[Tropical] Tropical Cyclone Discussion

[Nashville EMWIN]

WTNT44 KNHC 030225
TCDAT4
TROPICAL DEPRESSION NINE DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT THU SEP 02 2004

WHILE I AM NOT CRAZY ABOUT RELOCATING A TROPICAL CYCLONE AT
NIGHT...AN SSMI PASS NEAR 23Z SUGGESTS THAT THE CENTER OF THE
DEPRESSION IS FARTHER EAST THAN PREVIOUSLY THOUGHT...NEAR THE
NORTHEAST EDGE OF THE DEEP CONVECTION.  ANALYSES FROM CIMSS SHOW
ABOUT 15 KT OF NORTHEASTERLY SHEAR OVER THE DEPRESSION...CONSISTENT
WITH THIS POSITIONING OF THE CENTER.  THE DEPRESSION HAS BEEN
MAINTAINING A BALL OF VERY COLD CONVECTION FOR THE LAST SEVERAL
HOURS...AND DVORAK INTENSITY ESTIMATES FROM TAFB AND SAB AT 00Z
WERE 30 KT.  HOWEVER...THESE ESTIMATES WERE BASED ON POSITIONS MORE
EMBEDDED IN THE CONVECTION...AND SO I AM INCLINED TO KEEP THE
INITIAL INTENSITY AT 25 KT.

WITH THE RELOCATION OF THE CENTER...THE INITIAL MOTION IS NOW
ESTIMATED TO BE 270/12.  THE DEPRESSION IS EMBEDDED IN A DEEP
EASTERLY FLOW SOUTH OF THE SUBTROPICAL RIDGE...WHICH IS FORECAST TO
BE MAINTAINED THROUGHOUT THE FORECAST PERIOD.  THERE IS GOOD
AGREEMENT AMONG THE GFDL...UKMET...AND GFS MODELS ON A BRISK
WESTWARD MOTION WHICH HAS BEEN FOLLOWED CLOSELY FOR THIS ADVISORY.
THE NOGAPS IS CONSIDERABLY SLOWER THAN THE REST OF THE GUIDANCE...
BUT APPEARS TO BE HAVING TROUBLE CONSOLIDATING A CIRCULATION DURING
THE FIRST COUPLE DAYS OF THE INTEGRATION...AND HAS BEEN DISCOUNTED.
THE OFFICIAL FORECAST IS A LITTLE SLOWER THAN THE PREVIOUS ADVISORY
AS A RESULT OF THE RELOCATION AND CHANGE IN THE INITIAL MOTION.

THE GFDL HAS UNBRIDLED ENTHUSIASM FOR THIS SYSTEM...TAKING THE
DEPRESSION TO CATEGORY FOUR STATUS IN ABOUT THREE DAYS.  BOTH THE
GFS AND UKMET SUGGEST THAT THE EASTERLY SHEAR WILL BE SLOW TO
DIMINISH AS THE DEPRESSION REMAINS ON THE SOUTH SIDE OF AN
UPPER-LEVEL ANTICYCLONE.  STEADY STRENGTHENING WILL BE
FORECAST...BUT MORE IN LINE WITH THE SHIPS MODEL GUIDANCE.

FORECASTER FRANKLIN


FORECAST POSITIONS AND MAX WINDS

INITIAL      03/0300Z  9.8N  29.4W    25 KT
 12HR VT     03/1200Z  9.9N  31.5W    35 KT
 24HR VT     04/0000Z 10.1N  34.7W    45 KT
 36HR VT     04/1200Z 10.4N  38.0W    50 KT
 48HR VT     05/0000Z 10.8N  41.0W    55 KT
 72HR VT     06/0000Z 11.5N  47.5W    65 KT
 96HR VT     07/0000Z 12.5N  53.5W    75 KT
120HR VT     08/0000Z 14.0N  59.5W    80 KT


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