WDPN31 PGTW 120300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 03W (YAGI) WARNING NR 
15//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 03W (YAGI), LOCATED APPROXIMATELY 279 NM SOUTH-
SOUTHWESTWARD OF YOKOSUKA, JAPAN, HAS TRACKED NORTHEASTWARD AT 03
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE 
IMAGERY (MSI) DEPICTS AN EXPOSED, SLIGHTLY ELONGATED LOW-LEVEL 
CIRCULATION CENTER (LLCC) WITH ISOLATED DEEP CONVECTION PERSISTING 
OVER THE SOUTHEAST QUADRANT. THERE IS GOOD CONFIDENCE IN THE INITIAL 
POSITION BASED ON THE MSI. MSI ALSO SHOWS EVIDENCE OF INTERACTION 
WITH A WEAK BAROCLINIC ZONE (BAIU BOUNDARY) POSITIONED TO THE NORTH 
WITH A STRATOCUMULUS FIELD ADVECTING INTO THE NORTHWEST PERIPHERY OF 
THE SYSTEM. A 112332Z SSMIS IMAGE CONTINUES TO INDICATE TIGHTLY-
CURVED SHALLOW BANDING WRAPPING INTO AN ELONGATED LLCC. THE INITIAL 
INTENSITY REMAINS ASSESSED AT 40 KNOTS BASED ON THE CONVECTIVE 
STRUCTURE AS WELL AS ON AN AVERAGE OF DVORAK CURRENT INTENSITY 
ESTIMATES FROM PGTW AND RJTD RANGING FROM 35 TO 45 KNOTS. ANIMATED 
WATER VAPOR IMAGERY INDICATES AN UNFAVORABLE ENVIRONMENT WITH 
MODERATE VERTICAL WIND SHEAR AND UPPER-LEVEL CONVERGENCE ASSOCIATED 
WITH A LOW OVER CENTRAL JAPAN. TS 03W HAS TURNED EASTWARD OVER THE 
PAST SIX HOURS AND IS NOW TRACKING ALONG THE NORTHERN PERIPHERY OF 
THE LOW-LEVEL SUBTROPICAL STEERING RIDGE. 
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM 
THE PREVIOUS PROGNOSTIC REASONING.
   B. TS 03W WILL CONTINUE TRACKING EASTWARD ALONG THE NORTHERN 
PERIPHERY OF THE STEERING RIDGE OVER THE NEXT 36 HOURS THEN WILL 
DRIFT SOUTHEASTWARD WITHIN A WEAK STEERING ENVIRONMENT AS A 
SECONDARY RIDGE BUILDS WEST OF THE SYSTEM. PASSAGE OVER COOLER 
WATER, INTERACTION WITH THE BAIU BOUNDARY AND A FURTHER INCREASE IN 
VWS WILL INDUCE STEADY DISSIPATION DURING THIS PERIOD, THEREFORE, TS 
03W IS NOW FORECAST TO DISSIPATE BY TAU 48. SOME SPREAD REMAINS IN 
THE DYNAMIC MODEL GUIDANCE, HOWEVER, OVERALL THERE IS HIGH 
CONFIDENCE IN THE JTWC FORECAST TRACK.//
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