WDPN31 PGTW 012100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (KIROGI)
WARNING NR 012//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 24.4N 148.3E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 312 NM WEST OF MINAMI TORI SHIMA
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 18 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY CONTINUES TO
SHOW TROPICAL STORM (TS) KIROGI (11W) EXPERIENCING STRONG WIND
SHEAR (25-30 KTS), WITH THE ENTIRETY OF THE SYSTEMS UPPER-LEVEL
OFFSET NORTHWARD OF THE PARTIALLY EXPOSED LOW LEVEL CIRCULATION
CENTER (LLCC). OVER THE PAST SIX HOURS, THE EXPOSED LLCC HAS SINCE
TUCKED BACK UNDER THE V-NOTCHED CONVECTION CANOPY, SHOWING
LOW-LEVEL BANDING CLOUDS IN THE SOUTHERN PERIPHERY ON ANIMATED
PROXYVIS SATELLITE IMAGERY.  SEA SURFACE TEMPS REMAIN FAVORABLE (28
TO 29 DEGREES CELSIUS) FOR DEVELOPMENT, OFFSET BY THE
AFOREMENTIONED VWS. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON ANIMATED HM9 PROXYVIS SATELLITE IMAGERY AND A
011800Z HM9 ENHANCED INFRARED SATELLITE IMAGE. THE INITIAL
INTENSITY OF 35 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON
MULTIAGENCY SUBJECTIVE INTENSITY ESTIMATES LISTED BELOW, AS WELL AS
THE FOLLOWING OBJECTIVE INTENSITY ESTIMATES: CIMSS ADT OF 34 KTS,
CIMSS AIDT OF 36 KTS, AND CIMSS DPRINT OF 28 KTS.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE
NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T2.5 - 35 KTS
   KNES: T2.0 - 30 KTS
   CIMSS ADT: 34 KTS AT 011750Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 25-30 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE 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 STROM 11W (KIROGI) WILL CONTINUE
TRACKING NORTHWESTWARD FOR THE NEXT 36 HOURS, ALONG THE
SOUTHWESTERN PERIPHERY OF THE STEERING RIDGE TO THE NORTHEAST.
AFTER TAU 36, THE STR IS EXPECTED TO EXTEND TO THE WEST, TURNING
THE SYSTEM WESTWARD THROUGH TAU 96. IN TERMS OF INTENSITY, NO
SIGNIFICANT ENVIRONMENTAL CHANGES ARE EXPECTED IN THE FIRST 24
HOURS OF THE FORECAST, WITH SUPPORTIVE SSTS AND ROBUST OUTFLOW
COMPETING WITH PERSISTENT HIGH VWS. THE SYSTEM IS FORECAST TO
MAINTAIN A STEADY WEAKENING TREND AS OUTFLOW BECOMES LESS FAVORABLE
AND DRY AIR ENTRAINMENT INCREASES. THUS, THE ENVIRONMENT WILL
BECOME INCREASINGLY UNFAVORABLE, AND 11W IS EXPECTED TO BEGIN
DISSIPATION SOUTH OF HONSHU BEFORE ULTIMATELY WEAKENING BELOW 25
KNOTS BY TAU 96 AS THE SYSTEM ENTERS THE EAST CHINA SEA.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE FROM ANALYSIS TO TAU 72
IS IN MODERATE AGREEMENT, WITH A GENERAL NORTHWESTWARD TRACK MOTION
FROM TAU ANALYSIS TO TAU 36 AND THEN WESTWARD MOTION THROUGH TAU
72.  TRACK GUIDANCE FROM TAU 72 THROUGH TAU 96 IS VERY DIVERSIFIED,
EXPANDING THE CROSS-TRACK SPREAD OF THIS PERIOD FROM 219NM TO 685NM
IN 24 HOURS. THEREFORE, THE FORECAST CONFIDENCE OF TRACK FOR THIS
LATER PERIOD IS LOW.  INTENSITY GUIDANCE CONTINUES TO WEAKEN THE
SYSTEMS INTENSITY THROUGH TAU 72, WITH COMPLETE DISSIPATION PRIOR
TO TAU 96.

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