ZCZC MIATCDAT5 ALL TTAA00 KNHC DDHHMM TROPICAL DEPRESSION TWENTY DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 PM EDT SAT OCT 01 2005 SATELLITE IMAGERY AND SURFACE OBSERVATIONS INDICATE THAT THE CENTER OF TROPICAL DEPRESSION TWENTY REMAINS BROAD THIS EVENING. HOWEVER...CONVECTION HAS INCREASED THIS EVENING...ESPECIALLY IN A POORLY CURVED BAND IN THE SOUTHEASTERN QUADRANT. THE INITIAL INTENSITY REMAINS 30 KT IN AGREEMENT WITH SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB. THE CIRRUS OUTFLOW IS FAIR IN THE EASTERN SEMICIRCLE AND IMPROVING IN THE WESTERN SEMICIRCLE. THE CENTER IS A LITTLE HARD TO FIND IN INFRARED IMAGERY...SO THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 285/5. SATELLITE IMAGERY AND EVENING RAWINSONDE DATA SHOWS LOW/MID/LEVEL RIDGING NORTH OF THE DEPRESSION...WHICH IN THE SHORT TERM SHOULD KEEP THE CYCLONE ON A WEST-NORTHWESTWARD TO WESTWARD TRACK. AFTER 24-36 HR...A MID/ UPPER-LEVEL TROUGH OVER THE CENTRAL UNITED STATES SHOULD MOVE NORTHEASTWARD...ALLOWING THE RIDGE TO BUILD WESTWARD TO THE WESTERN GULF COAST. THIS SHOULD CAUSE THE DEPRESSION TO TURN WESTWARD OR EVEN WEST-SOUTHWESTWARD. THE TRACK GUIDANCE IS IN GOOD AGREEMENT ON THIS SCENARIO THROUGH 72 HR. AFTER THAT...THINGS BECOME MORE UNCERTAIN AS THE LARGE-SCALE MODELS HAVE A VARIETY OF FORECASTS OF HOW THE PATTERN AROUND THE DEPRESSION WILL EVOLVE. SOME MODELS STALL THE DEPRESSION OVER THE SOUTHWESTERN GULF...WHILE OTHERS MOVE IT INTO MEXICO. OTHERS DISSIPATE IT AS A NEW SYSTEM FORMS EAST OF THE DEPRESSION IN THE CARIBBEAN...OR NORTHEAST OF THE DEPRESSION ALONG A COLD FRONT FORECAST TO MOVE INTO THE GULF OF MEXICO. THE OFFICIAL FORECAST CONTINUES THE TREND OF THE PREVIOUS ADVISORY OF MOVING THE CYCLONE WEST-SOUTHWESTWARD INTO MEXICO... ALBEIT AT A SLOWER SPEED THAN THE PREVIOUS TRACK. HOWEVER...THE CONFIDENCE THAT THIS WILL HAPPEN IS DECREASING. CONDITIONS APPEAR FAVORABLE FOR STRENGTHENING THROUGH 72 HR WHILE THE CYCLONE IS OVER WATER...AS VERTICAL SHEAR IS FORECAST TO BE LIGHT. THE INTENSITY FORECAST THUS CALLS FOR THE SYSTEM TO BRIEFLY BECOME A TROPICAL STORM BEFORE MAKING LANDFALL ON YUCATAN... FOLLOWED BY WEAKENING OVER LAND AND RE-INTENSIFICATION OVER THE BAY OF CAMPECHE. EVEN WITH LAND INTERACTION...SHIPS CALLS FOR THE SYSTEM TO REACH HURRICANE STRENGTH IN 72 HR AND THE INTENSITY FORECAST FOLLOWS THIS. HOWEVER...THE LATEST GFDL RUN DOES NOT STRENGTHEN THE CYCLONE ABOVE 40 KT. THE INTENSITY FORECAST ASSUMES THE CYCLONE WILL DISSIPATE OVER THE MOUNTAINS OF MEXICO AFTER LANDFALL IN ABOUT 84 HR. SHOULD THAT LANDFALL NOT OCCUR OR BE DELAYED...THE LARGE-SCALE MODELS SUGGEST THE ENVIRONMENT MAY BECOME LESS FAVORABLE FOR DEVELOPMENT DUE TO AN UPPER-LEVEL LOW FORMING OVER THE GULF OF MEXICO AND A COLD FRONT MOVING TOWARD THE SOUTHWESTERN GULF. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 02/0300Z 19.3N 87.0W 30 KT 12HR VT 02/1200Z 19.7N 88.2W 35 KT...INLAND 24HR VT 03/0000Z 20.3N 90.2W 25 KT...INLAND 36HR VT 03/1200Z 20.8N 92.0W 35 KT...OVER WATER 48HR VT 04/0000Z 21.0N 93.8W 50 KT 72HR VT 05/0000Z 20.5N 96.0W 65 KT 96HR VT 06/0000Z 20.0N 98.5W 30 KT...INLAND 120HR VT 07/0000Z...DISSIPATED $$ NNNN
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Page last modified: Sunday, 02-Oct-2005 02:55:12 UTC