WDPN31 PGTW 010900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (KIROGI) WARNING NR 
010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.9N 150.9E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 220 NM SOUTHWEST OF MINAMI TORI SHIMA
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 17 KTS
   SIGNIFICANT WAVE HEIGHT: 21 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY
EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) DISPLACED TO THE
SOUTHWEST OF DISORGANIZED FLARING CONVECTION. A 010326Z AMSR2
MICROWAVE IMAGE REVEALED A DISORGANIZED AREA OF CONVECTION AND
SHALLOW BANDING FEATURES OUTLINING THE LLCC. THE INITIAL POSITION
IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE PARTIALLY EXPOSED
CIRCULATION. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM
CONFIDENCE BASED ON A 010325Z AMSR2 WINDSPEED IMAGE, WHICH SHOWS A
BAND OF 40-45 KNOT WINDS IN PLACE ACROSS THE NORTHEASTERN
SEMICIRCLE OF THE CIRCULATION. THE ENVIRONMENT IS ASSESSED AS
MARGINALLY UNFAVORABLE, WITH WARM SEA SURFACE TEMPERATURES (SSTS)
AND MODERATE POLEWARD OUTFLOW OFFSET BY MODERATE TO HIGH VERTICAL
WIND SHEAR (VWS).

INITIAL WIND RADII BASIS: PERSISTENCE 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   CIMSS SATCON: 46 KTS AT 010326Z
   CIMSS ADT: 34 KTS AT 010540Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 20-25 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 STORM 11W IS FORECAST TO TRACK
NORTHWESTWARD ALONG THE WESTERN PERIPHERY OF THE STR THROUGH TAU
36. THE STR IS EXPECTED TO EXTEND TO THE WEST, WHICH WILL TURN THE
SYSTEM WEST-NORTHWESTWARD INITIALLY, THEN WESTWARD THROUGH TAU 120.
IN TERMS OF INTENSITY, A GRADUAL WEAKENING TREND WILL CONTINUE AS
11W IS EXPECTED TO BE HAMPERED BY MODERATE TO HIGH VWS, WITH
INCREASED DRY AIR ENTRAINMENT. GIVEN THE UNFAVORABLE ENVIRONMENT,
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 TRACK GUIDANCE REMAINS IN GOOD
AGREEMENT, WITH MINIMAL SPREAD IN EITHER DETERMINISTIC CONSENSUS
MEMBERS OR THE GEFS AND EPS ENSEMBLES THROUGH TAU 72. BY TAU 96,
CROSS TRACK SPREAD INCREASES 255NM, WITH THE GFS DETERMINISTIC
TRACKER FURTHER SOUTH, CLOSER TO AMAMI OSHIMA. THUS THE JTWC
FORECAST, LIES NEAR THE MULTI-MODEL CONSENSUS, IS PLACED WITH HIGH
CONFIDENCE THROUGH TAU 72, WITH MEDIUM CONFIDENCE BY TAU 96. 

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