WDPN31 PGTW 200300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 01W (ONE) WARNING NR 
003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 7.9N 157.9E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 63 NM NORTH-NORTHWEST OF POHNPEI
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 13 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS DAYTIME
WANING AND INITIAL REDEVELOPMENT OF DEEP CONVECTION OVER A COMPACT
LOW-LEVEL CIRCULATION CENTER. THE INITIAL POSITION IS PLACED WITH
HIGH CONFIDENCE BASED ON 192242Z METOP-C AND 192329Z METOP-B
FULL-COVERAGE ASCAT PASSES. THE INITIAL INTENSITY OF 35 KTS IS
ASSESSED WITH HIGH CONFIDENCE BASED ON THE AFOREMENTIONED ASCAT
DATA, AND IS ALSO CONSISTENT WITH RECENT PGTW DVORAK CURRENT
INTENSITY AND AUTOMATED DVORAK ESTIMATES.

INITIAL WIND RADII BASIS: 192242Z METOP-C AND 192329Z METOP-B ASCAT
SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: LOW- TO MID-LAYER RIDGING TO THE
NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T2.0 - 30 KTS
   CIMSS SATCON: 37 KTS AT 192215Z
   CIMSS ADT: 34 KTS AT 192330Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THE FORECAST TRACK IS SHIFTED
NORTHWARD FROM THE PREVIOUS WARNING BASED ON A RELOCATION OF THE
PREVIOUS STORM POSITION APPROXIMATELY 70 NM TO THE NORTH. HOWEVER,
THE OVERALL FORECAST PHILOSOPHY HAS NOT CHANGED FROM THE PREVIOUS
WARNING.

FORECAST DISCUSSION: TS 01W WILL TURN FROM A NORTHWESTWARD TO A
GENERALLY WESTWARD TRACK OVER THE NEXT 24 TO 36 HOURS AS THE
PRIMARY STEERING INFLUENCE TRANSITIONS FROM LOW- TO MID-LAYER
RIDGING TO THE NORTHEAST TO A BUILDING SUBTROPICAL RIDGE TO THE
NORTH. ENVIRONMENTAL CONDITIONS INCLUDING LOW VERTICAL WIND SHEAR,
HIGH SST, AND RADIAL OUTFLOW ALOFT WILL CONTINUE TO SUPPORT STEADY
INTENSIFICATION. HOWEVER, THE SYSTEM IS EXPECTED TO TRACK INTO AN
AREA OF INCREASING SOUTHWESTERLY VERTICAL WIND SHEAR AND INGEST A 
DRIER SUBTROPICAL AIR MASS FROM TAU 24 ONWARD. DISSIPATION TO BELOW
THE WARNING THRESHOLD INTENSITY OF 25 KNOTS BY TAU 96 IS
ANTICIPATED UNDER THESE INCREASINGLY UNFAVORABLE CONDITIONS.

MODEL DISCUSSION: AVAILABLE NUMERICAL MODEL TRACK FORECAST GUIDANCE
REMAINS IN GOOD AGREEMENT REGARDING A GENERALLY NORTHWESTWARD
TRACK IN THE NEAR-TERM FOLLOWED BY AN INCREASINGLY WESTWARD TRACK
AFTER TAU 24. NAVGEM IS THE SOLE OUTLIER IN TERMS OF TRACK
ORIENTATION, INDICATING A TRACK TO THE NORTH OF THE PRIMARY
GUIDANCE ENVELOPE LIKELY DUE TO STRONG INTENSIFICATION IN THE MODEL
ON THE CURRENT RUN. THE CURRENT TRACK FORECAST IS PLACED WITH
MEDIUM CONFIDENCE WITHIN THE PRIMARY MODEL GROUPING, SLIGHTLY TO
THE SOUTH OF THE CONSENSUS TRACK. ASIDE FROM THE LATEST NAVGEM
SOLUTION, GLOBAL AND MESOSCALE DYNAMIC MODELS, INCLUDING HWRF AND
COAMPS-TC, REMAIN IN GOOD AGREEMENT REGARDING THE INTENSITY
FORECAST TREND. SHIPS STATISTICAL-DYNAMICAL INTENSITY GUIDANCE
INDICATES HIGHER INTENSITIES, WHICH REMAINS AS A LOW PROBABILITY
OUTCOME IF THE SYSTEM VERY QUICKLY ORGANIZES OVER THE NEXT 12-24
HOURS AND MODIFIES THE ENVIRONMENT SIGNIFICANTLY TO WARD OFF THE
NEGATIVE IMPACTS OF INCREASING SHEAR AND DRIER AIR ENTRAINMENT.
GIVEN THE SMALL SIZE OF THE SYSTEM AND CURRENT STARTING POINT AS A
WEAK TROPICAL STORM, A LONGER SURVIVAL OF THE SYSTEM IS ASSESSED AS
A LOW PROBABILITY OUTCOME. CONFIDENCES IN BOTH THE TRACK AND
INTENSITY FORECASTS ARE MEDIUM BASED ON MARGINAL UNCERTAINTY IN THE
SHIFTING STEERING ENVIRONMENT AND NEAR-TERM INTENSIFICATION TREND,
RESPECTIVELY.

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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