WDPN31 PGTW 082100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 05W (HAGUPIT) WARNING NR 
013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 8.7N 137.0E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 38 NM NORTHWEST OF NGULU
   MOVEMENT PAST 6 HOURS: WESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL STORM (TS) 05W (HAGUPIT) HAS TRACKED WESTWARD OVER THE
PAST SIX HOURS WITH AN OBSCURED LOW LEVEL CIRCULATION CENTER (LLCC) 
AND A SMALL INCREASE IN CONVECTIVE ACTIVITY AROUND THE CENTER. 
WESTERLY 
SHEAR REMAINS EVIDENT WITH THE CONVECTION AND MID-LEVEL CIRCULATION 
DISPLACED EASTWARD AS DEPICTED BY ANIMATED ENHANCED INFRARED (EIR) 
SATELLITE IMAGERY. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE 
BASED
ON ANIMATED EIR IMAGERY OF THE LLCC AND 1654Z AMSR2 MICROWAVE
IMAGERY. THE INITIAL INTENSITY OF 35 KTS IS ASSESSED WITH MEDIUM
CONFIDENCE BASED ON THE AGENCY DVORAK FIXES AND CIMSS INTENSITY
ESTIMATES LISTED BELOW THOUGH THE 1430Z OSCAT DATA SHOWS INTENSITY
COULD BE LOWER. ENVIRONMENTAL CONDITIONS ARE MARGINAL FOR CONTINUED
DEVELOPMENT WITH HIGH (29-30 C) SEA SURFACE TEMPERATURES AND
MODERATE POLEWARD OUTFLOW BALANCED BY THE EVIDENT MID-LEVEL SHEAR
AND DRY AIR ENTRAINMENT FROM THE WEST.

INITIAL WIND RADII BASIS: 081430Z OSCAT SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) POSITIONED FAR TO THE NORTHEAST.

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: 39 KTS AT 1900Z
   CIMSS ADT: 41 KTS AT 1900Z
   CIMSS AIDT: 38 KTS AT 1900Z
   CIMSS D-MINT: 24 KTS AT 1849Z
   CIMSS D-PRINT: 27 KTS AT 1900Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD
   OTHER FACTORS: DRY MID-LEVEL AIR ALONG THE WESTERN FLANK AND
MODERATE MID-LEVEL WESTERLY SHEAR.

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL STORM (TS) 05W (HAGUPIT) IS FORECAST
TO CONTINUE TRACKING WEST-NORTHWESTWARD UNDER THE STEERING
INFLUENCE OF THE STR TO THE NORTHEAST OVER THE NEXT 72 HOURS.
AFTERWARDS, THE TRACK IS EXPECTED TO SHIFT FURTHER POLEWARD AS THE
INFLUENCE OF THE STR WANES. THE TRACK IS HEAVILY DEPENDENT ON THE
VERTICAL EXTENT OF THE SYSTEM. IT IS POSSIBLE THAT THE CIRCULATION 
WILL DRIFT
FURTHER WESTWARD AS IT SHALLOWS OUT AND IS OVERCOME BY LOW LEVEL
WIND FLOW. TS HAGUPIT IS FORECASTED TO WEAKLY HOLD 35 KT INTENSITY
OVER THE NEXT 36 HOURS BEFORE THE PROLONGED EXPOSURE TO WESTERLY
SHEAR AND DRY AIR ENTRAINMENT INITIATE A TERMINAL WEAKENING PHASE.
THE SYSTEM IS EXPECTED TO DISSIPATE OVER WATER BY TAU 120.

MODEL DISCUSSION: CROSS TRACK SPREAD AMONGST THE MULTI MODEL
CONSENSUS IS 70 NM BY TAU 36 INCREASING TO 200+ NM BY THE END OF
THE FORECAST PERIOD SHOWING A LARGE DISAGREEMENT AMONGST THE MODEL
GUIDANCE ON THE NORTHWARD PROGRESSION OF THE SYSTEM. THE JTWC
FORECASTED TRACK IS PLACED CLOSE TO THE MULTI MODEL CONSENSUS WITH
MEDIUM CONFIDENCE ACCOUNTING FOR EXPECTED TRACK CHANGES SHOULD THE
SYSTEM SHALLOW OUT AT A QUICKER PACE. INTENSITY GUIDANCE IS SPREAD
UP TO 25 NM BY THE END OF THE FORECAST PERIOD WITH STATISTICAL
DYNAMICAL MODELS RELUCTANT TO INITIATE THE FORECASTED WEAKENING
TREND. THE JTWC FORECASTED INTENSITY REFLECTS VALUES SLIGHTLY LOWER
THAN THE MULTI MODEL CONSENSUS AFTER TAU 36, AND IS MORE IN LINE WITH 
GFS
AND EXPERIMENTAL AI SOLUTIONS. INTENSITY CONFIDENCE THROUGHOUT THE
FORECAST PERIOD IS MEDIUM.

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