WDPN31 PGTW 172100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 09W (IN-FA) 
WARNING NR 007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.2N 132.5E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 364 NM SOUTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 17 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A BROAD,
ELONGATED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH PARTIALLY
EXPOSED BANDING ON THE WESTERN SIDE AND DEEP FLARING CONVECTION
TO THE EAST. A 171626Z AMSR2 89GHZ MICROWAVE IMAGE DEPICTS SHALLOW
BANDING TO THE WEST OF DEEP CONVECTION WHICH EXTENDS TO THE SOUTH
INDICATING THE ASYMETRIC NATURE OF THE SYSTEM. THE INITIAL POSITION
IS PLACED WITH MEDIUM CONFIDENCE BASED THE EXPOSED BANDING IN EIR.
THE INITIAL INTENSITY OF 30 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON THE DVORAK ESTIMATES FROM PGTW, RJTD AND KNES.
ENVIRONMENTAL ANALYSIS INDICATES MARGINALLY FAVORABLE CONDITIONS
WITH CONVERGENT UPPER-LEVEL WESTERLIES OFFSET BY ROBUST EQUATORWARD
OUTFLOW AND WARM SST VALUES.

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

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) OVER THE
NORTHEASTERN AND EASTERN PERIPHERY OF THE SYSTEM. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   RJTD: T2.0 - 30 KTS
   KNES: T2.5 - 35 KTS
   CIMSS ADT: 34 KTS AT 171740Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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: TD 09W IS TRACKING NORTHWESTWARD ALONG THE
PERIPHERY OF THE STR TO THE NORTH BUT WILL BEGIN GRADUALLY TURNING
WEST-NORTHWESTWARD AFTER TAU 24 AS THE STR BEGINS TO SHIFT
WESTWARD. AT THE SAME TIME, THE SYSTEM SHOULD BEGIN TO SLOWLY 
INTENSIFY AS ENVIRONMENTAL CONDITIONS GRADUALLY IMPROVE WITH 
CONVERGENCE ALOFT WEAKENING AND ALLOWING THE SYSTEM TO DEVELOP MORE 
ROBUST POLEWARD OUTFLOW AND SUPPORT A MORE CONSOLIDATED LOW LEVEL
CIRCULATION. AFTER TAU 72, TD 09W WILL TURN WESTWARD AS THE STR TO
THE NORTH CONTINUES TO BUILD. AS IMPROVED ENVIRONMENTAL CONDITIONS
PERSIST, TD 09W WILL STEADILY INCREASE IN INTENSITY THROUGHOUT THE
REMAINDER OF THE FORECAST WITH A PEAK INTENSITY OF 85 KNOTS
ANTICIPATED BY TAU 120.  

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN MEDIUM CONFIDENCE
UP TO TAU 36, BUT CROSS-TRACK MODEL SPREAD BEGINS TO INCREASE
AFTERWARDS REACHING 150 NM AT TAU 72. MODEL UNCERTAINTY CONTINUES
TO INCREASE AFTER TAU 72, WITH ECMWF TRACKING SOUTHWESTWARD AT TAU
120 AND NVGM TRACKING NORTHWESTWARD. 

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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