[Tropical] Tropical Cyclone Discussion

[Nashville EMWIN]

WTNT44 KNHC 172028
TCDAT4
HURRICANE DANIELLE DISCUSSION NUMBER  18
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT TUE AUG 17 2004

THE EYE IS NO LONGER OBSERVED ON VISIBLE SATELLITE IMAGES AND THE
CLOUD PATTERN HAS CONTINUED TO BECOME ELONGATED ON A NORTH-SOUTH
DIRECTION. HOWEVER...MICROWAVE DATA SUGGEST THAT THE EYE IS LOCATED
TO THE SOUTH OF THE AREA OF DEEP CONVECTION. ALTHOUGH CI NUMBERS
INDICATE WINDS OF 90 KNOTS...THE T-NUMBERS ARE COMING DOWN. INITIAL
INTENSITY IS LOWERED TO 85 KNOTS. DANIELLE COULD MAINTAIN HURRICANE
INTENSITY FOR THE NEXT DAY OR SO BUT A MORE RAPID WEAKENING IS
LIKELY THEREAFTER. DANIELLE SHOULD BECOME EXTRATROPICAL BY DAY FIVE
OR BEFORE.

DANIELLE IS MOVING NORTHWARD OR 355 DEGRES AT 16 KNOTS. THE
HURRICANE IS BEING STEERED BY THE FLOW BETWEEN THE SUBTROPICAL
RIDGE AND A MIDDLE-LEVEL TROUGH TO THE NORTHWEST OF THE CYCLONE.
DANIELLE IS EXPECTED TO BE EMBEDDED WITHIN A WEAK MID-LATITUDE
SOUTHWESTERLY FLOW WHICH WILL CAUSE THE CYCLONE TO SLOW DOWN
BETWEEN THE 36 AND 72 HOUR PERIOD. THEREAFTER...THE OFFICIAL
FORECAST CALLS FOR AN INCREASE IN FORWARD SPEED AS SUGGESTED BY
NOGAPS...UK AND THE GFDL MODELS.  BOTH THE CANADIAN AND GFS GLOBAL
MODELS MOVE THE CYCLONE VERY LITTLE. THIS IS PROBABLY DUE TO THE
FACT THE THESE TWO MODELS WEAKEN THE CYCLONE CONSIDERABLY AND MOVE
IT WITH THE LOW-LEVEL FLOW. ON THE OTHER HAND...THE GFDL...NOGAPS
AND UK TRIO...MAINTAIN A DEEPER CIRCULATION WHICH IS MORE LIKELY TO
STEER THE CYCLONE WITH THE MEAN LAYER SOUTHWESTERLY FLOW.

ON THIS TRACK...THE CYCLONE WILL BE PASSING NEARBY OR OVER THE
AZORES BETWEEN 4 AND 5 DAYS.

FORECASTER AVILA

FORECAST POSITIONS AND MAX WINDS

INITIAL      17/2100Z 25.8N  40.5W    85 KT
 12HR VT     18/0600Z 28.0N  41.0W    75 KT
 24HR VT     18/1800Z 30.0N  40.0W    65 KT
 36HR VT     19/0600Z 32.0N  39.0W    55 KT
 48HR VT     19/1800Z 33.5N  37.5W    50 KT
 72HR VT     20/1800Z 34.5N  36.0W    45 KT
 96HR VT     21/1800Z 38.0N  30.0W    40 KT
120HR VT     22/1800Z 46.0N  20.0W    40 KT...EXTRATROPICAL


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