WTNT41 KNHC 281458
TCDAT1
TROPICAL DEPRESSION SIXTEEN DISCUSSION NUMBER   1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL162010
1100 AM EDT TUE SEP 28 2010
 
SURFACE OBSERVATIONS AND SATELLITE IMAGES INDICATE THAT THE LOW
PRESSURE AREA OVER THE NORTHWESTERN CARIBBEAN SEA HAS ACQUIRED A
SUFFICIENTLY WELL-DEFINED CENTER OF CIRCULATION AND ORGANIZED DEEP
CONVECTION TO BE CLASSIFIED AS A TROPICAL CYCLONE.  THE SURFACE
DATA INDICATE THAT THE SYSTEM IS VERY CLOSE TO TROPICAL STORM
INTENSITY.  SOUTH-SOUTHWESTERLY VERTICAL SHEAR ASSOCIATED WITH A
LARGE UPPER-LEVEL TROUGH MOVING INTO THE SOUTHEASTERN UNITED STATES
SHOULD LIMIT INTENSIFICATION AS THE SYSTEM MOVES ACROSS CUBA AND
TOWARD SOUTHEASTERN FLORIDA.  THE OFFICIAL INTENSITY FORECAST IS
SIMILAR TO THE STATISTICAL/DYNAMICAL LGEM GUIDANCE.  BY 48
HOURS...DYNAMICAL GUIDANCE SHOWS THE CYCLONE MERGING WITH A FRONTAL
ZONE.  DISSIPATION SHOULD OCCUR IN 72 HOURS OR SOONER AS THE MODELS
DEPICT A NEW BAROCLINIC DEVELOPMENT NEAR THE CAROLINAS.

INITIAL MOTION IS ABOUT 020/9.  THE CYCLONE IS EXPECTED TO CONTINUE
A GENERALLY NORTH-NORTHEASTWARD MOTION AHEAD OF THE AFOREMENTIONED
MID- TO UPPER-LEVEL TROUGH...AND WEST OF A SUBTROPICAL ANTICYCLONE. 
THE OFFICIAL TRACK FORECAST IS NEAR THE WESTERN SIDE OF THE MODEL
ENVELOPE.

IT SHOULD BE NOTED THAT THE STRONGEST WINDS AND HEAVIEST RAINS
ASSOCIATED WITH THIS SYSTEM ARE OCCURING WELL TO THE SOUTHEAST OF
THE CENTER.  IF THIS STRUCTURE PERSISTS...THE TRACK OF THE CENTER
WILL BE RELATIVELY UNIMPORTANT SINCE SIGNIFICANT IMPACTS WILL BE
CONFINED TO THE EASTERN PORTION OF THE CIRCULATION.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      28/1500Z 20.6N  82.5W    30 KT
 12HR VT     29/0000Z 21.6N  81.8W    35 KT
 24HR VT     29/1200Z 23.5N  80.7W    40 KT
 36HR VT     30/0000Z 26.5N  80.0W    40 KT
 48HR VT     30/1200Z 31.0N  78.5W    40 KT...POST-TROP/EXTRATROP
 72HR VT     01/1200Z...DISSIPATED
 
$$
FORECASTER PASCH
 


WTNT41 KNHC 290242
TCDAT1
TROPICAL DEPRESSION SIXTEEN DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL162010
1100 PM EDT TUE SEP 28 2010

TROPICAL DEPRESSION SIXTEEN CONTINUES TO HAVE A STRUCTURE MORE
CHARACTERISTIC OF A WESTERN NORTH PACIFIC/NORTH INDIAN OCEAN
MONSOON DEPRESSION.  SURFACE OBSERVATIONS CONTINUE TO INDICATE
WINDS OF 20 KT OR LESS OVER AN AREA ENCOMPASSING 100 N MI IN
DIAMETER FROM THE CENTER...AND THAT THE STRONGEST WINDS AND
CONVECTION ARE 250-300 N MI AWAY FROM THE CENTER IN THE
SOUTHEASTERN QUADRANT.  AN EARLIER AIR FORCE RESERVE HURRICANE
HUNTER MISSION IN THIS AREA FOUND FLIGHT-LEVEL WINDS SUPPORTING AN
INITIAL INTENSITY OF 30 KT.  SURFACE OBSERVATIONS INDICATE THAT THE
CENTRAL PRESSURE IS NEAR 997 MB.

