WDXS31 PGTW 141500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 19S (FABIEN) WARNING NR 
002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 4.7S 81.1E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 533 NM EAST-NORTHEAST OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: WESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 22 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
RAPIDLY CONSOLIDATING AND INTENSIFYING SYSTEM, WITH BROAD OUTER
BANDS WRAPPING INTO A SMALL, DEVELOPING CENTRAL DENSE OVERCAST. A
141036Z SSMIS 91GHZ MICROWAVE IMAGE SHOWS A WELL-DEFINED BAND OF
DEEP CONVECTION WRAPPING UP THE WESTERN SIDE OF THE CORE OF THE
SYSTEM, AND A DEVELOPING MICROWAVE EYE FEATURE. THE 37GHZ IMAGE
ALSO SHOWED A NASCENT MICROWAVE EYE, WHICH SUPPORTS THE ASSESSMENT
OF RAPID INTENSIFICATION. LATE RECEIPT OF A 141317Z SSMIS
COLOR-ENHANCED 37GHZ IMAGE REVEALS A CYAN RING FEATURE AND
WELL-DEFINED MICROWAVE EYE. THE INITIAL POSITION IS ASSESSED WITH
MEDIUM CONFIDENCE BASED ON AN EXTRAPOLATION OF THE LOW-LEVEL
MICROWAVE EYE IN THE 37GHZ MICROWAVE IMAGE NOTED ABOVE. THE INITIAL
INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A BLEND OF
THE AGENCY DVORAK CURRENT INTENSITY ESTIMATES RANGING BETWEEN T3.0
AND T4.0, ALONG WITH THE CIMSS ADT, DEEP MICRONET AND OPEN-AIIR,
THE LATER OF WHICH ESTIMATED THE INTENSITY AT 59 KNOTS. ANALYSIS
REVEALS A FAVORABLE ENVIRONMENT, WITH LOW (5-10 KTS) VWS, GOOD
RADIAL OUTFLOW ALOFT AND WARM SSTS. THE SYSTEM IS CURRENTLY
TRACKING WEST-SOUTHWEST ALONG THE NORTHERN SIDE OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) TO THE SOUTH.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: NORTHERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) TO THE SOUTH. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   KNES: T4.0 - 65 KTS
   FMEE: T3.0 - 45 KTS
   CIMSS ADT: 43 KTS AT 141230Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE RADIAL

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: THROUGH THE NEXT 48 HOURS, TC 19S (FABIEN) IS
FORECAST TO CONTINUE TRACKING TOWARDS THE WEST-SOUTHWEST ALONG THE
NORTHERN SIDE OF A STR WHICH EXTENDS EAST-WEST ALONG THE 15TH
LATITUDE TO THE SOUTH. THE PASSAGE OF AN UPPER-LEVEL MID-LATITUDE
TROUGH BY TAU 72 WILL BREAK THE STEERING RIDGE AND CREATE AN
OPPORTUNITY FOR THE SYSTEM TO TURN MORE POLEWARD. CONSISTENT WITH
THE PREVIOUS FORECAST, THERE ARE SIGNIFICANT DIFFERENCES BETWEEN
THE US AND EUROPEAN MODELS ON THE STRENGTH OF THE TROUGH AND HOW
MUCH OF AN INFLUENCE IT WILL HAVE ON THE TRACK OF TC 19S. IN THE
ECMWF SOLUTION, THE TROUGH PASSES SAFELY TO THE SOUTH WITH LITTLE
INFLUENCE ON TC 19S OTHER THAN A SLOWING OF THE TRACK SPEED AS IT
TRACKS SOUTHWEST THROUGH THE LATER PORTIONS OF THE FORECAST PERIOD.
BASED ON ANALYSIS OF THE CURRENT GLOBAL MODEL FIELDS, THE ECMWF
SOLUTION IS THE MORE LIKELY SCENARIO. IN THE GFS ALTERNATE
SCENARIO, THE TROUGH IS MUCH DEEPER, RESULTING IN TC 19S PERFORMING
A SHARP TURN POLEWARD AND THEN SOUTHEASTWARD AHEAD OF THE TROUGH.
WITH MODERATE RADIAL OUTFLOW ALREADY ESTABLISHED, THE SYSTEM HAS
ALREADY RAPIDLY INTENSIFIED. GOING FORWARD, DEVELOPMENT OF A STRONG
POLEWARD OUTFLOW CHANNEL IN THE NEXT 48 HOURS WILL SUPPORT
CONTINUED RAPID INTENSIFICATION. THE PRESENCE OF THE CYAN RING
FEATURE IN THE MICROWAVE IMAGERY PROVIDES ADDITIONAL CONFIDENCE IN
THE NEAR-TERM PROBABILITIES OF RI. THE FORECAST CALLS FOR A PEAK OF
100 KNOTS BY TAU 48. AFTER THIS POINT, UPPER-LEVEL OUTFLOW IS
EXPECTED TO WEAKEN SLIGHTLY, ACCOMPANIED BY MODERATELY INCREASED
SHEAR AND SOME MID-LEVEL DRY AIR ENTRAINMENT, WHICH WILL LEAD TO A
SLOW WEAKEN TREND THROUGH THE REMAINDER OF THE FORECAST PERIOD. 

