WDPN31 PGTW 011500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 14W (KOINU) WARNING NR 009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 18.4N 128.7E
   INITIAL INTENSITY: 75 KTS
   GEOGRAPHIC REFERENCE: 489 NM SOUTH OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 25 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
SYMMETRIC TYPHOON STRENGTH CIRCULATION WITH A TRANSIENT 15NM EYE
THAT IS BEING OBSCURED BY RECENT FLARING CONVECTION. A 010849Z
SSMIS AND 011219Z AMSU-B 89GHZ MICROWAVE IMAGES REVEALS AN
IMPROVING EYE WITH BUILDING DEEP CONVECTIVE BANDING IN
ALL QUADRANTS. A FORTUITOUS 011223Z ASCAT-B SCATTEROMETRY PASS
REVEALS AN EXPANSIVE AND MORE SYMMETRIC WIND FIELD THAT STILL
SLIGHTLY FAVORS THE SOUTHERN SEMICIRCLE. THE INITIAL POSITION IS
PLACED WITH HIGH CONFIDENCE BASED ON A 15NM EYE EVIDENT IN EIR AND
SSMIS IMAGERY. THE INITIAL INTENSITY OF 75 KTS IS ASSESSED WITH
MEDIUM CONFIDENCE BASED ON THE MAJORITY OF INTENSITY GUIDANCE SUCH
AS AGENCY DVORAK ESTIMATES AND CIMSS ADT, AIDT AND DPRINT,
INDICATING 75-79KTS.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR)
POSITIONED TO THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T3.5 - 55 KTS
   KNES: T4.5 - 77 KTS
   CIMSS ADT: 77 KTS AT 011130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: STRONG EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: MEDIUM

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TY 14W (KOINU) HAS CONTINUED TO RAPIDLY
INTENSIFY OVER THE PAST 6 HOURS AND IS FORECAST TO CONTINUE
TRACKING NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE STR TO
THE NORTHEAST. AS THE STR CONTINUES TO BUILD AND MIGRATE WESTWARD,
THIS RESULTS IN A GRADUAL WESTWARD ARC TOWARD THE SOUTHERN TIP OF
TAIWAN. IN TERMS OF INTENSITY, 14W WILL RAPIDLY SURGE TO AROUND
100KTS BY TAU 24, FUELED BY WARM SSTS (30C), LOW VERTICAL WIND
SHEAR AND IMPROVING OUTFLOW ALOFT. NEAR TAU 60, 14W IS FORECAST TO
REACH ITS PEAK INTENSITY OF 110KTS AND POSSIBLY HIGHER BEFORE VWS
INCREASES AND FAVORABLE OUTFLOW IS LOST. THE SYSTEM IS FORECAST TO
MAKE LANDFALL OVER SOUTHERN TAIWAN NEAR 110KTS AND PROCEED WESTWARD
GRADUALLY WEAKENING THROUGH THE FORECAST PERIOD. IT IS IMPORTANT TO
NOTE THAT IF THE STR TO THE NORTHEAST BUILDS UP MORE RAPIDLY OR
EXTENDS POLEWARD OF 14W AS ECMWF AND COAMPS-TC HAVE RECENTLY
INDICATED, THIS WOULD CAUSE A MORE DRAMATIC WESTWARD COURSE CHANGE,
KEEPING THE SYSTEM OVER OPEN WATERS AND MORE IMPORTANTLY AWAY FROM
THE TAIWANESE MOUNTAIN RANGE, ALL OF WHICH COULD ALLOW FOR
ADDITIONAL INTENSIFICATION THROUGH THE FORECAST PERIOD.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN FAIR AGREEMENT WITH A
MAJORITY OF THE MEMBERS CLOSELY FOLLOWING THE JTWC FORECAST TRACK.
AS PREVIOUSLY MENTIONED ABOVE, COAMPS-TC AND ECMWF ENSEMBLE
INDICATE A MORE DRAMATIC WESTWARD COURSE OVER OPEN WATERS AND INTO
THE NORTHERN REGIONS OF THE SOUTH CHINA SEA. THE JTWC TRACK
FORECAST IS PLACED CLOSE TO THE MULTI-MODEL CONSENSUS INITIALLY
WITH HIGH CONFIDENCE AND WITH MEDIUM CONFIDENCE THEREAFTER.
RELIABLE MODEL INTENSITY GUIDANCE IS IN GOOD AGREEMENT WITH ALL
MEMBERS QUICKLY INTENSIFYING THE SYSTEM THROUGH TAU 48, AFTER WHICH
THE MEMBERS THAT INDICATE LANDFALL (HFAS, HWRF, DECAY-SHIPS)
QUICKLY WEAKEN THE SYSTEM WHILE COAMPS-TC CONTINUES TO INTENSIFY.
AS SOME MEMBERS ARE INDICATING LANDFALL AND OTHERS REMAIN OVER OPEN
WATER, THERE IS A DRAMATIC SPREAD IN THE MEMBER GUIDANCE BY TAU
120. THEREFOR, THE JTWC INTENSITY FORECAST REMAINS ABOVE THE
MULTI-MODEL CONSENSUS INITIALLY WITH MEDIUM CONFIDENCE AND WITH LOW
CONFIDENCE THEREAFTER.

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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