WDPN31 PGTW 091500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 06W (NOUL) WARNING NR 27//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 06W (NOUL), LOCATED APPROXIMATELY 208 NM EAST-
NORTHEAST OF MANILA, PHILIPPINES HAS TRACKED NORTHWESTWARD AT 08 
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE 
IMAGERY DEPICTS A DEEPENING SYMMETRIC CORE STRUCTURE THAT HAS 
MAINTAINED A SHARP WELL-DEFINED 13-NM EYE WHICH SUPPORTS THE INITIAL 
POSITION WITH HIGH CONFIDENCE. RECENT IMAGERY IN THE WATER VAPOR 
LOOP SHOWS DRY AIR FROM THE SOUTH HAS STARTED TO GET PULLED INTO THE 
CIRCULATION, WEAKENING THE OUTER CONVECTIVE BANDING. A 091000Z SSMIS 
91GHZ MICROWAVE IMAGE SHOWS A MICROWAVE EYE FEATURE SURROUNDED BY A 
SYMMETRIC EYE WALL WITH THE MOST INTENSE CONVECTION ALONG THE 
SOUTHERN PERIPHERY. THE MICROWAVE IMAGE ALSO SHOWS THE DRY AIR 
WRAPPING AROUND THE EASTERN PERIPHERY OF THE SYSTEM. THE INITIAL 
INTENSITY HAS BEEN INCREASED TO 115 KNOTS BASED ON CONSENSUS DVORAK 
INTENSITY ESTIMATES OF T6.0 (115 KNOTS) BY PGTW, KNES, AND RJTD. 
UPPER LEVEL ANALYSIS SHOWS RADIAL OUTFLOW WITH LOW VERTICAL WIND 
SHEAR (VWS) WHICH, COMBINED WITH SEA SURFACE TEMPERATURES (SST) 
ABOVE 30 CELSIUS, IS CREATING A FAVORABLE ENVIRONMENT FOR 
INTENSIFICATION. TY NOUL IS TRACKING ALONG THE SOUTHWESTERN 
PERIPHERY OF A DEEP LAYERED SUB-TROPICAL RIDGE (STR) TO THE 
NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM 
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. OVER THE NEXT 12 TO 18 HOURS, TY NOUL WILL TRACK NORTHWESTWARD 
AND CONTINUE TO INTENSIFY UNDER FAVORABLE ENVIRONMENTAL CONDITIONS 
PRIOR TO MAKING LANDFALL ALONG THE NORTHEASTERN LUZON COASTLINE. 
BEYOND TAU 24, AN APPROACHING MID-LATITUDE TROUGH WILL WEAKEN THE 
STEERING STR, CAUSING THE SYSTEM TO TURN POLEWARD. AS TY 06W TRACKS 
POLEWARD AND ROUNDS THE STR AXIS, THE COMBINED EFFECTS OF INCREASING 
VWS AND DECREASING SST WILL ERODE THE CONVECTIVE STRUCTURE AND BEGIN 
A STEADY WEAKENING TREND. BEYOND TAU 48, TY NOUL WILL TRANSITION TO 
A NORTHEASTWARD TRAJECTORY AND BEGIN TO INTERACT WITH THE MID-
LATITUDE WESTERLIES.
   C. AFTER TAU 72, TY 06W WILL ACCELERATE NORTHEASTWARD AHEAD OF 
THE APPROACHING MID-LATITUDE TROUGH AND BEGIN EXTRATROPICAL 
TRANSITION (ETT). VWS WILL RAPIDLY INCREASE ABOVE 40 KNOTS AND SST 
WILL DROP OFF BELOW 26 CELSIUS, FURTHER EXACERBATING THE WEAKENING 
TREND. THE SYSTEM IS FORECAST TO COMPLETE ETT BY THE END OF THE 
FORECAST PERIOD. DYNAMIC MODEL GUIDANCE HAS COME INTO VERY TIGHT 
AGREEMENT REGARDING THE TRACK FORECAST WITH ONLY MODERATE SEPARATION 
IN FORWARD SPEED ONCE THE SYSTEM ACCELERATES NORTHEASTWARD. GIVEN 
THE OVERALL MODEL AGREEMENT, THERE IS HIGH CONFIDENCE IN THE JTWC 
TRACK FORECAST.//
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