WDPN31 PGTW 020300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (KIROGI) WARNING NR 
013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.4N 147.8E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 1052 NM EAST-SOUTHEAST OF SASEBO, JAPAN
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A FULLY EXPOSED
LOW LEVEL CIRCULATION CENTER (LLCC) WITH REMNANT DEEP CONVECTION
NOW CONSTRAINED TO THE EASTERN SEMI-CIRCLE AND DISPLACED 150 NM OR
MORE FROM THE CENTER DUE TO THE PRESENCE OF A DEEP UPPER LEVEL
LOW TO THE WEST PUMPING A STEADY FLOW OF 40 PLUS KNOT WINDS
OVERHEAD. THE INITIAL POSITION WAS PLACED WITH HIGH CONFIDENCE
BASED ON MULTI-AGENCY FIXES ON THE EXPOSED LLCC. THE AVAILABLE
OBJECTIVE AND SUBJECTIVE INTENSITY DATA SUPPORTS A RANGE OF 30 TO
35 KNOTS. THE INITIAL INTENSITY WAS SET TO 35 KNOTS, WHICH IS
LIKELY GENEROUS, BASED ON A 012331Z ASCAT-B PASS INDICATING THE
PRESENCE OF 35 KNOT WINDS UNDER THE REMNANT CONVECTION IN THE
NORTHEAST QUADRANT ALONG THE OUTERMOST EXTENT OF THE CIRCULATION.
GFS ANALYSIS INDICATES GENERALLY LOW MID-LEVEL MOISTURE VALUES,
WITH AN INTRUSION OF PARTICULARLY DRY AIR AT 500 MB. THE PRIMARY
STEERING MECHANISM IS LOW TO MID-LAYER SUBTROPICAL RIDGING (STR) TO
THE EAST, WITH SOME ENHANCEMENT IN THE FLOW BY THE UPPER LOW. ALTHOUGH 
SEA SURFACE TEMPERATURES REMAIN FAVORABLE (28 TO 29 CELSIUS), IT IS 
NOT ENOUGH TO OVERCOME THE OVERALL UNFAVORABLE
ENVIRONMENTAL CONDITIONS.

INITIAL WIND RADII BASIS: 012331Z ASCAT-B SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: LOW TO MID-LEVEL SUBTROPICAL RIDGING TO
THE EAST, ENHANCED BY DEEP UPPER LEVEL LOW TO THE WEST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T2.0 - 30 KTS
   KNES: T2.0 - 30 KTS
   CIMSS ADT: 37 KTS AT 012340Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 25-30 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: WEAK POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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: TROPICAL STORM 11W (KIROGI) WILL CONTINUE TRACKING NORTHWESTWARD OVER THE NEXT 36 HOURS, ALONG THE SOUTHWESTERN PERIPHERY OF THE STEERING RIDGE TO THE NORTHEAST. AFTER TAU 36, THE TRACK WILL BECOME MORE WESTERLY IN RESPONSE TO AN EXTENSION OF THE STR OVER JAPAN. DYNAMICAL AND STATISTICAL GUIDANCE INDICATES THAT TS KIROGI WILL REMAIN IN AN UNFAVORABLE ALIGNMENT WITH THE UPPER LOW, WITH SUSTAINED HIGH VERTICAL WIND SHEAR OVER THE NEXT 36 TO 48 HOURS. A DISSIPATION TREND IS EXPECTED TO CONTINUE, DROPPING BELOW 35 KNOTS WITHIN 12 HOURS, WITH FULL DISSIPATION INTO A TROPICAL DISTURBANCE BY TAU 96, IF NOT SOONER. 

MODEL DISCUSSION: MULTI-MODEL ACROSS TRACK SPREAD IS ONLY 130 NM AT 
TAU 72, WHILE ALONG TRACK SPREAD IS ABOUT 260 NM, WHICH RESULTS FROM 
SOME MODELS DISSIPATING TS 11W EARLIER THAN OTHERS. THE HAFS-A MODEL 
IS AN INTERESTING OUTLIER, WITH A BURST OF RE-INTENSIFICATION JUST 
PRIOR TO MAKING LANDFALL OVER SOUTHERN KYUSHU, HOWEVER GIVEN 
PERSISTENT UNFAVORABLE CONDITIONS, THAT SOLUTION IS NOT BEING 
CONSIDERED. OVERALL FORECAST TRACK AND INTENSITY IS ASSESSED AT HIGH 
GIVEN THE GOOD MODEL AGREEMENT THROUGH THE END OF THE FORECAST, BUT 
NOTING THAT DISSIPATION COULD OCCUR SOONER THAN FORECAST. 

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