WDXS31 PGTW 310300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 19S (FYTIA) WARNING NR 
004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.0S 44.8E
   INITIAL INTENSITY: 100 KTS
   GEOGRAPHIC REFERENCE: 233 NM NORTHWEST OF ANTANANARIVO,
MADAGASCAR
   MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 23 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL CYCLONE (TC) 19S (FYTIA) HAS CONTINUED TO IMPROVE
STRUCTURALLY OVER THE PAST SIX HOURS. THE WELL DEFINED EYE FEATURE
HAS CLEARED AND TEMPERATURES WITHIN THE EYE HAVE WARMED AS DEPICTED
VIA ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY. THE EASTERN
SIDE OF THE CIRCULATION SHOWS SOME SIGNS OF DEGRADATION DUE TO
INTERACTION WITH TOPOGRAPHICAL FEATURES. THOUGH THERE IS SOME TILT
TO THE STRUCTURE, THE LOW LEVEL CIRCULATION CENTER (LLCC) REMAINS
WELL ALIGNED WITH DEEP CONVECTIVE ACTIVITY. THE INITIAL POSITION IS
PLACED WITH HIGH CONFIDENCE BASED ON ANIMATED EIR IMAGERY OF THE
WELL DEFINED EYE FEATURE. THE INITIAL INTENSITY OF 100 KTS IS
ASSESSED WITH HIGH CONFIDENCE BASED ON A OBJECTIVE ESTIMATES AND
AGENCY FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: 1848Z METOP-B SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: NEAR EQUATORIAL RIDGE (NER) POSITIONED
TO THE NORTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   CIMSS SATCON: 89 KTS AT 310000Z
   CIMSS ADT: 102 KTS AT 310000Z
   CIMSS AIDT: 102 KTS AT 310000Z
   CIMSS D-MINT: 87 KTS AT 302210Z
   CIMSS D-PRINT: 90 KTS AT 310000Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL
   OTHER FACTORS: LANDFALL

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: INITIAL INTENSITY HAS INCREASED SINCE
LAST FORECAST AND PRIOR TO LANDFALL

FORECAST DISCUSSION: TC FYTIA WILL CONTINUE TRACKING SOUTHEASTWARD
UNDER THE INFLUENCE OF A NEAR EQUATORIAL RIDGE TO THE NORTH AND IS
EXPECTED TO SOON MAKE LANDFALL OVER THE WESTERN PORTION OF
MADAGASCAR. WHILE IT WILL RETAIN SOME OF ITS STRUCTURE WHILE
TRACKING INLAND, A QUICKER WEAKENING TREND WILL INITIATE AS HIGHER
TOPOGRAPHY CHIPS AWAY AT THE CORE. THIS WILL BRING THE INTENSITY OF
THE STORM DOWN TO 50 KTS AT TAU 12 AND FURTHER TO 35 KTS AT TAU 24.
TC FYTIA WILL THEN RE-EMERGE AS A WEAKENED CIRCULATION ALONG THE
EASTERN COAST OF MADAGASCAR AND VENTURE OUT INTO THE SOUTHERN
INDIAN OCEAN. THE RE-EMERGENCE WILL COINCIDE WITH THE START OF A
HANDOFF IN STEERING MECHANISM BETWEEN THE NEAR EQUATORIAL RIDGE TO
THE NORTH AND A SUBTROPICAL RIDGE OVER THE CENTRAL INDIAN OCEAN.
WARM SEA SURFACE TEMPERATURES (29 C TO 30 C) WILL FACILITATE A
STRENGTHENING TREND ALONG WITH GOOD OUTFLOW, BUT THIS SHORT LIVED
TREND WILL BE HINDERED BY INCREASING SHEAR AND DRY AIR ENTRAINMENT.
THE FORECAST TRACK PUTS THE CIRCULATION ON A HEAD ON COURSE TOWARDS
THE SUBTROPICAL JET RESULTING IN A COMPLETED SUBTROPICAL TRANSITION
BY TAU 120.

MODEL DISCUSSION: CROSS TRACK SPREAD AMONGST MODEL GUIDANCE IS
UNDER 50 NM FOR THE MAJORITY OF THE FORECAST PERIOD, EXCLUDING
INTERPOLATIONS OF NAVGEM. THE JTWC FORECAST TRACK IS PLACED CLOSE
TO THE MULTI MODEL CONSENSUS BUT FAVORS TIMING EXCLUDING NAVGEM
INFLUENCE AND IS ASSESSED WITH HIGH CONFIDENCE. INTENSITY GUIDANCE
SPREAD IS CLOSE TO 100 KTS, WITH MODELS STRUGGLING TO RESOLVE
TOPOGRAPHIC INTERACTION AND THE ASSOCIATED RATE OF WEAKENING. THE
JTWC FORECAST INTENSITY IS PLACED SLIGHTLY BELOW THE MULTI MODEL
CONSENSUS FOR THE FIRST 24 HOURS AND THEN REFLECTS VALUES IN LINE
WITH THE CONSENSUS FOR THE REMAINDER OF THE FORECAST PERIOD. THE
FORECAST INTENSITY IS PLACED WITH MEDIUM CONFIDENCE BASED ON
DETERMINISTIC AND ENSEMBLE MODELS AGREEING ON WEAKENING AND
RE-STRENGTHENING TRENDS, BUT CONSIDERING THE UNCERTAINTY ASSOCIATED
WITH POST-LANDFALL INTENSIFICATION INITIAL CONDITIONS.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   TRACK 72-120 HR: HIGH
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: LOW//
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