Tropical Storm DOLPHIN Advisory Pzt, 11.05.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 07W (DOLPHIN) WARNING
NR 17//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 07W (DOLPHIN), LOCATED APPROXIMATELY 135 NM
NORTHEAST OF POHNPEI, HAS TRACKED NORTHWARD AT 07 KNOTS OVER THE
PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
CONTINUES TO DEPICT AN ELONGATED SIGNATURE WITH CURVED BANDING
WRAPPING INTO A SLOWLY-CONSOLIDATING LOW-LEVEL CIRCULATION CENTER
(LLCC). A 101628Z SSMI MICROWAVE IMAGE REVEALS BROKEN CONVECTIVE
BANDING OVER WITH THE BULK OF THE DEEP CONVECTION DISPLACED
WESTWARD. THE CURRENT POSITION IS BASED ON EXTRAPOLATION FROM A
101451Z GCOM AND 101628Z SSMI IMAGERY. THE INITIAL INTENSITY REMAINS
AT 40 KNOTS BASED ON AN OLDER 101124Z ASCAT PASS SHOWING 35 TO 40
KNOT CIRCULATION WITH 45 KNOT WIND BARBS ALONG THE SOUTHERN
PERIPHERY. UPPER-LEVEL CONDITIONS REMAIN MARGINAL WITH EASTERLY
DIFFLUENT FLOW ALOFT AND MODERATE (20 TO 25 KNOTS) VERTICAL WIND
SHEAR (VWS). HOWEVER, SEA SURFACE TEMPERATURES ABOVE 29 CELSIUS
REMAIN CONDUCIVE FOR DEVELOPMENT. TS 07W IS TRACKING SLOWLY POLEWARD
TOWARDS A BREAK IN THE STEERING SUB-TROPICAL RIDGE (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 TO TRACK POLEWARD OVER THE NEXT 12 HOURS
AS AN UPPER-LEVEL TROUGH PASSES TO THE NORTH CAUSING THE BREAK IN
THE STEERING STR. AFTERWARD, THE STR WILL REBUILD AND TURN TS 07W ON
A WEST-NORTHWESTWARD TRAJECTORY. UPPER-LEVEL CONDITIONS WILL REMAIN
MARGINAL OVER THE NEXT 48 HOURS LEADING TO A MODEST INTENSIFICATION.
BEYOND TAU 48, AN IMPROVING ENVIRONMENT, WITH LOW VWS (05 TO 10
KNOTS) AND AN INCREASING POLEWARD OUTFLOW CHANNEL WILL LEAD TO AN
INCREASED INTENSIFICATION RATE.
   C. IN THE EXTENDED TAUS, TS DOLPHIN WILL REMAIN ON A WEST-
NORTHWESTWARD TRACK UNDER THE STEERING INFLUENCE OF THE STR. BY THE
END OF THE FORECAST PERIOD ANOTHER APPROACHING MID-LATITUDE TROUGH
WILL CAUSE THE STEERING STR TO WEAKEN AGAIN, ALLOWING TS 07W TO TURN
SLIGHTLY POLEWARD TOWARDS A BREAK IN THE STR. ENVIRONMENTAL
CONDITIONS WILL REMAIN FAVORABLE AND SUPPORT FURTHER
INTENSIFICATION. DYNAMIC MODEL GUIDANCE REMAINS IN GOOD AGREEMENT
REGARDING THE TRACK AND OVERALL SPEED, LEADING TO HIGH CONFIDENCE IN
THE JTWC FORECAST.//
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