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| #63606 (Received by flhurricane at: 10:31 PM 30.Dec.2005) TCDAT5 TROPICAL STORM ZETA DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 10 PM EST FRI DEC 30 2005 ZETA IS ROUGHLY HALF OF A TROPICAL STORM... WITH MOST OF THE CONVECTION EAST OF THE CENTER... BUT STILL SOME OF IT NEAR THE FAIRLY TIGHT CIRCULATION CENTER. DVORAK T-NUMBERS ARE UNCHANGED FROM SIX HOURS AGO AND THE INTENSITY ESTIMATES REMAIN 35 TO 45 KT. HI-RES WIND ESTIMATES FROM A QUIKSCAT OVERPASS AT ABOUT 2015Z WERE AS STRONG AS ABOUT 45 KT NEAR THE CIRCULATION CENTER... SO THE ADVISORY INTENSITY IS MAINTAINED AT 45 KT. THE QUIKSCAT DATA INDICATED TROPICAL STORM-FORCE WINDS FARTHER FROM THE CENTER IN THE EASTERN SEMICIRCLE THAN PREVIOUSLY THOUGHT. WHILE THE FEW 50-60 KT VECTORS WERE NOT LIKELY REPRESENTATIVE... 30-40 KT VECTORS WERE WIDESPREAD IN THE OUTER BANDING EVEN OUTSIDE OF THE DEEPEST CONVECTION. THE WIND RADII IN THE NORTHEASTERN AND SOUTHEASTERN QUADRANTS HAVE BEEN EXPANDED ACCORDINGLY. ZETA IS STILL MOVING NORTHWESTWARD AT ABOUT 6 KT... BUT A LITTLE MORE TO THE RIGHT AT ABOUT 320 DEGREES... PRESUMABLY DUE TO THE ASYMMETRIC CONVECTIVE PATTERN DRAGGING THE LOW-LEVEL CENTER A LITTLE NORTHWARD. THE DYNAMICAL MODELS GENERALLY DO NOT HAVE A GOOD HANDLE ON THE STRENGTH OF THE CIRCULATION OR ITS RECENT MOTION... SO THE OFFICIAL FORECAST RELIES HEAVILY ON THE ANTICIPATED STEERING FLOW. THE NORTHWESTWARD MOTION WILL PROBABLY CONTINUE OVERNIGHT UNTIL THE UPPER-LEVEL WESTERLIES FULLY OVERTAKE AND SIGNIFICANTLY SHEAR THE TROPICAL STORM. ZETA MIGHT HOLD ON TO TROPICAL STORM STATUS FOR ALMOST ANOTHER 24 HOURS AS SUGGESTED BY THE SHIPS GUIDANCE. AS ZETA WEAKENS IT SHOULD BE STEERED INCREASINGLY BY THE LOW- TO MID-LEVEL FLOW TO THE SOUTH OF A NARROW EAST-WEST ORIENTED RIDGE... SO THE OFFICIAL FORECAST TRACK GRADUALLY BENDS TO THE WEST AS ZETA LIKELY DEGENERATES INTO A REMNANT LOW WITHIN THE NEXT COUPLE OF DAYS. FORECASTER KNABB FORECAST POSITIONS AND MAX WINDS INITIAL 31/0300Z 25.9N 37.5W 45 KT 12HR VT 31/1200Z 26.1N 38.2W 40 KT 24HR VT 01/0000Z 26.2N 39.1W 30 KT 36HR VT 01/1200Z 26.2N 40.3W 25 KT...DISSIPATING 48HR VT 02/0000Z 26.3N 41.6W 25 KT...REMNANT LOW 72HR VT 03/0000Z...DISSIPATED |
