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HURRICANE IRENE DISCUSSION NUMBER   4
NATIONAL WEATHER SERVICE MIAMI FL
5 AM EDT THU OCT 14 1999
 
SATELLITE POSITION ESTIMATES FROM TAFB AND SAB SUGGEST THE CENTER
HAS MOVED SLIGHTLY WEST OF DUE NORTH AND HAS SLOWED DOWN A BIT.
ALTHOUGH THE HURRICANE HUNTER AIRCRAFT IS UNABLE TO FLY NEAR THE
COAST OF CUBA DUE TO AIR FORCE REGULATIONS...THEY WERE ABLE TO
USE THE ON-BOARD RADAR TO ESTIMATE A CENTER.  THEIR ESTIMATE IS
CONSISTENT WITH THE SATELLITE TRENDS...AND THE INITIAL MOTION
ESTIMATE IS NOW 355/6 KT.  

WITH THE PASSAGE OF THE MID- TO UPPER-TROPOSPHERIC TROUGH OVER THE 
U.S. EAST COAST THE STEERING CURRENTS NEAR IRENE SHOULD WEAKEN. 
MOST OF THE OBJECTIVE TRACK GUIDANCE IS IN AGREEMENT WITH A SLOW
GENERALLY NORTHWARD MOTION THROUGH 24-36 HRS. THE OFFICIAL FORECAST 
SHOWS A SLOW GENERAL NORTHWARD SPEED DURING THE NEXT DAY OR SO. 
TOWARDS THE END OF THE FORECAST PERIOD...A NEW MID-LATITUDE TROUGH
...CURRENTLY OVER NORTHWESTERN NORTH AMERICA...IS EXPECTED TO MOVE
INTO THE MIDWEST.  THIS SHOULD PRODUCE A SOUTH-SOUTHWESTERLY
STEERING ENVIRONMENT FOR IRENE.  SEVERAL MODELS...BAMD...THE GFDL
AND UKMET...SHOW A NORTH-NORTHEAST TURN AND AN INCREASE IN SPEED 
BETWEEN 48 AND 72 HRS.  WHILE THE GUIDANCE IS MORE TIGHTLY CLUSTERED
ON THIS SCENARIO...THERE REMAINS SIGNIFICANT UNCERTAINTY IN THIS
PORTION OF THE FORECAST. THE OFFICIAL FORECAST IS SHIFTED SLIGHTLY
TO THE LEFT OF THE PREVIOUS ADVISORY...AND IS A COMPROMISE BETWEEN
THE UKMET AND GFDL GUIDANCE LATER IN THE PERIOD. 
 
IRENE CONTINUES TO HAVE AN IMPRESSIVE SATELLITE SIGNATURE WITH THE
CENTER EMBEDDED WITHIN VERY COLD CONVECTION...TOPS TO -80C. BASED 
ON SATELLITE-BASED DVORAK ESTIMATES...THE INITIAL INTENSITY IS NOW
65 KT MAKING IRENE A HURRICANE. THE WESTERN PORTION OF CUBA IS
RATHER FLAT AND NARROW...AND HISTORICALLY HAS HAD MINIMAL IMPACT 
ON THE INTENSITY OF TROPICAL CYCLONES WHICH CROSS OVER THE REGION.
WITH WELL-ESTABLISHED UPPER-LEVEL OUTFLOW AND WARM WATERS FURTHER
STRENGTHENING IS FORECAST OVER THE SOUTHEASTERN GULF OF MEXICO...IN
AGREEMENT WITH SHIPS. HOWEVER INCREASING UPPER-LEVEL SOUTHWESTERLY
WINDS MAY LIMIT INTENSIFICATION LATER IN THE FORECAST PERIOD.
 
ALL INTERESTS IN FLORIDA SHOULD CLOSELY MONITOR THE PROGRESS OF
THIS STRENGTHENING STORM.  ADDITIONAL WATCHES...OR WARNINGS...MAY 
BE REQUIRED FOR SOME PORTION OF FLORIDA...AND THE KEYS...LATER
TODAY.
 
GUINEY
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     14/0900Z 21.6N  83.7W    65 KTS
12HR VT     14/1800Z 22.5N  83.8W    65 KTS
24HR VT     15/0600Z 23.7N  83.8W    70 KTS
36HR VT     15/1800Z 24.9N  83.7W    80 KTS
48HR VT     16/0600Z 26.0N  83.5W    80 KTS
72HR VT     17/0600Z 28.5N  82.5W    70 KTS...INLAND
 
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