ZCZC MIATCDAT1 ALL TTAA00 KNHC DDHHMM HURRICANE IRIS DISCUSSION NUMBER 11 NATIONAL WEATHER SERVICE MIAMI FL 5 AM EDT SUN OCT 07 2001 AFTER MOVING MOSTLY WESTWARD...EVEN WOBBLING A LITTLE SOUTH OF WEST...THE HURRICANE APPEARS TO HAVE RESUMED A WEST-NORTHWEST MOTION OF ABOUT 285/15. GLOBAL MODELS MAINTAIN A RIDGE TO THE NORTH OF THE IRIS DURING THE FORECAST PERIOD...AND THIS RIDGE IS PREDICTED TO STRENGTHEN A BIT OVER THE EASTERN GULF OF MEXICO IN A COUPLE OF DAYS. BECAUSE OF THE MORE WESTWARD MOTION OVER THE PAST 6-12 HOURS...THE OFFICIAL FORECAST TRACK HAS BEEN ADJUSTED JUST SLIGHTLY TO THE SOUTH OF THE PREVIOUS ONE. THIS IS ROUGHLY IN THE MIDDLE OF THE NUMERICAL GUIDANCE SUITE WHICH IS FAIRLY TIGHTLY CLUSTERED. THE AVN MODEL IS SOMEWHAT TO THE NORTH OF THE OFFICIAL FORECAST...HOWEVER THAT MODEL HAS EXHIBITED A SLIGHT NORTHWARD BIAS FOR IRIS THUS FAR. ALTHOUGH THE SATELLITE PRESENTATION HAS BEEN RATHER RAGGED-LOOKING...LATEST AERIAL RECONNAISSANCE OBSERVATIONS SUGGEST THAT IRIS IS MAINTAINING ITS STRENGTH. THE EYE WALL IS STILL CLOSED AND...EVEN THOUGH THE HIGHEST FLIGHT LEVEL WINDS SO FAR ON THIS MISSION WERE 76 KNOTS...THE CENTRAL PRESSURE READING WAS DOWN TO 987 MILLIBARS. RECENTLY...A GPS DROPSONDE SHOWED A SPOT SURFACE WIND SPEED OF 70 KNOTS JUST NORTH OF THE CENTER. IT IS PRESUMED THAT SLIGHTLY STRONGER SURFACE WINDS EXIST SOMEWHERE OVER THE NORTHERN SEMICIRCLE OF THE HURRICANE. AN UPPER-LEVEL CYCLONE HAS BEEN ROTATING AROUND THE SOUTHERN SEMICIRCLE OF IRIS...AND PERHAPS INTERFERING WITH THE OUTFLOW. THAT LOW IS NOW SOUTHEAST OF THE HURRICANE...AND APPEARS TO BE INCREASING ITS SEPARATION FROM IRIS. WE ANTICIPATE THAT THE ENVIRONMENT WILL BECOME MORE FAVORABLE FOR INTENSIFICATION AS THE HURRICANE ENTERS THE NORTHWEST CARIBBEAN SEA. THE SHIPS MODEL BRINGS IRIS TO MAJOR HURRICANE STATUS IN 48 HOURS... AND THE OFFICIAL FORECAST IS JUST SLIGHTLY MORE CONSERVATIVE. FORECASTER PASCH FORECAST POSITIONS AND MAX WINDS INITIAL 07/0900Z 17.1N 76.1W 75 KTS 12HR VT 07/1800Z 17.7N 78.0W 80 KTS 24HR VT 08/0600Z 18.3N 80.7W 85 KTS 36HR VT 08/1800Z 18.5N 83.5W 90 KTS 48HR VT 09/0600Z 18.5N 86.0W 95 KTS 72HR VT 10/0600Z 18.5N 90.0W 45 KTS...INLAND NNNN