WTNT44 KNHC 160858
TCDAT4
TROPICAL DEPRESSION FOUR DISCUSSION NUMBER   1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042009
500 AM EDT SUN AUG 16 2009
 
DATA FROM THE WFO TAMPA RADAR INDICATE THAT THE DISTURBANCE IN THE
EASTERN GULF OF MEXICO HAS BECOME SIGNIFICANTLY BETTER ORGANIZED
OVERNIGHT. A QUIKSCAT PASS NEAR 00Z SUGGESTED THAT THERE PROBABLY
WAS A CLOSED SURFACE CIRCULATION. GIVEN THIS...ADVISORIES ARE BEING
INITIATED ON A NEW TROPICAL DEPRESSION. ALTHOUGH THERE WAS A SHIP
REPORT FROM A CARNIVAL CRUISE LINE VESSEL OF 40 KT...THIS REPORT IS
NOT CONSIDERED TO BE REPRESENTATIVE OF THE SURFACE WINDS. DOPPLER
VELOCITIES FROM THE TAMPA RADAR ALSO DO NOT SUPPORT TROPICAL STORM
STRENGTH AT THIS TIME. HOWEVER...THE EXCELLENT RADAR PRESENTATION
AND DEEP CONVECTION SUGGESTS THAT STORM STATUS IS LIKELY TO BE
ATTAINED SOON. VERTICAL SHEAR IS VERY LOW...AND THE INTENSITY
GUIDANCE FROM THE HWRF AND GFDL SUGGEST A MIDDLE-RANGE TROPICAL
STORM BY LANDFALL.  IT SHOULD BE NOTED THAT SOME ADDITIONAL
STRENGTHENING PRIOR TO LANDFALL BUT AFTER THE 12 HOUR 45 KT
FORECAST INTENSITY SHOWN BELOW IS LIKELY. 
 
THE INITIAL MOTION IS 330/13.  THE CYCLONE IS MOVING AROUND THE
PERIPHERY OF THE SUBTROPICAL RIDGE AND IS EXPECTED TO MAINTAIN THIS
APPROXIMATE TRACK UNTIL LANDFALL. THE OFFICIAL FORECAST IS CLOSE TO
A CONSENSUS OF A FAIRLY TIGHTLY CLUSTERED GUIDANCE SUITE.

THIS IS A VERY SMALL TROPICAL CYCLONE...AND ITS EFFECTS ARE LIKELY
TO REMAIN RATHER CLOSE TO THE PATH OF THE CENTER.
 

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      16/0900Z 27.7N  83.9W    30 KT
 12HR VT     16/1800Z 29.2N  85.0W    45 KT
 24HR VT     17/0600Z 31.0N  86.7W    40 KT...INLAND
 36HR VT     17/1800Z 33.0N  87.5W    20 KT...DISSIPATING INLAND
 48HR VT     18/0600Z...DISSIPATED
 
$$
FORECASTER FRANKLIN
 

WTNT44 KNHC 161437
TCDAT4
TROPICAL DEPRESSION FOUR DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042009
1100 AM EDT SUN AUG 16 2009
 
VISIBLE SATELLITE IMAGERY AND DATA FROM THE TAMPA WSR-88D INDICATE
DEVELOPING DEEP CONVECTIVE BANDING OVER THE EAST SEMICIRCLE OF THE
TROPICAL CYCLONE. IT APPEARS THAT THE WINDS ASSOCIATED WITH THE
STRONGER BANDS MAY NOT YET BE MIXING DOWN TO THE SURFACE...AS NOAA
BUOY 42036 LOCATED JUST TO THE NORTH-NORTHWEST OF THE CIRCULATION
CENTER IS REPORTING WINDS OF LESS THAN 15 KT. AIRCRAFT
RECONNAISSANCE WILL BE INVESTIGATING THE CYCLONE SHORTLY TO HELP
DETERMINE IF IT HAS BECOME A TROPICAL STORM.
 
ALTHOUGH REGIONAL UPPER-AIR SOUNDINGS AND WATER VAPOR IMAGERY
SUGGEST THAT THE THERMODYNAMIC ENVIRONMENT IS ONLY MARGINALLY
FAVORABLE...THE UPPER-LEVEL SOUTHERLY FLOW OVER THE DEPRESSION IS
QUITE DIFFLUENT. CONSEQUENTLY...THE OFFICIAL INTENSITY FORECAST
STILL REFLECTS STRENGTHENING JUST BEFORE LANDFALL. AFTER THAT
TIME...WEAKENING AND DISSIPATION IS FORECAST WITHIN 48 HOURS AS THE
SYSTEM MOVES INLAND OVER THE NORTHERN GULF COAST.
 
THE INITIAL MOTION IS 330/13. THE CYCLONE IS MOVING AROUND THE
PERIPHERY OF THE SUBTROPICAL RIDGE AND IS EXPECTED TO MAINTAIN THIS
APPROXIMATE HEADING UNTIL LANDFALL. THE OFFICIAL FORECAST IS CLOSE
TO A CONSENSUS OF A FAIRLY TIGHTLY CLUSTERED GUIDANCE SUITE.
 
ALTHOUGH THE DEPRESSION IS VERY SMALL AND HAS A LIMITED WIND
FIELD....HEAVY RAINFALL IS LIKELY NEAR THE TRACK OF THE CYCLONE
ACROSS THE FLORIDA PANHANDLE...SOUTHWESTERN GEORGIA AND SOUTHERN
ALABAMA.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      16/1500Z 28.7N  84.6W    30 KT
 12HR VT     17/0000Z 30.2N  85.8W    50 KT
 24HR VT     17/1200Z 32.1N  87.1W    35 KT...INLAND
 36HR VT     18/0000Z 34.0N  88.2W    20 KT...DISSIPATING INLAND
 48HR VT     18/1200Z...DISSIPATED
 
$$
FORECASTER BRENNAN
 

