WDPN31 PGTW 150300
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 22W (TWENTYTWO)// 
WARNING NR 05//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
    A. TROPICAL STORM 22W MAINTAINED A RELATIVELY FAST TRACK WEST-
NORTHWESTWARD AS IT CONTINUES TO CONSOLIDATE. ANIMATED WATER VAPOR
IMAGERY SHOWS MULTIPLE FEEDER BANDS WRAPPING TIGHTER INTO A WELL-
DEFINED LOW LEVEL CIRCULATION CENTER. THE SAME ANIMATION ALSO 
DEPICTS GOOD POLEWARD OUTFLOW INTO A NARROW TROPICAL UPPER 
TROPOSPHERIC TROUGH (TUTT) TO THE NORTHEAST. UPPER LEVEL ANALYSIS
INDICATES THE SYSTEM IS JUST TO THE SOUTH OF AN ANTICYCLONE IN A 
REGION OF LOW VERTICAL WIND SHEAR (VWS). THE CURRENT INTENSITY IS
BASED ON DVORAK ESTIMATES FROM PGTW AND KNES AND THE CURRENT
POSITION IS BASED ON ANIMATED MULTISPECTRAL IMAGERY AND FROM A 
RADAR POSITION REPORT FROM NWS GUAM. TS 22W IS TRACKING ALONG THE
SOUTHERN PERIPHERY OF A LOW- TO MID-LEVEL SUBTROPICAL RIDGE TO THE
NORTH OVER WARM SEA SURFACE TEMPERATURES (SST'S) WELL IN EXCESS OF
28 DEGREES CELSIUS.
3. FORECAST REASONING.
    A. THE FORECAST PHILOSOPHY HAS NOT CHANGED SIGNIFICANTLY SINCE
THE PREVIOUS BULLETIN. THIS TRACK FORECAST IS MORE WESTWARD IN
TRAJECTORY AND SLOWER AT THE EXTENDED TAUS.
    B. TS 22W IS EXPECTED TO CONTINUE TRACKING ALONG THE STEERING
RIDGE DESCRIBED IN PARA 2.A. THE ENVIRONMENTAL CONDITIONS WILL
BECOME EVEN MORE FAVORABLE FOR DEVELOPMENT WITH INCREASING POLEWARD
OUTFLOW AS THE TUTT TO THE NORTHEAST MOVES WESTWARD AND CLOSER TO
THE SYSTEM AND VWS REMAINS LIGHT. ADDITIONALLY, ALONG TRACK SST'S
WILL FURTHER INCREASE AFTER TAU 36. BEFORE TAU 72, A WEAK MID-
LATITUDE TROUGH APPROACHING FROM THE NORTHWEST WILL CAUSE A WEAKNESS
IN THE STEERING RIDGE AND JOG THE SYSTEM MORE POLEWARD OF TRACK.
    C. AFTER TAU 72, TS 22W WILL RESUME A MORE WESTWARD TRAJECTORY
AS A SECONDARY AND DEEPER RIDGE NORTH OF TAIWAN WILL ASSUME STEERING
OF THE SYSTEM. THE ENVIRONMENTAL CONDITIONS WILL REMAIN FAVORABLE
FOR CONTINUED DEVELOPMENT - THE SYSTEM IS EXPECTED TO EXCEED 
100-KNOT CENTRAL WIND SPEED BY TAU 120. THE AVAILABLE NUMERIC AIDS
ARE IN GOOD AGREEMENT UP TO TAU 48 WHERE THEY START TO DIVERGE 
SLIGHTLY. NOGAPS AND WBAR ARE ON THE RIGHT OF THE ENVELOPE AND 
EGRR ON THE LEFT. ADDITIONALLY, NOGAPS, GFDN, AND EGRR ARE FASTER
THAN THE REST OF THE GROUP. THIS TRACK FORECAST LIES IN THE MIDDLE
OF THE PACK, TO THE LEFT AND SLOWER THAN CONSENSUS. //
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