[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT45 KNHC 110843
TCDAT5
SUBTROPICAL STORM NICOLE DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT MON OCT 11 2004

NICOLE HAS TRIED TO BECOME A TROPICAL STORM THIS MORNING...AS A
PERSISTENT CLUSTER OF CONVECTION HAS DEVELOPED NORTHEAST OF THE
CENTER WHILE AMSU OVERPASSES FROM SUNDAY EVENING INDICATED A WARM
CORE MIGHT BE PRESENT.  HOWEVER...THERE IS NO EVIDENCE OF CONVECTION
TRYING TO WRAP AROUND THE CENTER OR OF ANY ANTICYCLONIC OUTFLOW.
INDEED...LATEST SATELLITE IMAGERY SUGGESTS A WESTERLY JET STREAK IS
APPROACHING THE CENTER...WHICH IS NOT EXACTLY THE UPPER-LEVEL WIND
PATTERN OF A SYSTEM COMPLETING TRANSITION INTO A TROPICAL CYCLONE.
THUS...NICOLE REMAINS A SUBTROPICAL STORM WITH 40 KT WINDS.

SURFACE OBSERVATIONS INDICATE THAT EXTRATROPICAL CYCLOGENESIS IS
OCCURRING NEAR SABLE ISLAND...WHERE THE PRESSURE HAS DROPPED TO
1001 MB AS OF 08Z.  DYNAMICAL MODELS ALL MERGE NICOLE WITH THIS LOW
IN 24 HR OR LESS...ALTHOUGH THE DETAILS DIFFER ON WHICH CYCLONE
WOULD BE DOMINANT DURING THE MERGER.  THE END RESULT SHOULD BE THE
SAME...A RATHER VIGOROUS EXTRATROPICAL SYSTEM SOUTH OF NOVA SCOTIA
OVER THE NEXT COUPLE OF DAYS.  THE INTENSITY FORECAST WILL CALL FOR
NICOLE TO INTENSIFY DUE TO BAROCLINIC FORCING EVEN WHILE LOSING
TROPICAL CHARACTERISTICS...FOLLOWED BY MERGER WITH THE LARGER LOW
AFTER 24 HR.  THERE IS A CHANCE THAT NICOLE MAY NOT SURVIVE FOR
EVEN 24 HR.

THE INITIAL MOTION IS NOW 045/16.  ALL GUIDANCE AGREES THAT NICOLE
SHOULD TURN NORTHWARD BEFORE MERGER WITH THE EXTRATROPICAL LOW
OCCURS...AND THIS IS FOLLOWED IN THE TRACK FORECAST.  IF NICOLE
MOVES FASTER OR LASTS LONGER THAN CURRENTLY FORECAST...IT MAY DO A
LEFT HOOK AROUND THE NORTH SIDE OF THE LARGER LOW BEFORE THE MERGER
IS COMPLETE.  THE FORECAST TRACK IS SIMILAR TO THE PREVIOUS
PACKAGE...BUT NUDGED A LITTLE TO THE EAST BASED ON THE INITIAL
POSITION.

FORECASTER BEVEN

FORECAST POSITIONS AND MAX WINDS

INITIAL      11/0900Z 34.9N  63.6W    40 KT
 12HR VT     11/1800Z 38.4N  62.8W    45 KT...BECOMING EXTRATROPICAL
 24HR VT     12/0600Z 41.5N  63.5W    50 KT...EXTRATROPICAL
 36HR VT     12/1800Z...ABSORBED BY EXTRATROPICAL LOW


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