WDPN31 PGTW 021500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 05W (AERE) WARNING NR 
009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 26.8N 128.3E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 32 NM NORTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 15 KTS
   SIGNIFICANT WAVE HEIGHT: 17 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A FULLY
EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) WITH A MAJORITY OF THE
CONVECTIVE STRUCTURES TO THE SOUTHERN PERIPHERY OF THE LLCC.
ANIMATED WATER VAPOR IMAGERY AND UPPER-LEVEL ATMOSPHERIC MOTION
VECTORS INDICATE A TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) IS NOW
POSITIONED JUST SOUTH OF 05W, INDUCING UNFAVORABLE VERTICAL WIND
SHEAR (VWS) AND UPPER-LEVEL SUBSIDENCE. ANIMATED RADAR IMAGERY
INDICATES WEAK AND FRAGMENTED CLOUD LINES WRAPPING INTO A BROAD
LLCC FROM ALL QUADRANTS. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON EIR AND ANIMATED RADAR IMAGERY. THE INITIAL
INTENSITY OF 40 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON
AGENCY DVORAK INTENSITY ESTIMATES AND CIMSS SATCON REFLECTING 40
KNOTS WHILE CIMSS ADT SHOWS A SLIGHTLY LOWER 33 KNOTS.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR) TO
THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T2.5 - 35 KTS
   KNES: T2.5 - 35 KTS
   CIMSS SATCON: 42 KTS AT 021034Z
   CIMSS ADT: 33 KTS AT 021140Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 25-30 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD
   OTHER FACTORS: TUTT JUST SOUTH THE LOW-LEVEL CIRCULATION CENTER

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: LOW

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TS 05W (AERE) IS FORECAST TO CONTINUE TRACKING
NORTH-NORTHWESTWARD THROUGH TAU 24 AND EVENTUALLY NORTHWARD BY TAU
36 UNDER THE STEERING INFLUENCE OF THE SUBTROPICAL RIDGE TO THE
EAST. CURRENTLY IN A MARGINALLY UNFAVORABLE ENVIRONMENT
CHARACTERIZED BY WARM SEA SURFACE TEMPERATURES (SST) (28-29C) AND
MODERATE POLEWARD OUTFLOW OFFSET BY SUBSIDENCE ALOFT AND HIGH VWS
(25-30) PROVIDED BY THE SYSTEMS PROXIMITY TO A TUTT TO THE
SOUTHEAST. THIS ENVIRONMENT WILL RESULT IN STAGNATION AND GRADUAL
DECREASING INTENSITIES THROUGH TAU 36. BETWEEN TAU 36 AND TAU 48
THE SYSTEM ALSO BEGINS TO SUCCUMB TO DRY AIR ENTRAINMENT AND
COOLING SSTS, FURTHER DECREASING THE SYSTEMS INTENSITY.  BETWEEN
TAU 48 AND TAU 72 TRACK SPEEDS WILL INCREASE AS THE SYSTEM
ACCELERATES POLEWARD OF THE STR AND CONTINUES TO DECREASE IN
INTENSITY. BETWEEN TAU 96 AND TAU 120 THE SYSTEM IS FORECAST TO
BEGIN IS FINAL DISSIPATION PHASE, HOWEVER ITS WORTH NOTING IN THE
EXTENDED PERIOD SOME MODEL SOLUTIONS SUGGEST, OR TRANSITION INTO A
SUBTROPICAL OR EXTRATROPICAL SYSTEM BUT IT IS TOO SOON TO TELL.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN GOOD AGREEMENT THROUGH
TAU 24 WITH A 117NM SPREAD IN THE SOLUTIONS. AFTER TAU 24 UKMET AND
GFS SHOW THE SYSTEM CONTINUING STRAIGHT INTO THE YELLOW SEA WHILE
THE REMAINDER OF THE GUIDANCE REFLECTS THE JTWC FORECAST OF A
RECURVE ALONG THE PERIPHERY OF THE STR TO THE EAST. RELIABLE
INTENSITY GUIDANCE IS IN FAIR AGREEMENT THROUGH TAU 24 WITH THE
EXCEPTION OF COAMPS-TC (NAVGEM VERSION) WHICH SHOWS A BRIEF
INTENSIFICATION TREND AFTER WHICH A GRADUAL DECLINE THROUGH THE
FORECAST PERIOD. COAMPS-TC (GFS VERSION) ALSO SPLITS FROM THE PACK
AT TAU 60 SHOWING A STEEP INCREASE FROM 30 KNOTS TO 50 KNOTS IN
INTENSITY BY TAU 120. FOR THESE REASONS, BOTH THE JTWC INTENSITY
AND TRACK FORECAST ARE PLACED WITH MEDIUM CONFIDENCE.

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