Tropical Depression NINE-E

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TROPICAL DEPRESSION NINE-E DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP092011
200 AM PDT WED SEP 21 2011
 
RADAR DATA FROM MEXICO AND SATELLITE IMAGERY INDICATE THAT THE AREA
OF LOW PRESSURE LOCATED SOUTHWEST OF THE GULF OF TEHUANTEPEC HAS
ACQUIRED ENOUGH ORGANIZATION TO BE CLASSIFIED AS A TROPICAL
DEPRESSION.  DVORAK INTENSITY ESTIMATES FROM BOTH TAFB AND SAB
SUPPORT AN INITIAL INTENSITY OF 30 KT.  THE DEPRESSION IS FORECAST
TO MOVE OVER WARM WATER AND REMAIN IN A LOW SHEAR ENVIRONMENT
DURING THE NEXT SEVERAL DAYS.  STEADY INTENSIFICATION IS 
THEREFORE ANTICIPATED AND THE OFFICIAL FORECAST SHOWS THE DEPRESSION 
BECOMING A HURRICANE IN ABOUT 48 HOURS.  THE NHC INTENSITY
FORECAST IS IN GOOD AGREEMENT WITH THE SHIPS MODEL.

THE INITIAL MOTION ESTIMATE IS 285/4.  THE DEPRESSION IS FORECAST TO
MOVE WEST-NORTHWESTWARD TO THE SOUTH OF A NARROW MID- TO UPPER-LEVEL
RIDGE THAT EXTENDS FROM MEXICO WESTWARD OVER THE EASTERN PACIFIC. 
THE RIDGE IS FORECAST TO STRENGTHEN OVER THE NEXT COUPLE OF DAYS
WHICH SHOULD CAUSE THE FORWARD SPEED OF THE CYCLONE TO INCREASE. 
THE TRACK GUIDANCE IS IN GENERAL AGREEMENT ON THIS SCENARIO...
HOWEVER THERE ARE DIFFERENCES IN HOW CLOSE THE DEPRESSION COMES TO
THE SOUTHERN COAST OF MEXICO.  BOTH THE GFS AND ECMWF SHOW A
NORTHWESTWARD MOTION DURING THE FIRST 12-24 HOURS...AND THESE
MODELS ARE ALONG THE RIGHT EDGE OF THE GUIDANCE ENVELOPE. 
MEANWHILE...THE GFDL...HWRF...AND NOGAPS MODELS ARE ALONG THE
SOUTHERN EDGE.  FOR NOW...THE OFFICIAL FORECAST IS BETWEEN THESE
EXTREMES AND IS NEAR THE MODEL CONSENSUS.  
 
INTERESTS ALONG THE SOUTHERN COAST OF MEXICO SHOULD MONITOR THE
PROGRESS OF THE DISTURBANCE.  ANY DEVIATION TO THE NORTH OF THE
FORECAST TRACK COULD REQUIRE WATCHES OR WARNINGS FOR A PORTION OF
THE COAST OF MEXICO.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  21/0900Z 13.4N  96.5W   30 KT  35 MPH
 12H  21/1800Z 13.6N  97.1W   40 KT  45 MPH
 24H  22/0600Z 14.1N  98.3W   45 KT  50 MPH
 36H  22/1800Z 14.6N  99.6W   55 KT  65 MPH
 48H  23/0600Z 15.1N 101.0W   65 KT  75 MPH
 72H  24/0600Z 16.2N 104.2W   75 KT  85 MPH
 96H  25/0600Z 17.5N 107.5W   85 KT 100 MPH
120H  26/0600Z 18.5N 111.0W   85 KT 100 MPH
 
$$
FORECASTER BROWN
 
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