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HURRICANE IRENE DISCUSSION NUMBER   7
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT THU OCT 14 1999
...VERY SLIGHT CORRECTION TO 12 HR FORECAST POSITION... 
IRENE IS POSING SOME FORECASTING CHALLENGES THIS EVENING.  A FEW
HOURS AGO...USING MORE RELIABLE CENTER FIXES FROM THE NOAA
AIRCRAFT...THE CENTER WAS RELOCATED SOMEWHAT TO THE WEST OF THE
PREVIOUS TRACK.  THIS WAS ALSO INDICATED BY KEY WEST RADAR...WHEN
THE EYE APPEARED TO REFORM IN THE VICINITY OF HAVANA.  MORE
RECENTLY...HOWEVER...THE RADAR PRESENTATION HAS DETERIORATED
MARKEDLY...AND THE LATEST FIXES FROM THE NOAA PLANE SHOW A SLOW AND
ERRATIC MOVEMENT.  HOWEVER...IRENE IS EXPECTED TO RESUME A NORTHWARD
COURSE AT AROUND 7 KNOTS.  THE RE-POSITIONING OF THE CENTER REQUIRES
A WESTWARD SHIFT OF THE FORECAST TRACK.  MID-TROPOSPHERIC HEIGHTS
ARE FORECAST TO RISE TO THE EAST OF FLORIDA AS A BROAD TROUGH MOVES
INTO THE CENTER PART OF THE U.S.  THIS SHOULD STEER IRENE NORTHWARD
SLOWLY FOR A DAY OR SO...WITH A GRADUAL BEND TOWARD THE
NORTH-NORTHEAST AT A SLIGHTLY FASTER FORWARD SPEED LATER IN THE
PERIOD.  THE CURRENT NHC FORECAST TRACK IS IN GOOD AGREEMENT WITH
THE U.K. MET. OFFICE AND LBAR GUIDANCE.
 
NOW THE OTHER CHALLENGE...FORECASTING THE INTENSITY.  IN SPITE OF
THE CURRENT RAGGEDNESS OF THE SYSTEM...WE STILL BELIEVE THAT THERE
IS A WINDOW OF OPPORTUNITY FOR STRENGTHENING AS IRENE MOVES OVER THE
SOUTHEASTERN GULF.  THUS THE OFFICIAL FORECAST SHOWS A SLIGHT
INCREASE IN STRENGTH...IN REASONABLE AGREEMENT WITH THE SHIPS MODEL
GUIDANCE.  HOWEVER...INCREASING SOUTHWESTERLY SHEAR COULD BE AN
INHIBITING FACTOR.
 
THE CURRENT FORECAST REQUIRES A NORTHWARD EXTENSION OF THE WATCHES
AND WARNINGS.
 
PASCH/JARVINEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     15/0300Z 23.4N  82.6W    65 KTS
12HR VT     15/1200Z 24.7N  82.6W    70 KTS
24HR VT     16/0000Z 26.0N  82.6W    70 KTS
36HR VT     16/1200Z 27.5N  82.5W    70 KTS...INLAND
48HR VT     17/0000Z 29.5N  82.0W    45 KTS...INLAND
72HR VT     18/0000Z 34.0N  81.0W    35 KTS...INLAND
 
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