WDPN32 PGTW 301500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 11W (SHANSHAN) 
WARNING NR 037//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 33.9N 132.9E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 46 NM EAST-SOUTHEAST OF IWAKUNI, JAPAN
   MOVEMENT PAST 6 HOURS: EASTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 0 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY AND A COMPOSITE
RADAR LOOP SHOW CONTINUED EROSION AND UNRAVELING OF CONVECTIVE 
TOPS AND FEEDER BANDS AS THE SYSTEM MADE ANOTHER LANDFALL - THIS TIME 
OVER THE NORTHERN TIP OF SHIKOKU. THE INITIAL POSITION IS PLACED WITH
HIGH CONFIDENCE BASED ON THE DEFINED LOW LEVEL CIRCULATION (LLC) ON
THE RADAR LOOP THAT WAS CONCENTRIC WITH THE EXPOSED LLC IN THE EIR
LOOP. THE INITIAL INTENSITY IS PLACED WITH MEDIUM CONFIDENCE BASED
ON EXTRAPOLATION FROM NEARBY WIND AND SEA LEVEL PRESSURE OBSERVATIONS
AND SUPPORTED BY RJTD AND THE HIGH END OF AUTOMATED DVORAK ESTIMATES. 
ANALYSIS INDICATES A HIGHLY UNFAVORABLE ENVIRONMENT DUE TO FRICTIONAL 
EFFECTS OF THE RUGGED ISLAND TERRAIN.

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 DPRNT: 30 KTS AT 301200Z
   CIMSS DMNT: 26 KTS AT 300925Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY UNFAVORABLE
   VWS: 10-15 KTS
   SST: OVER LAND
   OUTFLOW: STRONG POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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: TROPICAL DEPRESSION SHANSHAN WILL CONTINUE TO
TRACK JUST SOUTH OF EASTWARD ALONG THE NORTHERN PERIPHERY OF THE 
STEERING STR ACROSS SHIKOKU, EXIT INTO AND DRIFT ACROSS THE KII 
CHANNEL BEFORE MAKING A FINAL LANDFALL OVER SOUTHERN HONSHU NEAR 
WAKAYAMA AROUND TAU 20. AFTERWARD, A SECONDARY STR TO THE WEST WILL 
COMPETE FOR STEERING AND PLACE THE SYSTEM IN A QUASI-STATIONARY MODE 
AS IT APPROACHES THE CENTRAL JAPANESE ALPS. THE UNFAVORABLE 
ENVIRONMENT WILL EVENTUALLY ERODE THE SYSTEM TO DISSIPATION BY TAU 
36, POSSIBLY SOONER.

MODEL DISCUSSION: THE NUMERICAL MODELS ARE IN TIGHT AGREEMENT UP TO 
TAU 24; AFTERWARD, THE MEMBERS DIVERGE SIGNIFICANTLY. IN VIEW OF 
THIS, THERE IS ONLY MEDIUM CONFIDENCE IN THE JTWC TRACK FORECAST. 
GIVEN THE VARIABILITY OF A LAND TRACK AND THE POSSIBILITY OF AN EARLY 
DISSIPATION, THERE IS LOW CONFIDENCE IN THE JTWC INTENSITY FORECAST. 

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