WTPS12 NFFN 131800
TROPICAL DISTURBANCE ADVISORY NUMBER B5 ISSUED FROM RSMC NADI
Dec 132031 UTC.

TROPICAL CYCLONE YASA CENTRE 995HPA WAS LOCATED NEAR 16.0S 172.0E AT
131800 UTC. POSITION POOR BASED ON HIMAWARI-8 IR IMAGERY AND
PERIPHERAL SURFACE REPORTS. CYCLONE MOVING SOUTHWEST AT ABOUT 4
KNOTS. MAXIMUM 10-MINUTE AVERAGE WINDS NEAR THE CENTRE ESTIMATED AT
ABOUT 35 KNOT INCREASING TO 50 KNOTS BY 141800 UTC..

EXPECT WINDS ABOVE 33 KNOTS WITHIN 180 NAUTICAL MILES IN NE QUADRANT
AND WITHIN 180 NAUTICAL MILES IN SE QUADRANT
AND WITHIN 120 NAUTICAL MILES IN SW QUADRANT
AND WITHIN 120 NAUTICAL MILES IN NW QUADRANT.

DEEP CONVECTION PERSISTENT IN LAST 12 HOURS AND WRAPPING ONTO
SUPPOSED LLCC WITH OVERALL ORGANISATION IMPROVING. SYSTEM LIES UNDER
AN UPPER RIDGE IN A LOW SHEARED ENVIRONMENT WITH GOOD OUTFLOW TO THE
SOUTH AND NORTH. CYCLONIC CIRCULATION EXTENDS UPTO 500HPA. SST IS
AROUND 30 DEGREES CELSIUS. DVORAK ANALYSIS BASED ON CURVED PATTERN,
WITH 0.60 WRAP ON LOG 10 SPIRAL, YIELDING DT=3.0. MET AND PT AGREE.
FT BASED ON DT THUS, YIELDING T3.0/3.0/D1.0/24HRS.

GLOBAL MODELS MOVE THE SYSTEM IN NORTHWARD TRACK AND THEN
SOUTHEASTWARDS WITH FURTHER INTENSIFICATION.


FORECASTS :
AT 12 HRS VALID AT 140600 UTC 16.2S 171.4E MOV WSW AT 03 KT WITH 45
KT CLOSE TO CENTRE
AT 24 HRS VALID AT 141200 UTC 15.9S 171.0E MOV N AT 02 KT WITH 50 KT
CLOSE TO CENTRE

OUTLOOK :
AT 36 HRS VALID AT 141800 UTC 15.3S 170.9E MOV WNW AT 02 KT WITH 55
KT CLOSE TO CENTRE
AT 48 HRS VALID AT 150600 UTC 14.9S 171.1E MOV NW AT 02 KT WITH 65 KT
CLOSE TO CENTRE


THE NEXT TROPICAL DISTURBANCE ADVISORY ON YASA WILL BE ISSUED AROUND
140200UTC.
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