WDPN31 PGTW 162100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 09W (NINE) WARNING 
NR 003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.1N 134.4E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 575 NM SOUTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS STEADY
CONSOLIDATION AND COOLING CLOUD TOPS OVER A BROAD LOW LEVEL
CIRCULATION CENTER. RECENT MICROWAVE IMAGERY SUCH AS A 161706Z ATMS
SERIES REVEAL AN ASYMMETRY TO THE SYSTEM INDICATIVE OF THE STORMS
EARLY STAGES, BUT THE CURRENT DVORAK ASSESMENT INDICATES THAT THE
SYSTEM IS DEVELOPING. LIKEWISE, MODEL PRESSURE FIELDS AND RADII OF
OUTERMOST ISOBARS AROUND THE CORE ARE FALLING CONSISTENTLY. OVER
THE PAST 24 HOURS, THE ESTIMATED CENTRAL PRESSURE HAS FALLEN 4MB AND
THE RADIUS OF THE OUTERMOST CLOSED ISOBAR HAS DECREASED MARKEDLY,
INDICATING THE SYSTEM IS CHANGING FROM A MONSOON DEPRESSION TO A
MORE TYPICAL TROPICAL CYCLONE. THE INITIAL POSITION IS PLACED WITH
LOW CONFIDENCE BASED ON THE BROAD NATURE OF THE CIRCULATION AND
LACK OF CONVECTION CYCLING INTO THE CORE. THE INITIAL INTENSITY OF
25 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A DVORAK
ASSESMENT OF T1.0 FROM PGTW AND A 161134Z ASCAT PARTIAL PASS THAT
VERIFIED 20-25KT SOUTHEASTERLIES OVER THE EASTERN PERIMETER OF THE
SYSTEM.

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

CURRENT STEERING MECHANISM: TD 09W IS BEING STEERED BY A LARGE
MONSOON GYRE THAT HAS SET UP OVER THE PHILIPPINE SEA. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.0 - 25 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T2.0 - 30 KTS
   CIMSS ADT: 33 KTS AT 161740Z

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

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: TROPICAL DEPRESSION 09W IS EXPECTED TO
CONTINUE GRADUAL CONSOLIDATION AND INTENSIFICATION AS IT TRACKS
SLOWLY TO THE NORTHWEST IN A FAVORABLE ENVIRONMENT UNDER WEAK
STEERING FLOW. IT IS CURRENTLY BEING NUDGED TO THE NORTHWEST BY THE
NEAR EQUATORIAL RIDGE BUT OVER THE NEXT 24 HOURS IT WILL TRACK AWAY
FROM THE INFLUENCE OF THE NEAR EQUATORIAL RIDGE AND GRADUALLY COME
UNDER THE INFLUENCE OF THE SUBTROPICAL RIDGE AND BEND TO A MORE
WESTERLY TRACK. GUIDANCE IS CONSISTENT IN INDICATING STEADY
INTENSIFICATION WITH A PEAK AS IT TRACKS SOUTH OF OKINAWA. COOLER
WATERS NORTH OF THE 20TH LATITUDE AND SUBSIDENCE TO THE NORTHWEST
OF THE RYUKUS ASSOCIATED WITH THE UPPER LEVEL LOW ARE EXPECTED TO
SLOW THE INTENSIFICATION OF THE SYSTEM AS IT PASSES THE RYUKUS.   

MODEL DISCUSSION: THERE REMAINS CONSIDERABLE SPREAD IN MODEL
GUIDANCE, PARTICULARLY OVER THE TAU 96-120 HOUR PERIOD. HOWEVER,
THE GUIDANCE HAS TIGHTENED CONSIDERABLY DURING THE PAST 24 HOURS,
WHEN A SIGNIFICANT PORTION OF  ENSEMBLE MEMBERS WERE TAKING A
POLEWARD TRACK TOWARDS AN UPPER LEVEL LOW SETTLING SOUTH OF KYUSHU. 
NOW ECMWF HAS COME INTO MUCH CLOSER AGREEMENT TO THE GFS SOLUTION
AND ENSEMBLE MEANS HAVE CONSOLIDATED TOWARDS A TRACK CLOSE TO AND
SOUTH OF OKINAWA. THE COMPLEX UPPER AIR PATTERN STEMMING FROM THE
MONSOON GYRE WILL ACT TO INCREASE UNCERTAINTY AND MODEL SPREAD
THROUGHOUT THE FORECAST, ESPECIALLY IN THE LATER TAUS. THE
INTENSITY FORECAST STAYS IN THE CENTER OF THE ENSEMBLE MEAN
THROUGHOUT THE FORECAST. STATISTICAL DYNAMICAL MODELS ARE BELOW THE
MEAN AFTER TAU 72, AND NO GUIDANCE INDICATES AN INTENSITY OVER
100KTS. 

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