WDPN31 PGTW 052100

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//

SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 05W (FIVE) WARNING

NR 001//

RMKS/

1. FOR METEOROLOGISTS.

2. 6 HOUR SUMMARY AND ANALYSIS.



SUMMARY:

   INITIAL POSITION: 8.4N 148.3E

   INITIAL INTENSITY: 30 KTS

   GEOGRAPHIC REFERENCE: 88 NM NORTH-NORTHWEST OF PULUWAT

   MOVEMENT PAST 6 HOURS: WESTWARD AT 07 KTS

   SIGNIFICANT WAVE HEIGHT: 14 FEET



SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:

THE STRUCTURE OF TROPICAL DEPRESSION (TD) 05W HAS IMPROVED

OVERNIGHT WITH CONSOLIDATING CONVECTIVE ACTIVITY SURROUNDING THE

LOW-LEVEL CIRCULATION CENTER (LLCC) AND COOLING CLOUD TOP

TEMPERATURES WITHIN SAID CONVECTION AS DEPICTED BY ANIMATED

ENHANCED INFRARED (EIR) SATELLITE IMAGERY. ENVIRONMENTAL CONDITIONS

ARE MARGINALLY FAVORABLE FOR CONTINUED SLOW BUT STEADY DEVELOPMENT

WITH WARM SEA SURFACE TEMPERATURES (29 C TO 30 C), LOW VERTICAL

WIND SHEAR (10-15 KTS), AND MODERATE EQUATORWARD OUTFLOW. THE

INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON EIR

IMAGERY OF THE CONSOLIDATING LLCC.  THE INITIAL INTENSITY OF 30 KTS

IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE STRONG CONSENSUS OF

SUBJECTIVE AND OBJECTIVE ESTIMATES LISTED BELOW.



INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND

RADII).



CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) CENTERED TO THE

NORTHEAST



AGENCY DVORAK AND AUTOMATED FIXES:

   PGTW: T2.0 - 30 KTS

   RJTD: T1.5 - 25 KTS

   KNES: T2.5 - 35 KTS

   CIMSS D-PRINT: 35 KTS AT 051800Z



FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE

   VWS: 10-15 KTS

   SST: 29-30 CELSIUS

   OUTFLOW: MODERATE EQUATORWARD



ANALYSIS CONFIDENCE:

   INITIAL POSITION: MEDIUM

   INITIAL INTENSITY: HIGH

   INITIAL WIND RADII: NOT APPLICABLE



3. FORECAST REASONING.



SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING

MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.



FORECAST DISCUSSION: TD 05W IS FORECASTED TO BE STEERED WESTWARD

UNDER THE INFLUENCE OF THE SUBTROPICAL RIDGE (STR) CENTERED TO THE

NORTHEAST. AS THE INFLUENCE OF THE STR WEAKENS AROUND TAU 48 THE

TRACK WILL SHIFT PROGRESSIVELY WEST-NORTHWESTWARD PUSHING THE

CENTER JUST NORTH OF YAP BETWEEN TAU 48 AND TAU 72. THIS FORECASTED

TRACK IS HIGHLY DEPENDENT OF THE STRENGTH OF THE STR LATE IN THE

FORECAST PERIOD. THE SYSTEM WILL SLOWLY STRENGTHEN OVER THE NEXT 36

HOURS. BETWEEN TAU 36 AND TAU 48 THE SYSTEM IS EXPECTED TO

ENCOUNTER A FAVORABLE AREA FOR IMPROVED OUTFLOW COINCIDING WITH A

TEMPORARY DECREASE IN VERTICAL WIND SHEAR ALLOWING FOR FURTHER

STRENGTHENING AND A PEAK INTENSITY OF 50 KTS BY TAU 48. AFTER TAU

72 THE OUTFLOW AND STRUCTURAL COMPOSITION OF THE STORM WILL DEGRADE

AS INCREASING WESTERLY SHEAR ALOFT AND DRY AIR ENTRAINMENT SLOWLY

WEAKEN THE SYSTEM. THE CENTER OF TD 05W WILL BE EAST OF THE

PHILIPPINES BY TAU 120 AT 40 KT INTENSITY.



MODEL DISCUSSION: CROSS TRACK SPREAD AMONGST THE MULTI MODEL

CONSENSUS IS AROUND 100 NM UNTIL TAU 48. AFTERWARDS GFS AND NAVGEM

PULL THE CONSENSUS NORTHWARD EVEN AS THE MAJORITY OF THE MEMBERS

FAVOR A TRACK FURTHER TO THE SOUTH. THE JTWC FORECASTED TRACK IS

PLACED SOUTH OF THE MULTI MODEL CONSENSUS, MORE REPRESENTATIVE OF

SOME OF THE EXPERIMENTAL AI SOLUTIONS. DUE TO THE INCREASE IN TRACK

SPREAD AFTER TAU 48 THE FORECASTED TRACK IS PLACED WITH MEDIUM

CONFIDENCE FOR THE FIRST 48 HOURS AND LOW CONFIDENCE THEREAFTER.

INTENSITY GUIDANCE IS SPREAD UP TO 25 KTS AT TAU 48. THE JTWC

FORECASTED INTENSITY IS PLACED SLIGHTLY ABOVE THE MULTI MODEL

CONSENSUS WITH MEDIUM CONFIDENCE THROUGHOUT THE FORECAST PERIOD.



FORECAST CONFIDENCE:

   TRACK 00-72 HR: MEDIUM

   TRACK 72-120 HR: LOW

   INTENSITY 00-72 HR: MEDIUM

   INTENSITY 72-120 HR: MEDIUM//

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