WDPN31 PGTW 010900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 14W (KOINU) WARNING NR 008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.9N 129.0E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 520 NM SOUTH OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 22 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A RAPIDLY
CONSOLIDATING TYPHOON STRENGTH TROPICAL CYCLONE. DEEP CONVECTIVE
BANDING IS NOW FULLY WRAPPING THE CIRCULATION AND A POSSIBLE
TRANSIENT EYE FEATURE IS NOW OBSERVABLE. A RECENT 010455Z ATMS
165GHZ MICROWAVE IMAGE SHOWS A NEARLY COMPLETE MICROWAVE EYE
FEATURE WITH DEEP CONVECTIVE BANDINGS PRIMARILY TO THE SOUTH OF THE
LLCC. A 010515Z AMSR2 MICROWAVE RADIOMETRY PARTIAL PASS REVEALS A
THICK BAND OF 50-60KT WINDS EVIDENT IN THE WESTERN REGION OF THE
FORMING EYE WALL. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON MSI AND ATMS IMAGERY. THE INITIAL INTENSITY OF
65 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A GROWING RANGE
OF DVORAK AND AUTOMATED INTENSITY ESTIMATES. WEAK TYPHOON STRENGTH
TROPICAL CYCLONES ARE NOTORIOUS FOR THE WIDE RANGE OF INTENSITY
ESTIMATES THEY GARNER, DUE TO THE VARIOUS DVORAK METHODS THAT CAN
BE USED. UNTIL A DEFINED EYE FEATURE FORMS, INTENSITY ESTIMATES MAY
FLUCTUATE, THUS OVERALL MEDIUM CONFIDENCE.

INITIAL WIND RADII BASIS: PERSISTENCE 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T3.0 - 45 KTS
   KNES: T4.0 - 65 KTS
   CIMSS SATCON: 70 KTS AT 010553Z
   CIMSS ADT: 67 KTS AT 010600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: STRONG EQUATORWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: HAVING RECENTLY ACHIEVED TYPHOON STRENGTH, TY
14W (KOINU) IS FORECAST TO CONTINUE TRACKING NORTHWESTWARD UNDER THE
STEERING INFLUENCE OF THE STR TO THE NORTHEAST. BY TAU 24, THIS STR
BEGINS TO BUILD BACK UP AND MIGRATE WESTWARD, RESULTING IN A
GRADUAL WESTWARD ARC TOWARD THE SOUTHERN TIP OF TAIWAN. IN TERMS OF
INTENSITY, 14W WILL RAPIDLY SURGE TO 100KTS BY TAU 36, FUELED BY
WARM SSTS (30C), LOW VERTICAL WIND SHEAR AND IMPROVING OUTFLOW
ALOFT. BY TAU 72, 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 INDICATE. THIS WOULD CAUSE A
MORE DRAMATIC WESTWARD COURSE, 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, ECMWF AND COAMPS-TC INDICATE A MORE
DRAMATIC WESTWARD COURSE OVER OPEN WATERS AND INTO THE NORTHERN
REGIONS OF THE SOUTH CHINA SEA. FOR THIS REASON THE JTWC TRACK
FORECAST IS PLACED 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 72, AFTER WHICH GRADUAL WEAKENING THROUGH THE FORECAST PERIOD.
AS SOME MEMBERS ARE INDICATING LANDFALL AND OTHERS REMAIN OVER OPEN
WATER, THERE IS A MODERATE SPREAD IN THE MEMBERS BY TAU 120.
THEREFOR, THE JTWC INTENSITY FORECAST REMAINS SLIGHTLY ABOVE THE
MULTI-MODEL CONSENSUS WITH OVERALL MEDIUM CONFIDENCE.

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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