WDPN31 PGTW 070900

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

SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 05W (HAGUPIT) WARNING NR

007//

RMKS/

1. FOR METEOROLOGISTS.

2. 6 HOUR SUMMARY AND ANALYSIS.



SUMMARY:

   INITIAL POSITION: 7.5N 142.9E

   INITIAL INTENSITY: 35 KTS

   GEOGRAPHIC REFERENCE: 309 NM EAST-SOUTHEAST OF YAP

   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 08 KTS

   SIGNIFICANT WAVE HEIGHT: 15 FEET



SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:

ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY

EXPOSED LOW-LEVEL CIRCULATION (LLC) WITH DEEP CONVECTION MOSTLY

CONFINED TO THE EASTERN AND NORTHERN SEMICIRCLES. FLARING

CONVECTIVE BANDS IN THE SOUTHWESTERN QUADRANT REMAIN DISORGANIZED

AND THE RESULTING MSI PRESENTATION IS ASYMMETRIC. THE INITIAL

POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED PRIMARILY ON THE

PARTIALLY EXPOSED LLC IN ANIMATED MSI. A 070253Z OSCAT IMAGE

REVEALS AN ELONGATED LOW-LEVEL CIRCULATION CENTER (LLCC) AND

SURROUNDING ASYMMETRIC WIND FIELD, WITH THE HIGHEST WIND SPEEDS OF

30-35 KTS IN THE NORTHERN SEMICIRCLE. THE INITIAL POSITION IS

PLACED WITH MEDIUM CONFIDENCE BASED ON THE OSCAT WIND SPEEDS AND A

CONSENSUS OF THE AGENCY DVORAK FIXES AND CIMSS INTENSITY ESTIMATES

LISTED BELOW. THE ENVIRONMENT IS CHARACTERIZED AS MARGINALLY

FAVORABLE WITH WEAK RADIAL OUTFLOW, WARM (29-30 C) SEA SURFACE

TEMPERATURES, AND LOW DEEP-LAYER VERTICAL WIND SHEAR (VWS). DRY AIR

ENTRAINMENT FROM THE WEST AND MODERATE (15-20 KTS)

WEST-NORTHWESTERLY MID-TROPOSPHERIC SHEAR ARE ACTING TO OFFSET THE

OTHER MORE FAVORABLE ENVIRONMENTAL FACTORS.



INITIAL WIND RADII BASIS: SCATTEROMETER DATA



CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A DEEP-LAYER

SUBTROPICAL RIDGE POSITIONED TO THE NORTHEAST.



AGENCY DVORAK AND AUTOMATED FIXES:

   PGTW: T2.5 - 35 KTS

   RJTD: T2.0 - 30 KTS

   RCTP: T2.5 - 35 KTS

   KNES: T2.5 - 35 KTS

   CIMSS SATCON: 36 KTS AT 070510Z

   CIMSS ADT: 35 KTS AT 070600Z

   CIMSS AIDT: 34 KTS AT 070600Z

   CIMSS D-MINT: 30 KTS AT 070343Z

   CIMSS D-PRINT: 27 KTS AT 070600Z



FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE

   VWS: 5-10 KTS

   SST: 29-30 CELSIUS

   OUTFLOW: WEAK RADIAL

   OTHER FACTORS: DRY MID-LEVEL AIR ALONG THE WESTERN FLANK AND

HIGH MID-LEVEL WEST-NORTHWESTERLY SHEAR.



ANALYSIS CONFIDENCE:

   INITIAL POSITION: MEDIUM

   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 ON A GENERALLY WEST-NORTHWESTWARD TRACK THROUGH THE

ENTIRE FORECAST PERIOD, PASSING JUST SOUTH OF YAP AROUND 081700Z.

THE TRACK SPEED IS EXPECTED TO SLOW AFTER TAU 72 AS 05W TURNS TO A

NORTHWESTWARD TRAJECTORY AS THE PRIMARY STEERING RIDGE MIGRATES

SLOWLY EASTWARD, SETTING UP A WEAK STEERING ENVIRONMENT. TS HAGUPIT

IS FORECAST TO INCREASE IN INTENSITY TO 40 KTS AT TAU 12, THEN

MAINTAIN 40 KTS THROUGH TAU 72 AS ENVIRONMENTAL CONDITIONS STYMIE

ANY FURTHER INTENSIFICATION. THE SYSTEM IS EXPECTED TO BEGIN

DISSIPATING OVER THE PHILIPPINE SEA AFTER TAU 72 IN AN AREA OF

ABUNDANT DRY MID-LEVEL AIR AND INCREASING VWS, BECOMING FULLY

DISSIPATED BY TAU 120.



MODEL DISCUSSION: MODEL TRACK GUIDANCE IS IN GOOD OVERALL AGREEMENT

ABOUT THE WEST-NORTHWESTWARD TRACK, WITH A CROSS-TRACK SPREAD OF

110 NM AT TAU 72 (DISCOUNTING NAVGEM AS AN OUTLIER WELL TO THE

NORTH). THE CROSS-TRACK SPREAD INCREASES TO 210 NM BY TAU 120 AND

THERE IS A NOTABLE ALONG-TRACK DISPARITY OF 170 NM THAT INDICATES

SOME UNCERTAINTY IN THE TRACK SPEED AS 05W ENTERS INTO A WEAKER

STEERING ENVIRONMENT. THE JTWC TRACK FORECAST IS PLACED NEAR THE

MULTIMODEL CONSENSUS WITH HIGH CONFIDENCE THROUGH TAU 72 AND MEDIUM

CONFIDENCE THEREAFTER. WITH THE EXCEPTION OF SHIPS SOLUTIONS,

INTENSITY GUIDANCE IS IN GENERALLY GOOD AGREEMENT ABOUT A NEAR-TERM

INTENSIFICATION FOLLOWED BY A PROLONGED PERIOD OF MAINTAINING

INTENSITY. THE JTWC INTENSITY FORECAST IS PLACED WITH MEDIUM

CONFIDENCE, CLOSE TO THE CONSENSUS THROUGH TAU 36, THEN SLIGHTLY

BELOW THE CONSENSUS TO ACCOUNT FOR THE MORE AGGRESSIVE SHIPS

MEMBERS.



FORECAST CONFIDENCE:

   TRACK 00-72 HR: HIGH

   TRACK 72-120 HR: MEDIUM

   INTENSITY 00-72 HR: MEDIUM

   INTENSITY 72-120 HR: MEDIUM//

NNNN