WDPN32 PGTW 081500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 07W (SEVEN) WARNING NR 
08//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 07W (SEVEN), LOCATED APPROXIMATELY 95 NM 
SOUTH-SOUTHWEST OF KOSRAE, HAS TRACKED EASTWARD AT 04 KNOTS OVER THE 
PAST SIX HOURS. THE SYSTEM IS BEING STEERED IN AN ATYPICAL EASTWARD 
DIRECTION BY ENHANCED LOW- TO MID-LEVEL, NEAR-EQUATORIAL WESTERLY 
FLOW. THE CURRENT POSITION IS BASED ON A 071132Z PGTW SATELLITE FIX 
AND A 081016Z ASCAT PASS. THE INTENSITY OF 35 KNOTS IS CONSISTENT 
WITH DVORAK SATELLITE INTENSITY ESTIMATES FROM PGTW AND KNES. TS 07W 
LIES EQUATORWARD OF AN UPPER-LEVEL RIDGE AXIS, IN AN AREA OF 
MODERATE SOUTHEASTERLY VERTICAL WIND SHEAR AND STRONG WESTWARD AND 
POLEWARD DIFFLUENCE ALOFT. DEEP CONVECTION HAS DEVELOPED OVER THE 
CIRCULATION CENTER, ALTHOUGH THE MAJORITY OF THE CONVECTION 
ASSOCIATED WITH THE SYSTEM REMAINS CONFINED TO THE NORTHWESTERN 
PORTION OF THE LOW-LEVEL CIRCULATION CENTER DUE TO THE PERSISTENT 
SHEAR.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM 
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 07W IS EXPECTED TO TURN POLEWARD AND EVENTUALLY WEST-
NORTHWESTWARD OVER THE NEXT 72 HOURS AS A BUILDING SUBTROPICAL RIDGE 
TO THE NORTH BECOMES THE PRIMARY STEERING MECHANISM. DECREASING 
VERTICAL WIND SHEAR, INCREASING WESTWARD AND POLEWARD OUTFLOW, AND 
PASSAGE OVER VERY WARM WATER WILL ALLOW THE SYSTEM TO CONTINUE 
INTENSIFYING. NUMERIC MODELS ARE IN POOR AGREEMENT REGARDING THE 
ORIENTATION OF THE UPCOMING TURN TO THE NORTHWEST AND ASSOCIATED 
TRACK SPEEDS. THE FIRST 72 HOURS OF THE CURRENT TRACK FORECAST IS 
CONSISTENT WITH A GROUPING OF MODELS THAT INCLUDES A MAJORITY OF 
CONSENSUS MEMBERS. BECAUSE OF THE COMPLEX STEERING PATTERN AND NOTED 
MODEL SPREAD, TRACK FORECAST CONFIDENCE IS LOW.  
   C. IN THE EXTENDED RANGE, TS 07W WILL CONTINUE TRACKING GENERALLY 
WEST-NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE SUBTROPICAL 
RIDGE. FAVORABLE UPPER-LEVEL SUPPORT AND PASSAGE OVER WARM WATER 
WILL SUPPORT ADDITIONAL INTENSIFICATION. NUMERICAL MODEL SPREAD, IN 
TERMS OF TRACK DIRECTION AND SPEED, REMAINS SIGNIFICANT IN THE 
EXTENDED PERIOD WITH NO APPARENT PRIMARY GROUPING. THE CURRENT 
EXTENDED RANGE FORECAST LIES NEAR THE MULTI-MODEL CONSENSUS, WITH 
LOW CONFIDENCE.//
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