[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 170300
TCDAT2
TROPICAL STORM KARL DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT THU SEP 16 2004

CONVENTIONAL AND MICROWAVE SATELLITE IMAGERY INDICATE TROPICAL
DEPRESSION TWELVE HAS BECOME MUCH BETTER ORGANIZED DURING THE PAST
6 HOURS. DVORAK INTENSITY ESTIMATES ARE 45 KT FROM TAFB AND 35 KT
FRAM SAB. A 16/1950Z QUIKSCAT OVERPASS INDICATED SOME 25-30 KT
UNCONTAMINATED WIND SPEEDS...WITH ONLY A FEW RAIN-CONTAMINATED
40-KT WINDS. THEREFORE...THE DEPRESSION IS ONLY BEING UPGRADED TO
35-KT TROPICAL STORM KARL.

THE INITIAL MOTION IS 280/12.  A SLIGHT SOUTHWARD ADJUSTMENT TO THE
INITIAL POSITION WAS MADE BASED ON RECENT MICROWAVE SATELLITE
POSITON ESTIMATES. NHC MODEL GUIDANCE REMAINS IN EXCELLENT
AGREEMENT ON A GENERAL WEST TO WEST-NORTHWESTWARD MOTION AROUND THE
SOUTHERN PERIPHERY OF THE STRONG SUBTROPICAL RIDGE TO THE NORTH FOR
THE NEXT 48 HOURS. AFTER THAT...A DEEP MID-LATITUDE TROUGH IS
FORECAST BY ALL OF THE MODELS TO DIG SOUTHWARD...TO VARYING
DEGREES...AND WEAKEN THE RIDGE TO THE NORTHWEST OF KARL. THIS
ALLOWS THE CYCLONE TO GRADUALLY TURN NORTHWEASTWARD AND EVENTUALLY
NORTHWARD. DUE TO THE UNCERTAINTY IN BOTH THE TIMING AND MAGNITUDE
OF THE DEVELOPMENT OF THIS LARGE MID-/UPPER-LEVEL TROUGH...THE
FORECAST MOTION WAS SLOWED SLIGHTLY AFTER 72 HOURS. THE OFFICIAL
TRACK IS SLIGHTLY LEFT OF THE PREVIOUS RTACK...TO ACCOUNT FOR THE
MORE SOUTHWARD INITIAL POSITION...AND IS CLOSE TO THE NHC MODEL
CONSENSUS.

THERE IS NO CHANGE TO THE PREVIOUS INTENSITY FORECAST OR REASONING.
KARL HAS A TIGHT INNER-CORE WIND FIELD AND A VERY FAVORABLE OUTFLOW
PATTERN ALREADY...SO A SLIGHTLY FASTER RATE OF INTENSIFICATION IS
EXPECTED DURING THE NEXT 36 HOURS. AFTER THAT...INCREASING EASTERLY
SHEAR MAY SLOW THE DEVELOPMENT PROCESS THROUGH 72 HOURS...WITH
STEADY INTENSIFICATION RESUMING AGAIN AFTER THAT.

FORECASTER STEWART


FORECAST POSITIONS AND MAX WINDS

INITIAL      17/0300Z 11.4N  33.9W    35 KT
 12HR VT     17/1200Z 11.7N  35.5W    45 KT
 24HR VT     18/0000Z 12.1N  37.4W    55 KT
 36HR VT     18/1200Z 12.5N  39.3W    65 KT
 48HR VT     19/0000Z 13.2N  41.1W    70 KT
 72HR VT     20/0000Z 15.5N  44.0W    75 KT
 96HR VT     21/0000Z 18.5N  45.5W    85 KT
120HR VT     22/0000Z 22.0N  46.5W    95 KT


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