WDPN31 PGTW 160900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 04W (SINLAKU) WARNING NR 030//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.7N 144.5E
   INITIAL INTENSITY: 100 KTS
   GEOGRAPHIC REFERENCE: 462 NM SOUTH-SOUTHEAST OF IWO TO
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 35 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS THE SLIGHTLY
CLOUD-FILLED EYE OF TYPHOON (TY) 04W (SINLAKU) AS IT CONTINUES TO
SLOWLY MOVE NORTH-NORTHEASTWARD ALONG THE NORTHERN MARIANA ISLANDS.
THE NORTHWESTERN EXTENSION OF THE NEAR EQUATORIAL RIDGE (NER)
CENTERED SOUTHEAST OF TY 04W IS THE PRIMARY STEERING MECHANISM. THE
NER IS CURRENTLY NOT WELL DEFINED AND SLIGHTLY ELONGATED, WHICH IS
WHY WE HAVE SEEN A SLOWER AND WOBBLIER PATH OF TY SINLAKU OVER THE
PAST FEW WARNINGS AS COMPARED TO WHAT MOST OF THE MODEL TRACK
GUIDANCE HAS FORECAST. ENVIRONMENTAL ANALYSIS SHOWS WARM (27-28 C)
SEA SURFACE TEMPERATURES, ROBUST RADIAL OUTFLOW, AND LOW (5-10 KTS)
VERTICAL WIND SHEAR (VWS). THOSE FAVORABLE CHARACTERISTICS ARE
CURRENTLY OFFSET BY DRY AIR ENTRAINMENT FROM A SURROUNDING AIR MASS
ULTIMATELY RESULTING IN AN INTENSITY STAGNATION. ADDITIONALLY, THE
EYE TEMPERATURE HAS COOLED FROM 14C TO 10C OVER THE PAST SIX HOURS.
THE PREVIOUSLY ASSESSED EYEWALL REPLACEMENT CYCLE (ERC) HAS
CONCLUDED, AS WITNESSED BY A 160338Z GW1 AMSR2 89 GHZ IMAGE SHOWING
A FULLY DEVELOPED OUTER EYEWALL WITH THE FORMER EYEWALL LARGELY
DISSIPATED. AS SUCH, TY 04W MAINTAINED 100 KTS OVER THE LAST 6
HOURS WITH THE COMPLETED ERC GIVING IT A BRIEF PERIOD OF SLIGHT
INTENSIFICATION DESPITE THE MARGINAL ENVIRONMENTAL CONDITIONS. DUE
TO THE JUXTAPOSITION OF CURRENT AND NEAR-FUTURE EXPECTED
ENVIRONMENTAL CONDITIONS, AS WELL AS THE OBJECTIVE AIDS AND DVORAK
ESTIMATES LISTED BELOW, THE OVERALL INTENSITY CONFIDENCE IS
ASSESSED AS MEDIUM, WHILE THE OVERALL POSITION CONFIDENCE IS
ASSESSED AS HIGH AND IS BASED ON THE ANIMATED VISIBLE SATELLITE
IMAGERY.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: NEAR EQUATORIAL RIDGE (NER) LOCATED
SOUTHEAST OF THE SYSTEM

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   RJTD: T6.0 - 115 KTS
   RCTP: T6.0 - 115 KTS
   CIMSS SATCON: 106 KTS AT 160410Z
   CIMSS ADT: 94 KTS AT 160540Z
   CIMSS AIDT: 92 KTS AT 160220Z
   CIMSS D-MINT: 102 KTS AT 160340Z
   CIMSS D-PRINT: 100 KTS AT 160540Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 5-10 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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: TY SINLAKU IS FORECAST TO CONTINUE TRANSITING
NORTHEASTWARD, UNDER THE INFLUENCE OF A NEAR EQUATORIAL RIDGE
CENTERED TO THE SOUTHEAST. THE NER IS FORECAST TO STRENGTHEN AND
BECOME MORE WELL-DEFINED BY TAU 36, INCREASING ITS STEERING
INFLUENCE ON TY 04W AND ACCOUNTING FOR A FASTER NORTH-NORTHEASTWARD
RECURVATURE THROUGHOUT THE CURRENT FORECAST PERIOD. TY 04W IS
EXPECTED TO CROSS INTO 26C WATERS AS EARLY AS TAU 24, AND ENCOUNTER
HIGH (30+ KTS) VWS BY TAU 48, COINCIDING WITH THE FORECAST
BEGINNING OF EXTRATROPICAL TRANSITION (ETT). BY TAU 72, TY SINLAKU
WILL BE POSITIONED DIRECTLY UNDERNEATH UPPER-LEVEL WESTERLY FLOW,
MARKING THE COMPLETION OF THE ETT. IN REGARD TO INTENSITY, TY 04W
IF FORECAST TO BEGIN WEAKENING, AS THE ENVIRONMENTAL CONDITIONS,
PARTICULARLY VWS AND SST, ARE EXPECTED TO BECOME MORE HOSTILE AS
SOON AS TY 04W APPROACHES THE 26C SST ISOTHERM AND STRONG
UPPER-LEVEL WESTERLIES. THE SYSTEM IS EXPECTED TO RETAIN 55-60 KTS
INTENSITY BY THE TIME IT TRANSITIONS INTO A COLD-CORE LOW.

MODEL DISCUSSION: ALL OBJECTIVE AIDS ARE IN GOOD AGREEMENT IN
REGARD TO THE FORECAST RECURVATURE SCENARIO, WITH NAVGEM REMAINING
THE ONLY OUTLIER, POSITION TO THE WEST OF THE MAIN GUIDANCE
ENVELOPE. THE TRACK FORECAST IS LAID WITH MEDIUM CONFIDENCE DUE TO
THE INITIALLY SMALL CROSS TRACK SPREAD OF 17 NM, EXPANDING TO 70 NM
BY TAU 72. ALL INTENSITY GUIDANCE SHOWS STEADY WEAKENING THROUGHOUT
THE REMAINDER OF THE FORECAST PERIOD, WITH STATISTICAL-DYNAMICAL
AND GFS DRIVEN COAMPS-TC SHARPLY DROPPING, WHILE HAFS WEAKENS MORE
GRADUALLY. THE JTWC INTENSITY FORECAST LIES ABOVE THE MULTI-MODEL
CONSENSUS FOR THE REMAINDER OF THE FORECAST PERIOD WITH OVERALL
MEDIUM CONFIDENCE.

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