Advisories

WDPN32 PGTW 102100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 13W (PEILOU) WARNING NR 
016//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.4N 154.1E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 725 NM WEST-NORTHWEST OF WAKE ISLAND
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS
PERSISTENT CONVECTION OVER THE LOW-LEVEL CIRCULATION CENTER OVER
THE PAST 6 HOURS, HOWEVER, A BRIEF GLIMPSE OF LOW-LEVEL CLOUD BANDS
EXPOSED IN THE SOUTHEASTERN QUADRANT REVEALED APPARENT
SOUTHEASTERLY SHEAR. A 101524 89 GHZ AMSR-2 MICROWAVE IMAGE
CONFIRMED THIS STRUCTURAL OFFSET. A 101404Z OCEANSAT-3 WIND SPEED
PRODUCT CONFIRMED 30-35 KT WINDS PERSISTING IN THE SOUTHERN
SEMICIRCLE. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE
BASED ON EXTRAPOLATION FROM THE AMSR-2 IMAGERY AND THE ANIMATED EIR
IMAGERY. THE INITIAL INTENSITY OF 35 KTS IS ASSESSED WITH MEDIUM
CONFIDENCE BASED ON THE SCATTEROMETRY DATA, DESPITE BEING WELL
BELOW THE AGENCY FIXES AND CIMSS OBJECTIVE INTENSITY ESTIMATES. THE
ENVIRONMENT IS CHARACTERIZED AS MARGINAL WITH HIGH SEA SURFACE
TEMPERATURES BEING OFFSET BY WEAK OUTFLOW ALOFT.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: EASTERN PERIPHERY OF A LARGE, LOW-LEVEL
CYCLONIC GYRE CENTERED TO THE WEST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T3.0 - 45 KTS
   KNES: T2.5 - 35 KTS
   CIMSS SATCON: 47 KTS AT 101800Z
   CIMSS ADT: 51 KTS AT 101800Z
   CIMSS AIDT: 40 KTS AT 101800Z
   CIMSS D-MINT: 45 KTS AT 101549Z
   CIMSS D-PRINT: 54 KTS AT 101800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: WEAK POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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: TROPICAL STORM (TS) 13W (PEILOU) IS FORECAST
TO CONTINUE ON A NORTHEASTWARD TRACK EMBEDDED IN THE SOUTHWESTERLY
MONSOON FLOW ON THE EASTERN EDGE OF THE BROAD CYCLONIC GYRE
SITUATED TO THE WEST. AFTER TAU 36 THE TRACK TURNS
EAST-NORTHEASTWARD UNDER THE INFLUENCE OF A SEPARATE SUBTROPICAL
RIDGE BUILDING IN FROM THE EAST. THE INTENSITY IS FORECAST TO
GRADUALLY WEAKEN THROUGHOUT THE FORECAST PERIOD AS THE SYSTEM
ENTERS A DRIER ENVIRONMENT AND EVENTUALLY MOVES INTO A HIGHER SHEAR
ENVIRONMENT. THE SYSTEM IS EXPECTED TO DISSIPATE OVER WATER BY TAU
48.

MODEL DISCUSSION: MODEL TRACK GUIDANCE IS IN GOOD AGREEMENT ABOUT
THE NORTHEASTWARD TRACK AND THE JTWC TRACK FORECAST IS PLACED NEAR
THE MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE. WITH THE EXCEPTION
OF SHIPS SOLUTIONS, MODEL INTENSITY GUIDANCE AGREES ON AN OVERALL
WEAKENING TREND AND DISSIPATION. THE JTWC INTENSITY FORECAST IS
PLACED ON THE LOWER END OF THE GUIDANCE ENVELOPE WITH MEDIUM
CONFIDENCE TO ACCOUNT FOR THE SHIPS OUTLIERS.

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