WDPN31 PGTW 050900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 14W (KOINU) WARNING NR 024//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.1N 120.1E
   INITIAL INTENSITY: 90 KTS
   GEOGRAPHIC REFERENCE: 196 NM SOUTH-SOUTHWEST OF TAIPEI, TAIWAN
   MOVEMENT PAST 6 HOURS: WESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 35 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) AND ANIMATED RADAR
IMAGERY DEPICTS TYPHOON 14W (KOINU) HAS TRAVERSED WESTWARD PAST THE
SOUTHERN TIP OF TAIWAN. WHILE THE SYSTEM HAS BEEN DEGRADED OVER THE
PAST SIX HOURS, RADAR IMAGERY STILL DEPICTS DEEP CONVECTIVE
LOW-LEVEL BANDING ON THE SOUTHERN SEMICIRCLE. A 050453Z AMSR2 89GHZ
MICROWAVE IMAGE DEPICTS A WELL DEFINED LOW LEVEL CIRCULATION (LLCC)
WITH FRAGMENTED BANDING OVER THE NORTHEASTERN QUADRANT. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON RADAR IMAGERY AND
THE AMSR2 MICROWAVE IMAGE. THE INITIAL INTENSITY OF 90 KTS IS
HEDGED ABOVE SUBJECTIVE DVORAK CURRENT INTENSITY ESTIMATES BASED ON
ADT AND AIDT ESTIMATES OF 97 AND 89 KNOTS, RESPECTIVELY.
ENVIRONMENTAL CONDITIONS REMAIN MARGINAL, WITH WARM SSTS AND
MODERATE EQUATORWARD OUTFLOW OFFSET BY LOW-MODERATE NORTHEASTERLY
SHEAR, DRY AIR ENTRAINMENT.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO
THE NORTH.


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T4.5 - 77 KTS
   KNES: T3.5 - 55 KTS
   CIMSS SATCON: 83 KTS AT 050431Z
   CIMSS ADT: 97 KTS AT 050600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD

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: TYPHOON 14W IS FORECAST TO CONTINUE ON A
WESTWARD TRACK THROUGH TAU 48, THE SYSTEM WILL SLOW DOWN AS IT
APPROACHES THE COAST OF CHINA, AS A STR OVER EAST-CENTRAL CHINA
BECOMES THE DOMINATE STEERING FEATURE. THE SYSTEM WILL THEN TURN TO
A MORE SOUTHWESTWARD TRACK THROUGH TAU 120. IN TERMS OF INTENSITY,
THE SYSTEM WILL MOVE INTO AN AREA OF VERY WEAK UPPER-LEVEL OUTFLOW,
COOLER SSTS, AS DRY AIR ENTRAINMENT IS ANTICIPATED TO INCREASE
THROUGH TAU 72. THE LESS FAVORABLE ENVIRONMENTAL FACTORS, ALONG
WITH POTENTIAL LAND INTERACTION OF THE OUTERMOST WIND FIELD, WILL
ALSO CONTRIBUTE TO THE SYSTEMS DECAY BY TAU 96 THROUGH TAU 120.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN FAIR AGREEMENT WITH A
BULK OF THE GUIDANCE GENERALLY FOLLOWING THE JTWC FORECAST TRACK
THROUGH TAU 48, AFTER WHICH CROSS TRACK SPREADING INCREASES.
THEREFORE, THE JTWC TRACK FORECAST IS PLACED INITIALLY WITH MEDIUM
CONFIDENCE AND WITH LOW CONFIDENCE THEREAFTER. RELIABLE MODEL
INTENSITY GUIDANCE IS IN GOOD AGREEMENT WITH MOST MEMBERS
INDICATING A SHARP WEAKENING TREND THROUGH TAU 48, WHILE THE HAFS-A
AND HWRF CONTINUE TO SHOW A RELATIVELY FLAT
INTENSITY THROUGH TAU 48. WITH AFTER ALL MEMBERS SHOW A MORE
GRADUAL DECLINE THROUGH TAU 120. FOR THIS REASON, THE JTWC
INTENSITY FORECAST IS PLACED WITH OVERALL MEDIUM CONFIDENCE.


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