WDXS31 PGTW 300900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 19S (FYTIA) WARNING NR 
002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.6S 42.5E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 120 NM EAST-SOUTHEAST OF NACALA,
MOZAMBIQUE
   MOVEMENT PAST 6 HOURS: EASTWARD AT 01 KTS
   SIGNIFICANT WAVE HEIGHT: 18 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
CYCLONE (TC) 19S (FYTIA) WITH A FORMATIVE EYE AND ROBUST OUTFLOW,
INDICATED BY DEFINED CIRRUS FILAMENTS EXPANDING OUTWARD FROM THE
SYSTEM. THE SYSTEM IS ANALYZED TO HAVE UNDERGONE RAPID
INTENSIFICATION (RI) OVER THE PAST 24 HOURS FROM 25 KTS TO 60 KTS.
THE EYE HAS BECOME MORE DEFINED NEAR 0800Z, HINTING AT A CONTINUED
RI TREND. A 300616Z METOP-B ASCAT IMAGE REVEALED A HIGHLY COMPACT
INNER-CORE WITH THE STRONGEST WINDS LOCATED IN A SMALL AREA IN THE
SOUTHERN SEMICIRCLE OF THE DEVELOPING EYEWALL. IT IS SOMEWHAT
SURPRISING THAT THE STRONGEST WINDS RECORDED WERE 45 KTS IN THE
ASCAT, WHEN COMPARED TO THE VISUAL REPRESENTATION OF THE SYSTEM. THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE ASCAT
AND THE EYE IN ANIMATED MSI. THE INITIAL INTENSITY OF 60 KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE HIGH END OF THE ASCAT
DATA AND THE INTENSITY ESTIMATES LISTED BELOW. ENVIRONMENTAL
ANALYSIS INDICATES THAT 19S REMAINS IN A HIGHLY FAVORABLE
ENVIRONMENT CHARACTERIZED BY ROBUST RADIAL OUTFLOW ALOFT, LOW (5-10
KTS) VERTICAL WIND SHEAR, AND WARM (29-30 C) SEA SURFACE
TEMPERATURES.

INITIAL WIND RADII BASIS: 300616Z METOP-B ASCAT SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: A COMPETING STEERING ENVIRONMENT WITH A
NEAR EQUATORIAL RIDGE (NER) TO THE NORTH AND A SUBTROPICAL RIDGE TO
THE SOUTHWEST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   FMEE: T4.0 - 65 KTS
   CIMSS ADT: 57 KTS AT 300600Z
   CIMSS AIDT: 57 KTS AT 300600Z
   CIMSS D-PRINT: 56 KTS AT 300600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC 19S IS FORECAST TO BEGIN PICKING UP SPEED
IN THE SOUTHEASTWARD DIRECTION AS THE SUBTROPICAL RIDGE NEAR
SOUTHERN AFRICA LOSES INFLUENCE ON THE SYSTEM. THE NER TO THE NORTH
WILL BECOME THE PRIMARY STEERING MECHANISM THROUGH TAU 72. LANDFALL
IS CURRENTLY FORECAST TO OCCUR NEAR TAU 18 CLOSE TO VILAMATSA,
MADAGASCAR. 19S WILL THEN TRAVERSE ACROSS CENTRAL MADAGASCAR AND
EMERGE BACK OVER WATER NEAR TAU 48. 19S IS THEN FORECAST TO
CONTINUE ON A SOUTHEASTWARD TRACK THROUGH THE REMAINDER OF THE
FORECAST PERIOD, AS THE NER MERGES WITH A BUILDING STR TO THE
SOUTHEAST. REGARDING INTENSITY, 19S IS FORECAST TO CONTINUE RAPIDLY
INTENSIFYING BEFORE MAKING LANDFALL. A PEAK INTENSITY OF 75 KTS IS
CURRENTLY FORECAST AT TAU 12, BUT AN EVEN HIGHER PEAK IS POSSIBLE
NEAR THE TIME OF LANDFALL AT TAU 18. THE SYSTEM WILL THEN WEAKEN
THROUGH TAU 48 AS IT CROSSES MADAGASCAR DUE TO TERRAIN INTERACTION.
A REINTENSIFICATION PHASE IS EXPECTED TO ENSUE AFTER TAU 48 AS THE
ENVIRONMENT BECOMES MORE FAVORABLE DUE TO THE SYSTEM TAPPING INTO
WARM SEA SURFACE TEMPERATURES ONCE AGAIN. HOWEVER, NORTHWESTERLY
SHEAR IS FORECAST TO INCREASE TO OVER 20 KTS NEAR AROUND TAU 72,
DISALLOWING A SECOND BOUT OF RI. AN INTENSITY OF AROUND 65 KTS IS
FORECAST FOR THE END OF THE FORECAST PERIOD. 

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN GOOD
AGREEMENT WITH A 160 NM CROSS-TRACK SPREAD AT TAU 72 AND MINIMAL
ALONG-TRACK SPREAD. MODELS STAY IN GOOD AGREEMENT THROUGH TAU 120
AS WELL, WITH NO NOTABLE OUTLIERS. THE JTWC TRACK FORECAST IS
PLACED CLOSE TO THE MULTI-MODEL CONSENSUS WITH OVERALL MEDIUM
CONFIDENCE DUE PRIMARILY TO SOME UNCERTAINTIES REGARDING THE
INTERACTION WITH MADAGASCAR. INTENSITY GUIDANCE IS IN RATHER POOR
AGREEMENT THROUGH TAU 24. INTENSITIES AT TAU 12 RANGE FROM 45 KTS
TO 75 KTS, AND SOME OF THE MORE RELIABLE INTENSITY MODELS SHOW A
STEADY INTENSITY BEFORE LANDFALL (HAFS-A AND COAMPS-TC). THE JTWC
INTENSITY FORECAST IS PLACED HIGHER THAN NEARLY ALL AVAILABLE
GUIDANCE THROUGH TAU 24 DUE TO THE CLEARLY HIGHLY FAVORABLE
ENVIRONMENT. AFTER TAU 24, MODELS AGREE ON WEAKENING THROUGH TAU
48 AND REINTENSIFICATION THROUGH TAU 120. THE JTWC INTENSITY FORECAST 
IS PLACED CLOSE TO THE CONSENSUS FROM TAU 72 ONWARD.

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