Tropical Storm PAUL

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TROPICAL STORM PAUL DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP172006
800 PM PDT SAT OCT 21 2006
 
PAUL IS A PARTLY SHEARED SYSTEM THIS EVENING...WITH A COUPLE OF
RECENT SSM/I OVERPASSES INDICATING THE CENTER IS JUST EAST OF THE
MAIN CONVECTION AND UNDER THE CIRRUS CANOPY.  ANALYSES FROM CIMSS
AT THE UNIVERSITY OF WISCONSIN SHOW ABOUT 20 KT OF EASTERLY SHEAR
OVER THE CENTER...ALTHOUGH SOME INCREASE IN OUTFLOW ON THE EAST
SIDE SUGGESTS THE SHEAR MAY BE DECREASING.  SATELLITE INTENSITY
ESTIMATES REMAIN 45 KT FROM TAFB AND SAB...SO THAT REMAINS THE
INITIAL INTENSITY.

THE MICROWAVE DATA SHOWS THE CENTER IS A LITTLE SOUTH OF THE
PREVIOUS TRACK...AND THE INITIAL MOTION IS NOW 275/6.  OTHER THAN
THIS...THERE IS NO CHANGE IN SYNOPTIC PATTERN OR FORECAST REASONING
SINCE THE LAST ADVISORY.  PAUL IS APPROACHING THE WESTERN END OF A
MID/UPPER-LEVEL RIDGE AND A LARGE MID/UPPER-LEVEL LOW CENTERED NEAR
29N124W.  THIS SHOULD CAUSE THE STORM TO TURN NORTHWARD BY 36 HR
AND NORTH-NORTHEASTWARD THEREAFTER.  ALL GUIDANCE AGREES WITH THIS
SCENARIO.  HOWEVER...THE GLOBAL MODELS FORECAST A MOTION TOWARD
CENTRAL OR SOUTHERN BAJA CALIFORNIA...WHILE THE GFDL REMAINS
FARTHER TO THE RIGHT WITH A TRACK INTO NORTHWESTERN MEXICO.  THE
GLOBAL MODELS SHOW PAUL SHEARING APART...WITH THE LOW-LEVEL CENTER
MOVING TO BAJA AND THE MID-LEVEL CENTER MOVING CLOSER TO THE GFDL
TRACK.  ON THE PREMISE THAT THE STORM WILL NOT SHEAR APART...THE
FORECAST TRACK IS BETWEEN THE MODEL CONSENSUS AND THE GFDL.

THE LARGE-SCALE MODELS FORECAST PAUL TO BE IN A LIGHT-MODERATE
SHEARING ENVIRONMENT FOR 36-48 HR.  THIS SHOULD ALLOW SOME
STRENGTHENING...WITH THE SHIPS...THE GFDL...AND THE FLORIDA STATE
SUPERENSEMBLE ALL FORECASTING  PAUL TO BECOME A HURRICANE.
AFTER THAT TIME...INCREASING SOUTHWESTERLY SHEAR SHOULD STOP
INTENSIFICATION.  THE GFDL CONTINUES TO FORECAST STRENGTHENING
AFTER 48 HR...CALLING FOR PAUL TO BECOME A MAJOR HURRICANE...BUT
THIS LOOKS OVERDONE GIVEN THE FORECAST SHEAR.  THE INTENSITY
FORECAST WILL FOLLOW THE SHIPS GUIDANCE AND KEEP PAUL A 65-KT
HURRICANE FROM 48 HR UNTIL LANDFALL.

THE WIND RADII FORECASTS HAVE BEEN REVISED BASED ON GUIDANCE AND THE
FORECAST MOTION.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      22/0300Z 15.9N 108.0W    45 KT
 12HR VT     22/1200Z 16.1N 109.1W    50 KT
 24HR VT     23/0000Z 16.8N 110.2W    55 KT
 36HR VT     23/1200Z 17.9N 110.9W    60 KT
 48HR VT     24/0000Z 19.9N 110.7W    65 KT
 72HR VT     25/0000Z 24.5N 108.5W    65 KT
 96HR VT     26/0000Z 29.0N 105.0W    20 KT...INLAND DISSIPATING
120HR VT     27/0000Z...DISSIPATED
 
$$
FORECASTER BEVEN
 
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