WDPN33 PGTW 240900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 11W (CO-MAY) WARNING NR 006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.9N 119.3E
   INITIAL INTENSITY: 70 KTS
   GEOGRAPHIC REFERENCE: 126 NM NORTHWEST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 22 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS PERSISTENT
SPIRAL BANDS OF DEEP CONVECTION ASSOCIATED WITH TYPHOON (TY) 11W
(CO-MAY). THE SYSTEM IS LOCATED WITHIN THE SOUTHWESTERN PERIPHERY
OF A LARGE-SCALE MONSOON GYRE CIRCULATION. THE GYRE AXIS IS ORIENTED
NEARLY PARALLEL TO THE SOUTHEASTERN COASTLINE OF CHINA, WITH THE
CENTRAL POINT OF ROTATION LOCATED TO THE SOUTHEAST OF TAIWAN. THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON A 240508Z
ATMS MICROWAVE PASS IN CONJUNCTION WITH THE ANIMATED VISIBLE IMAGERY 
SHOWING RECENT FLARE-UPS OF OVERSHOOTING TOPS AT THE FOCAL POINT OF THE 
CONVECTIVE BANDING. THE INITIAL INTENSITY OF 70 KTS IS ASSESSED WITH 
LOW CONFIDENCE BASED ON A COMBINATION OF AGENCY DVORAK FIXES AND 
OBJECTIVE ESTIMATES INDICATING POTENTIAL TYPHOON LEVEL STRENGTH 
INTENSITIES. ADDITIONAL ENVIRONMENTAL ANALYSIS REVEALS MARGINAL 
CONDITIONS, WITH WARM (29-30 C) SEA SURFACE TEMPERATURES (SST), STRONG 
EQUATORWARD AND POLEWARD OUTFLOW, ABUNDANCE OF DEEP-LAYER MOISTURE, LOW 
(5-10 KTS) VERTICAL WIND SHEAR (VWS), OFFSET HOWEVER BY INCREASING 
SIGNIFICANT FRICTIONAL EFFECTS OF LAND INTERACTION.

INITIAL WIND RADII BASIS: A 240212 METOP-C ASCAT PASS

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: T3.0 - 45 KTS
   KNES: T3.5 - 55 KTS
   DEMS: T4.0 - 65 KTS
   CIMSS SATCON: 67 KTS AT 240507Z
   CIMSS ADT: 69 KTS AT 240630Z
   CIMSS AIDT: 63 KTS AT 240730Z
   CIMSS D-MINT: 52 KTS AT 240533Z
   CIMSS D-PRINT: 57 KTS AT 240730Z

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

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: LOW
   INITIAL WIND RADII: MEDIUM

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TY 11W IS CURRENTLY IN THE PROCESS OF
FINISHING A COUNTERCLOCKWISE TRACK LOOP, WHILE APPROACHING THE WESTERN
COAST OF LUZON, PHILIPPINES. OTHERWISE FAVORABLE ENVIRONMENTAL
CONDITIONS ARE BEGINNING TO BE FULLY OFFSET BY THE PROXIMITY OF
LAND AND THE WIND FIELD INTERACTION WITH THE TERRAIN, AS THE SYSTEM
APPROACHES LAND. THE LIKELY PEAK INTENSITY OF 70 KTS IS FORECAST
TO BE GRADUALLY REDUCED OVER THE NEXT 12 HOURS, FOLLOWED BY A MORE
DRASTIC WEAKENING AS THE SYSTEM HEADS NORTHEASTWARD AND CROSSES THE
ISLAND, WHILE ACCELERATING. WITHIN 24 HOURS, TY 11W IS EXPECTED TO
REEMERGE NORTHEAST OF LUZON, WITH MAXIMUM WINDS EXPECTED AROUND 50
KTS. AFTERWARD, THE SYSTEM WILL CONTINUE ON A NORTHEASTWARD TRACK
ALONG THE EASTERN PERIPHERY OF THE GYRE AND THE NORTHWESTERN EDGE
OF A NER TO THE SOUTHEAST. AROUND TAU 48, TY 11W IS FORECAST TO
SLOW DOWN AND BEGIN TURNING NORTHEASTWARD AS IT BECOMES ABSORBED
INTO THE BELT OF WESTERLIES ASSOCIATED WITH THE MONSOON GYRE. AT
THE END OF THE FORECAST PERIOD, TY 11W WILL BECOME A WAVE, AS
OPPOSED TO A DISCRETE TROPICAL SYSTEM, WITH ELEVATED (25-30 KTS)
WINDS ASSOCIATED WITH THE GYRE.

MODEL DISCUSSION: DETERMINISTIC TRACK MODEL GUIDANCE IS IN FAIR
AGREEMENT THROUGHOUT THE FORECAST, AS WITNESSED BY 50 NM CROSS-TRACK 
SPREAD AT TAU 12, AROUND THE TIME OF LANDFALL OVER LUZON, EXPANDING TO 
90 NM UPON REEMERGENCE 12 HOURS LATER. THE GUIDANCE SPREAD INCREASES 
SIGNIFICANTLY AFTER TAU 24, WITH GALWEM SUGGESTING A NORTHWESTWARD 
TURN, WHILE GFS IS TRACKING NORTHEASTWARD THROUGHOUT THE FORECAST 
PERIOD. TRACK GUIDANCE UNCERTAINTY CAN BE ATTRIBUTED TO HOW DIFFERENT 
MODELS HANDLE THE TIMELINE AND INTENSITY CHANGE ASSOCIATED WITH THE 
SYSTEM BEING ABSORBED INTO THE LARGER GYRE CIRCULATION. JTWC TRACK 
FORECAST IS LAID CLOSER TO THE GUIDANCE FROM THE DETERMINISTIC GFS, 
HOWEVER, GIVEN THE LARGE CROSS-TRACK SPREAD, UNCERTAINTY REMAINS HIGH. 
INTENSITY GUIDANCE IS IN BETTER AGREEMENT, WITH ALL CONSENSUS MEMBERS
CURRENTLY PREDICTING STEADY WEAKENING THROUGH TAU 48. AT THAT TIME,
THE INTENSITY SPREAD IS JUST 10 KTS, BETWEEN THE LOWEST HAFS OF 25
KTS AND COAMPS-TC AT 35 KTS. AFTER THAT, UNCERTAINTY INCREASES,
WITH MAJORITY OF THE MODELS PREDICTING STABILIZATION OF INTENSITY, OR 
EVEN SLIGHT INCREASES, AS THE SYSTEM ESSENTIALLY DISSOLVES INTO THE
LARGER CIRCULATION.

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