Tuesday, 29 January 2013

Current Southern Hemisphere Tropical Systems: Tropical Cyclone 13S Felleng




291500Z POSITION NEAR 14.3S 54.6E.
TROPICAL CYCLONE (TC) 13S (FELLENG), LOCATED APPROXIMATELY 420 NM
NORTH OF LA REUNION, HAS TRACKED WEST-SOUTHWESTWARD AT 08 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
SHOWS THE SYSTEM HAS SIGNIFICANTLY DEEPENED WITH CONVECTIVE BANDS
WRAPPING TIGHTER INTO A SYMMETRICAL, ALBEIT CLOUD-FILLED 22-NM EYE.
THE INITIAL POSITION IS FIXED WITH HIGH CONFIDENCE BASED ON THE EYE
FEATURE IN THE ABOVE ANIMATION. THE INITIAL INTENSITY IS SUPPORTED BY
DVORAK ESTIMATES FROM PGTW, KNES, FIMP, AND FMEE. UPPER LEVEL
ANALYSIS INDICATES THE SYSTEM IS IN THE VICINITY OF A RIDGE AXIS IN
AN AREA OF LIGHT TO MODERATE (10-15 KNOT) VERTICAL WIND SHEAR (VWS).
FURTHERMORE, ANIMATED WATER VAPOR IMAGERY SHOWS A STRONG POLEWARD
OUTFLOW. THE CYCLONE IS TRACKING ALONG THE NORTHWEST EXTENSION OF A
DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE SOUTHEAST. AFTER TAU 24,
A MID-LATITUDE TROUGH APPROACHING FROM THE SOUTHWEST IS EXPECTED TO
WEAKEN THE STR AND CAUSE TC 13S TO TRACK MORE POLEWARD. THE SYSTEM IS
FORECAST TO FURTHER INTENSIFY DUE TO THE CONTINUED FAVORABLE UPPER
LEVEL ENVIRONMENT, ENHANCED BY AN OPENING OF A POLEWARD OUTFLOW
CHANNEL WITH THE APPROACH OF THE AFOREMENTIONED MID-LATITUDE TROUGH.
HOWEVER, AFTER TAU 72, TC FELLENG WILL GRADUALLY WEAKEN AS VWS
INCREASES AND SEA SURFACE TEMPERATURES BEGIN TO COOL. THE AVAILABLE
NUMERIC GUIDANCE IS IN TIGHT AGREEMENT WITH THE SOLE EXCEPTION OF
WBAR THAT CONTINUES TO DEFLECT THE VORTEX TO THE RIGHT OF THE MODEL
ENVELOPE. THERE IS HIGH CONFIDENCE IN THE JTWC TRACK FORECAST WHICH
IS LAID JUST TO THE LEFT OF CONSENSUS TO OFFSET WBAR. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 291200Z IS 30 FEET.
 
- JTWC + Eumetsat 

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