WDXS31 PGTW 210900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 19S (FABIEN) 
WARNING NR 026//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 10.7S 68.9E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 304 NM SOUTHWEST OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: SOUTH-SOUTHWESTWARD AT 03 KTS
   SIGNIFICANT WAVE HEIGHT: 17 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS FLARING DEEP
CONVECTION PARTIALLY OBSCURING THE LLCC AND SURROUNDING TIGHTLY
WRAPPED LOW LEVEL CLOUD LINES. A 210446Z AMSU-B 89GHZ MICROWAVE
IMAGE INDICATES AN ELONGATED CIRCULATION WITH DETERIORATING
CONVECTION AND RAMPANT DRY AIR ENTRAINMENT. THE INITIAL POSITION IS
PLACED WITH HIGH CONFIDENCE BASED ON MSI AND AMSU-B IMAGERY. THE
INITIAL INTENSITY OF 35KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON A RANGE OF DVORAK AND AUTOMATED INTENSITY ESTIMATES
INDICATING 25-45KTS.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: COMPETING STEERING ENVIRONMENT WITH A
SUBTROPICAL RIDGE (STR) OVER NORTHERN MADAGASCAR AND A NEAR
EQUATORIAL RIDGE (NER) SOUTH OF SRI LANKA.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   KNES: T2.0 - 30 KTS
   FIMP: T3.0 - 45 KTS
   CIMSS SATCON: 35 KTS AT 210355Z
   CIMSS ADT: 34 KTS AT 210600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 0-5 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: WEAK POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   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) WILL CONTINUE TRACKING
GENERALLY POLEWARD OVER THE NEXT 48 HOURS. DURING THIS TIME, THE
ENVIRONMENT SURROUNDING THE SYSTEM WILL PROVIDE ENOUGH ENERGY TO
MAINTAIN ITS CURRENT INTENSITY, DUE PRIMARILY TO RELATIVELY LOW
VERTICAL WIND SHEAR (VWS) AND MARGINALLY FAVORABLE OUTFLOW. THE
SYSTEM WILL BECOME MORE ASYMMETRIC AS THE UPPER-LEVEL CIRCULATION
TILTS AND DECOUPLES FROM THE LLCC BY TAU 24. THE EXPOSED AND
QUICKLY DETERIORATING LLCC WILL THEN TURN SHARPLY WESTWARD AND
DISSIPATE BY TAU 72.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN FAIR AGREEMENT WITH A
BULK OF THE GUIDANCE GENERALLY FOLLOWING THE JTWC FORECAST TRACK,
WITH SEVERAL MEMBERS SHOWING INCREASING CROSS TRACK DISCREPANCY
THROUGH THE FORECAST PERIOD. FOR THIS REASON THE JTWC FORECAST
TRACK IS PLACED WITH MEDIUM CONFIDENCE. RELIABLE MODEL INTENSITY
GUIDANCE IS ON GOOD AGREEMENT WITH ALL MEMBERS SHOWING GENERAL
STAGNATION THROUGH TAU 48 AND DISSIPATION THEREAFTER. FOR THIS
REASON THE JTWC INTENSITY FORECAST IS PLACED WITH HIGH CONFIDENCE.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   INTENSITY 0 - 72 HR: HIGH//
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