WDPN31 PGTW 300900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 14W (KOINU) WARNING NR 
004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.7N 131.1E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 674 NM SOUTH-SOUTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY
EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) DUE TO PERSISTENT
MODERATE MID-UPPER LEVEL VERTICAL WIND SHEAR (VWS). A 300433Z AMSR2
89GHZ MICROWAVE IMAGE REVEALS A BROAD LOW LEVEL CIRCULATION THAT IS
STRUGGLING TO FORM A SINGLE, DOMINANT LLCC. A LARGE FIELD OF
FRAGMENTED AND SOMEWHAT DISORGANIZED LOW LEVEL CLOUD LINES IS
VISIBLE TO THE NORTHEAST OF THE CIRCULATION. THE INITIAL POSITION
IS PLACED WITH HIGH CONFIDENCE BASED ON MSI AND AMSR2 IMAGERY. THE
INITIAL INTENSITY OF 35 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON A GENERAL AGREEMENT AMONGST DVORAK AND AUTOMATED INTENSITY
ESTIMATES WHICH ALL CONGREGATE AROUND 35KTS WITH CIMSS SATCON
LEADING THE PACK AT 41KTS.

INITIAL WIND RADII BASIS: PERSISTENCE 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T2.0 - 30 KTS
   CIMSS SATCON: 41 KTS AT 300600Z
   CIMSS ADT: 33 KTS AT 300600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD
   OTHER FACTORS: MODERATE MID-LEVEL VERTICAL WIND SHEAR 

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS 14W (KOINU) IS FORECAST TO CONTINUE
GRADUALLY ALTERING COURSE TO STEADY UP ON A NORTH-NORTHWESTERLY
HEADING, AS THE STEERING RIDGE TO THE NORTH CONTINUES TO BREAK
DOWN. OVER THE NEXT 36 HOURS, THE SYSTEM WILL GRADUALLY INTENSIFY
AS IT FIGHTS OFF PERSISTENT NORTHEASTERLY SHEAR, EVENTUALLY
REACHING 50KTS BY TAU 36. AFTER TAU 36, THE STR TO THE NORTHEAST IS
FORECAST TO BUILD WESTWARD, WHICH WILL PUSH 14W INITIALLY
WEST-NORTHWESTWARD AND EVENTUALLY WESTWARD TOWARD THE SOUTHERN TIP
OF TAIWAN. IN TERMS OF INTENSITY, BY TAU 48 THE CHANCES FOR RAPID
INTENSIFICATION INCREASE CONSIDERABLY. AS THE SYSTEM APPROACHES THE
20TH PARALLEL, IT WILL TAP INTO DUAL CHANNEL OUTFLOW, BOTH POLEWARD
AND EQUATORWARD WHICH WHEN COUPLED WITH DECREASED VWS AND WARM
(30C) SSTS, WILL QUICKLY INTENSIFY 14W TO AROUND 85KTS BY TAU 72.
IN THE EXTENDED TRACK FORECAST, AS THE SYSTEM APPROACHES THE
SOUTHERN TIP OF TAIWAN, THE ENHANCED DUAL CHANNEL OUTFLOW IS LOST,
RESULTING IN A SLIGHTLY REDUCED INTENSIFICATION TREND THROUGH THE
FORECAST PERIOD AND A RESULTANT PEAK INTENSITY OF 110KTS BY TAU
120.  

MODEL DISCUSSION: WITH THE EXCEPTION OF NVGM, NUMERICAL MODELS ARE
IN FAIR AGREEMENT WITH A 120NM SPREAD IN SOLUTIONS BY TAU 72. AFTER
TAU 72, ECMWF AND ITS ENSEMBLE TAKE A MORE DIRECT WESTWARD COURSE
THROUGH THE LUZON STRAITS WHILE THE REMAINING GUIDANCE FOLLOWS THE
JTWC TRACK FORECAST. FOR THIS REASON, THE INITIAL TRACK FORECAST IS
PLACED WITH HIGH CONFIDENCE, AND WITH MEDIUM CONFIDENCE THEREAFTER.
RELIABLE MODEL INTENSITY GUIDANCE IS IN FAIR AGREEMENT WITH ALL
MEMBERS INDICATING GRADUAL INTENSIFICATION THROUGH TAU 48 AND MOST
INDICATE A MORE AGGRESSIVE INTENSIFICATION TREND THEREAFTER.
COAMPS-TC AND HWRF ARE THE ONLY MEMBERS THAT BREACH 100KTS, WITH
COAMPS-TC (GFS VERSION) PEAKING NEAR 150KTS. DUE PRIMARILY TO
DECAY-SHIPS LACKLUSTER INTENSITY FORECAST, BY TAU 120 THERE IS A
CONSIDERABLE GAP IN INTENSITY GUIDANCE, AMOUNTING TO NEARLY A 100KT
SPREAD. THE JTWC INTENSITY FORECAST IS THEREFOR PLACED ABOVE THE
MULTI-MODEL CONSENSUS BUT BELOW THE AFOREMENTIONED MOST AGGRESSIVE
MEMBERS. THE INTENSITY FORECAST IS PLACED 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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