Tropical Storm DOLPHIN Advisory 10.05.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 07W (DOLPHIN) WARNING
NR 14//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 07W (DOLPHIN), LOCATED APPROXIMATELY 138 NM
EAST-SOUTHEAST OF POHNPEI, HAS TRACKED WEST-NORTHWESTWARD AT 09
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY (MSI) DEPICTS AN ELONGATED SIGNATURE WITH SLIGHTLY WEAKENED
CONVECTIVE BANDING WRAPPING INTO AN OBSCURED LOW LEVEL CIRCULATION
CENTER (LLCC). A 092318Z ASCAT PASS SHOWS 30 TO 35 KNOT CIRCULATION
WITH A FEW 40 KNOT WIND BARBS ON THE NORTHEASTERN QUADRANT. THE
CURRENT POSITION IS BASED ON THE MSI AND AFOREMENTIONED ASCAT IMAGE
WITH GOOD CONFIDENCE. THE INITIAL INTENSITY OF 35 KNOTS IS BASED ON
AN OVERALL ASSESSMENT OF DVORAK INTENSITY ESTIMATES FROM ALL
REPORTING AGENCIES, 092318Z ASCAT PASS AS WELL AS CURRENT STRUCTURE.
UPPER-LEVEL ANALYSIS INDICATES A MARGINALLY-FAVORABLE ENVIRONMENT
UNDER EASTERLY DIFFLUENT FLOW WITH MODERATE (20 TO 25 KNOTS)
VERTICAL WIND SHEAR (VWS); HOWEVER, SEA SURFACE TEMPERATURES ABOVE
29 CELSIUS ARE CONDUCIVE FOR DEVELOPMENT. TS 07W IS CURRENTLY
TRACKING UNDER THE STEERING INFLUENCE OF THE STR TO THE NORTH.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 07W WILL CONTINUE TRACKING WEST-NORTHWESTWARD UNDER THE
STEERING STR THROUGH TAU 24. THEREAFTER, AN UPPER-LEVEL TROUGH
PASSING TO THE NORTH WILL CAUSE A BREAK IN THE RIDGE, ALLOWING TS 07W
TO SHIFT NORTHWESTWARD. THE STR IS EXPECTED TO REBUILD AND RESUME
THE STEERING ENVIRONMENT BY TAU 60. UPPER-LEVEL ENVIRONMENTAL
CONDITIONS WILL REMAIN MARGINALLY-FAVORABLE OVER THE NEXT 48 HOURS
LEADING TO SLOW INTENSIFICATION. BEYOND TAU 48, AN IMPROVING
ENVIRONMENT WITH DECREASING VWS AND AN INCREASING POLEWARD OUTFLOW
CHANNEL WILL LEAD TO FURTHER INTENSIFICATION.
   C. IN THE EXTENDED TAUS, TS DOLPHIN WILL REMAIN ON A WEST-
NORTHWESTWARD TRAJECTORY UNDER THE STEERING INFLUENCE OF THE STR.
CONTINUED FAVORABLE ENVIRONMENTAL CONDITIONS WILL SUPPORT
INTENSIFICATION, REACHING A PEAK INTENSITY OF 90 KNOTS AT TAU 120.
DYNAMIC MODEL GUIDANCE IS OVERALL IN GOOD AGREEMENT; HOWEVER, THERE
IS SIGNIFICANT TRACK SPEED DIFFERENCE IN THE EXTENDED PERIOD,
LEADING TO LOW CONFIDENCE IN THE JTWC FORECAST.//
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