WTNT43 KNHC 190257
TCDAT3
TROPICAL DEPRESSION THREE DISCUSSION NUMBER   1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032008
1100 PM EDT FRI JUL 18 2008
 
OVER THE PAST SEVERAL HOURS...CONVECTION ASSOCIATED WITH THE AREA OF
LOW PRESSURE OFF THE GEORGIA COAST HAS BECOME MORE CONCENTRATED
WITH AMPLE MID-LEVEL ROTATION. PERSISTENT NORTHWESTERLY WINDS FROM
A SKIDAWAY INSTITUTE OF OCEANOGRAPHY 50 METER TOWER A SHORT
DISTANCE WEST OF THE MAIN AREA OF CONVECTION INDICATE THAT THE
CIRCULATION HAS BECOME BETTER DEFINED SINCE THIS AFTERNOON.
CONSEQUENTLY...ADVISORIES ARE INITIATED ON TROPICAL DEPRESSION
THREE. THERE ARE NO INDICATIONS...EITHER FROM COASTAL RADAR OR
SURFACE OBSERVATIONS...THAT THE SYSTEM HAS ACQUIRED MUCH IN THE WAY
OF STRONG WINDS YET...AND THE INITIAL INTENSITY IS SET AT 25 KT.

THE INITIAL MOTION IS ESTIMATED TO BE 040/5.  STEERING CURRENTS ARE
WEAK...WITH THE DEPRESSION SITTING BETWEEN A MID-LEVEL RIDGE EAST
OF THE BAHAMAS AND A WEAKER ONE OVER THE TENNESSEE VALLEY.  MODEL
GUIDANCE IS IN PRETTY GOOD AGREEMENT THAT A SLOW NORTHEASTWARD
MOTION WILL CONTINUE...VERY CLOSE TO THE COAST OF THE CAROLINAS...
FOR THE NEXT DAY OR TWO...WITH A GRADUAL ACCELERATION INTO THE
WESTERLIES BEFORE THE SYSTEM BECOMES ABSORBED BY THE NEXT
MID-LATITUDE SHORT WAVE.  THE OFFICIAL FORECAST IS NEAR THE
CONSENSUS OF THE TIGHTLY PACKED GUIDANCE...ALTHOUGH I'LL NOTE THAT
BOTH THE GFDL AND HWRF HAVE TRACKS THAT ESSENTIALLY STRADDLE THE
COASTLINE.  BECAUSE THE FORECAST TRACK IS NEARLY PARALLEL TO THE
ORIENTATION OF THE COASTLINE...IT IS IMPOSSIBLE TO PINPOINT A
POSSIBLE LANDFALL LOCATION AT THIS TIME.

THE ENVIRONMENT DOES NOT SEEM CONDUCIVE TO RAPID DEVELOPMENT.  THE
UPPER-LEVEL WINDS ARE SOMEWHAT DIVERGENT...BUT THERE IS A LOT OF
DRY AIR NEARBY OVER THE SOUTHEASTERN UNITED STATES.  EXCEPT FOR THE
CLIMATOLOGY AND PERSISTENCE MODEL SHIFOR...NONE OF THE INTENSITY
GUIDANCE MAKES THE SYSTEM A TROPICAL STORM.  HOWEVER...THE SHIPS
FORECAST SEEMS TO BE BASED ON SSTS THAT LOOK AT LEAST 1C COOLER
THAN WHAT THE COASTAL BUOYS ARE REPORTING RIGHT NOW...SO I'M GOING
TO GO A LITTLE ABOVE THAT GUIDANCE AND SHOW JUST ENOUGH
STRENGTHENING TO MAKE THE SYSTEM A TROPICAL STORM.  THE FORECAST
TRACK AND INTENSITIES REQUIRE THE ISSUANCE OF TROPICAL STORM
WATCHES AND WARNINGS.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      19/0300Z 31.9N  79.6W    25 KT
 12HR VT     19/1200Z 32.4N  79.1W    30 KT
 24HR VT     20/0000Z 33.4N  78.0W    35 KT
 36HR VT     20/1200Z 34.4N  76.6W    35 KT
 48HR VT     21/0000Z 35.5N  75.0W    35 KT
 72HR VT     22/0000Z 38.0N  70.5W    35 KT
 96HR VT     23/0000Z...ABSORBED
 
$$
FORECASTER FRANKLIN
 

WTNT43 KNHC 190833
TCDAT3
TROPICAL DEPRESSION THREE DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032008
500 AM EDT SAT JUL 19 2008
 
SATELLITE...RADAR AND SURFACE OBSERVATIONS INDICATE THAT THERE HAS
BEEN LITTLE CHANGE IN THE STRUCTURE OF THE DEPRESSION DURING THE
PAST FEW HOURS. THE CENTER IS DIFFICULT TO LOCATE BUT APPEARS TO BE
ON THE NORTHWESTERN EDGE OF A CYCLONICALLY CURVED CONVECTIVE BAND.
INITIAL INTENSITY REMAINS AT 25 KNOTS.  THE ENVIRONMENT IS
MARGINALLY FAVORABLE FOR DEVELOPMENT AND ONLY A SLIGHT INCREASE IN
INTENSITY IS INDICATED IN THE FORECAST. NEVERTHERELESS...THE SYSTEM
COLD BECOME A 35-KNOT TROPICAL STORM. AN AIR FORCE PLANE WILL CHECK
THE DEPRESSION LATER TODAY.
 
