WDPN31 PGTW 302100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (KIROGI)       
WARNING NR 004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.1N 154.5E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 560 NM EAST OF ANDERSEN AFB, GUAM
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
CENTRAL DENSE OVERCAST (CDO) FEATURE OBSCURING THE LOW-LEVEL 
CIRCULATION CENTER (LLCC) WITH A CONVECTIVE BAND OVER THE NORTHERN 
SEMICIRCLE. A 301807Z SSMIS 91 GHZ COLOR COMPOSITE MICROWAVE IMAGE 
INDICATES A COMPACT SYSTEM WITH CONVECTIVE BANDING WRAPPING INTO A 
SMALL, WELL-ORGANIZED CORE. THE CONVECTIVE BANDING WITHIN THE CORE 
WRAPS INTO A WELL-DEFINED LLCC, WHICH SUPPORTS THE INITIAL POSITION 
WITH HIGH CONFIDENCE. ANIMATED WATER VAPOR IMAGERY AND CIMSS MID-UPPER 
LEVEL WINDS IMAGERY SHOW AN UPPER-LOW AND DEEP TROUGH WEST AND 
NORTHWEST OF THE SYSTEM. DESPITE SOME PRESSURE ON THE WESTERN 
PERIPHERY, THIS TROUGH IS BOOSTING POLEWARD OUTFLOW AND AIDING IN THE 
RECENT INTENSIFICATION AND CONSOLIDATION OF THE SYSTEM. THE INITIAL 
INTENSITY OF 45 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE 
PGTW, KNES DVORAK ESTIMATES AS WELL AS THE CIMSS ADT ESTIMATE AND A 
301700Z DPRINT ESTIMATE OF 43 KNOTS. ADDITIONALLY, A 301549Z AMSR2 
WINDSPEED IMAGE REVEALS A SWATH OF 40-50 KNOT WINDS OVER THE NORTHERN 
SEMICIRCLE WITH A PATCH OF 50-60 KNOT WINDS (UNDER DEEP CONVECTIVE 
BURST) OVER THE NORTHERN QUADRANT.

INITIAL WIND RADII BASIS: AMSR2 WINDSPEED DATA

CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR)
POSITIONED TO THE EAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.5 - 35 KTS
   KNES: T3.0 - 45 KTS
   CIMSS ADT: 45 KTS AT 301740Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 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 (TS) 11W IS FORECAST TO GRADUALLY 
TURN NORTHWESTWARD AS IT TRANSITIONS TO THE STEERING INFLUENCE OF A 
STRONG STR POSITIONED TO THE NORTH. TS 11W WILL CONTINUE TRACKING 
NORTHWESTWARD TO WEST-NORTHWESTWARD THROUGH THE FORECAST PERIOD. DUE 
TO FAVORABLE CONDITIONS THROUGH TAU 24 AND THE COMPACT NATURE OF THE 
SYSTEM, TS 11W WILL INTENSIFY TO 60 KNOTS BY TAU 24. AFTER TAU 24, THE 
SYSTEM IS FORECAST TO TRACK UNDER THE EASTERN PERIPHERY OF THE UPPER 
LOW, WITH INCREASING VERTICAL WIND SHEAR (VWS), WHICH WILL LEAD TO A 
STEADY WEAKENING TREND. THE UPPER LOW WILL CONTINUE TO TRACK WESTWARD 
ALONG WITH THE SYSTEM WITH STRONG VWS AND WEAK DIVERGENCE PERSISTING 
THROUGH THE FORECAST PERIOD.       

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT 
THROUGH TAU 72 WITH A 130 NM SPREAD IN SOLUTIONS AT TAU 72. AFTER TAU 
72, GUIDANCE DIVERGES TO 300 NM AT TAU 120 LENDING MEDIUM CONFIDENCE 
TO THE JTWC EXTENDED TRACK FORECAST. COAMPS-TC AND HAFS-A INTENSITY 
GUIDANCE INDICATES A PEAK OF 55 TO 60 KNOTS AT TAU 24. THE JTWC 
INTENSITY CONSENSUS (ICNW) PEAKS SLIGHTLY LOWER AT 53 KNOTS DUE TO 
DECAY SHIPS (NAVGEM AND GFS VERSIONS), WHICH ARE PEAKING AT ABOUT 47 
KNOTS. AFTER TAU 36, INTENSITY GUIDANCE GENERALLY SHOWS A STEADY 
WEAKENING TREND AND LARGER SPREAD, ESPECIALLY IN THE EXTENDED PERIOD 
WITH LOW CONFIDENCE IN THE JTWC INTENSITY FORECAST.

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