WTNT45 KNHC 012044
TCDAT5
 
TROPICAL DEPRESSION FIVE DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL052012
500 PM AST WED AUG 01 2012
 
DURING THE DAY...VISIBLE SATELLITE IMAGES SHOWED THAT THE LOW-LEVEL
CIRCULATION OF THE LOW PRESSURE SYSTEM TO THE EAST OF
THE WINDWARD ISLANDS HAS BECOME BETTER DEFINED.  DEEP CONVECTION
HAS PULSED A BIT...AND IS SOMEWHAT LACKING OVER THE NORTHERN PART
OF THE CIRCULATION.  HOWEVER THE SYSTEM HAS NOW ACQUIRED SUFFICIENT
ORGANIZATION TO BE CLASSIFIED AS A TROPICAL DEPRESSION.  THE
INITIAL WIND SPEED IS SET AT 30 KT IN ACCORDANCE WITH DVORAK
ESTIMATES FROM TAFB AND SAB.  FORECASTING INTENSITY CHANGE IS
ALWAYS A CHALLENGE...AND IS PARTICULARLY TRUE IN THIS CASE.
MODERATE VERTICAL SHEAR...ASSOCIATED WITH A LARGE UPPER-LEVEL LOW
TO THE NORTH OF THE DEPRESSION...IS LIKELY TO AFFECT THE SYSTEM FOR
THE NEXT COUPLE OF DAYS.  THUS ONLY SLOW STRENGTHENING IS
ANTICIPATED DURING THE FIRST HALF OF THE FORECAST PERIOD.  LATER
ON...THE INTENSITY FORECAST UNCERTAINTY INCREASES.  OUR BEST TWO
GLOBAL MODELS ARE AT ODDS AS TO HOW THE SYSTEM WILL EVOLVE AS IT
MOVES OVER THE CARIBBEAN.  THE GFS FORECASTS THE UPPER-LEVEL
ENVIRONMENT TO BECOME QUITE CONDUCIVE FOR STRENGTHENING BY THE END
OF THE FORECAST PERIOD...WHEREAS THE ECMWF MODEL SHOWS THE SYSTEM
DEGENERATING INTO A TROPICAL WAVE.  THE OFFICIAL FORECAST LEANS
TOWARD TO THE GFS...BUT TIME WILL TELL.
 
THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 285/16.  GLOBAL MODELS
DEPICT A STRONG MID-TROPOSPHERIC ANTICYCLONE TO THE NORTH OF THE
TROPICAL CYCLONE FOR THE NEXT SEVERAL DAYS.  THIS STEERING PATTERN
SHOULD CAUSE A WEST-NORTHWESTWARD TO WESTWARD MOTION AT ABOUT THE
SAME SPEED THROUGH MUCH OF THE FORECAST PERIOD.  A WEAKNESS OVER
THE GULF OF MEXICO COULD CAUSE SOME SLOWING AND BIT OF A
NORTHWESTWARD TURN LATE IN THE PERIOD.  THE COMPUTER MODELS ARE IN
GOOD AGREEMENT...AND THE NHC TRACK FORECAST IS NOT FAR FROM THE
MODEL CONSENSUS.
 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  01/2100Z 12.2N  49.0W   30 KT  35 MPH
 12H  02/0600Z 12.7N  51.3W   40 KT  45 MPH
 24H  02/1800Z 13.3N  54.5W   45 KT  50 MPH
 36H  03/0600Z 13.8N  57.7W   50 KT  60 MPH
 48H  03/1800Z 14.4N  60.9W   55 KT  65 MPH
 72H  04/1800Z 15.5N  67.0W   55 KT  65 MPH
 96H  05/1800Z 16.5N  73.0W   60 KT  70 MPH
120H  06/1800Z 17.5N  78.0W   65 KT  75 MPH
 
$$
FORECASTER PASCH/BLAKE
 

WTNT45 KNHC 020240
TCDAT5
 
TROPICAL DEPRESSION FIVE DISCUSSION NUMBER   2
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL052012
1100 PM AST WED AUG 01 2012
 
SINCE THE PREVIOUS ADVISORY...CONVECTION ASSOCIATED WITH THE
DEPRESSION HAS WANED. HOWEVER...IT IS NOT UNUSUAL FOR CONVECTION 
TO FLUCTUATE IN ASSOCIATION WITH WEAK AND DEVELOPING TROPICAL
CYCLONES. EROSION OF THE INNER CORE CONVECTION IS ALSO LIKELY DUE
TO THE ENTRAINMENT OF DRY MID-LEVEL AIR INTO THE NORTHWEST QUADRANT
AS NOTED IN VARIOUS WATER VAPOR PRODUCTS OVER THE PAST 8 HOURS. THE
INITIAL INTENSITY REMAINS AT 30 KT...WHICH IS SUPPORTED BY A
UW-CIMSS ADT INTENSITY ESTIMATE OF T2.2/32 KT.

