WDPN31 PGTW 301500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 05W (FIVE) WARNING 
NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.3N 130.9E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 465 NM SOUTH-SOUTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 9 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A COLD
DENSE OVERCAST (CDO) CURVING INTO AND OBSCURING THE LOW LEVEL
CIRCULATION CENTER (LLCC). ANIMATED MID LEVEL WATER VAPOR IMAGERY
INDICATES THE PRESENCE OF A TROPICAL UPPER TROPOSPHERIC TROUGH
(TUTT) CELL TO THE NORTHWEST OF THE SYSTEM PROVIDING ENHANCED
OUTFLOW TO THE EAST AND SOUTH. A PARTIAL 301201Z METOP-B ASCAT
IMAGE SHOWS THE EASTERN SEMICIRCLE OF THE SYSTEM IS COMPRISED OF 25
KNOT WINDS WITH POCKETS OF 30-35 KNOT WINDS IN THE SOUTHEASTERN
PERIPHERY OF THE LOW LEVEL CIRCULATION (LLC). THE INITIAL POSITION
IS PLACED WITH LOW CONFIDENCE BASED ON THE CDO OBSCURING THE LLCC
AND PARTIAL ASCAT COVERAGE. THE INITIAL INTENSITY OF 25 KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE RANGE OF AGENCY DVORAK
INTENSITY ESTIMATES AND THE PARTIAL ASCAT PASS.

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

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE
NORTHEAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T1.0 - 25 KTS
   KNES: T1.5 - 25 KTS

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

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.

FORECAST DISCUSSION: TD 05W IS FORECAST TO TRACK NORTH-NORTHWEST
UNDER THE STEERING INFLUENCE OF THE SUBTROPICAL RIDGE (STR) TO THE
NORTHEAST. CURRENTLY IN A MARGINALLY FAVORABLE ENVIRONMENT
CHARACTERIZED BY WARM SEA SURFACE TEMPERATURES (SST) (30C) AND
MODERATE OUTFLOW ALOFT ENHANCED BY THE TUTT CELL TO THE NORTHWEST
SLIGHTLY OFFSET BY MODERATE VERTICAL WIND SHEAR (20-25 KTS). THIS
ENVIRONMENT IS FORECAST TO STEADILY INCREASE TD 05W THROUGH TAU 36,
AFTER WHICH THE SYSTEM IS FORECAST TO PASS OVER OKINAWA AND REACH
ITS PEAK INTENSITY OF 50 KTS BY TAU 48. BETWEEN TAU 48 AND TAU 72
AS THE SUBTROPICAL RIDGE IS BROKEN DOWN BY A PASSING MID-LATITUDE
TROUGH THE SYSTEM WILL BEGIN TO TRACK NORTH-NORTHWESTWARD AND
EVENTUALLY NORTHWARD AS SIGNIFICANT AMOUNTS OF DRY AIR BEGIN TO
ENTRAIN THE SYSTEM. THROUGH THE REMAINING FORECAST PERIOD, AS THE
SYSTEM CONTINUES TO APPROACH THE STR AXIS SEA SURFACE TEMPERATURES
DROP (24-25C) AND SIGNIFICANT DRY AIR ENTRAINMENT IS FORECAST TO
BEGIN DISSIPATING 05W. BY TAU 120 THE SYSTEM IF FORECAST TO BE
FULLY ENTRAINED BY DRY AIR AND NEARING FULL DISSIPATION.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN FAIR AGREEMENT WITH THREE
NOTABLE EXCEPTION SHOWING SIGNIFICANT LEFT AND RIGHT TRACK
DEVIATIONS RESPECTIVELY. AVNI (GFS) AND AEMI (GFS ENSEMBLE) SHOW A
NOTABLE LEFT OF CONSENSUS TRACK WHILE NVGM UNREALISTICALLY TRACKS
THE SYSTEM STRAIGHT INTO THE STR TO THE EAST. THE BULK OF THE
GUIDANCE HOWEVER SHOWS A TIGHT CONSENSUS WITH ONLY A 40NM SPREAD AT
TAU 48 AFTER WHICH SOLUTIONS BEGIN TO FAN OUT THROUGH THE FORECAST
PERIOD. FOR THESE REASONS, THE JTWC FORECAST TRACK HAS BEEN PLACED
WITH MEDIUM CONFIDENCE. RELIABLE INTENSITY GUIDANCE IS IN GOOD
AGREEMENT THAT TD 05W WILL STEADILY INCREASE IN INTENSITY THROUGH
TAU 48, HOWEVER COAMPS-TC SHOWS A SIGNIFICANTLY MORE AGGRESSIVE
INTENSITY TREND PEAKING AT 70 KNOTS AT TAU 60. THIS AGREEMENT OF
INTENSITY GUIDANCE WITH THE EXCEPTION OF COAMPS-TC IS WHY JTWC
FORECAST TRACK IS PLACED WITH MEDIUM CONFIDENCE.

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