[Tropical] Tropical Cyclone Discussion

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WTNT43 KNHC 250844
TCDAT3
TROPICAL STORM LISA DISCUSSION NUMBER  24
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT SAT SEP 25 2004

SHORTWAVE AND ENHANCED BD CURVE INFRARED IMAGERY DEPICT A STRONG
BURST OF DEEP CONVECTION JUST TO THE SOUTH OF THE LOW CENTER AND A
DEVELOPING BAND WRAPPING IN FROM THE EAST. DVORAK CURRENT INTENSITY
ESTIMATES ARE 35 KT FROM ALL AGENCIES. THE INITIAL INTENSITY IS
INCREASED TO 35 KT. THE SOUTHEAST QUADRANT OF AN UPPER HIGH
CONTINUES TO PRODUCE 10 TO 20 KT OF SHEAR OVER LISA. HOWEVER...THIS
NORTHERLY SHEAR IS STILL FORECAST TO WEAKEN OVER THE NEXT 24 HOURS.
THE OFFICIAL FORECAST CALLS FOR SLOW STRENGTHENING THROUGH 72 HOURS
THEN LEVELS OFF JUST BELOW HURRICANE STRENGTH AS THE TROPICAL
CYCLONE IS EXPECTED TO ENCOUNTER SOUTHWESTERLY SHEAR. THE INTENSITY
FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY AND FOLLOWS THE SHIPS.

INITIAL MOTION IS 315/8 KT. WITH THE EXCEPTION OF THE GFS...THE
AVAILABLE DYNAMICAL MODELS ARE INDICATING EITHER A TURN TO THE
WEST-NORTHWEST OR NORTHWEST BY DAY 4. THIS MOTION IS PROVIDED BY A
MID-LEVEL RIDGE EXPECTED TO BUILD IN FROM THE NORTHWEST BEHIND A
MID-UPPER TROUGH CURRENTLY SITUATED OVER THE MID-ATLANTIC. THIS IS
THE SAME RIDGE THAT IS CURRENTLY STEERING HURRICANE JEANNE. THE GFS
REMAINS IN THE WEAKNESS AFTER 96 HOURS WITH A TURN TO THE NORTH.
THE UKMET...ON THE OTHER HAND...REFLECTS A CONSIDERABLY STRONGER
RIDGE BEYOND 72 HOURS. THE OFFICIAL FORECAST IS TO THE LEFT OF THE
PREVIOUS FORECAST BEYOND 72 HOURS AND IS BASED OFF OF A CONSENSUS
OF ALL THE MODELS WITH THE EXCEPTION OF THE UKMET.

FORECASTER ROBERTS/BEVEN

FORECAST POSITIONS AND MAX WINDS

INITIAL      25/0900Z 15.2N  45.2W    35 KT
 12HR VT     25/1800Z 16.2N  46.2W    40 KT
 24HR VT     26/0600Z 17.5N  47.1W    45 KT
 36HR VT     26/1800Z 19.0N  48.0W    50 KT
 48HR VT     27/0600Z 20.5N  48.6W    55 KT
 72HR VT     28/0600Z 24.0N  50.0W    60 KT
 96HR VT     29/0600Z 27.0N  51.0W    60 KT
120HR VT     30/0600Z 29.5N  51.5W    60 KT


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