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HURRICANE JULIETTE DISCUSSION NUMBER  19
NATIONAL WEATHER SERVICE MIAMI FL
2 PM PDT TUE SEP 25 2001

AIR FORCE RESERVE UNIT AIRCRAFT OBSERVATIONS CONFIRM THAT JULIETTE
IS AN INTENSE CATEGORY 4 HURRICANE.  THE MINIMUM SEA LEVEL
PRESSURE...MEASURED BY DROPSONDE...WAS 923 MB.  WHEREAS A NUMBER OF
PAST HURRICANES HAVE HAD LOWER CENTRAL PRESSURES ESTIMATED BY
SATELLITE...THIS IS APPARENTLY THE SECOND LOWEST SEA LEVEL PRESSURE
MEASUREMENT ON RECORD IN AN EASTERN NORTH PACIFIC HURRICANE.  ONLY
AVA IN JUNE OF 1973 HAD A LOWER MEASURED PRESSURE...915 MB.  MAXIMUM
FLIGHT LEVEL WINDS WERE 131 KNOTS...AT 700 MB.  USING THE 90 PERCENT
CONVERSION FACTOR YIELDS 120 KNOTS FOR THE SURFACE WIND.
HOWEVER...FOR SUCH A LOW CENTRAL PRESSURE AND A SMALL EYE WE FEEL IT
IS WARRANTED TO NUDGE THE INTENSITY ESTIMATE UPWARD JUST SLIGHTLY.
THE RECON DATA SUGGESTS THE FORMATION OF CONCENTRIC EYEWALLS...AND
SOME FLUCTUATIONS IN INTENSITY DUE TO THE INNER CORE CHANGES ARE
LIKELY OVER THE NEXT 12 TO 24 HOURS.  GRADUAL WEAKENING IS FORECAST
THEREAFTER DUE TO SLIGHTLY COOLER WATERS.  HOWEVER THE OFFICIAL
INTENSITY FORECAST DOES NOT SHOW AS RAPID A WEAKENING AS THE SHIPS 
GUIDANCE.

THERE HAVE BEEN TROCHOIDAL WOBBLES IN THE TRACK TODAY...BUT THE 
OVERALL MOTION IS ESTIMATED TO BE 285/10.  THE OFFICIAL TRACK 
FORECAST IS SIMILAR TO THE PREVIOUS ONE.  GLOBAL MODELS INDICATE 
THAT THE 500 MB HIGH OVER NORTHERN BAJA WILL GRADUALLY WEAKEN AND 
SHIFT EASTWARD.  THIS SHOULD CAUSE JULIETTE'S HEADING TO VEER TOWARD 
THE NORTHWEST...AND EVENTUALLY NORTH-NORTHWEST.  NUMERICAL GUIDANCE 
ALSO INDICATES A SLOWING OF FORWARD SPEED.  

EVEN IF JULIETTE IS NOT FORECAST TO MOVE DIRECTLY OVER BAJA...
A TROPICAL STORM OR HURRICANE WATCH SHOULD SOON BE REQUIRED FOR 
PORTIONS OF THAT PENINSULA DUE TO THE LARGE SIZE OF THIS SEVERE 
HURRICANE.

FORECASTER PASCH
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     25/2100Z 16.5N 107.7W   125 KTS
12HR VT     26/0600Z 17.6N 108.9W   125 KTS
24HR VT     26/1800Z 19.0N 110.0W   120 KTS
36HR VT     27/0600Z 20.3N 110.8W   110 KTS
48HR VT     27/1800Z 21.5N 111.5W   100 KTS
72HR VT     28/1800Z 23.0N 112.5W    85 KTS
 
 
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