WDPN32 PGTW 302100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 11W (SHANSHAN) 
WARNING NR 038//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 33.8N 134.1E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 104 NM EAST-SOUTHEAST OF IWAKUNI, JAPAN
   MOVEMENT PAST 6 HOURS: EASTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: OVER LAND

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
DEPRESSION 11W (SHANSHAN) WITH A QUICKLY ERODING APPEARANCE. THE
CONVECTION IS BEGINNING TO DISAPPEAR, LEAVING THE DISORGANIZED
LOW-LEVEL CIRCULATION CENTER (LLCC) PARTIALLY EXPOSED.
ENVIRONMENTAL ANALYSIS INDICATES THAT 11W IS IN AN UNFAVORABLE
ENVIRONMENT CHARACTERIZED BY STRONG POLEWARD OUTFLOW ALOFT AND
RELATIVELY LOW VERTICAL WIND SHEAR STRONGLY OFFSET BY THE RUGGED
TERRAIN OF JAPAN. THE INITIAL POSITION IS PLACED WITH MEDIUM
CONFIDENCE BASED ON A COMBINATION OF THE ANIMATED EIR IMAGERY AND
RADAR IMAGERY. THE INITIAL INTENSITY OF 30 KTS IS ASSESSED WITH
MEDIUM CONFIDENCE BASED ON NEARBY SURFACE OBSERVATIONS FROM CAPE
MUROTO REPORTING 28 KNOT WINDS (CONVERTED TO 1-MIN AVERAGE).

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

CURRENT STEERING MECHANISM: SHALLOW LAYER OF SOUTHWEST EXTENSION OF
THE SUBTROPICAL RIDGE (STR) TO THE EAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE
   RJTD: T2.0 - 30 KTS
   CIMSS DPRINT: 34 KTS AT 301800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 10-15 KTS
   SST: OVER LAND
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: TERRAIN INTERACTION

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: 11W IS FORECAST TO TRACK EAST-SOUTHEASTWARD
OVER THE NEXT 12 HOURS. AFTERWARD, A SECONDARY STR TO THE WEST WILL
COMPETE FOR STEERING AND WILL CAUSE THE SYSTEM TO BECOME NEARLY
QUASI-STATIONARY THROUGH TAU 24 BEFORE EVENTUALLY BEGINNING A
NORTHWARD TURN AS THE STEERING BECOMES MORE DEFINED IN THE
NORTH-SOUTH ORIENTATION. 11W IS FORECAST TO MAINTAIN 30 KTS THROUGH
TAU 12 AS IT RETURNS BACK OVER WATER NEAR THE KII CHANNEL.
AFTERWARDS, 11W IS FORECAST TO BEGIN WEAKENING AGAIN AS IT DRIFTS
NORTHWARD AND MAKES A FINAL LANDFALL SOUTH OF KYOTO. DISSIPATION IS
ANTICIPATED TO OCCUR QUICKLY AFTER MAKING THIS FINAL LANDFALL.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN POOR AGREEMENT
AFTER TAU 12 WITH HIGH VARIANCE IN THE NORTHWARD TURN. ECMWF TURNS
THE SYSTEM BACK NORTHWESTWARD AFTER TAU 12 WHILE NAVGEM AND GALWEM
MAKE UP THE OTHER END OF CONSENSUS, TURNING THE SYSTEM
NORTHEASTWARD. MODELS ALSO DIFFER IN THE AMOUNT OF TIME
QUASI-STATIONARY AND OVER WATER. THE HIGH VARIANCE IN MODELS LENDS
LOW CONFIDENCE IN THE JTWC TRACK FORECAST. INTENSITY GUIDANCE IS
ALSO IN POOR AGREEMENT WITH MODELS DISAGREEING ON THE ONSET OF
DISSIPATION DUE TO DIFFERENCES IN TRACK AND TIME OVER WATER. SOME
MODELS SUGGEST A SLIGHT INTENSIFICATION WINDOW AS THE VORTEX
REMAINS QUASI-STATIONARY OFFSHORE. AS A RESULT, THE JTWC INTENSITY
FORECAST IS ALSO PLACED WITH LOW CONFIDENCE.

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