Tropical Storm ATSANI Advisory Sa, 18.08.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 17W (ATSANI) WARNING NR 15//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON(TY) 17W (ATSANI), LOCATED APPROXIMATELY 717 NM EAST OF
ANDERSEN AFB, GUAM HAS TRACKED NORTHWESTWARD AT 11 KNOTS OVER THE
PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE DEPICTS
DEEPENED CONVECTION WITH TIGHTLY-CURVED BANDS WRAPPING INTO A WELL-
DEFINED 8 NM DIAMETER EYE THAT SUPPORTS THE HIGH CONFIDENCE IN THE
CURRENT POSITION. THE INITIAL INTENSITY OF 105 KNOTS IS BASED ON
CORRESPONDING DVORAK INTENSITY ESTIMATES FROM ALL REPORTING
AGENCIES. UPPER-LEVEL ANALYSIS INDICATES FAVORABLE ENVIRONMENT WITH
LOW VWS AND RADIAL OUTFLOW SUPPORTED BY AN ANALYZED POINT-SOURCE.
NEAR RADIAL OUTFLOW AND LOW VWS. TY 17W IS TRACKING ALONG THE
SOUTHWESTERN PERIPHERY OF A STR TO THE NORTHEAST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE. HOWEVER, THE SYSTEM IS EXPECTED TO
REACH PEAK INTENSITY SOONER.
   B. TY 17W WILL REMAIN ON A NORTHWESTWARD TRAJECTORY THROUGH TAU
72 UNDER THE STEERING STR. VERY FAVORABLE ENVIRONMENTAL AND UPPER-
LEVEL CONDITIONS ARE EXPECTED TO PERSIST ALLOWING THE SYSTEM TO
FURTHER INTENSIFY LEADING TO A PEAK INTENSITY OF 140 BY TAU 36.
AFTER TAU 48, INCREASING VWS WILL BEGIN TO WEAKEN THE SYSTEM.
   C. IN THE EXTENDED TAUS, TY 17W CONTINUES TO TRACK NORTHWESTWARD
UNDER THE STEERING STR. THE COMBINED EFFECTS OF LOWER OHC VALUES
AND INCREASED VWS WILL CONTINUE TO DECAY TY ATSANI. AVAILABLE MODEL
GUIDANCE REMAINS IN TIGHT AGREEMENT LENDING HIGH CONFIDENCE IN THE
JTWC FORECAST TRACK.//
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