HOME	ARCHIVES	FORECASTS	IMAGERY	ABOUT TPC	RECONNAISSANCE

ZCZC MIATCDEP5 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM IVO DISCUSSION NUMBER   3
NATIONAL WEATHER SERVICE MIAMI FL
2 AM PDT TUE SEP 11 2001
 
THE SHIP ZDEB2 WAS LOCATED 135 N MI NORTH-NORTHEAST OF THE CENTER OF
THE TROPICAL CYCLONE AT 06Z AND REPORTED A WIND OF 100/37 KNOT AND
1006.5 MB PRESSURE.  THE SHIP IS ONLY A FEW MILES OFF OF THE COAST
OF MEXICO.  THE DEPRESSION IS UPGRADED TO TROPICAL STORDM IVO ON THE
BASIS OF THE SHIP REPORTS AS WELL AS A 2.5 DVORAK CLASSIFICATION
FROM TAFB.  A 04Z SSMI PASS SHOWS THAT THE CLOUD STRUCTURE DOES NOT
SUGGEST A WELL DEFINED CIRCULATION.  THE SHIPS MODEL ANALYSIS OF THE 
00Z AVIATION MODEL GIVES 23 KNOT EASTERLY VERTICAL WIND SHEAR FOR 24 
HOURS OVER THE STORM FOLLOWED BY WEAKENING SHEAR.  SO IF IVO CAN 
HOLD TOGETHER FOR A DAY...THERE COULD BE AN OPPORTUNITY FOR 
STRENGTHENING TO A HURRICANE.  THIS IS THE SHIPS FORECAST AND THE 
OFFICIAL FORECAST.  IN CONTRAST THE GFDL MODEL SHOWS A VERY WEAK 
SYSTEM THROUGH 72 HOURS.

THE INITIAL MOTION IS 285/11.  THE 00Z AVIATION MODEL MAINTAINS A 
MID-LEVEL ANTICYCLONE OVER MEXICO.  THIS SHOULD KEEP IVO ON A 
285-300 DEGREE HEADING FOR THE NEXT 72 HOURS.  ONLY THE GFDL MODEL 
DOES NOT SHOW THIS SCENARIO.  IT SHOWS A VERY SLOW WEST-NORTHWEST 
DRIFT FOR NEARLY 72 HOURS.  THE OFFICIAL FORECAST FOLLOWS THE 
CONSENSUS OF THE GUIDANCE AND IS SIMILAR TO THE PREVIOUS ADVISORY.
 
UNTIL THE STORM STARTS TO MOVE AWAY FROM THE COAST IN A DAY OR 
SO...IT COULD GENERATE HEAVY RAINS IN COASTAL REGIONS WITH FLASH 
FLOODING IN MOUNTAINOUS AREAS.
 
FORECASTER LAWRENCE
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     11/0900Z 15.5N 103.2W    35 KTS
12HR VT     11/1800Z 16.0N 104.9W    40 KTS
24HR VT     12/0600Z 16.7N 107.0W    45 KTS
36HR VT     12/1800Z 17.8N 109.2W    55 KTS
48HR VT     13/0600Z 18.9N 111.1W    65 KTS
72HR VT     14/0600Z 21.0N 115.0W    65 KTS
  
NNNN