WDXS31 PGTW 020300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 19S (FYTIA) WARNING NR 
008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.6S 52.0E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 185 NM WEST OF ST DENIS
   MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
CYCLONE (TC) 19S (FYTIA) AS A SLOWLY CONSOLIDATING LOW LEVEL
CIRCULATION CENTER (LLCC) WITH CONVECTION ATTEMPTING TO BUILD
AROUND THE CENTER. OVER THE PAST SIX HOURS CLOUD TOP TEMPERATURES
HAVE WARMED AND PRESSURE FROM NORTHERLY FLOW ON THE EASTERN SIDE IS
EVIDENT, INDICATING THE STORM HAS BEEN ABLE TO GAIN LITTLE
STRENGTH. SUPPORTING ARE WARM (28-29 C) SEA SURFACE TEMPERATURES
AND MODERATE POLEWARD OUTFLOW. THE INITIAL POSITION IS PLACED WITH
HIGH CONFIDENCE BASED ON EIR IMAGERY OF THE LLCC AND A 011842Z
METOP-C ASCAT. THE INITIAL INTENSITY OF 45 KTS IS ASSESSED WITH
HIGH CONFIDENCE BASED ON THE PREVIOUSLY MENTIONED ASCAT AND PGTW
AGENCY FIX.

INITIAL WIND RADII BASIS: 011842Z METOP-C ASCAT

CURRENT STEERING MECHANISM: COMPETING STEERING BETWEEN THE
NEAR-EQUATORIAL RIDGE (NER) POSITIONED TO THE NORTHWEST AND THE
SUBTROPICAL RIDGE (STR) OVER THE CENTRAL INDIAN OCEAN. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   CIMSS SATCON: 49 KTS AT 020000Z
   CIMSS ADT: 49 KTS AT 020000Z
   CIMSS AIDT: 44 KTS AT 020000Z
   CIMSS D-MINT: 39 KTS AT 012204Z
   CIMSS D-PRINT: 44 KTS AT 020000Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   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 WILL CONTINUE TO TRACK TO THE SOUTHEAST
AS THE SUBTROPICAL RIDGE OVER THE CENTER OF THE INDIAN OCEAN
CONTINUES TO EXERT MORE INFLUENCE OVER THE CIRCULATION. THE SYSTEM
HAS SLOWED AS THE STEERING MECHANISM TRANSITION TAKES PLACE GIVING
TC 19S A BIT MORE TIME TO GAIN STRENGTH OVER WARM WATER. THIS
STRENGTHENING PERIOD WILL BE SHORT LIVED AS VERTICAL WIND SHEAR
WILL INCREASE UP TO 30 KTS WHILE DRY AIR ENTRAINMENT AND COOLER SEA
SURFACE TEMPERATURES BECOME ADDITIONAL HINDRANCE TO DEVELOPMENT.
PEAK INTENSITY IS FORECAST AT 55 KTS AROUND TAU 24 AND STEADY
WEAKENING IS EXPECTED AFTERWARDS. BETWEEN TAUS 72 AND 96
SUBTROPICAL TRANSITION WILL INITIATE AS THE STRUCTURE OF THE STORM
COLLAPSES, CONDITIONS BECOME MORE UNFAVORABLE, AND THE LLCC DRIFTS
UNDER THE MID-LATITUDE WESTERLIES. TC 19S WILL COMPLETE SUBTROPICAL
TRANSITION BY TAU 96.

MODEL DISCUSSION: CROSS TRACK MODEL GUIDANCE IS APPROXIMATELY 50 NM
THROUGHOUT THE FORECAST PERIOD EXCLUDING THE INFLUENCE OF NAVGEM
WHICH DEPICTS A SLOWER TRACK POSITIONED TO THE EAST. THE JTWC
FORECASTED TRACK IS PLACED CLOSE TO THE MULTI-MODEL CONSENSUS
ADJUSTED FOR THE OUTLYING NAVGEM DEPICTION WITH MEDIUM CONFIDENCE.
INTENSITY GUIDANCE IS SPREAD UP TO 25 KTS WITH COAMPS-TC AND HAFS-A
CONTINUING TO DEPICT UNREALISTIC, GIVEN FORECASTED ENVIRONMENTAL
CONDITIONS, WAVERING INTENSITIES THROUGHOUT THE FORECAST. THE JTWC
FORECASTED INTENSITY IS PLACED SLIGHTLY ABOVE THE MULTI-MODEL
CONSENSUS WITH MEDIUM CONFIDENCE.   

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