THERE ARE MULTIPLE LOW-LEVEL CLOUD SWIRLS PRESENT...AND THE CENTER
APPEARS TO RE-FORM FROM TIME TO TIME.  THE INITIAL MOTION OF 035/7
IS THUS A BIT UNCERTAIN.  OTHER THAN THAT...THERE IS NO CHANGE IN
THE FORECAST PHILOSOPHY FROM THE PREVIOUS ADVISORY...AND ONLY MINOR
CHANGES TO THE FORECAST TRACK.  A COMBINATION OF A DEEP-LAYER
TROUGH OVER THE SOUTHEASTERN UNITED STATES AND EASTERN GULF OF
MEXICO AND A LOW/MID-LEVEL RIDGE OVER THE WESTERN ATLANTIC SHOULD
STEER THE CYCLONE NORTH-NORTHEASTWARD WITH ACCELERATION FOR THE
NEXT 12-24 HOURS...FOLLOWED BY A QUICK NORTHWARD MOTION.  THERE IS
SOME SPREAD IN BOTH THE SPEED AND DIRECTION OF MOTION BY 48 HR. 
THE GFS... GFDL...AND HWRF ARE MUCH FASTER AND TO THE LEFT OF THE
REST OF THE GUIDANCE...WHILE THE NOGAPS...GFDN...AND GFS ENSEMBLE
MEAN ARE SLOWER AND TO THE RIGHT.  THESE DIFFERENCES LIKELY RESULT
FROM THE MODEL HANDLING OF THE DEPRESSION INTERACTING WITH A
DEVELOPING BAROCLINIC LOW OVER THE EASTERN UNITED STATES.  THE NEW
FORECAST TRACK IS DOWN THE MIDDLE OF THE GUIDANCE ENVELOPE CLOSE TO
THE CONSENSUS MODELS.

THE DEPRESSION IS CURRENTLY IN AN ENVIRONMENT OF 15 KT OF
SOUTHWESTERLY VERTICAL WIND SHEAR...WHICH THE LARGE-SCALE MODELS
FORECAST TO INCREASE DURING THE NEXT 12-24 HR.  THUS...NEITHER THE
ENVIRONMENT NOR THE CURRENT STRUCTURE ARE CONDUCIVE FOR SIGNIFICANT
STRENGTHENING.  THE INTENSITY FORECAST IS THE SAME AS IN THE
PREVIOUS ADVISORY...WITH MODEST STRENGTHENING ALONG THE LINES OF
THE SHIPS AND LGEM MODELS.  EXTRATROPICAL TRANSITION IS EXPECTED TO
BEGIN IN ABOUT 24 HR OR SO AND BE COMPLETE BY 36-48 HR.  THE
CYCLONE IS FORECAST TO BE ABSORBED BY THE EASTERN U. S. BAROCLINIC
LOW AFTER 48 HR...AS FORECAST BY MOST OF THE DYNAMICAL GUIDANCE.
 
UNLESS THE STRUCTURE CHANGES RADICALLY IN THE NEXT 12-24 HOURS...IT
IS LIKELY THAT THERE WILL CONTINUE TO BE A LARGE AREA OF LIGHT
WINDS NEAR THE CENTER.  THE STRONGEST WINDS SHOULD OCCUR IN AREAS
WELL TO THE EAST OF THE FORECAST TRACK.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      29/0300Z 21.9N  81.9W    30 KT
 12HR VT     29/1200Z 23.3N  81.2W    35 KT
 24HR VT     30/0000Z 26.3N  80.2W    40 KT
 36HR VT     30/1200Z 30.6N  79.3W    40 KT...POST-TROP/EXTRATROP
 48HR VT     01/0000Z 36.3N  78.0W    35 KT...POST-TROP/EXTRATROP
 72HR VT     02/0000Z...ABSORBED BY EXTRATROPICAL LOW
 
$$
FORECASTER BEVEN
 


WTNT41 KNHC 290857
TCDAT1
TROPICAL DEPRESSION SIXTEEN DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL162010
500 AM EDT WED SEP 29 2010
 
