WDPN33 PGTW 031500
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 22W WARNING NR 26//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
    A. TROPICAL STORM (TS) 22W (NALGAE), LOCATED APPROXIMATELY 460 
NM EAST-SOUTHEAST OF HANOI, VIETNAM, HAS TRACKED WESTWARD AT 07 
KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED (IR) SATELLITE 
IMAGERY SHOWS AN ELONGATED, PARTIALLY EXPOSED LOW LEVEL CIRCULATION 
CENTER (LLCC) WITH A SIGNIFICANT DECREASE IN DEEP CONVECTION, WHICH 
IS SHEARED TO THE WEST. A 031023Z SSMIS MICROWAVE SATELLITE IMAGE 
DEPICTS AN EXPOSED, BROAD LLCC. THE INITIAL POSITION IS BASED ON THE 
IR AND SSMIS IMAGERY WITH FAIR CONFIDENCE. THE INITIAL INTENSITY IS 
BASED ON THE PGTW, KNES, AND RJTD DVORAK ESTIMATES RANGING FROM 35 
TO 55 KNOTS. UPPER LEVEL ANALYSIS INDICATES THE LLCC IS LOCATED 
SOUTH OF THE SUBTROPICAL RIDGE AXIS IN AN AREA OF MODERATE VERTICAL 
WIND SHEAR (VWS) AND WATER VAPOR IMAGERY SHOWS GOOD EQUATORWARD 
OUTFLOW.
3.  A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY.
    B. TS 22W IS CURRENTLY TRACKING ALONG THE SOUTHERN PERIPHERY OF 
A DEEP LAYER SUBTROPICAL STEERING RIDGE, WHICH IS EXPECTED TO REMAIN 
THE PRIMARY STEERING INFLUENCE THROUGHOUT THE FORECAST PERIOD. TS 
22W IS FORECAST TO WEAKEN DUE TO MODERATE VWS AND LAND INTERACTION 
AS TS 22W SKIRTS THE SOUTHERN COAST OF HAINAN. AFTER TAU 48, THE 
SYSTEM WILL MAKE LANDFALL OVER VIETNAM AND DISSIPATE AS A 
SIGNIFICANT TROPICAL CYCLONE BY TAU 72. NUMERICAL MODEL GUIDANCE IS 
IN GOOD AGREEMENT EXCEPT FOR WBAR, WHICH ERRONEOUSLY TRACKS THE 
SYSTEM NORTHWARD INTO THE SUBTROPICAL STEERING RIDGE. THIS FORECAST 
IS SLIGHTLY SOUTH OF MODEL CONSENSUS TO ACCOUNT FOR THIS ERROR.//
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