Tropical Depression FIFTEEN-E

ZCZC MIATCDEP5 ALL
TTAA00 KNHC DDHHMM
TROPICAL DEPRESSION FIFTEEN-E DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP152008
200 AM PDT SAT OCT 04 2008
 
SHORTWAVE INFRARED SATELLITE IMAGERY AND AN AMSU-B MICROWAVE
OVERPASS DEPICT AN EXPOSED SURFACE CIRCULATION CENTER WELL TO THE
EAST OF AN ISOLATED BANDING FEATURE.  UW-CIMSS SHEAR PRODUCT
INDICATES 15 TO 20 KT OF EASTERLY SHEAR AFFECTING THE CLOUD
PATTERN.  DVORAK SATELLITE INTENSITY ESTIMATES OF 25 TO 35 KT AND A
0420Z ASCAT SWATH REVEALING A SIMILAR INTENSITY OVER THE NORTH
QUADRANT SUPPORT HOLDING THE INITIAL INTENSITY AT 30 KT.

IT'S INTERESTING TO NOTE THAT THE GFS IS DEVELOPING A TROPICAL
CYCLONE IN 36 HOURS EAST OF THE DEPRESSION AND 20 TO 30 KT OF
SOUTHEASTERLY SHEAR...APPARENTLY FROM THE CYCLONES' OUTFLOW
PATTERN.  THIS PARTICULAR FEATURE ALSO APPEARS TO BE INFLUENCING
THE SHIPS MODEL.  SINCE THERE IS NO EVIDENCE YET THAT THIS
GFS-FORECAST CYCLONE IS ACTUALLY DEVELOPING...THE INTENSITY
FORECAST FOLLOWS THE INTENSITY CONSENSUS MODEL...STRENGTHENING THE
DEPRESSION TO A HURRICANE IN 4 DAYS.  THE INTENSITY FORECAST IS
SLIGHTLY HIGHER THAN THE SHIPS MODEL BEYOND DAY 3.         
  
THE ESTIMATED INITIAL MOTION APPEARS TO BE A TEMPORARY EASTWARD
DRIFT WITHIN THE SHALLOW LAYER CROSS-EQUATORIAL WESTERLY FLOW.  A
LARGE AMPLITUDE MID- TO UPPER LEVEL TROUGH EXTENDING FROM CENTRAL
MEXICO TO JUST NORTH OF THE DEPRESSION IS ALSO SUPPORTING THIS
EASTWARD MOTION.  THE GLOBAL MODELS ALL SUGGEST THAT A SOUTHWEST
EXTENSION OF THE SUBTROPICAL RIDGE WILL BUILD IN OVER THE SOUTHWEST
GULF AND SOUTHERN MEXICO IN RESPONSE TO THE TROUGH MOVING NORTHEAST
OUT OF THE AREA AROUND 24 TO 36 HOUR PERIOD.  THIS EXPECTED CHANGE
IN THE SYNOPTIC STEERING PATTERN SHOULD CAUSE THE SYSTEM TO TURN
BACK TOWARD THE WEST-NORTHWEST.  THROUGH THE REMAINING FORECAST
PERIOD...THE DYNAMICAL MODELS ALL SHOW A CONTINUED WEST-
NORTHWESTWARD MOTION ALBEIT WITH A DISAGREEMENT IN FORWARD SPEED. 
THE HWRF DEPICTS A SIGNIFICANTLY STRONGER RIDGE ESTABLISHING OVER
MEXICO AS COMPARED TO THE OTHER GUIDANCE.  THE OFFICIAL FORECAST IS
QUITE SIMILAR TO THE PREVIOUS TRACK AND IS BASED ON A CONSENSUS OF
THE DYNAMICAL MODELS...BUT A BIT SLOWER THAN THE HWRF.
 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      04/0900Z 13.6N  98.8W    30 KT
 12HR VT     04/1800Z 13.7N  99.0W    35 KT
 24HR VT     05/0600Z 13.8N  99.7W    40 KT
 36HR VT     05/1800Z 13.9N 100.6W    45 KT
 48HR VT     06/0600Z 14.1N 101.6W    50 KT
 72HR VT     07/0600Z 15.0N 103.5W    55 KT
 96HR VT     08/0600Z 16.0N 105.0W    65 KT
120HR VT     09/0600Z 17.0N 106.5W    65 KT
 
$$
FORECASTER ROBERTS
 
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