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HURRICANE IRIS DISCUSSION NUMBER 15
NATIONAL WEATHER SERVICE MIAMI FL
5 AM EDT MON OCT 08 2001
IRIS IS BECOMING A DANGEROUS HURRICANE. LATEST INFORMATION FROM THE
HURRICANE HUNTER AIRCRAFT SHOW THAT THE SYSTEM HAS STRENGTHENED
RAPIDLY OVER THE PAST SEVERAL HOURS. THE INNER CORE IS VERY TIGHT
AND RECON REPORTED CONCENTRIC EYE WALLS...WITH AN INNER EYE DIAMETER
OF AROUND 8 N MI...OR LESS. THE CENTRAL PRESSURE HAS FALLEN
PRECIPITOUSLY...AT A RATE OF MORE THAN 3 MB/HR SINCE 00Z...WITH THE
LATEST DROPSONDE MEASURING 963 MB. IRIS IS APPROACHING MAJOR
HURRICANE STATUS...INDEED IT MAY BE ONE ALREADY. HOWEVER IT IS
POSSIBLE THAT AN EYE WALL REPLACEMENT CYCLE IS UNDERWAY...SO THERE
MAY BE SOME UPWARD/DOWNWARD FLUCTUATIONS IN INTENSITY TODAY.
NOTWITHSTANDING...THE CYCLONE IS OVER A REGION OF HIGH UPPER-OCEANIC
HEAT CONTENT AND THE UPPER-LEVEL OUTFLOW IS BECOMING BETTER-DEFINED.
THEREFORE A NET INCREASE IN STRENGTH IS LIKELY BEFORE LANDFALL.
THE OFFICIAL INTENSITY FORECAST MAY BE CONSERVATIVE...BUT WE HAVE
LITTLE GUIDANCE FOR SUCH RAPIDLY INTENSIFYING HURRICANES.
THE MOTION IS WEST...OR SLIGHTLY SOUTH OF DUE WEST...260/17. THERE
IS A PRONOUNCED DEEP-LAYER ANTICYCLONE TO THE NORTH OF IRIS...AND
GLOBAL MODELS INDICATE A CONTINUATION OF THIS REGIME OVER THE NEXT
FEW DAYS. NUMERICAL TRACK GUIDANCE SHOWS A WEST TO
WEST-SOUTHWESTWARD MOTION...AND SO DOES THE OFFICIAL FORECAST.
SINCE THERE IS THE POSSIBILITY OF A MORE SOUTHWARD EXCURSION OF THE
HURRICANE THAN SHOWN HERE...A HURRICANE WARNING IS ISSUED FOR THE
COAST OF HONDURAS...AND A HURRICANE WARNING IS RECOMMENDED FOR THE
CARIBBEAN COAST OF GUATEMALA.
FORECASTER PASCH
FORECAST POSITIONS AND MAX WINDS
INITIAL 08/0900Z 17.1N 83.1W 95 KTS
12HR VT 08/1800Z 17.0N 85.5W 105 KTS
24HR VT 09/0600Z 16.8N 88.5W 80 KTS...INLAND
36HR VT 09/1800Z 16.6N 91.5W 30 KTS...INLAND
48HR VT 10/0600Z 16.5N 94.5W 20 KTS...INLAND
72HR VT 11/0600Z 16.5N 98.5W 20 KTS...INLAND
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