Tropical Storm ZETA

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TROPICAL STORM ZETA DISCUSSION NUMBER  25
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
10 AM EST THU JAN 05 2006
 
A 05/0836Z QUIKSCAT OVERPASS THAT CAME IN SHORTLY AFTER THE PREVIOUS
ADVISORY HAD BEEN ISSUED INDICATED SEVERAL 30-35 KT UNCONTAMINATED
WIND VECTORS NORTH THROUGH EAST OF THE CENTER. SINCE THAT TIME...
CONVECTION HAS CONTINUED TO INCREASE TO THE EAST OF THE FULLY
EXPOSED LOW-LEVEL CENTER. THE 12Z DVORAK SATELLITE SHEAR PATTERN
CURRENT INTENSITY ESTIMATE FROM THE TAFB WAS 35 KT... AND
CONVECTION HAS DEVELOPED EVEN CLOSER TO THE CENTER SINCE THAT
ANALYSIS WAS MADE. IN ADDITION... SHIP ZCIH7 LOCATED ABOUT 135 NMI
NORTH OF THE CENTER REPORTED AN EAST WIND OF 30 KT... WHICH MATCHED
UP WELL WITH NEARBY QUIKSCAT WINDS. SO...REGRETFULLY...THE
INTENSITY HAS BEEN INCREASED TO 35 KT AND ZETA IS A TROPICAL STORM
ONCE AGAIN. THIS INTENSITY IS ALSO SUPPORTED BY A 05/0915Z UW-CIMSS
AMSU INTENSITY ESTIMATE OF 1006 MB AND 38 KT.
 
THE INITIAL MOTION IS 300/07 KT.  THERE IS NO SIGNIFICANT CHANGE TO
THE PREVIOUS FORECAST TRACK OR REASONING. ZETA IS EXPECTED TO
CONTINUE MOVING WEST-NORTHWESTWARD TO NORTHWESTWARD AROUND THE
SOUTHWESTERN PERIPHERY OF A DEEP-LAYER RIDGE SITUATED TO THE
NORTHEAST OF THE TROPICAL STORM. WATER VAPOR IMAGERY AND UW-CIMSS
SATELLITE WIND ANALYSES INDICATE A SHARP MID-LEVEL SHORTWAVE TROUGH 
LOCATED ALONG 56W LONGITUDE MOVING QUICKLY EASTWARD. THIS SYSTEM IS
EXPECTED TO GRADUALLY LIFT ZETA POLEWARD AND/OR SHEAR THE SYSTEM
APART... LEAVING BEHIND A REMNANT LOW PRESSURE SYSTEM BY 24-36
HOURS. BY 72 HOURS...THE REMNANT LOW MAY EVEN BECOME ABSORBED INTO
A FRONTAL SYSTEM THAT IS ACCOMPANYING THE SHORTWAVE TROUGH.
 
THE SHIPS MODEL'S 850-200 MB SHEAR OF 68 KT IS NOT THE ACTUAL SHEAR 
AFFECTING ZETA. THE GLOBAL MODELS INDICATE THE 850-300 MB WESTERLY
SHEAR TO ONLY BE AROUND 30-35 KT. AS A RESULT... ZETA MIGHT BE ABLE
TO MAINTAIN TROPICAL STORM INTENSITY FOR ANOTHER 12 HOURS OR SO
BEFORE THE CYCLONE ENCOUNTERS VERY HOSTILE MID-LEVEL WESTERLY WINDS
BEHIND THE APPROACHING SHORTWAVE TROUGH PREVIOUSLY MENTIONED.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      05/1500Z 22.4N  47.6W    35 KT
 12HR VT     06/0000Z 23.3N  48.5W    30 KT
 24HR VT     06/1200Z 24.3N  49.7W    25 KT...DISSIPATING
 36HR VT     07/0000Z 25.3N  51.1W    25 KT...REMNANT LOW
 48HR VT     07/1200Z 26.3N  53.6W    20 KT...REMNANT LOW
 72HR VT     08/1200Z 29.0N  56.5W    20 KT...REMNANT LOW
 96HR VT     09/1200Z...DISSIPATED OR ABSORBED

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