Advisories

WDPN31 PGTW 080300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 15E (NOLO) WARNING NR 
070//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 26.9N 156.0E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 1097 NM SOUTHEAST OF MISAWA AB, JAPAN
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 17 KTS
   SIGNIFICANT WAVE HEIGHT: 32 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN
ASYMMETRIC CENTRAL DENSE OVERCAST OBSCURING THE LOW-LEVEL CIRCULATION 
CENTER, WITH RAPIDLY CYCLING DEEP CONVECTION. TROPICAL STORM 15E 
CONTINUES TO STRUGGLE AGAINST VIGOROUS EASTERLY VERTICAL WIND SHEAR 
WITH LIMITED SUCCESS. A 072302Z METOP-SGA1 89GHZ MICROWAVE IMAGE 
REVEALS LIMITED CONVECTIVE BANDING OVER THE SOUTHERN SEMICIRCLE, WITH 
A WEAKLY DEFINED LOW-LEVEL CIRCULATION CENTER. THE INITIAL INTENSITY 
IS ASSESSED AT 55 KNOTS BASED ON THE 3.5 (55 KNOTS) CIS FROM ALL 
AGENCIES AND THE CIMSS OBJECTIVE INTENSITY ESTIMATES RANGING FROM 51-
58 KNOTS.

INITIAL WIND RADII BASIS: SAR DATA 

CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR)
ENTRENCHED TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T3.5 - 55 KTS
   RCTP: T3.5 - 55 KTS
   CIMSS ADT: 51 KTS AT 072340Z
   CIMSS D-MINT: 58 KTS AT 072044Z
   CIMSS D-PRINT: 58 KTS AT 080040Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE WESTWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL STORM (TS) 15E IS FORECAST TO TRACK
WEST-NORTHWESTWARD ALONG THE SOUTHWESTERN PERIPHERY OF THE STR
THROUGH TAU 36, WITH A SHORT-LIVED PERIOD OF REINTENSIFICATION TO
65 KNOTS DUE TO DECREASING VERTICAL WIND SHEAR (VWS). AFTER TAU 36,
TS 15E WILL TRACK NORTHWARD TO NORTHEASTWARD WHILE ENCOUNTERING
INCREASING VWS ASSOCIATED WITH THE STRONG MIDLATITUDE WESTERLIES.
BY TAU 72, TS 15E WILL ACCELERATE AND BEGIN EXTRA-TROPICAL
TRANSITION (ETT) THEN COMPLETE ETT BETWEEN TAU 96 AND TAU 120 AS IT
GAINS FRONTAL CHARACTERISTICS AND TRACKS UNDER THE JET.    

MODEL DISCUSSION: THE PHYSICS-BASED MODELS INDICATE INCREASING
UNCERTAINTY FROM TAU 24 TO TAU 60 AS THE SYSTEM RECURVES AROUND THE
WESTERN PERIPHERY OF THE STR, WITH A LARGE CROSS-TRACK SPREAD AT
THE RECURVE POINT. AFTER TAU 60, THERE IS INCREASING UNCERTAINTY
DUE TO MAJOR DIFFERENCES IN ALONG-TRACK SPEEDS. AI-BASED AND
DETERMINISTIC ENSEMBLES CONTINUE TO SUPPORT THE JTWC TRACK FORECAST
WITH MEDIUM CONFIDENCE. DUE TO THE PROXIMITY (ABOUT 700NM FROM TAU
36 TO TAU 48) WITH TS 27W, THERE IS A LOW PROBABILITY FOR WEAK
BINARY INTERACTION. THE VAST MAJORITY OF ENSEMBLE SOLUTIONS DEPICT
A RECURVATURE, WITH ONLY A FEW SOLUTIONS INDICATING QUASI-STATIONARY 
OR ERRATIC TRACKS ASSOCIATED WITH THE WEAK BINARY INTERACTION.  

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
NNNN