ALTHOUGH THE SATELLITE APPEARANCE OF TROPICAL DEPRESSION SIXTEEN HAS
CHANGED LITTLE SINCE THE LAST ADVISORY...DOPPLER RADAR DATA FROM
KEY WEST AND MIAMI...ALONG WITH RADAR RADAR FROM CUBA INDICATE
CONVECTION HAS INCREASED IN THE NORTHERN SEMICIRCLE. ALSO...AN AIR
FORCE RESERVE RECONNAISSANCE AIRCRAFT FLYING BETWEEN FLORIDA AND
CUBA HAS INDICATED SURFACE WINDS OF 33 KT IN UNCONTAMINATED SFMR
DATA ABOUT 80-120 NMI EAST-NORTHEAST OF THE CENTER...WHICH IS MUCH
CLOSER TO THE CENTER THAN SEEN NOTED IN PRIOR SURFACE OBSERVATIONS
AND RECON DATA. THE LARGEST DOPPLER RADAR VELOCITY VALUES DETECTED
THUS FAR HAVE BEEN 40-44 KT BETWEEN 6000-12000 FT. THIS INDICATES
THAT THE DEPRESSION IS VERY NEAR BECOMING A TROPICAL STORM. 
 
THE DEPRESSION IS ON TRACK AND THE THE INITIAL MOTION ESTIMATE IS
020/12. 00Z UPPER-AIR DATA AND WATER VAPOR IMAGERY INDICATED THE
MID- TO UPPER-LEVEL FLOW ACROSS THE EASTERN GULF OF MEXICO...THE
SOUTHEASTERN U.S. AND THE EXTREME NORTHWESTERN CARIBBEAN SEA HAS
BEEN STEADILY BACKING AROUND FROM THE WEST TO THE SOUTH-SOUTHWEST
DURING THE PAST 24 HOURS. AS A SERIES OF STRONG SHORTWAVE TROUGHS
DIG SOUTHWARD DOWN THE WEST SIDE OF THE LONGWAVE TROUGH LOCATED
ALONG 85W...THE FLOW ACROSS FLORIDA SHOULD BECOME MORE SOUTHERLY.
THIS FLOW PATTERN SHOULD ACCELERATE THE DEPRESSION TO THE 
NORTH-NORTHEAST ACROSS SOUTHEASTERN FLORIDA AS A TROPICAL CYCLONE
TODAY...AND INTO THE CAROLINAS AS AN EXTRATROPICAL LOW PRESSURE
SYSTEM IN 36 HOURS OR SO. ALTHOUGH THE MODEL CONSENSUS HAS SHIFTED
A LITTLE TO THE EAST IN THE LATEST MODEL RUNS...THE STRONG BACKING
FLOW PATTERN MENTIONED PREVIOUSLY ARGUES FOR KEEPING THE FORECAST
TRACK ALONG THE WESTERN OR LEFT SIDE OF THE MODEL GUIDANCE 
ENVELOPE. AS A RESULT...THE OFFICIAL FORECAST TRACK IS JUST AN
EXTENSION OF THE PREVIOUS ADVISORY TRACK.
 
THE VERTICAL SHEAR IS EXPECTED TO DECREASE SLIGHTLY DURING THE NEXT
12 HOURS BEFORE INCREASING TO ABOVE 30 KT IN ABOUT 36 HOURS. AS A
RESULT...THERE WILL BE A BRIEF WINDOW OF OPPORTUNITY FOR SOME
STRENGTHENING TO OCCUR PRIOR TO THE CYCLONE MAKING LANDFALL ALONG
THE SOUTHEASTERN FLORIDA COAST LATER TODAY. EXTRATROPICAL
TRANSITION IS EXPECTED TO BEGIN IN 24 HOURS OR SO AND BE COMPLETE
BY 36-48 HR AS THE SYSTEM NEARS THE COAST OF THE CAROLINAS WHERE IT
IS EXPECTED TO MERGE WITH A FRONTAL SYSTEM. BY 48 HOURS...THE LOW
IS FORECAST TO BE ABSORBED BY A LARGER U. S. BAROCLINIC OVER THE
NORTHEASTERN  UNITED STATES. THE OFFICIAL INTENSITY FORECAST IS
SIMILAR TO THE PREVIOUS ADVISORY AND IS A BLEND OF THE SHIPS AND
LGEM INTENSITY MODELS. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      29/0900Z 23.3N  81.4W    30 KT
 12HR VT     29/1800Z 25.2N  80.7W    35 KT
 24HR VT     30/0600Z 28.9N  79.7W    40 KT
 36HR VT     30/1800Z 33.8N  78.6W    40 KT...POST-TROP/EXTRATROP
 48HR VT     01/0600Z 40.0N  77.3W    35 KT...POST-TROP/EXTRATROP
 72HR VT     02/0600Z...DISSIPATED
 
$$
FORECASTER STEWART
 


