WDPN31 PGTW 292100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 14W (KOINU) WARNING 
NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.5N 133.2E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 460 NM NORTHWEST OF YAP
   MOVEMENT PAST 6 HOURS: WESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 13 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED CIRA PROXY VISIBLE SATELLITE IMAGERY DEPICTS A COMPLEX SCENE 
OF DEEP CONVECTION FRACTURED INTO TWO PRIMARY MASSES. BEST TRACKING 
HAD BEEN ALONG THE SOUTHEASTERN MASS, HOWEVER IT HAS BEEN GRADUALLY 
DECLINING WHILE THE CONVECTION TO THE NORTHWEST HAS BEEN IMPROVING IN 
APPEARANCE. HOWEVER, BOTH APPEAR TO BE IN AN ENVELOPE OF A BROAD LOW 
LEVEL CIRCULATION CENTER (LLCC). THE FOOTPRINTS OF THE MOST RECENT 
ASCAT PASSES MISSED THE LLCC, BUT SUGGEST EITHER AN ELONGATED LLCC, OR
THE POSSIBILITY OF TWO DISTINCT LLCCS. NO OTHER RECENT MICROWAVE
IMAGERY IS AVAILABLE TO HELP REFINE THE INITIAL POSITION, WHICH WAS
ASSESSED WITH LOW CONFIDENCE BASED ON THE LARGER LOW LEVEL BANDING
OBSERVED IN THE PROXY VISIBLE IMAGERY, AND SERVES AS A CENTRAL POINT 
OF THE SCENARIOS DESCRIBED ABOVE. THIS POSITION IS IN AGREEMENT WITH 
THE GFS AND ECMWF ANALYZED CENTERS. ALTHOUGH THE ASCAT PASSES INDICATE 
THE PRESENCE OF 35 KNOT WINDS, THESE ARE UNDER THE DEEP CONVECTION TO 
THE NORTHWEST AND APPROXIMATELY 100 NM FROM THE ASSESSED CENTER. THE 
INITIAL INTENSITY WAS ASSESSED AT 30 KNOTS GIVEN THE OVERALL POOR 
ORGANIZATION OF THE LOW LEVEL VORTEX AND IN AGREEMENT WITH AGENCY 
DVORAK FIXES FROM T1.5 TO T2.0, AS WELL AS AVAILABLE OBJECTIVE 
INTENSITY ESTIMATES. CIMSS WIND SHEAR ESTIMATES ARE GENERALLY 
FAVORABLE AT 10 TO 15 KNOTS. TD 14W IS TRACKING WESTWARD UNDER THE 
INFLUENCE OF MID-LEVEL SUB-TROPICAL RIDGING (STR) TO THE NORTH, WITH 
MODERATE EQUATORWARD OUTFLOW.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: MID-LEVEL SUB-TROPICAL RIDGING TO THE
NORTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   KNES: T2.0 - 30 KTS
   CIMSS ADT: 27 KTS AT 291730Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   INITIAL INTENSITY: LOW
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

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

FORECAST DISCUSSION: GFS SUGGESTS TD KOINU WILL CONTINUE TO
STRUGGLE IN CONSOLIDATING AN LLCC OVER THE NEXT 36 HOURS, WHILE
OTHER ENVIRONMENTAL FACTORS REMAIN FAVORABLE. A STAIR-STEP TYPE
PATTERN IS INDICATED, AS A WEAK MID-LATITUDE SHORTWAVE TROUGH
MOVES PAST, WEAKENING THE STR FLOW ENOUGH TO ALLOW TD 14W TO GAIN
LATITUDE. AFTER TAU 36, THE VORTEX SHOULD BECOME MORE ESTABLISHED,
ALLOWING FOR A MORE PRONOUNCED INTENSIFICATION TREND.  AFTER DAY 3,
DEEP LAYER RIDGING REBUILDS TO THE NORTH AND REORIENTS THE TRACK
BACK TO A WEST-NORTHWESTWARD TRAJECTORY, GENERALLY HEADING TOWARDS
SOUTHERN TAIWAN. SHEAR AND MOISTURE CONDITIONS LOOK FAVORABLE AT
THE EXTENDED RANGE, WITH TD KOINU REACHING A PEAK OF 95 KNOTS AT
TAU 120. 

MODEL DISCUSSION: THERE WAS SIGNIFICANT UNCERTAINTY IN THE ENSEMBLE
GUIDANCE IN PRIOR CYCLES, WITH A PRONOUNCED POSSIBILITY FOR A
BI-FURCATED TRACK SOLUTION. HOWEVER, THE PROBABILITY OF AN EARLY
RECURVATURE TOWARDS JAPAN HAS SIGNIFICANTLY DECREASED. THE ENSEMBLE
MEANS ARE NOW IN ALIGNMENT WITH THE BULK OF THE MULTI-MODEL SPREAD,
ALTHOUGH CONFIDENCE REMAINS LOW UNTIL THE LLCC MORE FIRMLY
CONSOLIDATES, AND ONCE ADDITIONAL SATELLITE DATA BECOMES AVAILABLE
TO BETTER ASSESS THE STRUCTURE. THE TIMING AND POSITIONING OF THE
VORTEX WILL PLAY A KEY ROLE IN THE FORECAST TRACK. GFS IS THE MORE
AGGRESSIVE OF THE MODELS FOR INTENSITY, HOWEVER, CLIMATOLOGY
SUPPORTS A FORECAST ON THE HIGHER END OF THE ENVELOPE.  

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