WDPN33 PGTW 241500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 11W (CO-MAY) WARNING NR 007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.1N 119.5E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 125 NM NORTHWEST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 03 KTS
   SIGNIFICANT WAVE HEIGHT: 22 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
CENTRAL DENSE OVERCAST (CDO) FEATURE PERSISTING OVER THE LAST TWO
HOURS, DESPITE TYPHOON (TY) 11W (CO-MAY) PROXIMITY TO LAND. DEEP
CONVECTION ASSOCIATED WITH THE SYSTEM REMAINED WELL ORGANIZED, GIVEN
THE PREDOMINANTLY FAVORABLE ENVIRONMENTAL CONDITIONS. ADDITIONAL
ANALYSIS REVEALS WARM (29-30 C) SEA SURFACE TEMPERATURES, ENHANCED
UPPER-LEVEL DIVERGENCE DUE TO ROBUST EQUATORWARD AND POLEWARD OUTFLOW 
CHANNELS, AND PLENTIFUL MID- TO UPPER-LEVEL MOISTURE. VERTICAL WIND 
SHEAR (VWS) REMAINS LOW (5-10 KTS), SUPPORTING MAINTENANCE OF DEEP 
CONVECTION IN THE NEAR TERM. HOWEVER, THESE FACTORS ARE INCREASINGLY 
OFFSET BY FRICTIONAL CONVERGENCE AND VORTICITY STRIPPING ASSOCIATED 
WITH THE PROXIMITY TO LAND, PARTICULARLY OVER THE EASTERN SEMICIRCLE 
OF THE CIRCULATION. THE SYSTEM CONTINUES TO BE EMBEDDED WITHIN THE 
SOUTHWESTERN QUADRANT OF A BROAD MONSOON GYRE, CHARACTERIZED BY A 
SYNOPTIC-SCALE CYCLONIC CIRCULATION. THE CENTER OF THE GYRE 
CIRCULATION IS POSITIONED SOUTHEAST OF TAIWAN, WITH THE AXIS GENERALLY 
ALIGNED PARALLEL TO THE SOUTHEASTERN CHINA COASTLINE. THE INITIAL 
POSITION IS DETERMINED WITH HIGH CONFIDENCE BASED ON A 241228Z METOP-B 
ASCAT PASS, CORROBORATED BY GFS PRESSURE MODEL FIELDS AND ALSO 
EXTRAPOLATION FROM A 241002Z F16 SSMIS PASS SHOWING THE LOCATION OF 
THE LLCC. THE INITIAL INTENSITY OF 65 KTS IS ASSESSED WITH MEDIUM 
CONFIDENCE, DERIVED FROM THE AFOREMENTIONED ASCAT PASS DATA, AS WELL 
AS A BLEND OF SUBJECTIVE DVORAK FIXES AND OBJECTIVE ESTIMATES LISTED 
BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SYSTEM IS EMBEDDED WITHIN THE
SOUTHWESTERN PERIPHERY OF A BROAD MONSOON GYRE, STEERED ALONG THE
TIGHT GRADIENT FLOW BETWEEN THE GYRE CENTER AND A NEAR EQUATORIAL
RIDGE (NER) TO THE EAST-SOUTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T3.5 - 55 KTS
   RCTP: T3.5 - 55 KTS
   KNES: T4.0 - 65 KTS
   DEMS: T4.0 - 65 KTS
   CIMSS AIDT: 60 KTS AT 240830Z
   CIMSS D-MINT: 49 KTS AT 241004Z
   CIMSS D-PRINT: 41 KTS AT 241300Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD
   OTHER FACTORS: PROXIMITY TO LAND

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 11W HAS COMPLETED A RECURVATURE LOOP AS IT
NEARS THE WEST COAST OF LUZON, PHILIPPINES. WHILE SYNOPTIC-SCALE
PARAMETERS REMAIN FAVORABLE FOR INTENSITY MAINTENANCE, LAND 
INTERACTION IS BEGINNING TO DOMINATE, IMPACTING THE LOW-LEVEL INFLOW 
AND RESULTING IN STRUCTURAL DISRUPTION OF THE VORTEX. SUBSEQUENTLY, A 
SHARPER DECLINE IN INTENSITY IS FORECAST AS THE CORE TRAVERSES NORTHERN 
LUZON ON A NORTHEASTWARD TRAJECTORY. SHORTLY AFTER TAU 12, THE SYSTEM 
IS EXPECTED TO REEMERGE OVER OPEN WATER NORTHEAST OF LUZON, WITH 
MAXIMUM SUSTAINED WINDS REDUCING TO 45-50 KTS. THEREAFTER, TY 11W WILL 
TRACK NORTHEASTWARD ALONG THE EASTERN FLANK OF THE GYRE, SKIRTING THE 
NORTHWESTERN PERIPHERY OF A NEAR-EQUATORIAL RIDGE (NER) TO THE 
SOUTHEAST. BY TAU 36, THE SYSTEM IS FORECAST TO GRADUALLY DECOUPLE 
FROM THE DEEP CONVECTION, SLOW DOWN, AND BEGIN INTEGRATING INTO THE 
WESTERLY COMPONENT OF THE BROADER GYRE. BY THE END OF THE FORECAST 
PERIOD, TY 11W IS EXPECTED TO TRANSITION INTO AN OPEN WAVE, WITH 
RESIDUAL WINDS OF 25-30 KTS EMBEDDED WITHIN THE MONSOON GYRE FLOW 
FIELD.

MODEL DISCUSSION: DETERMINISTIC TRACK MODEL GUIDANCE SHOWS GOOD
CONSENSUS THROUGH TAU 24, WITH A CROSS-TRACK SPREAD OF APPROXIMATELY 
40 NM AT LANDFALL OVER LUZON, EXPANDING TO 60 NM BY TAU 24. BEYOND TAU 
24, MODEL DISPERSION INCREASES SIGNIFICANTLY, PRIMARILY DUE TO 
VARIATIONS IN HOW GUIDANCE DEPICTS THE INTERACTION AND SUBSEQUENT 
ABSORPTION OF TY 11W INTO THE LARGER-SCALE MONSOON GYRE. GALWEM 
CONTINUES TO DEPICT A MORE WESTWARD DEFLECTION, WHEREAS MAJORITY OF 
THE GUIDANCE ENVELOPE MAINTAINS A CONSISTENT NORTHEASTWARD TRACK. THE 
JTWC OFFICIAL TRACK FORECAST IS LAID CLOSE TO THE MULTI-MODEL 
CONSENSUS, BUT ACKNOWLEDGES THE UNCERTAINTY DUE TO THE WIDENING 
ENVELOPE OF SOLUTIONS. INTENSITY GUIDANCE IS IN BETTER ALIGNMENT, WITH 
CONSENSUS INDICATING STEADY WEAKENING THROUGH TAU 48, WITH 15 KTS 
GUIDANCE SPREAD. DETERMINISTIC GFS GUIDANCE IS CURRENTLY THE MOST 
CONSERVATIVE, WITH 25 KTS INTENSITY AT TAU 48, WHILE OTHER MEMBERS OF 
THE CONSENSUS OSCILLATE CLOSER TO 30-35 KTS. AFTER TAU 36 HOWEVER, 
MODEL CONSISTENCY DEGRADES AS THE SYSTEM BECOMES NON-DISCRETE AND 
MERGES INTO THE LARGER GYRE CIRCULATION ENVIRONMENT.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM//
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