WDPN33 PGTW 250300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (CO-MAY) WARNING NR 
009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.3N 120.8E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 162 NM NORTH OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: XX FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
THE LOW LEVEL CIRCULATION CENTER (LLCC) OF TS 11W APPEARS TO HAVE
MADE A SECOND LANDFALL, ALONG THE WESTERN COAST OF LUZON, IN THE
VICINITY OF LUNA, PHILIPPINES, AROUND THE 242000Z HOUR. HOWEVER,
THERE IS CONSIDERABLE UNCERTAINTY IN THIS ANALYSIS AS WELL AS THE
CURRENT POSITION OF THE LLCC DUE TO THE LACK OF NEARBY SURFACE
OBSERVATIONS, RADAR COVERAGE AND HIGHLY AMBIGUOUS SATELLITE DATA. A
242143Z WSF-M 89GHZ MICROWAVE IMAGE REVEALED AN UPPER-LEVEL
ROTATION LOCATED OFFSHORE TO THE SOUTHWEST OF VIGAN. HOWEVER, THE
37GHZ IMAGE REVEALED A MUCH MORE AMBIGUOUS STRUCTURE, WITH A
POTENTIAL LLCC ALREADY OVER LAND EAST OF LUNA. LATER ANIMATED MSI
SHOWED A WELL-DEFINED MID- TO UPPER-LEVEL ROTATION WEST OF THE
NORTHWEST TIP OF LUZON. ANALYSIS OF SURFACE OBSERVATIONS FROM
BAGUIO, VIGAN, AND LAOAG CITY STRONGLY SUPPORT A LLCC OVER
WEST-CENTRAL LUZON AT ANALYSIS TIME, BUT CONFIDENCE IS LOW. GFS AND
ECMWF MODEL SOUNDINGS SUGGEST STRONG (20-25KT) SOUTHEASTERLY
MID-LEVEL SHEAR, SUPPORTING THE ANALYSIS THAT THE VORTEX HAS
DECOUPLED, AND THE UPPER-LEVEL VORTEX HAS RAPIDLY PUSHED OFF TO THE
NORTHWEST SINCE LANDFALL. THE INITIAL INTENSITY IS ASSESSED WITH
LOW CONFIDENCE AS WELL, WITH THE ONLY AVAILABLE ESTIMATE BEING THE
D-PRINT, COMING IN AT 48 KNOTS. ENVIRONMENTAL CONDITIONS ARE
UNFAVORABLE, WITH SIGNIFICANT TERRAIN INTERACTION, VORTEX
DECOUPLING, MODERATE TO HIGH MID-LEVEL SHEAR AND DECREASING OUTFLOW
ALOFT.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SYSTEM IS EMBEDDED IN THE SOUTHERN
PERIPHERY OF A LARGE CYCLONIC ROTATION FROM OKINAWA TO LUZON, ROUGHLY 
CENTERED ON TAIWAN, WHILE TO THE EAST A DEEP-LAYER SUBTROPICAL RIDGE 
(STR) IS SITUATED OVER THE PHILIPPINE SEA.  

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE
   RJTD: T4.0 - 65 KTS
   RCTP: T5.0 - 90 KTS
   CIMSS D-PRINT: 48 KTS AT 250020Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 10-15 KTS
   SST: OVER LAND
   OUTFLOW: MODERATE POLEWARD
   OTHER FACTORS: WEAK EQUATORWARD OUTFLOW, MODERATE SOUTHEASTERLY
MID-LEVEL SHEAR AND TERRAIN INTERACTION. 

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: THE LLCC ASSOCIATED WITH TS 11W HAS SLOWED
DOWN AS IT HAS DECOUPLED FROM THE UPPER-LEVEL VORTEX AND INTERACTED
WITH THE HIGH ELEVATION TERRAIN NORTHEAST OF BAGUIO. AS THE SYSTEM
CROSSES THE CORDILLERA RANGE, IT IS LIKELY TO PERFORM A LEE-SIDE
JUMP, REFORMING ALONG THE NORTHERN COAST OF LUZON NEAR APARRI. THE
LEE-SIDE JUMP WILL OCCUR QUITE RAPIDLY ONCE IT STARTS. UPON
COMPLETION OF THE JUMP, TS 11W WILL START TO PICK UP SPEED AND IS
EXPECTED TO MOVE BACK OVER THE SOUTHERN LUZON STRAIT AND BE
POSITIONED JUST EAST OF THE BATANES ISLANDS BY TAU 12. THE SYSTEM
IS EXPECTED TO CONTINUE ACCELERATING ALONG THE GRADIENT BETWEEN THE
EASTERN SIDE OF THE LARGE CYCLONIC ROTATION TO THE WEST AND THE STR
TO THE EAST, WITH THE CENTER EXPECTED TO BE JUST SOUTH OF
ISHIGAKIJIMA BY TAU 24. PERSISTENT MODERATE TO STRONG SOUTHEASTERLY
SHEAR WILL CONTINUE TO WEAKEN THE SYSTEM AFTER IT MOVES BACK OVER
WATER, AND THE SYSTEM WILL AT THE SAME TIME START TO INTERACT WITH
THE LARGE CYCLONIC ROTATION CENTERED ON TAIWAN AND THE REMNANTS OF
TS 10W EMBEDDED WITHIN IT. THIS INTERACTION WILL PULL THE TRACK A
BIT MORE NORTHWARD FOR A TIME, BUT THE SYSTEM IS NOT EXPECTED TO BE
FULLY CAPTURED BY TS 10W. THE LLCC ASSOCIATED WITH TS 11W WILL
BROADEN OUT AS IT CONTINUES WEAKENING, WITH THE HIGHEST WINDS
LOCATED ON THE SOUTHEASTERN PERIPHERY OF THE CIRCULATION THROUGH
THE FORECAST PERIOD. BY TAU 36, THE SYSTEM TURNS EASTWARD IN THE
VICINITY OF OKINAWA AS THE LARGE CYCLONIC CIRCULATION REORIENTS AND
EVOLVES INTO A REVERSE ORIENTED MONSOON TROF, PULLING THE REMNANTS
OF TS 11W EASTWARD ALONG A BELT OF STRONG SOUTHWESTERLIES TO THE
SOUTH. 

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN SURPRISINGLY
GOOD AGREEMENT, THOUGH NONE OF THE GLOBAL MODELS ARE PICKING UP ON
THE RECENT ERRATIC TRACK MOTION AND POTENTIAL LEE-SIDE JUMP.
HOWEVER, ONCE THE LEE-SIDE JUMP IS COMPLETE, THE TRACK MOTION
SHOULD RESUME ITS OVERALL NORTHEASTWARD PROGRESSION AS IT COMES
UNDER THE INFLUENCE OF THE DEEP STEERING FLOW. THE JTWC FORECAST IS
POSITIONED CLOSE TO THE MULTI-MODEL CONSENSUS MEAN THROUGH THE
ENTIRE FORECAST PERIOD. INTENSITY GUIDANCE IS IN GOOD AGREEMENT ON
STEADY WEAKENING THROUGH THE FORECAST PERIOD, THOUGH MOST OF THE
MODELS DEPICT INTENSIFICATION BEGINNING AROUND TAU 48 AS THE
TRACKERS JUMP CIRCULATIONS TO A POTENTIAL NEW VORTEX THAT MAY
DEVELOP TO THE NORTHEAST OF OKINAWA. 

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