WDXS33 PGTW 180900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 14S (TALIAH) WARNING NR 
035//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 30.9S 76.3E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 1213 NM SOUTHEAST OF PORT LOUIS, MAURITIUS
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
CYCLONE (TC) 14S (TALIAH) CONTINUING TO OPPOSE THE WESTERLY
VERTICAL WIND SHEAR (VWS), AS WITNESSED BY AN INCREASING DECOUPLING
OF THE VORTEX. LOW-LEVEL CIRCULATION (LLCC) IS NEARLY FULLY
EXPOSED, WHILE THE CONVECTIVE ACTIVITY IS CONTAINED WITHIN THE
SOUTHEASTERN SECTOR OF THE SYSTEM. ANALYSIS REVEALS SIGNIFICANT
MID-LEVEL DRY AIR INTRUSION, PARTICULARLY OVER THE WESTERN SEMICIRCLE. 
THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE 
EXTRAPOLATION FROM AN 180435Z ASCAT-C PASS, SHOWING A CLEAR, YET 
SLIGHTLY ELONGATED LLCC. THE INITIAL INTENSITY OF 40 KTS IS ASSESSED 
WITH MEDIUM CONFIDENCE BASED ON THE AFOREMENTIONED ASCAT PASS SHOWING 
A BROAD AREA OF 30-35 KT WINDS OVER THE SOUTHEASTERN SECTOR OF THE 
SYSTEM, WITH SOME 40 KT WIND BARBS JUST UNDER THE STRONGEST 
CONVECTION. THE ENVIRONMENTAL CONDITIONS ARE CURRENTLY MARGINALLY 
UNFAVORABLE, WITH COOL (23-24C) SEA SURFACE TEMPERATURES (SST), 
MODERATE TO HIGH (20-25KTS) VWS AND SIGNIFICANT DRY AIR INTRUSION, 
OFFSET ONLY BY A SUSTAINED, STRONG POLAR OUTFLOW.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED TO THE EAST-NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   KNES: T2.0 - 30 KTS
   DEMS: T2.5 - 35 KTS
   FMEE: T2.5 - 35 KTS
   FIMP: T2.5 - 35 KTS
   CIMSS ADT: 33 KTS AT 180600Z
   CIMSS AIDT: 37 KTS AT 180630Z
   CIMSS D-PRINT: 34 KTS AT 180630Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 20-25 KTS
   SST: 23-24 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: SIGNIFICANT MID-LEVEL DRY AIR WRAPPING INTO THE
SYSTEM, PRIMARILY FROM THE WEST

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: OVER THE NEXT 12 HOURS TC 14S IS FORECAST TO
MAKE A WESTWARD TURN, ALONG THE SOUTHWESTERN PERIPHERY OF A
WEAKENING SUBTROPICAL RIDGE (STR) TO THE EAST. WITH LACK OF A
STRONG STEERING INFLUENCE, THE SYSTEM IS FORECAST TO BRIEFLY SLOW
DOWN. AROUND TAU 24-36 HOWEVER, A FAST MOVING MID-LEVEL RIDGE WILL
PASS TO THE SOUTH OF THE TC TALIAH, RESULTING IN THE SYSTEM MAKING
A SLIGHT WEST-NORTHWESTWARD TURN. AS THE RIDGE PASSES TOWARDS THE
EAST, IT WILL ALLOW TC 14S TO BEGIN TURNING WEST-SOUTHWESTWARD. WITH 
INCREASINGLY HOSTILE ENVIRONMENT, THE SYSTEM IS EXPECTED TO WEAKEN AND 
DISSIPATE AS A TROPICAL CYCLONE BY THE END OF THE FORECAST PERIOD - NO 
LATER THAN TAU 48.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN FAIR AGREEMENT IN 
REGARDS TO THE TRACK, AS IT IS DRIVEN BY THE CHANGING STEERING 
ENVIRONMENT. THE CROSS TRACK SPREAD IS JUST ABOVE 80NM BY TAU 48 AND 
THE JTWC TRACK IS LAID WITH MEDIUM CONFIDENCE CLOSE TO THE MULTI-MODEL 
CONSENSUS. THE MAIN TRACK OUTLIER IS NAVGEM, WHICH IS FORECASTING A 
MORE SOUTHERLY INITIAL TRACK, AS WELL AS A TIGHTER TURN BY TAU 48. 
MAJORITY OF THE OTHER MODELS ARE IN RELATIVELY TIGHT AGREEMENT, WHICH 
SPREADS OUT SIGNIFICANTLY BEYOND TAU 48. INTENSITY MODEL GUIDANCE IS 
IN GOOD AGREEMENT WITH ALL TRACKERS SUGGESTING A STEADY WEAKENING, 
CULMINATING IN DISSIPATION BY TAU 48.

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