WTNT43 KNHC 310243
TCDAT3
TROPICAL DEPRESSION THREE DISCUSSION NUMBER   1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032007
1100 PM EDT MON JUL 30 2007
 
THE AREA OF LOW PRESSURE THAT PASSED TO THE WEST OF BERMUDA EARLIER
TODAY HAS BEEN MAINTAINING CONSISTENT DEEP CONVECTION FOR THE LAST
15 HOURS OR SO.  THE LOW-LEVEL CIRCULATION CENTER...EXPOSED FOR
MUCH OF THE DAY...HAS MADE A COUPLE OF FORAYS UNDERNEATH THE
CONVECTION...AND IS WELL-ENOUGH INVOLVED WITH THE CONVECTION TO
CONSIDER THE SYSTEM A TROPICAL DEPRESSION.  SHIP REPORTS AND
QUIKSCAT OBSERVATIONS SUGGEST AN INTENSITY OF 30 KT.  WITH ANOTHER
TWELVE HOURS OR SO OVER WARM WATERS...THE CYCLONE WILL HAVE AN
OPPORTUNITY TO REACH STORM STRENGTH AS IT ACCELERATES
NORTHEASTWARD...BUT SOUTHWESTERLY SHEAR SHOULD KEEP ANY DEVELOPMENT
AS A TROPICAL SYSTEM MINIMAL...AND THE CYCLONE IS EXPECTED TO
BECOME A FRONTAL LOW WITHIN ABOUT 24 HOURS.  LARGE-SCALE MODELS
GENERALLY SUGGEST THAT THE SYSTEM COULD BE A VIGOROUS EXTRATROPICAL
LOW FOR SEVERAL DAYS ACROSS THE NORTH ATLANTIC.  

THE INITIAL MOTION IS 020/14.  A LARGE MID-LATITUDE TROUGH ALONG THE
ATLANTIC U.S. COAST WILL STEER THE DEPRESSION GENERALLY
NORTHEASTWARD UNTIL THE CYCLONE BECOMES EXTRATROPICAL.  MODEL
GUIDANCE IS IN GOOD AGREEMENT AND THE OFFICIAL FORECAST FOLLOWS A
BLEND OF THE GFDL...HWRF...AND GFS GUIDANCE.  THE EXTRATROPICAL
PORTION OF THE FORECAST IS IN GOOD AGREEMENT WITH THE GFS GUIDANCE.  
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      31/0300Z 36.1N  66.0W    30 KT
 12HR VT     31/1200Z 38.2N  64.5W    35 KT
 24HR VT     01/0000Z 42.5N  60.0W    35 KT...EXTRATROPICAL
 36HR VT     01/1200Z 47.5N  52.0W    40 KT...EXTRATROPICAL
 48HR VT     02/0000Z 52.5N  43.0W    40 KT...EXTRATROPICAL
 72HR VT     03/0000Z 58.0N  30.0W    40 KT...EXTRATROPICAL
 96HR VT     04/0000Z 61.0N  23.0W    45 KT...EXTRATROPICAL
120HR VT     05/0000Z 65.0N  15.0W    45 KT...EXTRATROPICAL
 
$$
FORECASTER FRANKLIN
 

WTNT43 KNHC 310858
TCDAT3
TROPICAL DEPRESSION THREE DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032007
500 AM EDT TUE JUL 31 2007
 
LATEST SATELLITE IMAGERY INDICATES A PARTIALLY EXPOSED LOW-LEVEL
CIRCULATION CENTER WITH THE DEEP CONVECTION OCCUPYING THE NORTH-
EASTERN SEMICIRCLE.  AT 0600 UTC...SHIPS C60Y4 AND ZCDM6 REPORTED
SUSTAINED 32 KT AND 31 KT WINDS RESPECTIVELY.  DVORAK INTENSITY
ESTIMATES FROM TAFB WERE 2.0...AND UW-CIMSS AUTOMATED 3-HR AVERAGED
INTENSITY ESTIMATES HAVE BEEN RUNNING AROUND 30 KT AS WELL.  BASED
ON THE ABOVE...THE INITIAL INTENSITY WILL BE HELD CONSERVATIVELY AT
30 KT. 

THE INITIAL MOTION IS ESTIMATED AT 025/18...A LITTLE FASTER THAN
EARLIER.  THE DEPRESSION IS CURRENTLY BEING STEERED AHEAD OF A
LARGE MID-LATITUDE TROUGH ALONG THE U.S. EASTERN SEABOARD. THE
DYNAMICAL MODEL GUIDANCE IS IN CLOSE AGREEMENT WITH AN ACCELERATION
TOWARD THE NORTHEAST AND EAST-NORTHEAST THROUGH 3 OR 4 DAYS.  THE
MODELS...HOWEVER...SIGNIFICANTLY DIFFER AS TO WHETHER THE CYCLONE
WILL BECOME ABSORBED IN THE FRONTAL SYSTEM CURRENTLY TO THE
NORTHWEST...OR REMAIN ITS OWN ENTITY. THE OFFICIAL TRACK FORECAST...
ALBEIT A LOW CONFIDENCE ONE...KEEPS THE SYSTEM SEPARATE THROUGH 5
DAYS SIMILAR TO THE PREVIOUS ADVISORY. 

THE CYCLONE IS STILL OVER 26-27C WATERS...AND A SMALL WINDOW OF
OPPORTUNITY REMAINS FOR IT TO REACH TROPICAL STORM STRENGTH BEFORE
TRANSITIONING TO AN EXTRATROPICAL CYCLONE.  FSU PHASE-SPACE
DIAGRAMS DERIVED FROM GLOBAL MODEL FIELDS SUGGEST FULL TRANSITION
IN ABOUT 24 TO 36 HOURS.  SHIPS GUIDANCE HAS THE EXTRATROPICAL
CYCLONE STRENGTHENING TO A POWERFUL 60 KT STORM IN 3 DAYS.  THE
OFFICIAL INTENSITY FORECAST DOES INDICATE STRENGTHENING BUT IS LESS
BULLISH THAN SHIPS AND A BIT HIGHER THAN THE PREVIOUS FORECAST. 

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      31/0900Z 37.8N  64.9W    30 KT
 12HR VT     31/1800Z 40.4N  62.5W    35 KT
 24HR VT     01/0600Z 44.5N  57.0W    40 KT...EXTRATROPICAL
 36HR VT     01/1800Z 49.2N  47.6W    45 KT...EXTRATROPICAL
 48HR VT     02/0600Z 55.0N  37.0W    45 KT...EXTRATROPICAL
 72HR VT     03/0600Z 59.0N  28.5W    50 KT...EXTRATROPICAL
 96HR VT     04/0600Z 61.0N  21.0W    50 KT...EXTRATROPICAL
120HR VT     05/0600Z 63.0N  13.5W    45 KT...EXTRATROPICAL
 
$$
FORECASTER MAINELLI
 