THE INITIAL MOTION REMAINS 285/16 KT. THERE IS NO SIGNIFICANT CHANGE
TO THE PREVIOUS FORECAST TRACK OR REASONING. A DEEP-LAYER
SUBTROPICAL RIDGE TO THE NORTH OF THE CYCLONE IS EXPECTED TO REMAIN
IN PLACE THROUGH THE FORECAST PERIOD....WHICH SHOULD KEEP THE
DEPRESSION MOVING IN A GENERAL WEST-NORTHWESTWARD MOTION THROUGH
120 H. THE NHC MODEL GUIDANCE IS IN EXCELLENT AGREEMENT ON THIS
SCENARIO...AND THE CURRENT FORECAST TRACK IS JUST AN UPDATE OF THE
PREVIOUS ADVISORY TRACK...AND LIES NORTH OF THE MODEL CONSENSUS DUE
TO THE MORE SOUTHERLY GFDL MODEL TRACK THAT IS CONSIDERED TO BE AN
OUTLIER DUE TO IT DEPICTING A MUCH WEAKER SYSTEM THAN FORECAST.

ONCE THE AFOREMENTIONED DRY AIR ENTRAINMENT PROCESS ABATES...
CONVECTION SHOULD REDEVELOP NEAR THE CENTER SINCE THE SYSTEM STILL
HAS A VERY ROBUST CIRCULATION AS NOTED IN RECENT SSMI AND AMSU
MICROWAVE SATELLITE DATA. HOWEVER...VERTICAL SHEAR CONDITIONS ARE
ONLY EXPECTED TO BE MARGINALLY CONDUCIVE FOR SLOW DEVELOPMENT TO
OCCUR OVER THE NEXT 48-72 HOURS. BY DAYS 4 AND 5...MORE SIGNIFICANT
INTENSIFICATION WILL BE POSSIBLE WHEN THE CYCLONE IS LOCATED OVER
THE WARMER CARIBBEAN SEA AND IN A MORE FAVORABLE UPPER-LEVEL WIND
ENVIRONMENT. THE INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS
ADVISORY...AND IS CLOSE TO A BLEND OF THE SHIPS AND LGEM INTENSITY
FORECAST MODELS.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  02/0300Z 12.6N  50.6W   30 KT  35 MPH
 12H  02/1200Z 13.0N  53.0W   35 KT  40 MPH
 24H  03/0000Z 13.6N  56.1W   40 KT  45 MPH
 36H  03/1200Z 14.2N  59.3W   45 KT  50 MPH
 48H  04/0000Z 14.7N  62.5W   50 KT  60 MPH
 72H  05/0000Z 15.8N  68.5W   55 KT  65 MPH
 96H  06/0000Z 16.8N  74.3W   60 KT  70 MPH
120H  07/0000Z 17.8N  78.7W   65 KT  75 MPH
 
$$
FORECASTER STEWART
 

WTNT45 KNHC 020841
TCDAT5
 
TROPICAL DEPRESSION FIVE DISCUSSION NUMBER   3
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL052012
500 AM AST THU AUG 02 2012
 
THUNDERSTORM ACTIVITY ASSOCIATED WITH THE DEPRESSION HAS GENERALLY
DIMINISHED DURING THE LAST SEVERAL HOURS...WITH DEEP CONVECTION NOW
CONFINED TO THE SOUTH OF THE LOW-LEVEL CENTER. ALTHOUGH DVORAK
T-NUMBERS HAVE DECREASED TO 1.5 AND 1.0 FROM TAFB AND SAB...THE
INITIAL INTENSITY IS HELD AT 30 KT. THERE IS A POSSIBILITY THAT THE
DEPRESSION COULD DEGENERATE INTO A REMNANT LOW OR TROPICAL WAVE
LATER TODAY IF THE CURRENT WEAKENING TREND CONTINUES.  IF THIS IS
THE CASE...THEN ADJUSTMENTS TO THE TROPICAL STORM WATCH MAY BE
NECESSARY.
 
LATEST FIXES SUGGEST THAT THE DEPRESSION HAS INCREASED ITS FORWARD
SPEED...WITH THE INITIAL MOTION ESTIMATE NOW 280/18.  LARGE-SCALE
MODELS AGREE THAT THE DEPRESSION WILL MOVE QUICKLY WESTWARD OR WEST-
NORTHWESTWARD ON THE SOUTH SIDE OF A LOW- TO MID-LEVEL RIDGE DURING
THE NEXT SEVERAL DAYS. LATER IN THE FORECAST PERIOD...THE SPREAD IN
THE GUIDANCE INCREASES...WITH THE UKMET SHOWING A MORE
NORTHWESTWARD TRACK AS THE CYCLONE RESPONDS TO A WEAKNESS TO THE
NORTH.  THE ECMWF/GFS SOLUTIONS SHOW A STRONGER RIDGE AND MAINTAIN A
WESTWARD HEADING.  THE NEW NHC TRACK FORECAST IS ADJUSTED SLIGHTLY
SOUTHWARD THROUGHOUT THE FORECAST PERIOD...WITH MORE WEIGHT GIVEN
TO THE MORE RELIABLE ECMWF/GFS OUTPUT ON DAYS 4-5.
 
