Tropical Storm NOUL Advisory Sat May 09

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 06W (NOUL) WARNING NR 25//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 06W (NOUL), LOCATED APPROXIMATELY 297 NM EAST OF
MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 11 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS
THE SYSTEM HAS SLIGHTLY WEAKENED WITH TIGHTLY CURVED BANDING
WRAPPING INTO AN OBSCURED LOW-LEVEL CIRCULATION CENTER. A 082248Z
SSMIS MICROWAVE IMAGE REVEALS BROKEN CONVECTIVE BANDING OVER THE
NORTHERN SEMI-CIRCLE WRAPPING INTO THE CENTER. THE CURRENT POSITION
IS BASED ON THE MSI, PGTW SATELLITE FIX AND AFOREMENTIONED MICROWAVE
IMAGE WITH GOOD CONFIDENCE. THE INITIAL INTENSITY HAS REDUCED TO 95
KNOTS BASED ON AN OVERALL ASSESSMENT OF DVORAK INTENSITY ESTIMATES
FROM ALL REPORTING AGENCIES. UPPER-LEVEL ANALYSIS INDICATES THE
SYSTEM IS LOCATED IN AN AREA OF LOW VERTICAL WIND SHEAR (VWS) AND
GOOD WESTWARD OUTFLOW. TY 06W CONTINUES TO TRACK WEST-NORTHWESTWARD
ALONG THE SOUTHERN PERIPHERY OF A 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 WILL CONTINUE TO TRACK GENERALLY WEST-NORTHWESTWARD
UNDER THE CONTINUED STEERING INFLUENCE OF THE STR, MAKING LANDFALL
IN NORTHEASTERN LUZON AROUND TAU 24. BY TAU 48, TY NOUL WILL ROUND
THE WESTERN PERIPHERY OF THE STEERING RIDGE AHEAD OF AN APPROACHING
MID-LATITUDE TROUGH. ADDITIONAL INTENSIFICATION IS ANTICIPATED PRIOR
TO LANDFALL UNDER THE FAVORABLE CONDITIONS OF LOW VWS, INCREASING
POLEWARD OUTFLOW, AND PASSAGE OVER AN AREA OF HIGH OCEAN HEAT
CONTENT. STEADY WEAKENING IS ANTICIPATED IN THE 48 TO 72 HOUR
TIMEFRAME DUE TO LAND INTERACTION AND INCREASING VWS AHEAD OF THE
AFOREMENTIONED MID-LATITUDE TROUGH. AVAILABLE MODEL GUIDANCE REMAINS
IN GENERALLY GOOD AGREEMENT THROUGH TAU 72, LENDING HIGH CONFIDENCE
TO THIS PORTION OF THE JTWC TRACK FORECAST.
   C. IN THE EXTENDED TAUS, TY 06W WILL ACCELERATE NORTHEASTWARD
AHEAD OF THE DEVELOPING MID-LATITUDE TROUGH. THE SYSTEM WILL
COMPLETE EXTRATROPICAL TRANSITION AND WEAKEN STEADILY DURING THIS
PERIOD DUE TO INCREASING VWS, DECREASING ALONG-TRACK SEA SURFACE
TEMPERATURES, AND DRY AIR ENTRAINMENT. MODEL GUIDANCE IS IN FAIR
AGREEMENT REGARDING TRACK DIRECTION BUT TRACK SPEEDS DIVERGE
SIGNIFICANTLY IN THE EXTENDED PERIOD. GIVEN NOTED MODEL SPREAD,
EXTENDED RANGE TRACK FORECAST CONFIDENCE REMAINS LOW.//
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