WDPN33 PGTW 110900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 26W (TORAJI) WARNING NR 009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.9N 121.0E
   INITIAL INTENSITY: 70 KTS
   GEOGRAPHIC REFERENCE: 503 NM SOUTHEAST OF HONG KONG
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 13 KTS

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TYPHOON (TY) 26W MADE LANDFALL AT 110030Z ALONG THE EASTERN COAST
OF LUZON AND HAS TRACKED INLAND OVER MOUNTAINOUS TERRAIN WITH
SIGNIFICANT WEAKENING. ANIMATED ENHANCED INFRARED (EIR) SATELLITE
IMAGERY DEPICTS RAPID WEAKENING OF CORE CONVECTION, WITH WARMING
CLOUD TOP TEMPERATURES OVER THE PAST 4-5 HOURS. A 110521Z AMSR2
89GHZ MICROWAVE IMAGE REVEALS DEEP CONVECTIVE BANDING OVER THE
NORTHERN SEMICIRCLE WRAPPING INTO THE SOUTHERN QUADRANT OF THE
LOW-LEVEL CIRCULATION CENTER, WITH AN ASYMMETRIC REGION OF DEEP
CONVECTION OVER THE WESTERN QUADRANT. THE ENVIRONMENTAL CONDITIONS
ARE ASSESSED AT MARGINAL DUE TO THE LAND INTERACTION, HOWEVER, THE
SYSTEM HAS MAINTAINED STRONG RADIAL OUTFLOW AND LOW VERTICAL WIND
SHEAR. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED
ON EIR IMAGERY AND THE AMSR2 IMAGE. RADAR IMAGERY THUS FAR HAS NOT
BEEN HELPFUL. THE INITIAL INTENSITY OF 70 KTS IS CONSERVATIVELY
ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE WEAKENED STRUCTURE AND
THE RJTD DVORAK FINAL-T ESTIMATE OF 4.0 (65 KNOTS) AND CURRENT
INTENSITY ESTIMATE OF 4.5 (77 KNOTS).

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR)
ENTRENCHED TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE
   RJTD: T4.5 - 77 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 10-15 KTS
   SST: OVER LAND
   OUTFLOW: STRONG RADIAL
   OTHER FACTORS: INTERACTION WITH ROUGH TERRAIN

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: MEDIUM

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TYPHOON (TY) 26W WILL TRACK WEST-NORTHWESTWARD
ALONG THE SOUTHERN PERIPHERY OF THE STR THROUGH TAU 72. TY TORAJI
WILL WEAKEN SLOWLY THROUGH TAU 48. DRY AIR ENTRAINMENT IS EXPECTED
TO HINDER DEVELOPMENT AFTER TAU 24, WITH SIGNIFICANT WEAKENING
AFTER TAU 48 AS THE ENVIRONMENT BECOMES VERY DRY THROUGH ALL LEVELS
OF THE ATMOSPHERE. AFTER TAU 60, EXTENSIVE DRY AIR WILL ENVELOP THE
SYSTEM LEADING TO A MORE RAPID WEAKENING RATE. ADDITIONALLY
VERTICAL WIND SHEAR WILL INCREASE TO HIGH LEVELS (20-25 KNOTS) AND
SST VALUES WILL DECREASE TO 26-27C). AFTER TAU 72, THE WESTERN
EXTENT OF THE STR WILL WEAKEN AS MIDLATITUDE WESTERLIES SHIFT INTO
SOUTHERN CHINA, WHICH WILL RESULT IN A WEAK STEERING INFLUENCE AND
A SLOWER, MORE ERRATIC TRACK MOTION.    

MODEL DISCUSSION: WITH THE EXCEPTION OF THE GFS VORTEX TRACKER,
WHICH TRACKS THE SYSTEM WEST-NORTHWESTWARD INTO SOUTHERN CHINA, THE
DETERMINISTIC TRACK GUIDANCE INDICATES AN ERRATIC, SLOW TRACK
MOTION AFTER TAU 72, WITH A SHARP SOUTHWARD TURN EAST OF HAINAN
ISLAND. EPS AND GEFS PROBABILISTIC GUIDANCE SHOWS A FAIRLY TIGHT
CLUSTER OF SOLUTIONS THROUGH TAU 72 THEN INCREASING UNCERTAINTY IN
THE EXTENDED FORECAST PERIOD. EPS SHOWS A BIFURCATION WITH HALF THE
SOLUTIONS TRACKING THE SYSTEM TOWARD HONG KONG AND THE OTHER HALF
TRACKING THE WEAK SYSTEM EQUATORWARD. THE BULK OF THE GEFS
SOLUTIONS TRACK THE SYSTEM WESTWARD TO WEST-NORTHWESTWARD.      

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