WDXS31 PGTW 150300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 19S (FABIEN) WARNING NR 
004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 5.2S 79.4E
   INITIAL INTENSITY: 75 KTS
   GEOGRAPHIC REFERENCE: 427 NM EAST-NORTHEAST OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 26 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY AND
MULTISPECTRAL SATELLITE IMAGERY (MSI), DEPICT A TIGHTLY COMPACT
INTENSE SYSTEM WITH DEEP CONVECTION WRAPPING INTO A LOW-LEVEL
CIRCULATION CENTER (LLCC). A WELL-TIMED 150036Z GMI 37GHZ IMAGE
LENDS HIGH CONFIDENCE TO THE INITIAL POSITION. THE INITIAL
INTENSITY INCREASED AGAIN, AS INDICATED BY MULTIPLE DVORAK AGENCY
FIXES, ALONG WITH OBJECTIVE DVORAK ESTIMATES FROM CIMMS ADT, OPEN
AIIR, AND THE NEW DEEP MICRONET (DMN). THE RAPIDLY INTENSIFYING
SYSTEM REMAINS IN A HIGHLY FAVORABLE ENVIRONMENT, WITH LOW (10-15
KTS) VWS, GOOD RADIAL OUTFLOW ALOFT, AND WARM SSTS (29-30C). THE
SYSTEM IS CURRENTLY TRACKING WEST-SOUTHWEST ALONG THE NORTHERN SIDE
OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) TO THE SOUTH.

INITIAL WIND RADII BASIS: PERSISTENCE. 

CURRENT STEERING MECHANISM: NORTHERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) TO THE SOUTH. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   KNES: T4.5 - 77 KTS
   DEMS: T4.5 - 77 KTS
   FMEE: T4.0 - 65 KTS
   CIMSS ADT: 72 KTS AT 150000Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC 19S (FABIEN) CONTINUES TRACKING TOWARDS THE
WEST-SOUTHWEST ALONG THE NORTHERN SIDE OF A STR AND STAY ON THIS
TRACK THROUGH THE FORECAST PERIOD. THE UPPER-LEVEL MID-LATITUDE
TROUGH IS STILL PLAGUING THE TIMING AND STRENGTH FOR TC FABIEN TO
MAKE A POLEWARD TURN WITH A BREAK IN THE STEERING RIDGE. THE LATEST
INFORMATION INDICATES THE TROUGH IS GOING TO BE WEAKER, KEEPING
FABIEN ON THE SAME WEST-SOUTHWEST TRACK. THE SIGNIFICANT
DIFFERENCES BETWEEN THE US AND EUROPEAN MODELS MENTIONED IN PREVIOUS 
FORECASTS STILL REIGNS TRUE. THE STRENGTH OF THE TROUGH AND THE 
INFLUENCE IT WILL HAVE ON FABIEN'S TRACK REMAINS THE DECIDING FACTOR, 
CONTINUING TO INDUCE LOW CONFIDENCE IN THE TRACK AND INTENSITY OF TC 
19S. DUE TO THE COMPACT NATURE OF THE SYSTEM, THE ECMWF SOLUTION 
APPEARS TO WASH OUT THE ALREADY INTENSE SYSTEM AND KEEPS THE TRACK 
HEADING TO THE WEST. HOWEVER, THE ECMWF STILL INDICATES TC 19S WILL 
HAVE A SLOWER TRACK SPEED AS IT APPROACHES THE LATER 96-120 TAUS. THE 
ALTERNATE GFS SCENARIO INDICATES A DEEPER TROUGH AND TURNS TC 19S 
SHARPLY TO THE EAST AT TAU 96, CREATING A NEAR BIFURCATION WITHIN THE 
TWO MODEL SOLUTIONS. THE NEAR RADIAL OUTFLOW IS ENHANCING THE RAPID 
DEVELOPMENT OF THE COMPACT SYSTEM. AS THE SYSTEM PROGRESSES FURTHER 
WEST-SOUTHWEST, IT WILL TAP INTO A STRONGER POLEWARD OUTFLOW CHANNEL, 
ENHANCING FURTHER RAPID INTENSIFICATION, BRINGING THE PEAK INTENSITY 
OF THE SYSTEM TO 105 KNOTS BY TAU 48. BY TAU 60, THE SYSTEM APPEARS TO
SLOW DRASTICALLY, WHICH COULD MISS THE APPROACHING TROUGH AND STAY
ON THE MOST LIKELY ECMWF TRACK. ONCE THE SYSTEM MOVES INTO A
QUASI-STATIONARY ENVIRONMENT, THE COMBINATION OF UPWELLING COOLER
WATER, AN INCREASE OF SHEAR, AND A LACK OF AN EXHAUST CHANNEL WILL
CAUSE FABIEN TO DECREASE IN INTENSITY THROUGH THE FORECAST PERIOD. 

MODEL DISCUSSION: TRACK GUIDANCE REMAINS HIGHLY UNCERTAIN, WITH A
SIGNIFICANT SPREAD OVER 400NM OF CROSS-TRACK SPREAD BETWEEN THE
UKMET ENSEMBLE AND GFS OUTLIERS. THE UKMET ENSEMBLE, UKMET, AND THE
CONSENSUS MEAN REMAIN GROUPED ON A SOUTHWESTWARD TRACK THROUGH THE
FORECAST PERIOD, WHICH IS CONSISTENT WITH THE PREVIOUS THREE MODEL
RUNS. THE OTHER CONSENSUS MEMBERS ARE ON THE SAME SOUTHWEST TRACK.
HOWEVER, AT TAU 96, EACH OF THE GFS, GEFS, AND NAVGEM MODELS TURN
SHARPLY SOUTHEAST. DUE TO THE SPLIT IN THE MODEL SOLUTIONS, THERE
IS ONLY MEDIUM CONFIDENCE IN THE SHORT TERM FOR BOTH THE TRACK AND
INTENSITY, WHICH REMAIN CLOSE TO MODEL CONSENSUS. DURING THE LATTER
PORTION OF THE JTWC FORECAST TRACK, CONFIDENCE DECREASES TO LOW DUE
TO THE UNCERTAINTY WITHIN THE MODELS. 

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: LOW//
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