Subject: Indian-S: 01 Active Tropical Cyclone In Southern Hemisphere

From: SIU Weather Processor <[email-masked]>
Date: Fri, 4 Dec 1998 13:39:13 -0600

384
WTXS31 PGTW 042100
1. TROPICAL CYCLONE 05S (BILLY) WARNING NR 009
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   041800Z3 --- NEAR 18.9S8 116.4E2
     MOVEMENT PAST SIX HOURS - 180 DEGREES AT 02 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
   RADIUS OF 050 KT WINDS - 025 NM SOUTHEAST SEMICIRCLE
                            020 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 075 NM SOUTHEAST SEMICIRCLE
                            070 NM ELSEWHERE
   REPEAT POSIT: 18.9S8 116.4E2
    ---
   FORECASTS:
   12 HRS, VALID AT:
   050600Z1 --- 19.6S6 116.1E9
   MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
   RADIUS OF 050 KT WINDS - 020 NM SOUTHEAST SEMICIRCLE
                            015 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 075 NM SOUTHEAST SEMICIRCLE
                                   OVER WATER
                            070 NM ELSEWHERE OVER WATER
   VECTOR TO 24 HR POSIT: 200 DEG/ 05 KTS
    ---
   24 HRS, VALID AT:
   051800Z4 --- 20.6S8 115.7E4
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   RADIUS OF 035 KT WINDS - 065 NM SOUTHEAST SEMICIRCLE
                                   OVER WATER
                            060 NM ELSEWHERE OVER WATER
   VECTOR TO 36 HR POSIT: 195 DEG/ 06 KTS
    ---
   36 HRS, VALID AT:
   060600Z2 --- 21.8S1 115.3E0
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   RADIUS OF 035 KT WINDS - 055 NM SOUTHEAST SEMICIRCLE
                                   OVER WATER
                            050 NM ELSEWHERE OVER WATER
   VECTOR TO 48 HR POSIT: 210 DEG/ 06 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   061800Z5 --- 22.8S2 114.7E3
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   RADIUS OF 035 KT WINDS - 050 NM SOUTHEAST SEMICIRCLE
                                   OVER WATER
                            045 NM ELSEWHERE OVER WATER
   VECTOR TO 72 HR POSIT: 215 DEG/ 06 KTS
    ---
   72 HRS, VALID AT:
   071800Z6 --- 24.7S3 113.3E8
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
    ---
REMARKS:
042100Z7 POSITION NEAR 19.1S1  116.3E1.
TROPICAL CYCLONE 05S (BILLY) HAS BEEN DRIFTING SOUTHWARD
AT 2 KNOTS OVER THE PAST 6 HOURS. THE WARNING POSITION IS
BASED ON 041730Z5 INFRARED SATELLITE IMAGERY AND EXTRAPOLATION
FROM A 041318Z7 MICROWAVE IMAGER PASS. THE WARNING INTENSITY OF 60
KNOTS IS BASED ON AN AVERAGE OF 041730Z5 SATELLITE INTENSITY
ESTIMATES. TROPICAL CYCLONE 05S (BILLY)IS DRIFTING SLOWLY SOUTHWARD
IN THE STEERING FLOW FROM THE SUBTROPICAL RIDGE TO ITS SOUTHEAST.
ANIMATED SATELLITE IMAGERY SHOWS THE SYSTEM BEGINNING TO ELONGATE AS
THE DEEP CONVECTION MOVES SOUTHWARD. TROPICAL CYCLONE 05S (BILLY)=S
LOW-LEVEL IS DIFFICULT TO LOCATE USING INFRARED IMAGERY AND THE
WARNING POSITION WAS EXTRAPOLATED FROM A MICROWAVE IMAGER PASS
WHICH SHOWED THE LOW-LEVEL NORTH OF THE DEEP CONVECTION. TROPICAL
CYCLONE 05S (BILLY) IS FORECAST TO CONTINUE MOVING SOUTHWARD
AND SOUTHWESTWARD IN THE MID-LEVEL STEERING FLOW AND IS FORECAST
TO MAKE LANDFALL AFTER THE 24-HOUR TRACK POSITION. TROPICAL
CYCLONE 05S (BILLY) HAS WEAKENED OVER THE PAST 6 HOURS.
AS THE SYSTEM MOVES SOUTHWARD IT WILL CONTINUE TO ENCOUNTER
INCREASING VERTICAL WIND SHEAR, AS WELL AS LAND INTERACTION
AFTER IT MAKES LANDFALL, WHICH WILL FURTHER WEAKEN THE SYSTEM.
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 041800Z IS 14 FEET. NEXT
WARNINGS AT 050300Z8 (DTG 050151Z2), 050900Z4 (DTG 050751Z8),
051500Z1 (DTG 051351Z5) AND 052100Z8 (DTG 051951Z1).//

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