Tropical Storm NANGKA Advisory 11 Ιουλ.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 11W (NANGKA) WARNING NR 30//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 11W (NANGKA), LOCATED APPROXIMATELY 855 NM EAST-
SOUTHEAST OF KADENA AB, OKINAWA, JAPAN, HAS TRACKED WEST-
NORTHWESTWARD AT 07 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED
IR SATELLITE IMAGERY SHOWS A WEAKENING SYSTEM WITH A CLOUD-FILLED
EYE AND SPIRAL BANDING LOCATED PRIMARILY OVER THE SOUTHERN SEMI-
CIRCLE DUE TO INCREASING VWS ALONG THE NORTHERN FLANK. THE INITIAL
POSITON IS BASED ON A MICROWAVE EYE FEATURE IN THE 101741Z GPM 37GHZ
IMAGE. THE INITIAL INTENSITY OF 105 KNOTS IS SUPPORTED BY DVORAK
ESTIMATES FROM PGTW AND RJTD. THE CYCLONE IS TRACKING ALONG
THE SOUTHERN PERIPHERY OF AN EXTENSION OF THE DEEP LAYERED STR TO
THE NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY 11W WILL CONTINUE TO TRACK WESTWARD TO WEST-NORTHWESTWARD
UP TO TAU 36 UNDER THE INFLUENCE OF THE STEERING STR. AFTERWARDS,
THS SYSTEM WILL BEGIN TO TURN MORE POLEWARD ALONG THE WESTERN
PERIPHERY OF THE STR. MARGINALLY-FAVORABLE UPPER-LEVEL CONDITIONS
ARE EXPECTED TO CONTINUE, LEADING TO A STEADY WEAKENING TREND
THROUGH TAU 72.
   C. IN THE EXTENDED TAUS, TY NANGKA WILL REVERT TO A NORTHWESTWARD
TRACK TOWARD THE RYUKYU ISLANDS AS THE STEERING INFLUENCE
TRANSITIONS TO A SECONDARY STR CURRENTLY POSITIONED SOUTH OF
MAINLAND JAPAN. VWS IS FORECAST TO DECREASE WITH IMPROVING POLEWARD
OUTFLOW, WHICH WILL ALLOW THE SYSTEM TO RE-INTENSIFY. DYNAMIC MODEL
GUIDANCE IS IN FAIR AGREEMENT WITH ALL MODELS NOW SHOWING A TRACK
TOWARD THE RYUKYU ISLANDS. HOWEVER, DUE TO THE LARGE SPREAD (ABOUT
280 NM) IN THE MODEL SOLUTIONS, THE JTWC TRACK FORECAST CONFIDENCE
LEVEL REMAINS LOW.//
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