WDPN32 PGTW 250900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 23W (KONG-REY) 
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.1N 144.1E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 96 NM NORTH-NORTHWEST OF ANDERSEN AFB
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 18 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL DEPRESSION (TD) 23W (KONG-REY) IS A HIGHLY ASYMMETRICAL,
SMALL VORT MAX ON THE NORTHERN PERIPHERY OF A MONSOON GYRE-LIKE
FEATURE. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A
COMPLEX, IRREGULAR AND DISORGANIZED LOW LEVEL CIRCULATION CENTER
(LLCC), WITH THE MAIN VORTEX RACING OFF TO THE NORTHEAST AND THREE
SMALLER SPINNERS IN A LINE EXTENDING FROM WEST TO SOUTH OF THE MAIN
VORTEX. ONLY WITH THE AVAILABILITY OF RADAR DATA FROM GUAM HAS THE
MAIN VORTEX HAS BEEN ABLE TO BE TRACKED THROUGH THE DAY. EARLIER
ASCAT AND OTHER SCATTEROMETER DATA SHOWED THE HIGHLY ASYMMETRIC
WIND FIELD ASSOCIATED WITH TD 23W, WITH LIGHT WINDS LESS THAN 15
KNOTS ACROSS THE SOUTHERN SIDE OF THE LLCC, WHILE WINDS TO THE
NORTH AND NORTHEAST EXCEED 35-40 KNOTS. THESE VALUES WERE VERIFIED
BY SHIP OBSERVATIONS OF ESE WINDS OF 40 KNOTS NEAR 16.5N, BY
SUSTAINED GALE FORCE WINDS WITH GUSTS NEAR 50 KNOTS AT SAIPAN, AND
RELATIVELY LIGHT WINDS OF 10-15 KNOTS AT ANDERSEN AB GUAM, AS THE
SYSTEM PASSED BETWEEN GUAM AND ROTA EARLIER TODAY. AFTER PASSING
THROUGH THE MARIANAS, THE SYSTEM PUT THE PEDAL DOWN, ACCELERATING
FROM 8 KNOTS TO 18 KNOTS IN JUST SIX HOURS. ANIMATED WATER VAPOR
IMAGERY SHOWS A LARGE UPPER-LEVEL LOW TO THE WEST-SOUTHWEST OF TD
23W. THIS FEATURE IS ENTRAINING SIGNIFICANT DRY AIR INTO THE SOUTHERN 
PORTION OF THE ROTATION ASSOCIATED WITH TD 23W AS WELL AS BRINGS 
STRONG SOUTHEASTERLY FLOW ALOFT OVER TOP OF TD 23W, WITH SHEAR 
CURRENTLY ESTIMATED AROUND 25-30 KNOTS. SO, WHILE SSTS REMAIN WARM 
AND POLEWARD OUTFLOW IS STRONG, THE COMBINATION OF DRY AIR AND
HIGH SHEAR RESULT IN AN UNFAVORABLE ENVIRONMENT FOR THE MOMENT.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: TIGHT GRADIENT BETWEEN AN EXTENSION OF
THE SUBTROPICAL RIDGE TO THE EAST AND THE STRONG UPPER-LEVEL LOW TO
THE SOUTHWEST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   RJTD: T1.5 - 25 KTS
   CIMSS SATCON: 32 KTS AT 250348Z
   CIMSS ADT: 29 KTS AT 250530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 25-30 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THE PEAK INTENSITY AT THE END OF THE
FORECAST HAS BEEN INCREASED BY 20 KNOTS WITH THE INTRODUCTION OF
THE POSSIBILITY OF RAPID INTENSIFICATION. 

