WDPN32 PGTW 212100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 05W (GAEMI) WARNING NR 
009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.0N 125.7E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 582 NM SOUTH-SOUTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 02 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS CYCLING DEEP
CONVECTION, WHICH AT THE MOMENT IS COMING OFF AN IMPRESSIVE BURST
OF ACTIVITY BUT IS RAPIDLY WANING. THE LOW LEVEL CIRCULATION CENTER
(LLCC) REMAINS DISPLACED TO THE NORTH-NORTHEAST FROM THE CENTER OF
THE CENTRAL DENSE OVERCAST (CDO) FEATURE, INDICATIVE OF PERSISTENT
NORTH-NORTHEASTERLY SHEAR AND A MISALIGNED VORTEX STRUCTURE. A
211651Z AMSR2 37GHZ MICROWAVE IMAGE SHOWED THAT, AT THAT TIME AT
LEAST, THE MOST INTENSE CONVECTION WAS DEVELOPING VERY CLOSE TO THE
LLCC, BUT COMPARING TO THE ANIMATED EIR, SHOWED THAT IT WAS SHEARED
OFF TO THE SOUTHWEST AS QUICKLY AS IT FORMED. A WEDGE OF DRY AIR
REMAINS STUBBORNLY IN PLACE, FROM THE SOUTHEAST WRAPPING UP TO THE
NORTHWEST OF THE LLCC, WHICH IS INHIBITING THE CONVECTION FROM
PUSHING OUT IN THAT DIRECTION. THE INITIAL POSITION IS ASSESSED
WITH HIGH CONFIDENCE BASED ON THE AMSR2 IMAGE NOTED ABOVE. THE
INITIAL INTENSITY IS INCREASED A NOTCH TO 55 KNOTS, WITH MEDIUM
CONFIDENCE, BASED ON A 1738Z DMINT ESTIMATE AND PERSISTENCE WITH A
SLOW BUT STEADY INTENSIFICATION TREND. THE LATEST CIMSS ANALYSIS
ESTIMATES SHEAR FROM 033 DEG AT 16 KNOTS, SLIGHTLY LOWER THAN THE
GFS MODEL ESTIMATED SHEAR BUT STILL TOO HIGH TO ALLOW FOR THE
SYSTEM TO SYMMETRIZE. THE ENVIRONMENT IS PRIMED, WITH VERY WARM
SSTS, HIGH OHC AND GOOD OUTFLOW (BEST TO EQUATORWARD). ALL THAT IS
NEEDED AT THIS POINT IS FOR THE SHEAR TO LESSEN AND THE VORTEX TO
ALIGN. THE SYSTEM HAS BEEN QUASI-STATIONARY OVER THE PAST 18 HOURS
AS A SMALL UPPER-LEVEL ANTICYCLONE DEVELOPED DUE NORTH OF THE
SYSTEM. EVEN STILL, WITH THE HIGH OHC, UPWELLING IS NOT HAVING A
SIGNIFICANT EFFECT ON THE SYSTEM. REANALYSIS OF A 210944Z RCM-1 SAR
PASS RESULTED IN A SIGNIFICANT INCREASE IN THE WIND RADII,
PARTICULARLY IN THE SOUTHEAST AND SOUTHWEST QUADRANTS, TO CAPTURE A
LONG FEEDER BAND WITH GALE- TO POTENTIALLY STORM-FORCE WINDS.

INITIAL WIND RADII BASIS: SAR DATA 

CURRENT STEERING MECHANISM: COMPETING STEERING PATTERN, WITH A
BLOCKING ANTICYCLONE ALOFT DUE NORTH OF THE SYSTEM AND RIDGING TO
THE SOUTH AND EAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T3.5 - 55 KTS
   RCTP: T3.5 - 55 KTS
   KNES: T3.5 - 55 KTS
   CIMSS SATCON: 44 KTS AT 211900Z
   CIMSS ADT: 44 KTS AT 211800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: STRONG EQUATORWARD
   OTHER FACTORS: MID-LEVEL DRY AIR TO THE EAST AND NORTH.

