WTNT43 KNHC 232033
TCDAT3
 
TROPICAL DEPRESSION EIGHTEEN DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL182011
500 PM EDT SUN OCT 23 2011
 
THE HURRICANE HUNTER AIRCRAFT INVESTIGATING THE LOW PRESSURE AREA
OVER THE WESTERN CARIBBEAN SEA HAS FOUND A WELL-DEFINED CENTER AND
SATELLITE IMAGERY INDICATES THAT THE DISTURBANCE HAS ACQUIRED JUST
ENOUGH CONVECTIVE ORGANIZATION FOR THE SYSTEM TO BE CLASSIFIED AS A
TROPICAL DEPRESSION.  THE INITIAL WIND SPEED IS SET AT 30 KT...
BASED ON A FEW BELIEVABLE 27 TO 28 KT SFMR WIND MEASUREMENTS.  THE
DEPRESSION IS OVER WARM WATER BUT IN AN AREA OF MODERATE
SOUTHEASTERLY VERTICAL SHEAR WITH DRY AIR TO THE NORTH AND WEST.
THE ENVIRONMENT DURING THE NEXT COUPLE OF DAYS IS NOT FORECAST TO
BE CONDUCIVE FOR SIGNIFICANT STRENGTHENING...BUT SHOULD NOT BE
HOSTILE ENOUGH TO PREVENT THE SYSTEM FROM BECOMING A TROPICAL
STORM. THE OFFICIAL FORECAST IS JUST SLIGHTLY ABOVE THE
STATISTICAL/DYNAMICAL SHIPS AND LGEM GUIDANCE.
 
THE INITIAL MOTION ESTIMATE IS A SOMEWHAT UNCERTAIN 335/5.  THE
CYCLONE IS FORECAST TO TURN WESTWARD DURING THE NEXT DAY OR TWO
TO THE SOUTH OF A MID-LEVEL RIDGE OVER THE EASTERN GULF OF MEXICO.
THE UNCERTAINTY IN THE TRACK FORECAST INCREASES GREATLY IN THE 3
TO 5 DAY TIME FRAME.  THE GFS AND NOGAPS MODELS MOVE THE SYSTEM
INLAND OVER CENTRAL AMERICA IN A FEW DAYS. CONVERSELY...THE
HWRF...ECMWF...AND UKMET MODELS TAKE THE CYCLONE INTO THE
SOUTHEASTERN GULF OF MEXICO IN THE LATTER PART OF THE FORECAST
PERIOD IN RESPONSE TO AN EASTWARD SHIFT OF THE ABOVEMENTIONED
RIDGE.  THE OFFICIAL FORECAST LIES BETWEEN THESE TWO EXTREMES...
AND IS CLOSE TO THE GFDL TRACK.

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  23/2100Z 15.9N  81.9W   30 KT  35 MPH
 12H  24/0600Z 16.4N  82.2W   35 KT  40 MPH
 24H  24/1800Z 16.8N  82.9W   40 KT  45 MPH
 36H  25/0600Z 17.0N  83.5W   45 KT  50 MPH
 48H  25/1800Z 17.1N  84.3W   50 KT  60 MPH
 72H  26/1800Z 17.3N  86.0W   50 KT  60 MPH
 96H  27/1800Z 17.7N  87.0W   50 KT  60 MPH
120H  28/1800Z 19.0N  88.0W   50 KT  60 MPH
 
$$
FORECASTER BROWN
 

