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Tropical Storm ZETA (Text)

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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

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