WDPN31 PGTW 201500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 01W (NOKAEN) WARNING NR 
024//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.7N 131.9E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 610 NM NORTHWEST OF YAP
   MOVEMENT PAST 6 HOURS: EASTWARD AT 15 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
STORM 01W (NOKAEN) WITH A HIGHLY ELONGATED AND FULLY EXPOSED
LOW-LEVEL CIRCULATION CENTER (LLCC). A 201256Z METOP-C ASCAT PASS
REVEALED THAT THE WIND FIELD REMAINS EXTREMELY ASYMMETRIC WITH A
BAND OF 30 KNOT WINDS CONFINED TO THE NORTHWESTERN AND WESTERN
PORTIONS OF THE CIRCULATION. 01W IS NOW ALMOST ENTIRELY VOID OF
DEEP CONVECTION WITH SMALL BURSTS DISPLACED FAR TO THE NORTHEAST. A
PROMINENT FIELD OF STRATOCUMULUS CLOUDS ARE WRAPPING INTO THE
SYSTEM FROM THE WEST, INDICATIVE OF VERY DRY MID-LEVEL AIR. THE
INITIAL POSITION AND INTENSITY ARE BOTH IS PLACED WITH HIGH
CONFIDENCE BASED ON THE AFOREMENTIONED ASCAT PASS. ENVIRONMENTAL
ANALYSIS INDICATES THAT 01W IS IN AN UNFAVORABLE ENVIRONMENT 
CHARACTERIZED BY MODERATE POLEWARD OUTFLOW ALOFT, MODERATE (15-20 KTS) 
VERTICAL WIND SHEAR, AND SIGNIFICANT DRY AIR ENTRAINMENT.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: A COMBINATION OF A NARROW EXTENSION OF
THE SUBTROPICAL RIDGE (STR) TO THE WEST AND THE STATIONARY FRONTAL
BOUNDARY

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T1.5 - 25 KTS
   RCTP: T1.5 - 25 KTS
   CIMSS ADT: 34 KTS AT 201130Z
   CIMSS AIDT: 34 KTS AT 201130Z
   CIMSS D-PRINT: 27 KTS AT 201130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 15-20 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE POLEWARD
   OTHER FACTORS: SIGNIFICANT AMOUNTS OF DRY AIR ENTRAINING INTO
THE SYSTEM FROM THE WEST

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: 01W IS FORECAST TO BEGIN A SOUTHEASTWARD TURN
OVER THE NEXT 12 HOURS AS THE VORTEX GETS PUSHED EQUATORWARD BY THE
FRONTAL BOUNDARY INTERACTING WITH THE STRENGTHENING COLD SURGE.
AFTER TAU 12, AS THE COLD SURGE FURTHER STRENGTHENS, THE TRACK IS
EXPECTED TO BECOME MORE SOUTHWARD. THE OVERALL ENVIRONMENT WILL
REMAIN UNFAVORABLE DUE TO DRY AIR COMPLETELY SMOTHERING THE VORTEX
AND SOUTHERLY SHEAR INCREASING. AS THE VORTEX FURTHER INTERACTS
WITH THE COLD SURGE AND FRONTAL BOUNDARY, IT IS EXPECTED TO BECOME
INCREASINGLY STRETCHED. BY TAU 24, 01W IS FORECAST TO BECOME UNRAVELED 
AND ABSORBED BY THE STRONG NORTHEASTERLY SURFACE FLOW. WINDS OF AROUND 
30 KTS, ASSOCIATED WITH THE BACKGROUND NORTHEASTERLY SURGE, WILL 
LIKELY PERSIST AS 01W WASHES OUT, HENCE THE DISSIPATION WITH AN 
INTENSITY ABOVE WARNING CRITERIA. 

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE GENERALLY AGREES
ON THE SOUTHEASTWARD TURN, BUT CROSS-TRACK SPREAD IS STILL QUITE
HIGH, AT AROUND 160 NM AT TAU 24. THE JTWC TRACK FORECAST IS PLACED
CLOSE TO THE MULTI-MODEL CONSENSUS WITH MEDIUM CONFIDENCE.
INTENSITY GUIDANCE AGREES ON AN INTENSITY OF AROUND 30-35 KTS
THROUGH TAU 24. THE JTWC INTENSITY FORECAST IS PLACED NEAR THE
CONSENSUS WITH HIGH CONFIDENCE.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   INTENSITY 00-72 HR: HIGH//
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