Advisories

WDPN31 PGTW 100300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 15E (NOLO) WARNING NR 
078//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 30.6N 146.8E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 455 NM SOUTHEAST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 26 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
STORM (TS) 15E AS A SHALLOW AND POORLY DEFINED SYSTEM WITH THE
CENTER OBSCURED BY A PERSISTENT PLUME OF WEAKLY ORGANIZED
CONVECTION. THE 092257Z ASCAT PASS REVEALED A SMALL PATCH OF
DESTRUCTIVE WINDS WITHIN THE NORTHERN QUADRANT AND AN OVERALL
ASYMMETRIC WIND FIELD. ENVIRONMENTAL ANALYSIS REVEALS A HIGHLY
UNFAVORABLE ENVIRONMENT, CHARACTERIZED BY HIGH (25-30 KTS) VERTICAL
WIND SHEAR (VWS), COOL (25-26 C) SEA SURFACE TEMPERATURES (SST),
NEGLIGIBLE OCEAN HEAT CONTENT (OHC), BARELY OFFSET BY ROBUST
POLEWARD OUTFLOW. THE INITIAL POSITION IS PLACED WITH MEDIUM
CONFIDENCE BASED ON EXTRAPOLATION FROM THE AFOREMENTIONED ASCAT.
THE INITIAL INTENSITY OF 50 KTS IS ASSESSED WITH HIGH CONFIDENCE
BASED ON THE ASCAT DATA.

INITIAL WIND RADII BASIS: 092257Z ASCAT DATA

CURRENT STEERING MECHANISM: WESTERN EXTENT OF A SUBTROPICAL RIDGE
(STR) CENTERED TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T2.0 - 30 KTS
   CIMSS SATCON: 48 KTS AT 100020Z
   CIMSS ADT: 37 KTS AT 100040Z
   CIMSS AIDT: 46 KTS AT 100040Z
   CIMSS D-MINT: 43 KTS AT 092240Z
   CIMSS D-PRINT: 52 KTS AT 100020Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY UNFAVORABLE
   VWS: 25-30 KTS
   SST: 25-26 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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: TS 15E IS FORECAST TO BEGIN TRACKING NORTHWARD
FOR THE NEXT 6-12 HOURS WHILE IT APPROACHES AND ROUNDS THE STEERING
RIDGE AXIS. PRIOR TO TAU 12, 15E WILL CROSS THE RIDGE AXIS AND
RECURVE TO THE NORTHEAST. 15E WILL MAINTAIN A NORTHEASTWARD
TRAJECTORY THROUGH THE REMAINDER OF THE FORECAST PERIOD, BEGINNING
EXTRATROPICAL TRANSITION NO LATER THAN TAU 12 AND COMPLETING
TRANSITION BY TAU 24. REGARDING INTENSITY, 15E IS EXPECTED TO
STEADILY WEAKEN THROUGH THE FORECAST PERIOD, AS THE ENVIRONMENT
CONTINUES TO DETERIORATE AS THE SYSTEM TRACKS POLEWARD. THE
SYSTEM'S CURRENT INTENSITY IS SUSTAINED ONLY BY THE STRONG POLEWARD
OUTFLOW CHANNEL, WHICH IS EXPECTED TO DEGRADE BY TAU 12-24 WHEN
NOLO MOVES UNDER THE WESTERLIES. AT AROUND TAU 12, 15E WILL BEGIN
INTERACTING WITH THE UPPER-LEVEL WESTERLIES AND ENTER THE
BAROCLINIC ZONE, THUS BEGINNING ITS TRANSITION INTO AN
EXTRATROPICAL SYSTEM. 15E IS EXPECTED TO BE FULLY EXTRATROPICAL AT
TAU 24. 

MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS IN GOOD
AGREEMENT THROUGH TAU 12, BUT DIVERGES SLIGHTLY THEREAFTER AS
MODELS DISAGREE ON THE SPEED AND TIMING OF THE RECURVE. THE
ALONG-TRACK SPREAD COMPOUNDS INTO A 150 NM SPREAD AT TAU 24 BETWEEN
THE SLOWEST (UKMET ENSEMBLE MEAN) AND THE FASTEST (GSM) MEMBERS. OF
NOTE, THE GFS DETERMINISTIC AND ENSEMBLE MEAN CONTINUE TO DEPICT
15E DISSIPATING WITHIN 24 HOURS, VICE EXTRATROPICAL TRANSITION. A
SCENARIO WHERE NOLO DISSIPATES PRIOR TO COMPLETING EXTRATROPICAL
TRANSITION IS UNLIKELY, THOUGH NOT IMPOSSIBLE GIVEN THE ANTICIPATED
HOSTILE ENVIRONMENT. AS A RESULT, THE JTWC TRACK FORECAST IS PLACED
CLOSER TO THE GFS, ECMWF, AND GSM MODEL SOLUTIONS AND FORECASTS FOR
EXTRATROPICAL TRANSITION. THE JTWC TRACK FORECAST IS PLACED WITH
OVERALL HIGH CONFIDENCE. RELIABLE INTENSITY AIDS ARE IN STRONG
AGREEMENT, LENDING HIGH CONFIDENCE TO THE JTWC INTENSITY FORECAST.

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