LARRY #6 - DISCUSSION

[AussieMark]

000
WTNT42 KNHC 030234
TCDAT2
TROPICAL STORM LARRY DISCUSSION NUMBER 6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT THU OCT 02 2003

THE HIGHEST FLIGHT LEVEL WIND SPEED REPORTED BY THE RECONNAISSANCE
AIRCRAFT THIS EVENING REMAINS THE 66 KNOTS AT 1500 FT REPORTED IN
THE PREVIOUS DISCUSSION...SO THE INITIAL WIND SPEED IS KEPT AT 50
KNOTS. THERE HAVE ALSO BEEN A COUPLE OF SHIP AND OIL RIG REPORTS
OF NEAR 50 KNOTS. INFRARED IMAGERY SHOWS A SIGNIFICANT DECREASE IN
DEEP CONVECTION SUGGESTING NO SHORT-TERM STRENGTHENING. BUT THERE
IS PLENTY OF TIME FOR LARRY TO STRENGTHEN AS IT DRIFTS OVER THE BAY
OF CAMPECHE...IF THE VERTICAL SHEAR NEAR 20 KNOTS IS NOT TOO MUCH
OF A NEGATIVE FACTOR. THE SHIPS MODEL INDICATES STRENGTHENING TO
NEAR HURRICANE FORCE BY 72 HOURS AND SO DOES THE OFFICIAL FORECAST.

THE INITIAL MOTION ESTIMATE IS 235/02 BASED ON 24 HOURS OF MOTION.
THE PAST 12 HOURS HAVE BEEN CLOSER TO 270/04. THE GLOBAL MODELS
ALL SHOW A SLOW SOUTH TO SOUTHWESTWARD DRIFT FOR 3 DAYS AS THE
STORM IS TRAPPED IN A WEAK STEERING CURRENT BETWEEN TWO HIGH
PRESSURE RIDGES. AFTER 3 DAYS THE MODELS DIVERGE. THE GFS AND GFDL
ARE NEARLY STATIONARY THROUGH DAY 5 IN THE BAY OF CAMPECHE. THE
NOGAPS MOVES THE STORM ACROSS MEXICO INTO THE PACIFIC BY DAY 4 AND
THE UKMET MOVES THE STORM NORTHWESTWARD ACROSS MEXICO AFTER DAY 3.
THE OFFICIAL FORECAST FOLLOWS A CONSENSUS OF THE VISIBLE SATELLITE
IMAGERY SHOWING A VERY SLOW MOTION TOWARD THE SOUTHWEST AND IS
ADJUSTED A LITTLE TO THE WEST OF THE PREVIOUS ADVISORY. IT SHOULD
BE NOTED THAT WHEN THE MOTION IS NEAR ZERO...THE DIRECTION OF
MOTION BECOMES MORE UNCERTAIN.

FORECASTER LAWRENCE


FORECAST POSITIONS AND MAX WINDS

INITIAL 03/0300Z 20.4N 94.1W 50 KT
12HR VT 03/1200Z 20.2N 94.2W 50 KT
24HR VT 04/0000Z 19.9N 94.4W 55 KT
36HR VT 04/1200Z 19.6N 94.6W 60 KT
48HR VT 05/0000Z 19.2N 94.9W 60 KT
72HR VT 06/0000Z 18.8N 95.1W 60 KT
96HR VT 07/0000Z 18.5N 95.5W 40 KT...INLAND
120HR VT 08/0000Z 18.0N 97.0W 20 KT...INLAND