Tropical Storm FOUR Advisory 30 Ιούν.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 04W (FOUR)
WARNING NR 05//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 04W (FOUR), LOCATED APPROXIMATELY 564 NM EAST OF
MANILA, PHILIPPINES, HAS TRACKED NORTHWESTWARD AT 06 KNOTS OVER
THE PAST SIX HOURS. THE CURRENT POSITION IS BASED ON RECENT MICROWAVE
SATELLITE IMAGERY INCLUDING A 291659Z AMSR2 AND A 291521Z GMI IMAGE.
THE INTENSITY OF 35 KNOTS IS CONSISTENT WITH DVORAK CURRENT INTENSITY
ESTIMATES OF T2.5 FROM PGTW AND KNES AND SUPPORTED BY EARLIER ASCAT-C
DATA INDICATING A MAXIMUM OF 30 TO 35 KNOT WINDS ASSOCIATED WITH THE
CIRCULATION. THE REDUCTION IN INTENSITY FROM THE PREVIOUS WARNING IS
NOT INDICATIVE OF A WEAKENING TREND, AS NEW DATA INDICATE THE SYSTEM
WAS LIKELY A BIT WEAKER SIX HOURS AGO THAN PREVIOUSLY ESTIMATED. TD
04W HAS MAINTAINED ITS STRUCTURE OVER THE PAST SIX HOURS WHILE
TRACKING NORTHWESTWARD ALONG THE PERIPHERY OF A SUBTROPICAL STEERING
RIDGE SITUATED TO THE NORTH AND EAST. THE AFOREMENTIONED MICROWAVE
SATELLITE IMAGES SHOW A PARTIALLY-EXPOSED LOW LEVEL CIRCULATION WITH
THE PRIMARY DEEP CONVECTION OFFSET TO THE SOUTHWEST DUE TO PERSISTENT
MODERATE NORTHEASTERLY VERTICAL WIND SHEAR (VWS). STRONG DIFFLUENCE
ALOFT HAS FUELED CONVECTIVE DEVELOPMENT DESPITE THE NEGATIVE IMPACT
OF VWS OVER THE CIRCULATION CENTER. SEA SURFACE TEMPERATURES ARE VERY
SUPPORTIVE AT ABOUT 30 DEGREES CELSIUS.
3. FORECAST REASONING.
  A. THERE IS NO MAJOR CHANGE TO THE FORECAST PHILOSOPHY FROM THE
PREVIOUS WARNING.
  B. TS 04W WILL CONTINUE TRACKING GENERALLY NORTHWESTWARD FOLLOWING
THE STEERING FLOW ASSOCIATED WITH THE SUBTROPICAL STEERING TO THE
NORTH AND EAST FOR THE NEXT 72 HOURS. VWS IS EXPECTED TO DECREASE
SLIGHTLY THROUGH TAU 48, WHICH SHOULD ALLOW THE SYSTEM TO INTENSIFY
SLOWLY WITH THE SUPPORT OF VERY WARM SEA SURFACE TEMPERATURES AND
STRONG DIFFLUENCE ALOFT. BY TAU 72, INCREASING VWS AND PASSAGE OVER
COOLER WATER WILL LIKELY INDUCE A WEAKENING TREND. NUMERICAL MODEL
TRACK FORECAST GUIDANCE COME INTO BETTER ALIGNMENT, WITH THE MAJORITY
OF AVAILABLE MODELS NOW INDICATING A TRACK NEAR SOUTHERN TAIWAN OR
SLIGHTLY TO THE SOUTH. THE JTWC TRACK FORECAST IS PLACED NEAR THE
MULTI-MODEL CONSENSUS THROUGH TAU 72, WITH FAIR CONFIDENCE.
  C. IN THE EXTENDED RANGE, TS 04W IS EXPECTED TO TRACK INLAND AND
DISSIPATE OVER SOUTHEASTERN CHINA. NUMERICAL GUIDANCE DIVERGES AFTER
TAU 72, ALTHOUGH ALL MODELS SUPPORT DISSIPATION. BECAUSE MOTION OF
THE WEAKENED SYSTEM IS LESS CERTAIN DURING THIS PERIOD, CONFIDENCE IN
THE EXTENDED FORECAST PORTION OF THE JTWC TRACK FORECAST IS LOW.//
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