MODEL DISCUSSION: TRACK GUIDANCE REMAINS HIGHLY UNCERTAIN, WITH
SIGNIFICANT SPREAD OVER 750NM OF CROSS-TRACK SPREAD BETWEEN THE
UKMET ENSEMBLE AND GFS OUTLIERS. THE UKMET ENSEMBLE, UKMET, NAVGEM
AND THE CONSENSUS MEAN ARE GROUPED TOGETHER ON A SOUTHWESTWARD
TRACK THROUGH THE FORECAST PERIOD. MEANWHILE THE REMAINDER OF THE
CONSENSUS MEMBERS ARE GROUPED TOGETHER ON A MORE POLEWARD TRACK
FURTHER TO THE EAST. HOWEVER, THE HWRF, GFS AND GFS ENSEMBLE
TRACKERS SPLIT OFF FROM THIS GROUP AROUND TAU 48, TAKING THE SYSTEM
SHARPLY EASTWARD THEN SOUTHEASTWARD THROUGH THE REMAINDER OF THE
FORECAST. THE GEFS AND ECENS ENSEMBLES ALSO SHOW LARGE SPREAD
AMONGST THE MEMBERS, PARTICULARLY AFTER TAU 48, LEADING TO HIGH
UNCERTAINTY IN THE EXTENDED FORECAST. THE JTWC FORECAST REMAINS
CONSISTENT WITH THE PREVIOUS FORECAST, AND LIES EAST AND SOUTH OF
THE CONSENSUS MEAN THROUGH THE FORECAST PERIOD. INTENSITY GUIDANCE
IS ALSO HIGHLY UNCERTAIN, WITH A LARGE SPREAD IN PEAK INTENSITIES
BETWEEN 60 AND 110 KNOTS. HWRF AND COAMPS-TC (GFS) MARK THE LOW END
OF THE INTENSITY SPREAD DUE TO THEIR QUICK TURN TO THE EAST, MOVING
THE SYSTEM INTO HIGHER SHEAR ENVIRONMENTS. MEANWHILE THE DECAY
SHIPS AND COAMPS-TC (NAVGEM), ALONG WITH NUMEROUS RI AIDS (DTOPS,
RIPA, RICN, AND RI25 TO RI45) SUPPORT THE HIGHER PEAK INTENSITY
BETWEEN 100-110 KNOTS. DUE TO THE RECENT RI TRENDS, THE JTWC
FORECAST TRACKS THE RI AIDS TRENDS TO A PEAK OF 100 KNOTS AT TAU
48, THEN TRACKS THE DECAY SHIPS THROUGH THE REMAINDER OF THE
FORECAST. 

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