WDXS31 PGTW 152100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 19S (FABIEN) WARNING NR 
007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 6.0S 76.7E
   INITIAL INTENSITY: 90 KTS
   GEOGRAPHIC REFERENCE: 259 NM EAST-NORTHEAST OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 37 FEET

SATELLITE ANALYSIS, INITIAL POSITION, AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED SATELLITE IMAGERY (EIR) DEPICTS A
COMPACT SYSTEM WITH RAGGED BANDS OF CONVECTION IN ALL QUADRANTS
WRAPPING INTO THE LOW LEVEL CIRCULATION CENTER (LLCC). A BULLSEYE
151609Z ASCAT-C PASS SHOWS A RELATIVELY SYMMETRICAL SYSTEM THAT HAS
TAKEN A SLIGHT JOG TO THE SOUTHWEST AS COMPARED TO THE PREVIOUS
ANALYSIS POSITIONS. IN ADDITION, EXAMINATION OF THE 151304Z M-PERC
EYEWALL REPLACEMENT TOOL SUGGESTS AN EYEWALL REPLACEMENT CYCLE
(ERC) HAS TAKEN PLACE. TC FABIEN IS IN A FAVORABLE ENVIRONMENT FOR
FURTHER TROPICAL DEVELOPMENT. THESE CONDITIONS ARE CHARACTERIZED BY
STRONG WESTWARD AND POLEWARD OUTFLOW ALOFT, AN IMPRESSIVE 850 MB
VORTICITY SIGNATURE, LOW (10-15 KTS) VERTICAL WIND SHEAR (VWS), AND
VERY WARM (28-29 C) SEA SURFACE TEMPERATURES (SST). THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON MULTI-AGENCY
FIXES, AS WELL AS THE AFOREMENTIONED ASCAT PASS. THE INITIAL
INTENSITY OF 90 KNOTS IS ASSESSED WITH HIGH CONFIDENCE BASED OFF A
BLEND OF MULTI-AGENCY DVORAK ESTIMATES AND A 151315Z RCM3 SAR PASS.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE
SOUTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   KNES: T5.0 - 90 KTS
   FMEE: T4.5 - 77 KTS
   CIMSS SATCON: 86 KTS AT 151606Z
   CIMSS ADT: 80 KTS AT 151900Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG WESTWARD AND POLEWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC 19S (FABIEN) IS RIDING THE NORTHWESTERN
PERIPHERY OF THE STR TO THE SOUTHEAST AND HAS APPEARED TO HAVE MADE
THE CHANGE IN TRAJECTORY TO THE SOUTHWEST. DURING TAUS 12 THROUGH
36, TC FABIEN WILL CONTINUE TO TRACK SOUTHWESTWARD AND STEADILY
INTENSIFY TO ITS PEAK INTENSITY OF 115 KTS BY TAU 36. BY THIS TIME,
THE STR TO THE SOUTHEAST WILL RECEDE AND THE STR OVER MADAGASCAR
WILL BECOME THE MAIN STEERING FEATURE. AS A RESULT, TC 19S WILL
CHANGE TO A WESTWARD TRACK BY TAU 48, OVER 100 NM SOUTH OF DIEGO
GARCIA. IN ADDITION, THE INTENSITY WILL BE ON A DECREASING TREND
DUE TO DRY AIR ENTRAINMENT FROM THE SOUTH WRAPPING INTO THE SYSTEM,
AS WELL AS UPWELLING THE STORM WILL BE PRODUCING BRINGING
RELATIVELY COOLER (26 C) SSTS TO THE SURFACE AS INDICATED BY THE
151200Z HWRF MODEL RUN. BETWEEN TAUS 72 AND 120, THE SYSTEM WILL
CHANGE IN TRAJECTORY TO THE WEST-NORTHWEST AS THE SYSTEM WILL
STRUGGLE BETWEEN THE STR OVER MADAGASCAR AND THE NEAR EQUATORIAL
RIDGE (NER) TO THE NORTHEAST. MOREOVER, THE INTENSITY WILL CONTINUE
TO STEADILY DECREASE TO 80 KNOTS BY TAU 120.

MODEL DISCUSSION: THE DETERMINISTIC AND ENSEMBLE MODELS ALL AGREE
THAT TC 19S WILL CONTINUE TO TRACK SOUTHWEST THROUGH TAU 48, THEN
TRACK WESTWARD AFTERWARDS. HOWEVER, BY TAU 72 AND BEYOND THERE IS
SOME UNCERTAINTY IN THE TRACK SOLUTIONS. THE JTWC FORECAST TRACK
CONSENSUS MEMBERS ARE IN GOOD AGREEMENT WITH TRACK SHOWING A 55 NM
SPREAD AT TAU 24 THAT GRADUALLY INCREASES TO 80 NM BY TAU 72.
NAVGEM IS THE OUTLIER SHOWING A MORE SOUTHERLY TRACK THAN A BULK OF
THE CONSENSUS MEMBERS. DUE TO THIS, THE JTWC TRACK IS PLACED WITH
MEDIUM CONFIDENCE SLIGHTLY RIGHT OF CONSENSUS THROUGH TAU 72, AND
LOW CONFIDENCE AFTERWARDS DUE TO THE SPORADIC BEHAVIOR OF THE
MODELS. IT SHOULD BE NOTED THAT THE COAMPS-TC AND HWRF TRACK
SOLUTIONS SHOW TC 19S HOOKING NORTHWARD, AND THEN BACK EASTWARD
JUST SOUTH OF DIEGO GARCIA IN THE LATER TAUS. THE JTWC INTENSITY
CONSENSUS MEMBERS ARE NOT IN GOOD AGREEMENT SHOWING A 40 KNOT
SPREAD BY TAU 24, MORE THAN LIKELY DUE TO THE RAPID INTENSIFICATION
TRIGGERS. HOWEVER, THEY DO AGREE WITH A DECREASING SCENARIO AFTER
TAU 36. THE JTWC INTENSITY FORECAST IS SET WITH MEDIUM CONFIDENCE
UP TO TAU 72, AND LOW CONFIDENCE IN THE LATER TAUS DUE TO THE
UNCERTAINTY OF TRACK PROGRESSION.

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