[Tropical] Tropical Cyclone Discussion

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WTNT43 KNHC 221435
TCDAT3

TROPICAL STORM LORENZO DISCUSSION NUMBER   5
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL132013
1100 AM AST TUE OCT 22 2013

THE CLOUD PATTERN OF LORENZO HAS BECOME BETTER ORGANIZED OVERNIGHT
AND THIS MORNING.  A BURST OF CONVECTION SEVERAL HOURS AGO HAS
MORPHED INTO A CENTRAL DENSE OVERCAST WITH A BAND WRAPPING AROUND
THE NORTHERN SEMICIRCLE OF THE CIRCULATION.  A SERIES OF MICROWAVE
IMAGES HAVE ALSO SHOWN A MID-LEVEL EYE THAT IS NOT COINCIDENT WITH
THE LOW-LEVEL CENTER DUE TO ABOUT 20 KT OF WESTERLY VERTICAL WIND
SHEAR.  UNLIKE YESTERDAY...HOWEVER...THE LOW-LEVEL CENTER IS
UNDERNEATH THE CONVECTIVE CLOUD CANOPY.  A BLEND OF TAFB/SAB DVORAK
INTENSITY ESTIMATES AND THE LATEST ADT VALUES IS USED TO RAISE THE
INITIAL INTENSITY TO 45 KT.

ANY FURTHER INTENSIFICATION OF LORENZO...IF ANY...IS LIKELY TO OCCUR
SOON SINCE THE CYCLONE SHOULD ENCOUNTER A SUBSTANTIAL INCREASE IN
NORTHWESTERLY SHEAR AND MOVE OVER GRADUALLY DECREASING SEA SURFACE
TEMPERATURES WITHIN 12 TO 24 HOURS. THE INCREASE IN SHEAR SHOULD
DISRUPT THE VERTICAL INTEGRITY OF CIRCULATION AND CAUSE A
DECOUPLING OF THE CYCLONE IN 24 TO 36 HOURS. THE SYSTEM IS LIKELY
BECOME AN OPEN TROUGH AHEAD OF AN ADVANCING FRONT BY 72 HOURS. THE
NHC INTENSITY FORECAST IS RAISED IN THE VERY SHORT TERM TO ACCOUNT
FOR THE GREATER INITIAL WIND SPEED...BUT LIKE THE PREVIOUS
ONE...SHOWS RAPID WEAKENING BY 48 HOURS. DISSIPATION IS NOW
FORECAST A DAY SOONER IN AGREEMENT WITH THE GLOBAL MODEL GUIDANCE.

LORENZO HAS BEEN MOVING WITH MORE OF AN EASTWARD COMPONENT OF
MOTION...AND THE INITIAL MOTION ESTIMATE IS 075/07. THE CYCLONE
SHOULD BE STEERED EAST-NORTHWESTWARD DURING THE NEXT DAY OR TWO
BETWEEN A MID-LEVEL RIDGE TO THE SOUTH AND A BELT OF WESTERLIES TO
THE NORTH. THE TRACK SHOULD BEND MORE TOWARD THE NORTHEAST IN ABOUT
48 HOURS AS THE STEERING FLOW BECOMING SOUTHWESTERLY AHEAD OF A
COLD FRONT. THE NHC TRACK FORECAST IS SLIGHTLY RIGHT OF THE
PREVIOUS ADVISORY THROUGH 36 HOURS BUT NOT AS FAR RIGHT AS THE
MULTI-MODEL CONSENSUS.

FORECAST POSITIONS AND MAX WINDS

INIT  22/1500Z 29.5N  52.0W   45 KT  50 MPH
 12H  23/0000Z 29.6N  50.8W   45 KT  50 MPH
 24H  23/1200Z 29.8N  49.7W   40 KT  45 MPH
 36H  24/0000Z 30.3N  48.7W   35 KT  40 MPH
 48H  24/1200Z 31.3N  47.4W   30 KT  35 MPH
 72H  25/1200Z...DISSIPATED

$$
FORECASTER KIMBERLAIN


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