WDPN31 PGTW 200900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 16W (SIXTEEN) 
WARNING NR 032//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.1N 130.1E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 462 NM SOUTH-SOUTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THAT TD 16W IS
STRUGGLING, WITH DISSIPATING CONVECTION WITH A PARTIALLY OBSCURED
LOW LEVEL CIRCULATION CENTER (LLCC). CIMSS VWS ANALYSIS INDICATES
AN UPPER-LEVEL ANTI-CYCLONE AND LOW VWS OVER TOP OF TD 16W, BUT THE
SATELLITE DEPICTION SUGGESTS OTHERWISE. ANALYSIS OF HWRF SYNTHETIC
SKEW-T INDICATES THE PRESENCE OF MODERATE (15-20 KNOTS) NORTHERLY
SHEAR OVER THE SYSTEM SUPPORTS THE OVERALL SATELLITE DEPICTION. THE
PARTIALLY EXPOSED LLCC IS TITLED UP-SHEAR OF THE MASS OF WEAKENING
CONVECTIVE ACTIVITY, UNDER CONVECTIVE BLOW OFF, LENDING ONLY MEDIUM
CONFIDENCE TO THE INITIAL POSITION.  THE INITIAL INTENSITY IS HELD
AT 30 KNOTS WITH MODERATE CONFIDENCE, HEDGED SLIGHTLY ABOVE THE
AVERAGE OF AGENCY INTENSITY ESTIMATES IN LIGHT OF THE ADT AND
SATCON ESTIMATES. THE SYSTEM IS TRACKING GENERALLY NORTHWESTWARD
ALONG THE SOUTHWEST SIDE OF THE DEEP STR TO THE NORTHEAST. BUT WITH
THE UNCERTAINTY IN THE INITIAL POSITION, THERE IS SOME DOUBT ON THE
TRACK MOTION AND IT APPEARS THE SYSTEM HAS CONTINUED TO TRACK
SLIGHTLY MORE EQUATORWARD THAN ANTICIPATED, DUE TO THE PRESENCE OF
LOW TO MID-LEVEL RIDGE TO THE NORTH.

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

CURRENT STEERING MECHANISM: DEEP-LAYER STR TO THE NORTHEAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T1.5 - 25 KTS
   CIMSS SATCON: 41 KTS AT 200337Z
   CIMSS ADT: 34 KTS AT 200550Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: WEAK RADIAL
   OTHER FACTORS: MODERATE MID-LEVEL NORTHERLY SHEAR BETWEEN
850MB-500MB. 

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   INITIAL INTENSITY: MEDIUM
   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: CONSISTENT WITH THE PREVIOUS FORECAST, TD 16W
IS EXPECTED TO CONTINUE TRACKING NORTHWESTWARD THROUGH TAU 48. THE
LOW TO MID-LEVEL RIDGE CURRENTLY ENTRENCHED TO THE NORTH IS
EXPECTED TO WEAKEN AND RETREAT EASTWARD OVER THE NEXT 24 HOURS,
ALLOWING TD 16W TO GRADUALLY TURN TO THE NORTH BY TAU 48. NEAR-TERM
MOTION BEING A BIT UNCERTAIN, A MORE GRADUAL TURN POLEWARD AND THUS
A TRACK FURTHER TO THE WEST IS A POSSIBILITY. THE SYSTEM IS
EXPECTED TO ROUND THE STR AXIS SHORTLY AFTER TAU 48, AND BEGIN
ACCELERATING TO THE NORTHEAST ALONG THE STRONG GRADIENT BETWEEN THE
DEEP STR AND A MID-LATITUDE TROUGH OVER NORTHERN CHINA. IN THE
UPPER-LEVELS, A WEAK ANTI-CYCLONE LIES OVER TOP OR JUST EAST OF TD
16W, PROVIDING WEAK RADIAL OUTFLOW. THE AFOREMENTIONED MID-LEVEL
SHEAR HOWEVER IS INHIBITING DEVELOPMENT OF A VERTICALLY STACKED
CORE AND OFFSETTING THE GOOD OUTFLOW AND WARM SSTS. THIS MID-LEVEL
SHEAR IS EXPECTED TO REMAIN IN PLACE THROUGH THE NEXT 24 TO 36
HOURS, BUT SHOULD WEAKEN ENOUGH TO ALLOW FOR SLOW INTENSIFICATION
TO A PEAK OF 40 KNOTS AT TAU 36. A VERY SHARP TROUGH AXIS LIES TO
THE WEST, FOLLOWING A LINE EXTENDING FROM SOUTHERN HONSHU, EAST OF
THE RYUKUS TO THE LUZON STRAIT. BEHIND THIS TROUGH LIES STRONG
NORTHEASTERLY FLOW AND AS THE SYSTEM APPROACHES THIS LINE BY AROUND
TAU 36, IT WILL BEGIN TO FEEL THE IMPACT OF RAPIDLY INCREASING
NORTHEASTERLY SHEAR AND BEGIN WEAKENING. THE SYSTEM IS FORECAST TO
FULLY DISSIPATE UNDER STRONG VWS, CONVERGENT FLOW ALOFT AND COOL
SSTS, NO LATER THAN TAU 96, BUT LIKELY CLOSER TO TAU 72. 

