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| #64733 (Received by flhurricane at: 3:34 PM 05.Jan.2006) TCDAT5 TROPICAL STORM ZETA DISCUSSION NUMBER 26 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 4 PM EST THU JAN 05 2006 ZETA HAS MAINTAINED A NICE TIGHT INNER-CORE CIRCULATION... AND ANOTHER BAND OF CONVECTION HAS RECENTLY DEVELOPED IN THE EASTERN SEMICIRCLE. DVORAK SUBJECTIVE SATELLITE DATA T-NUMBERS FROM THE TAFB HAVE BEEN VARYING BETWEEN 30 KT AND 35 KT OVER THE PAST 6 HOURS... AND ODT VALUES HAVE BEEN AS HIGH AS T3.0/45 KT. LOW-CLOUD DRIFT WINDS FROM UW-CIMSS ARE RUNNING AROUND 40 KT...EQUAL TO ABOUT 32-KT SURFACE WINDS... SO THE INITIAL INTENSITY WILL REMAIN AT 35 KT FOR THIS ADVISORY. THIS INTENSITY IS ALSO SUPPORTED BY A 05/1613Z UW-CIMSS AMSU INTENSITY ESTIMATE OF 1007 MB AND 35 KT. THE INITIAL MOTION ESTIMATE IS NOW 310/07 KT. ZETA REMAINS ON TRACK AND THE CYCLONE IS EXPECTED TO MOVE NORTHWESTWARD AROUND THE SOUTHWESTERN PERIPHERY OF A LOW- TO MID-LEVEL SUBTROPICAL RIDGE THAT IS CURRENTLY CENTERED NEAR THE AZORES ISLANDS. WATER VAPOR IMAGERY INDICATES A SHARP MID-LEVEL SHORTWAVE TROUGH IS NOW LOCATED ALONG 53W LONGITUDE AND CONTINUES TO MOVE EASTWARD AT 30 KT. ZETA IS FORECAST TO WEAKEN AS IT INTERACTS WITH AND GETS LIFTED NORTHWARD BY THE SHORTWAVE TROUGH DURING THE FORECAST PERIOD. CONVECTION "SHOULD" GET SHEARED AWAY BY 24 HOURS OR SO... LEAVING BEHIND A REMNANT LOW PRESSURE SYSTEM THAT MAY BECOME ABSORBED BY A TRAILING FRONTAL SYSTEM IN 48 HOURS...OR LESS. THE OFFICIAL FORECAST TRACK IS CLOSE TO THE PREVIOUS TRACK AND THE GUNA MODEL CONSENSUS. JUST ABOUT THE TIME THE CONVECTION APPEARS TO WANE... NEW CONVECTION REFIRES JUST EAST OF THE CENTER. CONVECTION HAS ALSO BECOME RATHER ACTIVE TO THE NORTHWEST OF ZETA BETWEEN THE LOW-LEVEL CENTER AND A PRE-FRONTAL SURFACE TROUGH ALONG 50W LONGITUDE... INDICATING THAT THERE IS STILL PLENTY OF AVAILABLE INSTABILITY AHEAD OF THE CYCLONE FOR IT TO TAP INTO. THEREFORE... ONLY SLOW WEAKENING IS EXPECTED FOR THE NEXT 12 HOURS OR SO... AFTER WHICH STRONG SHEAR BEHIND THE AFOREMENTIONED SHORTWAVE TROUGH "SHOULD" DECAPITATE THE CYCLONE. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 05/2100Z 23.0N 48.2W 35 KT 12HR VT 06/0600Z 23.8N 49.0W 30 KT 24HR VT 06/1800Z 24.7N 50.5W 25 KT...DISSIPATING 36HR VT 07/0600Z 25.7N 52.8W 25 KT...REMNANT LOW 48HR VT 07/1800Z 27.0N 55.0W 20 KT...REMNANT LOW 72HR VT 08/1800Z 31.0N 56.5W 20 KT...REMNANT LOW 96HR VT 09/1800Z...DISSIPATED OR ABSORBED |
