WDXS31 PGTW 311500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 19S (FYTIA) WARNING NR 
005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.1S 46.5E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 122 NM NORTH-NORTHWEST OF ANTANANARIVO,
MADAGASCAR
   MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: XX FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL CYCLONE (TC) 19S (NYTIA) MADE LANDFALL IN WESTERN
MADAGASCAR NEARLY 10 HOURS AGO (310200Z) AND HAS CONTINUED TO TRACK
SOUTHEASTWARD AND FARTHER INLAND. ALTHOUGH THE CYCLONE HAS BEEN
INTERACTING WITH MADAGASCARS RUGGED TOPOGRAPHY THROUGHOUT THE LAST
FEW HOURS, TC 19S HAS MAINTAINED A RELATIVELY UNIFORM CENTRAL
STRUCTURE, WITH SUPPORTIVE CONVECTIVE BANDS EXTENDING INTO THE
NORTHERN AND EASTERN SEMICIRCLES. THE EYE-FEATURE THAT WAS OBSERVED
ON ANIMATED MSI BEFORE LANDFALL HAS BECOME CLOUD-FILLED, OBSCURING
THE LOW-LEVEL CIRCULATION CENTER (LLCC). THE ENVIRONMENT HAS BEEN
ASSESSED AS UNFAVORABLE DUE TO PERSISTENT INTERACTION WITH
MADAGASCARS WESTERN DRY REGION AND INCREASING ELEVATION FROM THE
ANKARATRA MOUNTAINS TO THE EAST. TC 19S CONTINUES TO RECEIVE ROBUST
UPPER-LEVEL SUPPORT WITH STRONG EQUATORWARD AND POLEWARD OUTFLOW,
OBSERVED ON ANIMATED ENHANCED WATER VAPOR IMAGERY. IN ADDITION,
VERTICAL WIND SHEAR (VWS) REMAINS LOW (5-10 KTS). THE INITIAL
POSITION HAS BEEN PLACED WITH HIGH CONFIDENCE BASED ON ANIMATED
ENHANCED INFRARED (EIR) IMAGERY. THE INITIAL INTENSITY OF 60 KTS IS
ASSESSED WITH LOW CONFIDENCE BASED ON STATISTICAL-DYNAMICAL MODEL
GUIDANCE.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: NEAR-EQUATORIAL RIDGE (NER) CENTERED
DIRECTLY TO THE NORTH-NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 5-10 KTS
   SST: OVER LAND
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: LOW
   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 IS FORECASTED TO TRACK GENERALLY
SOUTHEASTWARD THROUGHOUT THE REMAINDER OF THE FORECAST PERIOD,
ALONG THE SOUTHERN PERIPHERY OF THE NER CENTERED DIRECTLY TO THE
NORTH-NORTHEAST UNTIL TAU 36. FOLLOWING TAU 36, A HAND-OFF IN
STEERING MECHANISMS IS EXPECTED TO OCCUR WHILE THE CYCLONE
CONTINUES THE FORECASTED SOUTHEASTWARD TRACK, ALONG THE WESTERN
PERIPHERY OF A SUBTROPICAL RIDGE (STR) CENTERED TO THE EAST.
BETWEEN TAU 36 AND TAU 120, TC 19S WILL TRACK SOUTHEASTWARD ALONG
THE WESTERN EXTENT OF THE AFOREMENTIONED STR UNTIL SUBTROPICAL
TRANSITION BEGINS NEAR TAU 96. REGARDING INTENSITY, TC 19S IS
FORECASTED TO CONTINUE WEAKENING THROUGH TAU 18 DUE TO CONTINUOUS
INTERACTION WITH CENTRAL MADAGASCARS MOUNTAINOUS TERRAIN. THE
CYCLONE IS EXPECTED TO WEAKEN TOWARD 35 KTS BEFORE RE-EMERGENCE
OVER WATER BETWEEN TAU 12 AND TAU 24. ONCE TC FYTIA TRACKS BACK
OVER OPEN WATER INTO THE SOUTHWESTERN INDIAN OCEAN, GRADUAL
INTENSIFICATION TO 55 KTS IS EXPECTED UNTIL TAU 96 AS SUPPORTIVE
SEA SURFACE TEMPERATURES BETWEEN 29-30 C AND STRONG UPPER-LEVEL
OUTFLOW COMPETES WITH INCREASING VERTICAL WIND SHEAR ABOVE 20 KTS.
BETWEEN TAU 96 AND TAU 120, TC 19S WILL BEGIN THE INITIAL WEAKENING
PHASE DUE TO INCREASING VERTICAL WIND SHEAR TO ABOVE 30 KTS,
DRY-AIR ENTRAINMENT, AND COOLER SEA SURFACE TEMPERATURES BELOW 26
C, RESULTING IN SUBTROPICAL TRANSITION BY TAU 120.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE AND ARTIFICIAL
INTELLIGENCE (AI) MODEL GUIDANCE REMAINS IN VERY GOOD AGREEMENT
THROUGHOUT THE ENTIRETY OF THE FORECAST PERIOD, WITH A CROSS-TRACK
SPREAD OF UNDER 90 NM THROUGH TAU 120. THE JTWC FORECAST TRACK HAS
BEEN PLACED CLOSE TO THE JTWC MULTI-MODEL CONSENSUS AND IS ASSESSED
WITH HIGH CONFIDENCE. REGARDING INTENSITY, ALL JTWC CONSENSUS
MEMBERS ILLUSTRATE A WEAKENING TREND THROUGH THE NEXT 12 HOURS DUE
TO INTERACTION WITH MADAGASCARS TERRAIN. FOLLOWING TAU 12, MOST
CONSENSUS SOLUTIONS CHARACTERIZE A GRADUAL INTENSIFICATION PHASE,
BUT STILL MAINTAINS A SPREAD OF NEAR 50 KTS AT TAU 36 AND 40 KTS AT
TAU 120. THE JTWC INTENSITY FORECAST HAS BEEN ASSESSED CLOSELY WITH
THE AVAILABLE STATISTICAL-DYNAMICAL SOLUTIONS AND THE GFS
DETERMINISTIC MODEL THROUGH THE INITIAL 12 HOURS OF THE FORECAST,
THEN ALIGNS CLOSELY WITH THE JTWC MULTI-MODEL INTENSITY CONSENSUS
THEREAFTER. DUE TO UNCERTAINTIES WITH THE INTENSITY FORECAST
BECAUSE OF LAND INTERACTION IN THE NEAR-TERM, THE RELATIVELY LARGE
FORECASTED INTENSITY SPREAD OF 50 KTS AT TAU 96, AND SUBTROPICAL
TRANSITION BETWEEN TAU 96 AND TAU 120, THE JTWC INTENSITY FORECAST
HAS BEEN ASSESSED WITH LOW CONFIDENCE. 

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