MODEL DISCUSSION: TRACK GUIDANCE IS BEGINNING TO SHOW INCREASED
UNCERTAINTY, EVEN IN THE EARLIER TAUS, WITH THE CONSENSUS MEMBERS
SHOWING A MARKED SPLIT INTO TWO OPPOSING CAMPS. THE UKMET ENSEMBLE
REMAINS THE LEFT OUTLIER AND IS NOW JOINED BY THE GALWEM AND
NAVGEM, INDICATING A FLATTER TRAJECTORY TOWARDS ISHIGAKIJIMA AND A
VERY WIDE TURN TO THE NORTHEAST THEREAFTER. THE OTHER CAMP CONSISTS
OF THE HWRF, GFS, ECMWF AND THEIR ENSEMBLES, WHICH FAVOR A MORE
POLEWARD TRACK AND SHARPER TURN TO THE NORTHEAST, WITH THE
CONSENSUS MEAN DOWN THE MIDDLE. THE JTWC FORECAST LIES ON THE
SOUTHERN SIDE OF THE ENVELOPE THROUGH TAU 24 IN LIGHT OF THE
RECENT, MORE EQUATORWARD MOTION VECTOR, THEN CLOSELY TRACKS THE GFS
SOLUTION THEREAFTER. CROSS-TRACK UNCERTAINTY IS THE MAIN CONFIDENCE
FACTOR THROUGH TAU 48, AND WITH THE SPLIT IN THE MODELS, LENDS ONLY
MEDIUM CONFIDENCE THROUGH TAU 48. ALONG TRACK UNCERTAINTY INCREASES
DRAMATICALLY AFTER THE RECURVE AND BECOMES THE PRIMARY CONFIDENCE
FACTOR THROUGH TAU 96, WITH LOW CONFIDENCE. INTENSITY GUIDANCE IS
MIXED, WITH THE CONSENSUS MEMBERS INDICATING A PEAK BETWEEN 40 TO
60 KNOTS, WITH HWRF BEING THE MOST BULLISH. THE JTWC FORECAST LIES
ON THE LOW END OF THIS RANGE THROUGH TAU 36, THEN WELL BELOW ALL
THE GUIDANCE THEREAFTER, AS THE UPPER-LEVEL PATTERN DOES NOT
SUPPORT CONTINUED TROPICAL STORM INTENSITY AFTER TAU 48, AS THE
MESOSCALE MODELS WOULD SUGGEST. HOWEVER, BEING THAT THE JTWC
FORECAST IS SO FAR BELOW THE GUIDANCE, THERE IS ONLY MEDIUM
CONFIDENCE THROUGH TAU 48, AND LOW CONFIDENCE THEREAFTER.   

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