Tropical Storm ATSANI Advisory 15 Αυγ.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 17W (ATSANI)
WARNING NR 03//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 17W (ATSANI), LOCATED APPROXIMATELY 201 NM
NORTH OF ENEWETAK, HAS TRACKED WEST-NORTHWESTWARD AT 04 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE
IMAGERY DEPICTS A CONSOLIDATING LOW-LEVEL CIRCULATION CENTER (LLCC)
WITH IMPROVED DEEP CONVECTIVE BANDING. A 141932Z SSMIS IMAGE
REFLECTS THE IMPROVED CONVECTIVE STRUCTURE AND SHOWS TIGHTLY-CURVED
CONVECTIVE BANDING WRAPPING INTO A DEFINED BUT BROAD CENTER,
THEREFORE, THERE IS FAIR CONFIDENCE IN THE CURRENT POSITION.
ANIMATED WATER VAPOR IMAGERY REVEALS RADIAL OUTFLOW ENHNACED BY A
STRONG TUTT TO THE NORTHEAST. THE CURRENT INTENSITY IS HEDGED
SLIGHTLY HIGHER THAN THE DVORAK INTENSITY ESTIMATES OF T2.0 (30
KNOTS) BASED ON THE RAPIDLY IMPROVING ORGANIZATION. TS 17W IS
EMBEDDED WITHIN A COMPETING STEERING ENVIRONMENT BETWEEN A
SUBTROPICAL RIDGE (STR) TO THE NORTH AND A NEAR-EQUATORIAL RIDGE
(NER) TO THE SOUTH.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. SLOW MOVEMENT IS EXPECTED OVER THE NEXT 36 TO 48 HOURS AS THE
SYSTEM REMAINS IN A COMPETING STEERING ENVIRONMENT. DYNAMIC GUIDANCE
CONTINUES TO SUPPORT A SLOW, PERHAPS QUASI-STATIONARY MOTION THROUGH
TAU 36 DUE TO THE COMPETING STEERING INFLUENCE. AFTER TAU 36,
DYNAMIC GUIDANCE IS IN FAIR AGREEMENT. BY TAU 48, THE NER IS
FORECAST TO WEAKEN AND SHIFT EASTWARD ALLOWING THE STR TO BUILD AND
BECOME THE DOMINANT STEERING INFLUENCE. THIS WILL ALLOW TS 17W TO
ACCELERATE WEST-NORTHWESTWARD THROUGH TAU 72. TS 17W IS EXPECTED TO
RAPIDLY INTENSIFY AFTER TAU 24 UNDER VERY FAVORABLE ENVIRONMENTAL
CONDITIONS TO INCLUDE RADIAL OUTFLOW, WARM SST AND HIGH OCEAN HEAT
CONTENT.
   C. IN THE EXTENDED TAUS, TS 17W WILL MAINTAIN A NORTHWESTWARD
TRAJECTORY AS THE SYSTEM TRACKS ALONG THE WESTERN PERIPHERY OF THE
STR. AVAILABLE MODEL GUIDANCE REMAINS IN FAIR AGREEMENT, HOWEVER,
THERE IS LOW OVERALL CONFIDENCE IN THE FORECAST TRACK DUE TO THE
ERRATIC MOTION EXPECTED IN THE SHORT-TERM.//
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