MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 11W (NANGKA) WARNING NR 50//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON (TY) 11W (NANGKA), LOCATED APPROXIMATELY 305 NM
SOUTH-SOUTHEAST OF IWAKUNI, JAPAN, HAS TRACKED NORTH-NORTHWESTWARD AT
12 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED IR SATELLITE
IMAGERY SHOWS THE SYSTEM HAS MAINTAINED AN OVERALL SYMMETRIC
CONVECTIVE SIGNATURE, EVEN AS THE EYE HAS BECOME CLOUD-FILLED. THE
INITIAL POSITION IS BASED ON THE MICROWAVE EYE FEATURE IN THE 151621Z
36GHZ GPM COLOR IMAGE WITH HIGH CONFIDENCE. THE INITIAL INTENSITY OF
80 KNOTS IS BASED ON CONGRUENT DVORAK ESTIMATES FROM PGTW, KNES, AND
RJTD. UPPER LEVEL ANALYSIS INDICATES A CONDITIONALLY FAVORABLE
ENVIRONMENT WITH LOW VERTICAL WIND SHEAR (VWS) AND EXCELLENT
DIVERGENT OUTFLOW; HOWEVER, DRY AIR ALONG THE WESTERN PERIPHERY IS
INHIBITING FURTHER INTENSIFICATION. TY 11W IS TRACKING
NORTH-NORTHWESTWARD UNDER AN EXTENSION OF THE STEERING SUB-TROPICAL
RIDGE (STR).
3. FORECAST REASONING.
A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. TY 11W WILL TRACK NORTH-NORTHWESTWARD ALONG THE WESTERN
EXTENSION OF THE STEERING STR THROUGH TAU 36. AFTERWARDS, IT WILL
RECURVE NORTHEASTWARD AS IT ROUNDS THE EDGE AND ACCELERATES ON THE
POLEWARD SIDE OF THE STR. THE SYSTEM WILL MAKE LANDFALL OVER SHIKOKU
PRIOR TO TAU 24 WHICH WILL BEGIN A RAPID WEAKENING TREND DUE TO LAND
INTERACTION. AS THE SYSTEM ENTERS THE SEA OF JAPAN, IT WILL FURTHER
ERODE DUE TO COLDER SSTS AND HIGH VWS.
C. IN THE EXTENDED TAUS, TY NANGKA WILL CONTINUE TO ACCELERATE TO
THE NORTHEAST AS IT CROSSES THE NORTHERN TIP OF HONSHU NEAR MISAWA.
POOR ENVIRONMENTAL CONDITIONS WILL CONTINUE TO WEAKEN THE SYSTEM
LEADING TO ITS DISSIPATION BY THE END OF THE FORECAST PERIOD.
AVAILABLE MODEL GUIDANCE REMAINS IN GOOD AGREEMENT OVER LENDING HIGH
CONFIDENCE TO THE JTWC FORECAST TRACK.//
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