WDPN31 PGTW 071500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 22W (TWENTYTWO) 
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.4N 110.7E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 347 NM SOUTHEAST OF HANOI, VIETNAM
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 10 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A PARTIALLY-
EXPOSED LOW-LEVEL CIRCULATION (LLC) WITH PERSISTENT CONVECTION 
OBSCURING THE CENTER. A 071124Z SSMIS 91GHZ IMAGE REVEALS A WEAKLY-
DEFINED LLC WITH FRAGMENTED BANDING. THEREFORE, THE INITIAL POSITION 
IS PLACED WITH MEDIUM CONFIDENCE. THE INITIAL INTENSITY OF 30 KTS IS 
ASSESSED WITH MEDIUM CONFIDENCE BASED ON RECENT ASCAT DATA AND IS 
HEDGED SLIGHTLY HIGHER THAN THE AGENCY DVORAK ESTIMATES. 
ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE WITH MODERATE POLEWARD AND 
EQUATORWARD OUTFLOW AND LOW (5-10KT) VERTICAL WIND SHEAR. SEA 
SURFACE TEMPERATURES OF 29-30C ARE CONDUCIVE.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: TD 22W IS LOCATED WITHIN A COMPETING
STEERING ENVIRONMENT WITH A NEAR-EQUATORIAL RIDGE TO THE EAST AND A
SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.0 - 25 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T1.5 - 25 KTS
   CIMSS ADT: 31 KTS AT 071130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD
   OTHER FACTORS: PROXIMITY TO LAND

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TD 22W IS TRACKING SLOWLY WITHIN A COMPETING
STEERING ENVIRONMENT AND IS EXPECTED TO TRACK SLOWLY NORTHWESTWARD
TO NORTH-NORTHWESTWARD THROUGH TAU 36 THEN TURN WESTWARD THROUGH
TAU 48 AS THE LOW- TO MID-LEVEL STR BECOMES THE PRIMARY STEERING
INFLUENCE. CONDITIONS SHOULD REMAIN FAVORABLE THROUGH TAU 24 WITH A
PEAK INTENSITY OF 40 KNOTS FORECAST AT TAU 24, POSSIBLY SLIGHTLY
HIGHER NEAR THE LANDFALL TIME. AFTER TAU 24, INTERACTION WITH LAND
IS EXPECTED TO HINDER DEVELOPMENT WITH GRADUAL WEAKENING ANTICIPATED 
AS THE SYSTEM TRACKS ACROSS HAINAN ISLAND. AS THE SYSTEM EMERGES 
OVER THE GULF OF TONKIN NEAR TAU 48, REINTENSIFICATION IS UNLIKELY 
DUE TO LAND INTERACTION AND INCREASING EASTERLY VERTICAL WIND SHEAR. 
AFTER TAU 48, TD 22W WILL TURN SOUTHWESTWARD UNDER A NORTHEAST-
SOUTHWEST ORIENTED STR. THE SYSTEM IS EXPECTED TO DISSIPATE BY TAU 
96 AS IT TRACKS INLAND OVER MOUNTAINOUS TERRAIN. 

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT
THROUGH TAU 48 WITH A 95NM SPREAD IN SOLUTIONS AT TAU 48 BUT
DIVERGE AFTER TAU 48 WITH A LARGE SPREAD AND INCREASED UNCERTAINTY
LENDING LOW CONFIDENCE TO THE JTWC FORECAST TRACK. THE JTWC
FORECAST TRACK IS POSITIONED NEAR THE MULTI-MODEL CONSENSUS (CONW).
INTENSITY GUIDANCE INDICATES A PEAK RANGING FROM 35 TO 45 KNOTS AT
TAU 36 WITH STEADY WEAKENING THROUGH THE REMAINDER OF THE FORECAST
PERIOD.      


FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: LOW
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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