WDPN32 PGTW 231500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 08W (HIGOS) WARNING 
NR 005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.8N 143.9E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 88 NM NORTHWEST OF ANDERSEN AFB
   MOVEMENT PAST 6 HOURS: WESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
COMPACT AND NEARLY FULLY EXPOSED LOW-LEVEL CIRCULATION CENTER
(LLCC) WITH BURSTS OF DEEP CONVECTION OFFSET TO THE NORTH. THE
VORTEX CONTINUES TO BE SIGNIFICANTLY TILTED NORTHWARD WITH HEIGHT.
OVERALL, THE APPEARANCE OF 08W HAS DEGRADED OVER THE PAST 6 HOURS
WITH LESS DEFINITION IN THE LLCC AND MORE DISORGANIZED CONVECTION.
ADDITIONALLY, A 231127Z METOP-C ASCAT PASS REVEALED THAT THE WINDS
WITHIN THE NORTHERN SEMICIRCLE HAVE WEAKENED TO 25-30 KTS, AND
WINDS WITHIN THE SOUTHERN SEMICIRCLE ARE NOW AROUND 10 KTS. THE
INITIAL POSITION AND INTENSITY ARE BOTH PLACED WITH HIGH CONFIDENCE
BASED ON THE ASCAT DATA. ENVIRONMENTAL ANALYSIS INDICATES THAT 08W
IS IN A MARGINAL ENVIRONMENT CHARACTERIZED BY WARM (29-30 C) SEA
SURFACE TEMPERATURES OFFSET BY WEAK OUTFLOW ALOFT AND MODERATE
(15-20 KTS) SOUTHERLY VERTICAL WIND SHEAR.

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

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.0 - 30 KTS
   KNES: T2.5 - 35 KTS
   CIMSS ADT: 43 KTS AT 231210Z
   CIMSS AIDT: 37 KTS AT 231210Z
   CIMSS D-MINT: 25 KTS AT 230827Z
   CIMSS D-PRINT: 27 KTS AT 231210Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: WEAK WESTWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: LOWERED THE PEAK INTENSITY TO 45 KTS

FORECAST DISCUSSION: 08W IS FORECAST TO TRACK NORTHWESTWARD, ALONG
THE SOUTHWESTERN PERIPHERY OF THE ELONGATED STR THROUGH TAU 48.
NEAR TAU 48, THE STR IS EXPECTED TO BUILD AND BECOME MORE
SYMMETRIC. 08W WILL THEN BEGIN TO ROUND THE WESTERN EXTENT OF THE
STR WITH A NORTHWARD TURN. THE TRACK WILL THEN BECOME NORTHEASTWARD
AS 08W ACCELERATES ALONG THE NORTHWESTERN PERIPHERY OF THE STR. THE
SYSTEM IS EXPECTED TO REMAIN WELL OFF THE COAST OF HONSHU AS IT
COMMENCES ITS RECURVE. EXTRATROPICAL TRANSITION IS FORECAST TO
BEGIN AT TAU 72 WITH COMPLETION AROUND TAU 96 AS THE SYSTEM BECOMES
EMBEDDED WITHIN THE STRONG MID-LATITUDE WESTERLY FLOW. IN TERMS OF
INTENSITY, 08W IS FORECAST TO GRADUALLY INTENSIFY OVER THE NEXT 60
HOURS TO A PEAK OF 45 KTS. VERTICAL WIND SHEAR IS EXPECTED TO
LESSEN, WHICH COULD ALLOW THE VORTEX TO BECOME MORE VERTICALLY
ALIGNED. HOWEVER, DRY AIR AND INTERACTION WITH THE WIND FIELD OF TY
07W (MEKKHALA) WILL LIMIT THE INTENSIFICATION OF THE SYSTEM. NEAR
TAU 72, SEA SURFACE TEMPERATURES WILL QUICKLY DROP AND SHEAR WILL
INCREASE, CAUSING 08W TO WEAKEN. BY TAU 96, WESTERLY SHEAR WILL
INCREASE TO OVER 50 KTS AND SEA SURFACE TEMPERATURES WILL DROP
BELOW 20 C AS 08W TRANSITIONS INTO A COLD-CORE CYCLONE. THERE STILL
REMAINS A CHANCE THAT 08W BECOMES ABSORBED BY THE WIND FIELD OF
07W AROUND TAU 72. THIS IS ESPECIALLY TRUE IF 08W IS UNABLE TO
DEVELOP VERY MUCH. IT NEEDS TO FORM A DISCRETE, TIGHT CIRCULATION
IN ORDER TO SURVIVE THE PASSAGE CLOSE TO 07W.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN WORSE
AGREEMENT THIS MODEL RUN WITH MULTIPLE MODELS NOW LOSING THE VORTEX
BEFORE 08W IS ABLE TO COMPLETE THE RECURVE. THERE REMAINS TWO
DISTINCT GROUPINGS IN THE GUIDANCE. ONE GROUP CONSISTS OF NAVGEM, 
UKMET, GALWEM, AND JGSM, WHICH IS SIGNIFICANTLY SLOWER AND TO THE 
WEST OF THE OTHER GROUP. THE SECOND GROUP, WHICH CONSISTS OF GFS, 
ECMWF, AND THE EXPERIMENTAL GOOGLE DEEPMIND, IS FASTER AND TO THE 
EAST. THE JTWC TRACK FORECAST IS PLACED CLOSE TO THE MEAN OF THE 
SECOND GROUP WITH LOW CONFIDENCE DUE TO THE POSSIBILITY OF AN EARLY 
DISSIPATION. INTENSITY GUIDANCE IS NOTABLY LOWER COMPARED TO THE 
PREVIOUS MODEL RUN. THE MOST AGGRESSIVE MODELS ARE HWRF AND COAMPS-TC 
(GFS BASED) WHICH NOW SHOW A PEAK INTENSITY OF 50-55 KTS. THIS IS 
ABOUT A 15 KT DECREASE FROM THE PEAK DEPICTED IN THE PREVIOUS MODEL 
RUN. THE JTWC INTENSITY FORECAST IS PLACED CLOSE TO THE CONSENSUS 
THROUGHOUT THE FORECAST PERIOD 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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