|
Show Selection: |
| #4894 (Received by flhurricane at: 5:27 PM 13.Aug.2004) TCDAT4 TROPICAL DEPRESSION FOUR DISCUSSION NUMBER 2 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 PM EDT FRI AUG 13 2004 CONVENTIONAL AND MICROWAVE SATELLITE IMAGERY CONTINUE TO INDICATE THAT TROPICAL DEPRESSION FIVE IS GETTING BETTER ORGANIZED. THE CYCLONE COULD POSSIBLY BE A TROPICAL STORM ALREADY...BUT THE INITIAL INTENSITY WAS HELD AT 30 KT BASED ON A BLEND OF DVORAK SATELLITE INTENSITY ESTIMATES OF T2.5...OR 35 KT...FROM TAFB AND T2.0...OR 30 KT...FROM SAB. HOWEVER...IT WOULD NOT TAKE MUCH MORE BANDING OR DEEP CONVECTION TO DEVELOP NEAR THE CENTER FOR THIS SYSTEM TO BECOME A TROPICAL STORM. THE INITIAL MOTION ESTIMATE REMAINS 280/13. THERE IS NO SIGNIFICANT CHANGE TO THE PREVIOUS TRACK REASONING. THE TRACK WAS SHIFTED A LITTLE TO RIGHT BASED ON THE CENTER BECOMING BETTER DEFINED A LITTLE FARTHER NORTH. BY 48 HOURS...ALL THE GLOBAL MODELS STILL AGREE ON A MID-LEVEL TROUGH DIGGING SOUTHEASTWARD AND THEN SOUTH AND SOUTHWESTWARD BETWEEN 35-40W LONGITUDE...WHICH SHOULD WEAKEN THE SUBTROPICAL RIDGE. THE QUESTION IS HOW MUCH WEAKENING OF THE RIDGE WILL OCCUR. SEVERAL OF THE NHC MODELS INDICATE A NORTHWARD MOTION AFTER 96 HOURS...BUT A SMALL POLEWARD STAIR-STEP IN THE TRACK...WITH A RETURN TO A WEST-NORTHWESTWARD MOTION...COULD OCCUR INSTEAD. THE OFFICIAL TRACK IS A COMPROMISE OF THOSE TWO SCENARIOS UNTIL MORE CONSISTENT MODEL GUIDANCE BECOMES AVAILABLE. ONLY SLOW INTENSIFICATION IS FORECAST GIVEN THE HIGH LATITUDE OF THE CYCLONE AND THE RELATIVELY COOL WATER...26-27C SSTS...THAT THE CYCLONE WILL BE PASSING OVER...EVEN THOUGH THE VERTICAL SHEAR IS EXPECTED TO REMAIN BELOW 10 KT THROUGH 48 HOURS. THE OFFICIAL INTENSITY FORECAST IS CLOSE TO THE SHIPS INTENSITY MODEL. HOWEVER ...IF THE CYCLONE TAKES A MORE SOUTHERLY TRACK AND STAYS OVER WARMER WATER...THEN IT COULD BECOME A HURRICANE BY 72 HOURS. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 13/2100Z 12.5N 24.0W 30 KT 12HR VT 14/0600Z 12.8N 25.9W 35 KT 24HR VT 14/1800Z 13.3N 28.3W 40 KT 36HR VT 15/0600Z 14.0N 30.9W 50 KT 48HR VT 15/1800Z 15.2N 34.1W 55 KT 72HR VT 16/1800Z 16.5N 38.0W 55 KT 96HR VT 17/1800Z 17.5N 42.0W 60 KT 120HR VT 18/1800Z 19.0N 45.5W 60 KT |
