z 19.5N  65.5W   60 KT  70 MPH
120H  12/0600Z 22.5N  69.5W   65 KT  75 MPH
 
$$
FORECASTER PASCH
 