THE BEST ESTIMATE OF THE INITIAL MOTION IS 035 DEGREES AT 4 KNOTS
AND THIS MOTION IS UNCERTAIN SINCE THE CENTER IS DIFFICULT TO
LOCATE. THE DEPRESSION IS EXPECTED TO BE EMBEDDED WITHIN THE
MID-LATITUDE WESTERLIES AND THIS PATTERN SHOULD CONTINUE TO STEER
THE CYCLONE TOWARD THE NORTHEAST WITH A SLIGHT INCREASE IN FORWARD
SPEED UNTIL ABSORBED BY A SHORT WAVE. THE OFFICIAL FORECAST IS IN
THE MIDDLE OF THE GUIDANCE ENVELOPE...VERY CLOSE TO THE MODEL
CONSENSUS.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      19/0900Z 32.4N  79.4W    25 KT
 12HR VT     19/1800Z 33.0N  78.7W    30 KT
 24HR VT     20/0600Z 34.0N  77.3W    35 KT
 36HR VT     20/1800Z 35.0N  76.0W    35 KT
 48HR VT     21/0600Z 36.5N  73.5W    35 KT
 72HR VT     22/0600Z 39.0N  69.0W    35 KT
 96HR VT     23/0600Z...ABSORBED
 
$$
FORECASTER AVILA
 

WTNT43 KNHC 191447
TCDAT3
TROPICAL DEPRESSION THREE DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032008
1100 AM EDT SAT JUL 19 2008
 
THE TROPICAL DEPRESSION IS CONTINUING TO ORGANIZE AND IS NEARING
TROPICAL STORM STRENGTH.  RADAR VELOCITY DATA FROM CHARLESTON AND
WILMINGTON SHOW THAT THE WIND FIELDS ALOFT ARE BECOMING BETTER-
DEFINED AND INCREASING. IN ADDITION...SHIP PDNN REPORTED 30 KT TO
THE SOUTHEAST OF THE CENTER AT 1200 UTC.  THE MAXIMUM WINDS ARE
KEPT AT 30 KT IN THIS ADVISORY AND AN AIR FORCE RESERVE
RECONNAISSANCE PLANE WILL BE IN THE AREA AROUND 1700 UTC TO
DETERMINE IF THE SYSTEM HAS BECOME A TROPICAL STORM.
 
ALTHOUGH THERE IS SOME DRY AIR TO THE NORTH...VERTICAL WIND SHEAR IS
FORECAST TO BE LOW FOR THE NEXT COUPLE OF DAYS AND THE SYSTEM IS
EXPECTED TO BE NEAR THE WARM GULF STREAM WATERS. SURPRISINGLY...
NEITHER THE GFDL NOR THE HWRF SHOW MUCH STRENGTHENING WITH THE
DEPRESSION.  WE'RE INCLINED TO THINK THAT SLOW INTENSIFICATION IS
LIKELY GIVEN THE ENVIRONMENTAL CONDITIONS...SO A SLOW INCREASE IN
WINDS IS INDICATED...CLOSE TO A BLEND OF THE SHIPS/SHIFOR GUIDANCE.
 
DATA FROM BUOY 41004 HAS BEEN HELPFUL IN TRACKING THE DEPRESSION...
WHICH APPEARS TO HAVE REFORMED A LITTLE TO THE EAST.  BEST ESTIMATE
OF INITIAL MOTION IS 050/6.  A WEAK MID-TROPOSPHERIC RIDGE TO THE
SOUTHEAST OF THE STORM SHOULD CONTINUE TO MOVE THE SYSTEM IN THIS
GENERAL DIRECTION AND AT A SIMILAR SPEED FOR THE NEXT DAY OR SO. 
THEREAFTER... THE DEPRESSION WILL BE CAUGHT UP IN A STRONGER
STEERING CURRENT BETWEEN A BUILDING RIDGE TO THE EAST AND A
DEEPENING MIDDLE-LATITUDE TROUGH. MODEL GUIDANCE IS IN GOOD
AGREEMENT ON TAKING THE SYSTEM NEAR THE SOUTH AND NORTH CAROLINA
COASTS DURING THE NEXT COUPLE OF DAYS.  THE OFFICIAL FORECAST IS
SHIFTED A LITTLE TO THE EAST OF THE PREVIOUS ONE...MOSTLY DUE TO
THE CENTER REFORMATION...AND LIES ON THE WESTERN SIDE OF THE
GUIDANCE ENVELOPE.  
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      19/1500Z 32.6N  78.5W    30 KT
 12HR VT     20/0000Z 33.3N  77.6W    35 KT
 24HR VT     20/1200Z 34.2N  76.3W    40 KT
 36HR VT     21/0000Z 35.1N  75.0W    45 KT
 48HR VT     21/1200Z 36.5N  73.0W    45 KT
 72HR VT     22/1200Z 40.5N  68.0W    45 KT
 96HR VT     23/1200Z...ABSORBED
 
$$
FORECASTER BLAKE/KNABB
 

