WDPN31 PGTW 012100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 05W (AERE) WARNING NR 
006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 23.0N 130.8E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 266 NM SOUTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 17 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS A
PARTIALLY-EXPOSED LOW-LEVEL CIRCULATION CENTER WITH FLARING DEEP
CONVECTION CONFINED TO THE NORTHERN AND EASTERN PERIPHERIES.
ANIMATED WATER VAPOR IMAGERY AND UPPER-LEVEL ATMOSPHERIC MOTION
VECTORS INDICATE THE CONTINUED PRESENCE OF A TROPICAL UPPER
TROPOSPHERIC TROUGH (TUTT), WHICH NOW EXTENDS OVER THE CENTER OF
THE SYSTEM. STRONG EASTERLY VERTICAL WIND SHEAR AND AN INJECTION OF
DRIER AIR FROM THE SOUTHWEST, BOTH ASSOCIATED WITH THE TUTT, HAVE
PREVENTED CONVECTION FROM PERSISTING OVER THE LOW-LEVEL CIRCULATION
CENTER DESPITE ROBUST POLEWARD AND EQUATORWARD DIFFLUENCE OVER THE
EASTERN PORTION OF THE CIRCULATION. THE INITIAL POSITION IS PLACED
WITH MEDIUM CONFIDENCE BASED ON AN EXPOSED LOW-LEVEL CENTER EVIDENT
IN INFRARED SATELLITE IMAGERY, AND IS CONSISTENT WITH RECENT FIX
POSITIONS FROM PGTW AND KNES. THE INITIAL INTENSITY OF 45 KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON A 011730Z PGTW DVORAK
ANALYSIS OF T3.0 AND A 011652Z AUTOMATED SATELLITE CONSENSUS
ESTIMATE OF 45 KNOTS.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK AND PERSISTENCE 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T2.5 - 35 KTS
   KNES: T2.0 - 30 KTS
   CIMSS SATCON: 45 KTS AT 011652Z
   CIMSS ADT: 37 KTS AT 011740Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 20-25 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD
   OTHER FACTORS: TUTT EXTENDING OVER THE LOW-LEVEL CIRCULATION
CENTER

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: TS 05W WILL TRACK GENERALLY WEST-NORTHWESTWARD
OVER THE NEXT 48 HOURS UNDER THE CONTINUED INFLUENCE OF THE DEEP
LAYER SUBTROPICAL STEERING RIDGE THE TO EAST. FORWARD MOTION WILL
SLOW IN THE 36 TO 48 HOUR TIMEFRAME AS THE SYSTEM APPROACHES THE
STEERING RIDGE AXIS. PASSAGE OVER WARM WATER AND SUPPORTIVE
DIFFLUENT FLOW WITH ASSOCIATED DEEP CONVECTIVE DEVELOPMENT OVER THE
EASTERN PORTION OF THE CIRCULATION ARE EXPECTED TO SUPPORT
ADDITIONAL NEAR-TERM INTENSIFICATION DESPITE NOTED PERSISTENT
EASTERLY VERTICAL WIND SHEAR AND ENTRAINMENT OF DRIER AIR. HOWEVER,
THE NEAR-TERM INTENSIFICATION WILL BE LIMITED AS TS 05W CONTINUES
TO TRACK UNDER THE FILLING, THOUGH PERSISTENT, TUTT.  AFTER TAU 48,
THE SYSTEM IS EXPECTED TO CREST THE RIDGE AXIS AND TURN TO THE
NORTHEAST, STEADY WEAKENING DUE PASSAGE OVER COOLER WATER, VERTICAL
WIND SHEAR AND LAND INTERACTION.  

MODEL DISCUSSION: TRACK AND INTENSITY MODEL FORECAST GUIDANCE IS IN
GOOD AGREEMENT THROUGH TAU 48, WITH SOME DIVERGENCE BY TAU 72,
LENDING MEDIUM CONFIDENCE TO THE EARLY PORTION OF THE FORECAST. THE
STRONGEST WINDS AND CONVECTION WILL LIKELY BE CONFINED TO THE
EASTERN AND NORTHERN PORTIONS OF THE CIRCULATION DURING THIS
PERIOD. AFTER TAU 48, MODEL TRACK FORECAST GUIDANCE DIVERGES WITH
THE NAVGEM, GALWEM, AND JGSM SOLUTIONS INDICATING A TRACK CURVING
TO THE SOUTH OF HONSU AND THE OTHER CONSENSUS MODELS CARRYING THE
SYSTEM FARTHER TO THE WEST. ENSEMBLE GUIDANCE SIMILARLY SHOWS A
WIDE RANGE OF POSSIBLE SOLUTIONS TO AS FAR WEST AS THE YELLOW SEA.
ULTIMATELY THE TRACK WILL DEPEND HIGHLY ON THE STRUCTURE AND
INTENSITY OF THE SYSTEM, WHICH IS EXPECTED TO DEGRADE QUICKLY IN
THE EXTENDED FORECAST PERIOD. THE CURRENT TRACK FORECAST FOR THE
EXTENDED PERIOD SPLITS THE DIFFERENCE BETWEEN THE PREVIOUS JTWC
FORECAST AND THE NEW CONSENSUS, AND LIES IN THE MIDDLE OF THE
GUIDANCE ENVELOPE. ADDITIONAL CHANGES TO THE LATER PORTION OF THE
FORECAST ARE LIKELY UNTIL TRACK FORECAST GUIDANCE COMES INTO BETTER
AGREEMENT.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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