UW-CIMSS AND SHIPS ANALYSES INDICATE 20 KT OF WESTERLY SHEAR...
ASSOCIATED WITH AN UPPER-LEVEL TROUGH TO THE NORTH...AFFECTING THE
CYCLONE. THE GUIDANCE SHOWS A CONTINUATION OF THIS SHEAR OVER THE
DEPRESSION THROUGH THE NEXT COUPLE OF DAYS...ESPECIALLY SINCE THE
SYSTEM WILL BE MOVING INTO AN ENVIRONMENT CHARACTERIZED BY STRONG
LOW- TO MID-LEVEL EASTERLY FLOW AND WEAKER FLOW ALOFT. ASSUMING THE
SYSTEM SURVIVES...GLOBAL MODELS SHOW A MORE FAVORABLE ENVIRONMENT
OVER THE WESTERN CARIBBEAN IN 4-5 DAYS...WHERE INTENSIFICATION COULD
OCCUR. GIVEN THE CURRENT TREND...THE NHC INTENSITY FORECAST IS
REDUCED...ESPECIALLY EARLY IN THE FORECAST PERIOD...AND IS LINE
WITH THE LATEST SHIPS/LGEM OUTPUT.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  02/0900Z 12.8N  52.6W   30 KT  35 MPH
 12H  02/1800Z 13.3N  55.2W   30 KT  35 MPH
 24H  03/0600Z 13.7N  58.5W   30 KT  35 MPH
 36H  03/1800Z 14.0N  61.6W   35 KT  40 MPH
 48H  04/0600Z 14.6N  64.9W   40 KT  45 MPH
 72H  05/0600Z 15.7N  71.3W   45 KT  50 MPH
 96H  06/0600Z 16.7N  76.7W   50 KT  60 MPH
120H  07/0600Z 18.0N  80.5W   60 KT  70 MPH
 
$$
FORECASTER KIMBERLAIN/AVILA
 

WTNT45 KNHC 021436
TCDAT5
 
TROPICAL DEPRESSION FIVE DISCUSSION NUMBER   4
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL052012
1100 AM AST THU AUG 02 2012

AFTER LOOKING VERY DISORGANIZED OVERNIGHT...SATELLITE IMAGERY THIS
MORNING SHOWS A MARGINALLY BETTER STRUCTURE WITH EVIDENCE OF
INCREASED CONVECTIVE BANDING.  NOAA BUOY 41040...TO THE NORTH OF
THE CENTER...REPORTED 31 KT WINDS.  THE INTENSITY IS KEPT AT 30 KT
PENDING THE ARRIVAL OF AN AIR FORCE HURRICANE HUNTER AIRCRAFT IN
THE CYCLONE...SCHEDULED FOR 1800 UTC.  DYNAMICAL GUIDANCE SHOWS
THAT THE VERTICAL SHEAR SHOULD DECREASE SOMEWHAT IN THE NEXT DAY OR
TWO AND THIS COULD ALLOW FOR SOME STRENGTHENING.  HOWEVER THE 1200
UTC SOUNDING FROM TRINIDAD SHOWED A LOW-TO MID-LEVEL EASTERLY JET
TO THE SOUTH OF THE LATITUDE OF THE DEPRESSION...AND THIS COULD BE
AN INHIBITING FACTOR FOR INTENSIFICATION.  THE OFFICIAL INTENSITY
FORECAST IS SIMILAR TO THE PREVIOUS ONE.

THE MOTION CONTINUES WESTWARD AT A FAIRLY SWIFT 17 KT.  A
MID-TROPOSPHERIC HIGH OVER THE WESTERN ATLANTIC SHOULD MAINTAIN A
WELL-DEFINED EASTERLY STEERING CURRENT OVER THE CARIBBEAN FOR THE
NEXT SEVERAL DAYS.  THIS PATTERN IS LIKELY TO KEEP THE CYCLONE ON A
MAINLY WESTWARD TRACK FOR THE NEXT 72 HOURS OR SO.  LATER IN THE
FORECAST PERIOD...AS THE SYSTEM NEARS A WEAKNESS IN THE RIDGE...A
GRADUAL TURN TOWARD THE WEST-NORTHWEST IS EXPECTED.  THE OFFICIAL
TRACK FORECAST IS NUDGED SLIGHTLY TO THE SOUTH OF THE PREVIOUS
ONE BUT IS OTHERWISE UNCHANGED.  THIS IS ALSO VERY CLOSE TO THE
DYNAMICAL MODEL CONSENSUS.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  02/1500Z 13.0N  54.3W   30 KT  35 MPH
 12H  03/0000Z 13.4N  56.9W   30 KT  35 MPH
 24H  03/1200Z 13.8N  60.4W   30 KT  35 MPH
 36H  04/0000Z 14.1N  63.6W   35 KT  40 MPH
 48H  04/1200Z 14.7N  66.8W   40 KT  45 MPH
 72H  05/1200Z 15.7N  73.0W   45 KT  50 MPH
 96H  06/1200Z 17.0N  78.0W   50 KT  60 MPH
120H  07/1200Z 18.5N  82.0W   60 KT  70 MPH
 
$$
FORECASTER PASCH
 

