WDPN31 PGTW 060900

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

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

003//

RMKS/

1. FOR METEOROLOGISTS.

2. 6 HOUR SUMMARY AND ANALYSIS.



SUMMARY:

   INITIAL POSITION: 7.4N 146.9E

   INITIAL INTENSITY: 35 KTS

   GEOGRAPHIC REFERENCE: 12 NM WEST OF SATAWAL

   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 06 KTS

   SIGNIFICANT WAVE HEIGHT: 15 FEET



SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:

ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS AN ELONGATED

AND PARTIALLY EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC). TROPICAL

STORM (TS) 05W HAS PERSISTENT DEEP CONVECTION OBSCURING THE EASTERN

FLANK OF THE STORM, SUGGESTING SOME TILT WITH HEIGHT. DRY AIR IS

PRESENT ALONG THE WESTERN AND SOUTHERN PERIPHERIES, SUPPRESSING

CONVECTION AND POTENTIALLY WRAPPING INTO THE CORE. ENVIRONMENTAL

ANALYSIS REVEALS A MARGINAL ENVIRONMENT, CHARACTERIZED BY LOW (0-5

KTS) VERTICAL WIND SHEAR, HIGH (29-30 C) SEA SURFACE TEMPERATURES,

AND MODERATE POLEWARD OUTFLOW, OFFSET BY THE RELATIVELY DRY

ENVIRONMENT. THE INITIAL POSITION IS PLACED WITH LOW CONFIDENCE

BASED ON A 060311Z AMSR2 MICROWAVE IMAGE REVEALING POORLY DEFINED

LOW-LEVEL CLOUD BANDING, USED IN CONJUNCTION WITH THE PARTIALLY

EXPOSED LLCC IN ANIMATED MSI. THE INITIAL POSITION IS PLACED WITH

MEDIUM CONFIDENCE BASED ON THE AGENCY SUBJECTIVE DVORAK FIXES AND

CIMMS AUTOMATIC INTENSITY ESTIMATES LISTED BELOW.



INITIAL WIND RADII BASIS: PERSISTENCE



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

NORTHEAST



AGENCY DVORAK AND AUTOMATED FIXES:

   PGTW: T2.5 - 35 KTS

   RJTD: T2.0 - 30 KTS

   KNES: T2.5 - 35 KTS

   CIMSS ADT: 35 KTS AT 060630Z

   CIMSS AIDT: 34 KTS AT 060630Z

   CIMSS D-MINT: 22 KTS AT 060638Z

   CIMSS D-PRINT: 24 KTS AT 060630Z



FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL

   VWS: 0-5 KTS

   SST: 29-30 CELSIUS

   OUTFLOW: MODERATE POLEWARD

   OTHER FACTORS: RELATIVELY DRY SURROUNDING ENVIRONMENT



ANALYSIS CONFIDENCE:

   INITIAL POSITION: LOW

   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: TS 05W (HAGUPIT) IS FORECAST TO CONTINUE

TRACKING ALONG THE SOUTHERN PERIPHERY OF THE STEERING STR CENTERED

TO THE NORTHEAST FOR THE NEXT 12-24 HOURS. BEGINNING BETWEEN TAU

24-36, A SHORTWAVE TROUGH TO THE NORTH WILL WEAKEN AND REORIENT THE

STR, ALLOWING 05W TO ASSUME A NORTHWESTWARD TRACK FOR THE REMAINDER

OF THE FORECAST PERIOD. HAGUPIT IS EXPECTED TO STRUGGLE WITH DRY

AIR FOR THE DURATION OF THE FORECAST PERIOD, PREVENTING SIGNIFICANT

INTENSIFICATION. 05W IS FORECAST TO GRADUALLY INTENSIFY THROUGH TAU

48-72 AS CONDITIONS MARGINALLY IMPROVE AS THE SHORTWAVE TROUGH

CREATES A TEMPORARILY FAVORABLE OUTFLOW CHANNEL. AFTER TAU 72,

HAGUPIT IS ANTICIPATED TO WEAKEN AS THE PREVIOUSLY FAVORABLE TROUGH

PASSES AND INTRODUCES CONVERGENT FLOW ALOFT, WHILE INCREASING

VERTICAL WIND SHEAR FORCES ADDITIONAL DRY AIR INTO THE CORE.



MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS IN GOOD

AGREEMENT IN A SHORT WESTWARD JAUNT THROUGH TAU 12 FOLLOWED BY A

GENERALLY NORTHWESTWARD TRACK FROM TAU 12 ONWARD. DISCOUNTING

OUTLIERS NAVGEM AND GSM, THE CROSS TRACK SPREAD IS APPROXIMATELY

160NM AND THE ALONG TRACK SPREAD IS APPROXIMATELY 90NM AT TAU 120.

AS A RESULT, THE JTWC TRACK FORECAST IS PLACED CLOSE TO THE

MULTI-MODEL CONSENSUS WITH OVERALL MEDIUM CONFIDENCE. RELIABLE

INTENSITY AIDS ARE IN MODERATE AGREEMENT. HAFS, HWRF, AND GFS

ENCOMPASS THE LOWER END OF INTENSITY ESTIMATES, WITH THOSE MODELS

HOVERING 05W AROUND 35-45 KTS FOR THE DURATION OF THE FORECAST

PERIOD. THE JTWC INTENSITY FORECAST LIES IN BETWEEN THE

AFOREMENTIONED MODELS AND THE MULTI-MODEL CONSENSUS WITH OVERALL

MEDIUM CONFIDENCE.



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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