WDPN32 PGTW 232100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 08W (HIGOS) WARNING 
NR 006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.9N 142.8E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 142 NM WEST-NORTHWEST OF ANDERSEN AFB
   MOVEMENT PAST 6 HOURS: WESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER WITH DEEP CONVECTION
FLARING OVER THE NORTHERN PERIPHERY. COMPARED TO 18-24 HOURS AGO,
THE CIRCULATION APPEARS MORE FRAGILE AND LESS ORGANIZED. CONVECTION
IS LARGELY ABSENT IN THE SOUTHERN SEMICIRCLE, AND EQUATORWARD
OUTFLOW ALOFT IS STILL RESTRICTED. A 231200Z GUAM SOUNDING FROM NWS
TIYAN REVEALED 20-30 KTS OF SOUTHEASTERLY WIND IN THE 300-150 MB
LAYER WITH LESS-THAN-IDEAL DRY AIR IN THE 750-200 MB LAYER. A
231127Z ASCAT-C PASS EVIDENCED A VERY COMPACT CIRCULATION WITH A
SMALL AREA OF 25-30 KT SURFACE WINDS IN THE NORTHEAST QUADRANT,
WHICH IS NOTICEABLY WEAKER THAN THE PRIOR ASCAT PASS AT 230019Z
DEPICTING 30-35 KTS OVER THE ENTIRE NORTH SIDE OF THE VORTEX. THE
ENVIRONMENT IS MARGINALLY UNFAVORABLE FOR DEVELOPMENT,
CHARACTERIZED BY WARM SEA SURFACE TEMPERATURE (SST) STRONGLY OFFSET
BY MODERATE TO HIGH VERTICAL WIND SHEAR (VWS) AND DRY AIR ABOVE THE
BOUNDARY LAYER. NO IMPROVEMENT IN ORGANIZATION WAS OBSERVED SINCE
THE ASCAT-C PASS. THEREFORE, THE INITIAL INTENSITY REMAINS AT 30
KTS WITH HIGH CONFIDENCE. THE INITIAL POSITION IS ASSESSED WITH
HIGH CONFIDENCE BASED ON THE EXPOSED CENTER ON ANIMATED SHORTWAVE
IR IMAGERY.

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

CURRENT STEERING MECHANISM: THE SOUTHWESTERN PERIPHERY OF A
SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.5 - 35 KTS
   KNES: T2.5 - 35 KTS
   CIMSS SATCON: 34 KTS AT 231710Z
   CIMSS ADT: 33 KTS AT 231930Z
   CIMSS AIDT: 34 KTS AT 231930Z
   CIMSS D-MINT: 26 KTS AT 231550Z
   CIMSS D-PRINT: 25 KTS AT 231830Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 20-25 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: HIGH
   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: DRIVEN BY A LOWER LEVEL STR, TROPICAL
DEPRESSION 08W WILL MOVE WEST-NORTHWESTWARD FOR THE NEXT 24 HOURS.
AS IT APPROACHES A BREAK IN THE STR, IT WILL TURN POLEWARD AND
CROSS THE RIDGE AXIS AT TAU 48. THE MID-LATITUDE WESTERLIES NORTH
OF THE AXIS WILL CAUSE HIGOS TO ACCELERATE TO THE NORTHEAST AND
UNDERGO RAPID EXTRATROPICAL TRANSITION. AT THE END OF THE PERIOD,
08W WILL BE ABSORBED INTO A FRONTAL SYSTEM. GIVEN THE ONGOING VWS,
LITTLE DEVELOPMENT OF 08W WILL OCCUR THROUGH TAU 12. THE
SOUTHEASTERLY VWS WILL SUBSIDE AS THE CIRCULATION TRAVERSES OVER
WARM SST OF 28-29 DEGREES CELSIUS AFTER TAU 12. THESE CONDITIONS
WILL ENABLE MODEST INTENSIFICATION OF 08W UNTIL IT BEGINS TO
INTERACT WITH THE LARGER, MORE POTENT CIRCULATION OF TYPHOON 07W
TOWARDS TAU 48. SIGNIFICANT DEEP-LAYER SOUTHERLIES INDUCED BY 07W
WILL LIKELY PREVENT FURTHER DEVELOPMENT. THE PROBABILITY IS
INCREASING THAT THE INTERACTION WILL CAUSE 08W TO OPEN UP INTO A
WAVE WITH 45 KT WINDS IN THE EASTERN SEMICIRCLE FROM TAU 48 TO TAU
60. IF THIS SCENARIO PLAYS OUT, 08W WILL LIKELY ACCELERATE AWAY
FROM AND ESCAPE 07W AT TAU 72, WITH THE WAVE CLOSING OFF INTO A
DISCRETE CIRCULATION. FOR NOW, THE FORECAST KEEPS 08W AS A DISCRETE
CIRCULATION THROUGH THE FORECAST PERIOD WITH GALES ISOLATED TO THE
EASTERN SIDE OF THE SYSTEM. AT TAU 72 AND BEYOND, HIGOS WILL COME
UNDER THE INFLUENCE OF STRONGER BAROCLINIC FORCING, INCLUDING
ENHANCED DIVERGENCE ALOFT THAT WILL KEEP THE SYSTEM WITH ELEVATED
WINDS THROUGH TAU 96.

MODEL DISCUSSION: THE MAJORITY OF RELIABLE TRACKERS DEPICT A
RECURVATURE SCENARIO FOR 08W. THE JTWC FORECAST TRACK IS LAID NEAR
THE MULTI-MODEL CONSENSUS, THOUGH WITH LOW CONFIDENCE DUE TO
UNCERTAINTIES PERTAINING TO THE INTERACTION WITH 07W. MODELS HAVE
GENERALLY SHIFTED WESTWARD OVER THE LAST SEVERAL CYCLES, WHICH
INCREASES THE LIKELIHOOD OF MORE SIGNIFICANT BINARY INTERACTION.
THE INTENSITY GUIDANCE LARGELY SHOWS MODEST DEVELOPMENT FOR THE
FIRST 72 HOURS BUT VARIES WITH TIMING. HAFS-A AND GFS ARE SLOWEST
AND SHOW INTENSIFICATION BEGINNING AT TAU 36. COAMPS-TC AND THE
EXPERIMENTAL GOOGLE DEEPMIND MODELS DEPICT FASTER INITIAL
DEVELOPMENT. THE JTWC INTENSITY FORECAST HEDGES BETWEEN THE TWO
DISTINCT GROUPS AND ACCOUNTS FOR THE PRESENT STRUCTURE OF HIGOS,
SHOWING INTENSIFICATION BEGINNING AT TAU 12. THE FORECAST INTENSITY
OF 45 KTS IS AT THE UPPER END OF THE INTENSITY GUIDANCE BUT IS
LOWER THAN THE PEAKS FROM THE PAST TWO MODEL CYCLES. BECAUSE OF THE
INCREASING LIKELIHOOD OF SOME SORT OF INTERACTION WITH 07W, THE
INTENSITY FORECAST IS ALSO ASSESSED WITH LOW CONFIDENCE.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: LOW
   TRACK 72-120 HR: LOW
   INTENSITY 00-72 HR: LOW
   INTENSITY 72-120 HR: LOW//
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