WDXS31 PGTW 162100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 19S (FABIEN) WARNING 
NR 011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 8.0S 74.3E
   INITIAL INTENSITY: 100 KTS
   GEOGRAPHIC REFERENCE: 120 NM EAST-SOUTHEAST OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 44 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
COMPACT SYSTEM WITH RAGGED BANDS OF CONVECTION WRAPPING INTO THE
LOW LEVEL CIRCULATION CENTER (LLCC). A 161323Z RCM3 SAR PASS
REVEALS THE SYSTEM HAS A SOMEWHAT ASYMMETRICAL 35 KNOT WIND FIELD
WITH AN AVERAGE DIAMETER OF 70 NM. EXAMINATION OF THE 161207Z
M-PERC EYEWALL REPLACEMENT TOOL SUGGESTS AN EYEWALL REPLACEMENT
CYCLE (ERC) MAY BE IN THE NEAR FUTURE. TC FABIEN IS IN A FAVORABLE
ENVIRONMENT FOR FURTHER TROPICAL DEVELOPMENT. THESE CONDITIONS ARE
CHARACTERIZED BY STRONG EQUATORWARD AND POLEWARD OUTFLOW ALOFT, A
PRONOUNCED 850 MB VORTICITY SIGNATURE, LOW (5-10 KTS) VERTICAL WIND
SHEAR (VWS), AND VERY WARM (28-29 C) SEA SURFACE TEMPERATURES
(SST). THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED
ON MULTI-AGENCY FIXES AND THE ABOVE MENTIONED EIR IMAGERY. THE
INITIAL INTENSITY OF 100 KNOTS IS ASSESSED WITH HIGH CONFIDENCE
BASED OFF A BLEND OF MULTI-AGENCY AND AUTOMATED DVORAK ESTIMATES,
AS WELL AS THE AFOREMENTIONED SAR PASS.

INITIAL WIND RADII BASIS: SAR DATA 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   KNES: T5.5 - 102 KTS
   FIMP: T5.5 - 102 KTS
   CIMSS SATCON: 94 KTS AT 161554Z
   CIMSS ADT: 110 KTS AT 161830Z

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

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC 19S (FABIEN) IS ROUNDING THE NORTHWESTERN
PERIPHERY OF THE STR TO THE SOUTHEAST. DURING TAUS 12 THROUGH 24,
TC FABIEN WILL CONTINUE TO TRACK SOUTHWESTWARD AND STEADILY
DECREASE IN INTENSITY TO 95 KTS. BY THIS TIME, THE STR TO THE
SOUTHEAST WILL RECEDE AND THE STR OVER MADAGASCAR WILL BECOME THE
DOMINATE STEERING FEATURE. AS A RESULT, TC 19S WILL ADJUST TO A
WESTWARD TRACK THROUGH TAUS 36 AND 48, WHILE CONTINUING TO DECREASE
IN INTENSITY TO 90 KNOTS AS A RESULT OF ENTERING A MORE HOSTILE
ENVIRONMENT FOR TROPICAL DEVELOPMENT. THIS ENVIRONMENT IS
CHARACTERIZED BY DRY AIR ENTRAINMENT FROM THE SOUTH WRAPPING INTO
THE SYSTEM, AN INCREASE IN MID-LEVEL WIND SHEAR, AND UPWELLING THE
STORM WILL BE PRODUCING BRINGING RELATIVELY COOLER (26 C) SSTS TO
THE SURFACE AS INDICATED BY THE 161800Z HWRF MODEL RUN. BETWEEN
TAUS 72 AND 96, THE SYSTEM WILL CHANGE IN TRAJECTORY TO THE
WEST-NORTHWEST AND SLOW DOWN IN TRACK SPEED AS IT 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 65 KNOTS BY TAU 120. 

MODEL DISCUSSION: THE DETERMINISTIC AND ENSEMBLE MODELS ALL AGREE
THAT TC 19S WILL CONTINUE TO TRACK SOUTHWEST THROUGH TAU 36, THEN
TRACK WESTWARD AFTERWARDS. HOWEVER, BY TAU 72 AND BEYOND THERE IS
SOME UNCERTAINTY IN THE TRACK SOLUTIONS. MOST DETERMINISTIC MODELS
SUGGEST A RECURVE SCENARIO BACK EASTWARD, WHERE AS THE ENSEMBLE
MODELS DO NOT SHOW THIS AT ALL. IN THE SHORT TERM, THE JTWC
FORECAST TRACK CONSENSUS MEMBERS ARE IN GOOD AGREEMENT SHOWING A 35
NM SPREAD AT TAU 12 THAT GRADUALLY INCREASES TO 72 NM BY TAU 48.
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. AS SEEN IN THE PAST SEVERAL MODEL RUNS, THE HIGH RESOLUTION
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 IN BETTER AGREEMENT
THAN PREVIOUS FORECASTS DISPLAYING A 30 KNOT SPREAD THROUGH TAU 24,
MORE THAN LIKELY DUE TO THE SMALL SIZE OF THE SYSTEM. HOWEVER, THEY
DO AGREE WITH A DECREASING SCENARIO AFTER TAU 12. 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//
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