WDPN31 PGTW 230300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 02W (SEPAT) WARNING NR 
003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 24.6N 144.7E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 186 NM EAST OF IWO TO
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTING A FULLY
EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) OF TROPICAL STORM (TS)
02W (SEPAT). MAJORITY OF THE CONVECTION IS CURRENTLY BEING PUSHED 
NORTH 
BY A LOW TO MODERATE (15-20 KTS) SOUTHWESTERLY SHEAR, WHILE A TROPICAL 
UPPER TROPOSPHERIC TROUGH (TUTT) CELL TO THE WEST IS LIMITING THE 
UPPER-LEVEL OUTFLOW. ENVIRONMENTAL ANALYSIS INDICATES THAT CONDITIONS 
REMAIN MARGINALLY FAVORABLE FOR DEVELOPMENT, WITH MODERATE POLEWARD 
OUTFLOW AND WARM SEA SURFACE TEMPERATURES (28-29 C). THE INITIAL 
INTENSITY ASSESSMENT OF 35 KTS CARRIES MEDIUM CONFIDENCE, BASED ON 
DVORAK ANALYSIS AND OBJECTIVE ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: 222330Z METOP-C ASCAT DATA 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T2.0 - 30 KTS
   CIMSS ADT: 31 KTS AT 222020Z
   CIMSS AIDT: 35 KTS AT 222020Z
   CIMSS D-MINT: 25 KTS AT 222129Z
   CIMSS D-PRINT: 28 KTS AT 230010Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD
   OTHER FACTORS: TUTT CELL CENTERED TO THE WEST LIMITING THE
OUTFLOW

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS SEPAT IS EXPECTED TO TRACK ALONG THE WESTERN 
EDGE OF A DEEP-LAYER STR POSITIONED TO ITS NORTHEAST. GRADUAL 
INTENSIFICATION IS LIKELY, SUPPORTED BY WARM OCEAN WATERS, WITH THE 
SYSTEM PROJECTED TO REACH A PEAK INTENSITY OF 40-45 KTS WITHIN 12-24 
HOURS AND MAINTAIN THAT STRENGTH FOR ADDITIONAL 24 HOURS. BEYOND THAT 
POINT, COOLING SEA SURFACE TEMPERATURES AND DIMINISHED POLEWARD 
OUTFLOW 
ARE ANTICIPATED TO CAUSE WEAKENING TREND TO BEGIN AROUND TAU 48-72. AS 
THE SYSTEM CURVES AROUND THE RIDGE AXIS, TS 02W WILL BEGIN MOVING 
NORTHEASTWARD AND CONTINUE TO WEAKEN, WITH FULL DISSIPATION LIKELY BY 
TAU 96.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE SHOWS FAIR AGREEMENT 
THROUGHOUT THE FORECAST PERIOD, WITH CROSS-TRACK SPREAD OF 135 NM AT 
TAU 48, INDICATING THE MAIN SOURCE OF UNCERTAINTY ASSOCIATED WITH THE 
TIMING AND POSITION OF THE RECURVATURE POINT. ALL AVAILABLE GUIDANCE 
HOWEVER, CONSISTENTLY PREDICTS TRACK ALONG THE WESTERN PERIPHERY OF A 
STR. NAVGEM REMAINS THE PRIMARY OUTLIER PROJECTING TIGHTEST TURN, OVER 
100 NM EAST OF THE COAST OF JAPAN. INTENSITY GUIDANCE ALSO SHOWS FAIR 
AGREEMENT, PREDICTING STEADY STRENGTHENING THROUGH TAUS 12-24. 
UNCERTAINTY ENVELOPE IMPROVED SINCE THE PREVIOUS ASSESSMENT AND 
THEREFORE JTWC INTENSITY IS LAID WITH MEDIUM CONFIDENCE AND CLOSE TO 
THE MULTI-MODEL CONSENSUS.

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