FORECAST DISCUSSION: TD 23W WILL CONTINUE TO RAPIDLY TRACK
NORTHWESTWARD FOR ANOTHER 12 HOURS, BEFORE THE PRIMARY STEERING
MECHANISM SHIFTS TO THE STR SITUATED TO THE NORTH, WHICH WILL
RESULT IN A GRADUAL TURN TO A MORE WESTWARD TRACK FROM TAU 24 TO
TAU 36. AFTER TAU 36, A STRONG STR IS FORECAST TO BUILD OVER
TAIWAN AND ASSUME THE PRIMARY STEERING ROLE, PUSHING TD 23W ONTO A
SLIGHTLY WEST-SOUTHWESTWARD TRACK FROM TAU 48 TO 72. BY TAU 72, THIS
STR OVER TAIWAN WILL SLIDE SOUTHWESTWARD AND WEAKEN, OPENING UP A
BREAK IN THE RIDGE TO THE NORTH OF TD 23W. AT THE SAME TIME, THE
STR CENTERED TO THE NORTHEAST OF THE MARIANAS WILL BUILD AND BECOME
THE DOMINANT STEERING INFLUENCE ON TD 23W AFTER TAU 72, AND TD 23W
WILL TURN ONTO A NORTHWESTWARD TRACK AFTER THIS POINT, CONTINUING
IN THIS DIRECTION THROUGH THE REMAINDER OF THE FORECAST PERIOD. IN
TERMS OF INTENSITY, THE UNFAVORABLE SHEAR CONDITIONS AND DRY AIR
ENTRAINMENT ARE EXPECTED TO PERSIST FOR THE NEXT 24 TO 36 HOURS AS
THE UPPER-LEVEL LOW REMAINS POSITIONED TO THE SOUTHWEST OF TD 23W.
THE LOW IS FORECAST TO STEADILY MOVE SOUTHWESTWARD AND FILL SUCH
THAT BY TAU 36 IT WILL HAVE DISAPPEARED FROM THE SCENE. THIS WILL
PUT TD 23W INTO A MORE FAVORABLE UPPER-LEVEL PATTERN, ALLOWING FOR
VORTEX CONSOLIDATION AND INTENSIFICATION BEGINNING JUST AFTER TAU
36. INCREASED DEEP-LAYER MOISTURE WILL SUPPORT INCREASED
CONVECTION, ALLOWING THE SYSTEM TO STEADILY INTENSIFY THROUGH TAU
96, EVEN IN THE FACE OF A RESUMPTION OF MODERATELY STRONG
SOUTHEASTERLY ENVIRONMENTAL FLOW. THE SYSTEM BEGINS TAPPING INTO A
POLEWARD OUTFLOW CHANNEL BY THE END OF THE FORECAST, WHICH WILL
ALLOW FOR A MORE SIGNIFICANT BOUT OF INTENSIFICATION, UP TO AT
LEAST 75 KNOTS AND POTENTIALLY MUCH MORE.  

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN GENERAL
AGREEMENT ON THE OVERALL FORECAST SCENARIO, HOWEVER, THE GUIDANCE
SHOWS FAIRLY SIGNIFICANT SPREAD IN CROSS-TRACK SPREAD, EVEN AS
EARLY AS TAU 72. THE GFS TRACKS THE SYSTEM SOUTH OF 16N AFTER TAU
48, MARKING THE SOUTHERN OUTLIER OF THE MODEL TRACKERS. THE NAVGEM
MEANWHILE KEEPS THE SYSTEM NORTH OF 20N BY TAU 72, MARKING THE
NORTHERN OUTLIER. THE SPREAD BETWEEN THESE TWO OUTLIERS REACHES
255NM BY TAU 72. THEREAFTER, THE NAVGEM TURNS THE SYSTEM SHARPLY
POLEWARD AFTER TAU 96, WITH THE TAU 120 POSITION NEAR MINAMI DAITO
JIMA. THE GFS IS MUCH SLOWER TO TURN THE SYSTEM AND THE TAU 120
POSITION IS NEAR 19N 128E, GENERATING A 510NM SPREAD BETWEEN THE
OUTLIERS. THE ECMWF GENERALLY TAKES A TRACK CLOSELY RESEMBLING THE
CONSENSUS MEAN THROUGH TAU 72, THEN TAKES A SLIGHTLY WIDER TURN,
SITTING SOUTH OF OKINAWA AT TAU 120. THE JTWC FORECAST MOST CLOSELY
TRACES THE GEFS ENSEMBLE MEAN AND LIES ON THE SOUTHERN EDGE OF THE
GUIDANCE ENVELOPE THROUGH TAU 72, THEN ON THE WESTERN SIDE THROUGH
TAU 120. CONFIDENCE IS MEDIUM, DECREASING TO LOW IN THE EXTENDED
FORECAST. INTENSITY GUIDANCE IS IN SOLID AGREEMENT THAT THE SYSTEM
WILL REMAIN FLAT IN TERMS OF INTENSITY FOR THE FIRST 36 HOURS OR
SO, BEFORE RAMPING UP SHARPLY AFTER TAU 48. THE HAFS-A SHOWS AN
EXTREMELY RAPID INTENSIFICATION WITH INTENSITY INCREASING FROM 40
KNOTS TO 110 KNOTS BETWEEN TAU 48 AND TAU 96. THE REMAINDER OF THE
GUIDANCE SHOWS INTENSIFICATION, ALBEIT AT A SLOWER PACE. THE
COAMPS-TC ENSEMBLE INTENSITY PROBABILITIES SHOW A 70 PERCENT CHANCE
OF RI IN THE EXTENDED FORECAST. HOWEVER, THIS IS THE FIRST RUN OF
THIS MODEL WITH THIS STORM AND THUS NEEDS TO BE EVALUATED CLOSELY, AND
THE POSSIBILITY OF RI AS THE SYSTEM RECURVES IS A DISTINCT
POSSIBILITY. 


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