Tropical cyclone discussions are intended for other forecasters to explain the rationale for the current forecast level of confidence. However, this information is also useful to decision makers. The discussions generally include

• Reasoning behind the forecast
• Techniques and guidance used
• Table of the 12-, 24-, 35-, 48-, 72-, 96-, and 120-hour positions and maximum wind speed
• Plans for watches and/or warnings
• Other meteorological decisions
• The forecaster's name
  

WTNT45 KNHC 230300 
TCDAT5 

HURRICANE ISIDORE DISCUSSION NUMBER  28
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT SUN SEP 22 2002

THE CENTER HAS MOVED SOUTH OF THE SHORT-TERM FORECAST TRACK...AND
MOVED INLAND OVER NORTHWESTERN YUCATAN A FEW HOURS AGO.  THUS THE
CYCLONE IS WEAKENING...AND WILL CONTINUE TO DO SO UNTIL IT MOVES
BACK OVER WATER.  ASIDE FROM THE INTERACTION WITH LAND...ATMOSPHERIC
AND OCEANIC CONDITIONS REMAIN QUITE FAVORABLE FOR INTENSIFICATION SO
THE OFFICIAL FORECAST CALLS FOR ISIDORE TO RECOVER ITS PREVIOUS
INTENSITY AND MORE...PRESUMING THAT IT RE-ENTERS THE GULF TOMORROW.
THE OFFICIAL WIND SPEED FORECASTS BY DAYS 2 AND 3 ARE BACK TO THOSE
SHOWN IN THE PREVIOUS ADVISORY.  HOWEVER...TROPICAL CYCLONE
INTENSITY FORECASTING HAS A LOT OF UNCERTAINTIES.  IF THE INNER CORE
STRUCTURE IS SEVERELY DISRUPTED BY THE CYCLONES TRANSIT OVER
LAND...IT MAY NOT BE ABLE TO RE-INTENSIFY AS MUCH AS ANTICIPATED.

THE FORWARD SPEED APPEARS TO HAVE SLOWED AND CURRENT MOTION IS 
ESTIMATED TO BE A SOUTHWESTWARD DRIFT...220/4.  THE MORE SOUTHERLY 
MOTION WAS PROBABLY THE RESULT OF MID-LEVEL RIDGING TO THE 
WEST-NORTHWEST OF ISIDORE.  GLOBAL MODELS AND THE GFDL HURRICANE 
MODEL AGREE THAT THE SYSTEM WILL TURN BACK TO THE WEST AND NORTHWEST 
WITHIN 12 TO 24 HOURS.  AFTERWARDS...A MID-TROPOSPHERIC RIDGE SHOULD 
BEGIN TO BUILD TO THE EAST OF ISIDORE...WHICH SHOULD INDUCE A MORE 
NORTHWARD MOTION.  NOT MUCH INCREASE IN FORWARD SPEED IS EXPECTED 
UNTIL A MID-LATITUDE TROUGH BEGINS TO AFFECT THE SYSTEM...PROBABLY 
BEYOND THIS FORECAST PERIOD.

THE THREE-DAY FORECAST POINT IMPLIES AN EVENTUAL THREAT TO EITHER 
THE NORTHWEST OR NORTHERN GULF OF MEXICO COAST...HOWEVER IT IS STILL 
TOO EARLY TO BE MORE SPECIFIC ABOUT THE THREAT.

FORECASTER PASCH
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      23/0300Z 20.8N  89.5W    90 KT
 12HR VT     23/1200Z 20.7N  90.3W    80 KT
 24HR VT     24/0000Z 21.0N  91.0W    95 KT
 36HR VT     24/1200Z 21.8N  92.0W   115 KT
 48HR VT     25/0000Z 22.8N  92.5W   125 KT
 72HR VT     26/0000Z 25.0N  93.0W   125 KT
 96HR VT     27/0000Z 27.0N  92.5W   100 KT
120HR VT     28/0000Z 29.0N  92.0W    90 KT
 
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