000 WTPZ45 KNHC 040839 TCDEP5 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