WDPN31 PGTW 080300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 06W (NOUL) WARNING NR 21//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 06W (NOUL), LOCATED APPROXIMATELY 545 NM EAST-
SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD
AT 11 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY SHOWS THE SYSTEM HAS MAINTAINED A SYMMETRIC CENTRAL DENSE
OVERCAST FEATURE WITH A CLOUD-FILLED EYE AND COMPACT FEEDER BANDS.
THE INITIAL POSITION IS BASED ON A MICROWAVE EYE ON A 072301Z 37 GHZ
F18 PASS WITH HIGH CONFIDENCE. THE INITIAL INTENSITY OF 100 KNOTS IS
BASED ON AN OVERALL ASSESSMENT OF DVORAK ESTIMATES FROM PGTW, KNES,
AND RJTD. UPPER LEVEL ANALYSIS INDICATES TY 06W IS SOUTH OF THE RIDGE
AXIS IN AN AREA OF LOW VERTICAL WIND SHEAR (VWS) AND EXCELLENT RADIAL
OUTFLOW. THE CYCLONE IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A
DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY 06W IS EXPECTED TO TRACK WEST-NORTHWESTWARD UNDER THE
CONTINUED STEERING INFLUENCE OF THE STR OVER THE NEXT 48 HOURS,
MAKING LANDFALL OVER NORTHERN LUZON NEAR ISABELA JUST AROUND TAU 48.
GENERALLY FAVORABLE UPPER-LEVEL OUTFLOW, LOW VWS, AND WARM WATER
SHOULD SUPPORT ADDITIONAL INTENSIFICATION PRIOR TO LANDFALL. AFTER
TAU 48, THE SYSTEM WILL BEGIN TO ROUND THE WESTERN EDGE OF THE STR IN
RESPONSE TO AN APPROACHING MID-LATITUDE TROUGH APPROACHING FROM THE
NORTHWEST. NUMERIC MODELS ARE IN GOOD AGREEMENT THROUGH TAU 72,
LENDING HIGH CONFIDENCE IN THE NEAR TO MID-TERM PORTION OF THE JTWC
TRACK FORECAST.
   C. IN THE EXTENDED PERIOD, TY NOUL WILL ACCELERATE NORTHEASTWARD
AS IT BEGINS EXTRA-TROPICAL TRANSITION. INCREASING VWS AND COOLING
SSTS WILL GRADUALLY ERODE THE SYSTEM BEFORE IT BECOMES A COLD CORE 
LOW BY END OF FORECAST. THIS PORTION OF THE JTWC TRACK FORECAST IS 
LAID JUST TO THE RIGHT OF AND SLIGHTLY FASTER THAN THE MULTI-MODEL
CONSENSUS WITH HIGH CONFIDENCE.//
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