WDPN31 PGTW 070300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 04W (MUN) WARNING NR 
022//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 35.0N 148.9E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 452 NM EAST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 18 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
STORM (TS) 04W (MUN) NEARLY COMPLETELY DEVOID OF ANY DEEP
CONVECTION AND SURROUNDED BY A FIELD OF DRY AIR. THE LAST BIT OF
WEAK CONVECTION CAN BE SEEN BEING HEAVILY SHEARED TO THE SOUTHWEST,
EXPOSING THE STILL WELL-DEFINED LOW-LEVEL CIRCULATION CENTER
(LLCC). ENVIRONMENTAL ANALYSIS INDICATES THAT 04W IS IN AN
UNFAVORABLE ENVIRONMENT CHARACTERIZED BY WEAK EQUATORWARD OUTFLOW
ALOFT, HIGH (30-35 KTS) NORTHEASTERLY VERTICAL WIND SHEAR,
SIGNIFICANT DRY AIR ENTRAINMENT, AND BORDERLINE (25-26 C) SEA
SURFACE TEMPERATURES. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE EXPOSED LOW-LEVEL CIRCULATION IN THE
ANIMATED MSI. THE INITIAL INTENSITY OF 45 KTS IS ASSESSED WITH
MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK AND OBJECTIVE
INTENSITY ESTIMATES LISTED BELOW. THE INTENSITY IS HELD SLIGHTLY
HIGHER DUE TO THE INTENSITY ESTIMATES UNDERESTIMATING THE WIND
SPEED IN RESPONSE TO THE DISSIPATING CONVECTION.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF BUILDING RIDGING
TO THE EAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T3.0 - 45 KTS
   RCTP: T2.5 - 35 KTS
   CIMSS SATCON: 48 KTS AT 070000Z
   CIMSS ADT: 35 KTS AT 070000Z
   CIMSS AIDT: 42 KTS AT 070000Z
   CIMSS DPRINT: 33 KTS AT 070000Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 30-35 KTS
   SST: 25-26 CELSIUS
   OUTFLOW: WEAK EQUATORWARD
   OTHER FACTORS: SIGNIFICANT DRY AIR ENTRAINMENT

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 04W IS FORECAST TO TRACK GENERALLY
NORTH-NORTHWESTWARD ALONG THE WESTERN BOUNDARY OF AN EXTENSION OF
RIDGING TO THE EAST THROUGH TAU 12. AFTER TAU 12, THE SYSTEM WILL
ROUND THE RIDGE AXIS AND TURN TO THE NORTHEAST. SUBTROPICAL
TRANSITION IS FORECAST TO BEGIN AT TAU 24 AND COMPLETE BY TAU 36 AS
THE VORTEX QUICKLY BECOMES ENTIRELY ENGULFED BY DRY AIR AND SEA
SURFACE TEMPERATURES CONTINUE TO DROP. ENVIRONMENTAL CONDITIONS ARE
EXPECTED TO ONLY WORSEN OVER THE NEXT 36 HOURS, WHICH WILL CAUSE
04W TO WEAKEN THROUGHOUT THE FORECAST PERIOD.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN OVERALL GOOD
AGREEMENT ON THE TRACK OF 04W WITH A MERE 39 NM CROSS-TRACK SPREAD
AT TAU 24. THERE IS SOME INCREASED ALONG-TRACK SPREAD AFTER TAU 24
DUE TO THE VORTEX BEGINNING TO INTERACT WITH THE STRONG UPPER-LEVEL
WESTERLIES. THE JTWC TRACK FORECAST IS PLACED CLOSE TO THE
MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE. INTENSITY GUIDANCE
AGREES ON WEAKENING FROM TAU 0 THROUGH TAU 36 WITH MINIMAL SPREAD
BETWEEN MODELS. THEREFORE, THE JTWC INTENSITY FORECAST IS ALSO
PLACED WITH HIGH CONFIDENCE, CLOSE TO CONSENSUS.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   INTENSITY 0 - 72 HR: HIGH//
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