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: DUE TO THE PRESENCE OF THE BUBBLE-ANTICYCLONE
PARKED NORTH OF TS 05W, NO SIGNIFICANT MOVEMENT IS EXPECTED IN THE
NEAR-TERM (6 TO 12 HOURS). THE ECMWF GLOBAL MODEL IS THE ONLY MODEL
THAT SHOWS THIS ANTICYCLONE ALOFT, THE GFS HAVING COMPLETELY MISSED
IT. THE ECMWF SHOWS THE ANTICYCLONE MOVING RAPIDLY TO THE SOUTHWEST
AND WEAKENING OVER THE NEXT 12-24 HOURS, REPLACED BY A STRONGER,
NORTH-SOUTH ORIENTED RIDGE EXTENDING SOUTH FROM NEAR HONSHU TO 10N.
THE SOUTHERN PORTION OF THIS RIDGE IS EXPECTED TO BREAK OFF INTO A
STRONG ANTICYCLONE TO THE EAST OF TS 05W BY TAU 36. THIS WILL HELP
TS 05W TO FINALLY BREAK OUT OF ITS QUASI-STATIONARY POSITION AND
ACCELERATE IT NORTHWARD AFTER TAU 24. THE SYSTEM WILL START TO
GRADUALLY MOVE ONTO A MORE NORTHWESTWARD TRACK AFTER TAU 48,
TOWARDS A BREAK IN THE RIDGING PATTERN OVER EASTERN CHINA. THE
FORECAST CALLS FOR TS 05W TO TRACK JUST SOUTHWEST OF ISHIGAKIJIMA,
THEN CLIP TO NORTH TIP OF TAIWAN, BEFORE MAKING LANDFALL IN EASTERN
CHINA AROUND TAU 96, BEFORE MOVING FURTHER INLAND OVER EASTERN
CHINA. EVEN AS THE VORTEX REMAINS MISALIGNED IN THE VERTICAL DUE TO
THE PERSISTENT SHEAR, THE LOW-LEVEL VORTEX IS STEADILY
STRENGTHENING, AS SHOWN IN THE SAR PASS FROM 9 HOURS AGO. THE
FREQUENT BURSTS OF CONVECTION ARE HELPING TO SPIN UP THE VORTEX AS
WELL, THUS THE FORECAST CALLS FOR SLOW BUT STEADY INTENSIFICATION,
UP TO TYPHOON STRENGTH WITHIN THE NEXT 24 HOURS. THE LATEST SHIPS
GUIDANCE FOR THE FULL-RANGE OF MODELS, SHOWS A SHARP DROP-OFF IN
SHEAR BEGINNING BY TAU 18, WHICH HAS BEEN A PERSISTENT FEATURE IN
THE MODELS FOR SOME TIME. WITH THE ENVIRONMENT PRIMED AND READY TO
GO, THE DROP-OFF OF SHEAR WILL PRECIPITATE A PERIOD OF RAPID
INTENSIFICATION (RI) BEGINNING AT TAU 24. THE PEAK INTENSITY OF AT
LEAST 95 KNOTS IS EXPECTED BY TAU 72, AS SHEAR IS EXPECTED TO
RAPIDLY INCREASE AGAIN AFTER THIS POINT. THE SYSTEM IS EXPECTED TO
MAINTAIN INTENSITY AS IT CROSSES THE RYUKYUS, BUT THEN RAPIDLY
WEAKEN AS IT INTERACTS WITH THE ISLAND OF TAIWAN, IS IMPACTED BY
STRONG SHEAR AND MOVES INTO COOLER WATERS AS IT APPROACHES EASTERN
CHINA. AFTER MAKING LANDFALL, THE SYSTEM WILL RAPIDLY WEAKEN,
NEARING DISSIPATION BY TAU 120. 

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN GOOD
AGREEMENT, WITH A SPREAD OF 210NM AT TAU 72, INCREASING TO 413NM BY
TAU 120. SOME ALONG-TRACK SPREAD BEGINS TO SHOW UP AFTER TAU 72,
WITH THE GFS LAGGING WELL BEHIND THE REMAINDER OF THE CONSENSUS
GUIDANCE. THE CROSS-TRACK ENVELOPE IS DEFINED BY THE UKMET ENSEMBLE
MEAN ON THE LEFT AND THE GFS ENSEMBLE MEAN ON THE RIGHT, AND A
TIGHT GROUPING OF NAVGEM, GFS, ECMWF, HWRF, HAFS-A AND CTCX ON THE
RIGHT SIDE, CONSISTENT WITH THE JTWC FORECAST TRACK. THE FORECAST
IS SET WITH MEDIUM CONFIDENCE, ONLY DUE TO THE UNCERTAINTY IN THE
NEAR-TERM STORM MOTION AND WHEN IT WILL FINALLY KICK OUT TO THE
NORTH. INTENSITY GUIDANCE IS IN FAIR AGREEMENT, WITH THE BULK OF
THE GUIDANCE SHOWING SLOW INTENSIFICATION TO TAU 36 THEN A SHARP
INCREASE TO A PEAK BETWEEN TAU 48 AND TAU 72, FOLLOWED BY A RAPID
WEAKENING. THE HAFS-A AND CTCX REMAIN THE MOST AGGRESSIVE OF THE
GUIDANCE, PEAKING AT OR ABOVE 100 KNOTS, WHILE THE REMAINDER KEEP
THE PEAK CLOSER TO 90 KNOTS. ADDITIONALLY, THE FRIA, RICN, RI25,
RI35 AND RI45 RI AIDS ARE TRIGGERED WITH THIS RUN. SHORT-TERM RI IS
UNLIKELY DUE TO THE SHEAR, BUT RI IS LIKELY, JUST STARTING A BIT
LATER IN THE FORECAST. THE JTWC FORECAST LIES CLOSE TO THE
CONSENSUS MEAN TO TAU 24 THEN TRACKS THE HAFS-A TO THE PEAK AND THE
MEAN AGAIN TO THE END OF THE FORECAST. CONFIDENCE IS INCREASING BUT
REMAINS MEDIUM.  

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
NNNN