543 

WDPN31 PGTW 170300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 04W (SINLAKU)
WARNING NR 033//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.5N 145.4E
   INITIAL INTENSITY: 80 KTS
   GEOGRAPHIC REFERENCE: 391 NM SOUTHEAST OF IWO TO
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 32 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TYPHOON (TY)
04W WITH A RAGGED, CLOUD-FILLED, AND POORLY-DEFINED CENTRAL EYE
FEATURE, IN ADDITION TO DRY AIR WRAPPING INTO THE CORE FROM THE WEST.
A 162011Z WSFM MICROWAVE IMAGE REVEALS THAT THE WEAK INNER EYEWALL HAS
COLLAPSED ALONG THE WESTERN QUADRANT WHILE THE DEEPEST CONVECTION IS
CONFINED TO THE OUTER EYEWALL APPROXIMATELY 45 NM FROM THE CENTER.
ENVIRONMENTAL ANALYSIS REVEALS A MARGINALLY UNFAVORABLE ENVIRONMENT
CHARACTERIZED BY MARGINAL (26-27 C) SEA SURFACE TEMPERATURES, LOW TO
MODERATE (15-20 KTS) VERTICAL WIND SHEAR, AND DRY AIR ENTRAINMENT,
OFFSET BY THE ROBUST DIVERGENCE ALOFT. THE INITIAL POSITION IS PLACED
WITH HIGH CONFIDENCE BASED ON THE ELONGATED AND POORLY-DEFINED EYE
FEATURE IN ANIMATED MSI. THE INITIAL INTENSITY OF 80 KTS IS ASSESSED
WITH MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK FIXES AND CIMSS
AUTOMATED INTENSITY ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE

CURRENT STEERING MECHANISM: THE WESTERN PERIPHERY OF THE SUBTROPICAL
RIDGE (STR) CENTERED TO THE SOUTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T5.0 - 90 KTS
   RJTD: T5.0 - 90 KTS
   KNES: T4.5 - 77 KTS
   CIMSS ADT: 84 KTS AT 170130Z
   CIMSS AIDT: 82 KTS AT 170130Z
   CIMSS DPRINT: 82 KTS AT 170130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY UNFAVORABLE
   VWS: 15-20 KTS
   SST: 26-27 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 04W (SINLAKU) WILL CONTINUE NORTHWESTWARD
TRACKING ALONG THE WESTERN PERIPHERY OF THE STR CENTERED TO ITS
SOUTHEAST FOR THE DURATION OF THE FORECAST. THE ENVIRONMENT IS
INCREASINGLY HOSTILE, WITH RISING VERTICAL WIND SHEAR, DRY AIR
ENTRAINMENT, AND COOLING SEA SURFACE TEMPERATURES AS THE STORM TRACKS
FARTHER POLEWARD. AFTER TAU 24, SINLAKU IS EXPECTED TO BEGIN
EXTRATROPICAL TRANSITION AS THE DRY AIR, SHEAR, AND COOL OCEAN SURFACE
ERODE THE TROPICAL CHARACTERISTICS. 04W IS EXPECTED TO BE COMPLETELY
EMBEDDED WITHIN THE UPPER-LEVEL JET AND COMPLETE EXTRATROPICAL
TRANSITION NO LATER THAN TAU 48. CONSEQUENTLY, 04W WILL CONTINUE ITS
STEADY TERMINAL WEAKENING TREND THROUGH COMPLETING EXTRATROPICAL
TRANSITION.

MODEL DISCUSSION: DETERMINISTIC TRACK MODEL GUIDANCE IS IN STRONG
AGREEMENT THROUGH THE DURATION OF THE FORECAST PERIOD, WITH A 60 NM
CROSS-TRACK SPREAD AT TAU 48 (DISCOUNTING NAVGEM AS THE LONE OUTLIER
SLIGHTLY FARTHER TO THE WEST OF THE MODEL ENVELOP). AS A RESULT, THE
JTWC TRACK FORECAST IS PLACED CLOSE TO THE MULTI-MODEL CONSENSUS WITH
HIGH CONFIDENCE. RELIABLE INTENSITY AIDS ARE ALSO IN STRONG AGREEMENT
THAT 04W WILL CONTINUE TO QUICKLY WEAKEN UNTIL TAU 48, LENDING HIGH
CONFIDENCE TO THE JTWC INTENSITY FORECAST.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   INTENSITY 0 - 72 HR: HIGH
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