Subject: Indian-S: 1. Tropical Cyclone 20s (alistair) Warning Nr 006

From: SIU Weather Processor <[email-masked]>
Date: Wed, 18 Apr 2001 08:50:50 -0500

WTXS31 PGTW 180900
1. TROPICAL CYCLONE 20S (ALISTAIR) WARNING NR 006
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   180600Z5 --- NEAR 13.5S9 125.7E5
     MOVEMENT PAST SIX HOURS - 235 DEGREES AT 18 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
   RADIUS OF 050 KT WINDS - 025 NM NORTH SEMICIRCLE
                            035 NM ELSEWHERE OVER WATER
   RADIUS OF 035 KT WINDS - 075 NM SOUTH SEMICIRCLE
                                   OVER WATER
                            060 NM ELSEWHERE
   REPEAT POSIT: 13.5S9 125.7E5
    ---
   FORECASTS:
   12 HRS, VALID AT:
   181800Z8 --- 14.9S4 123.4E0
   MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
   RADIUS OF 050 KT WINDS - 035 NM SOUTH SEMICIRCLE
                            025 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 075 NM SOUTH SEMICIRCLE
                                   OVER WATER
                            060 NM ELSEWHERE
   VECTOR TO 24 HR POSIT: 245 DEG/ 13 KTS
    ---
   24 HRS, VALID AT:
   190600Z6 --- 16.1S8 120.9E2
   MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT
   RADIUS OF 050 KT WINDS - 040 NM SOUTH SEMICIRCLE
                            030 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 085 NM SOUTH SEMICIRCLE
                            075 NM ELSEWHERE
   VECTOR TO 36 HR POSIT: 245 DEG/ 13 KTS
    ---
   36 HRS, VALID AT:
   191800Z9 --- 17.1S9 118.4E4
   MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT
   RADIUS OF 050 KT WINDS - 040 NM SOUTH SEMICIRCLE
                            030 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 090 NM SOUTH SEMICIRCLE
                            080 NM ELSEWHERE
   VECTOR TO 48 HR POSIT: 250 DEG/ 13 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   200600Z8 --- 18.1S0 115.8E5
   MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT
   RADIUS OF 050 KT WINDS - 055 NM SOUTH SEMICIRCLE
                            045 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 120 NM SOUTH SEMICIRCLE
                            105 NM ELSEWHERE
   VECTOR TO 72 HR POSIT: 255 DEG/ 13 KTS
    ---
   72 HRS, VALID AT:
   210600Z9 --- 19.5S5 110.3E5
   MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT
   RADIUS OF 050 KT WINDS - 055 NM SOUTH SEMICIRCLE
                            045 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 120 NM SOUTH SEMICIRCLE
                            105 NM ELSEWHERE
    ---
REMARKS:
180900Z8 POSITION NEAR 13.8S2  125.1E9.
TROPICAL CYCLONE (TC) 20S (ALISTAIR), LOCATED APPROXIMATELY 200 NM
NORTHEAST OF YAMPI SOUND, AUSTRALIA, HAS TRACKED WEST-SOUTHWESTWARD
AT 18 KNOTS OVER THE PAST 6 HOURS. THE WARNING POSITION IS BASED ON
180530Z7 VISIBLE AND INFRARED SATELLITE IMAGERY. THE WARNING
INTENSITY IS BASED ON CURRENT INTENSITY ESTIMATES OF 55 KNOTS.
ANIMATED MULTI-SPECTRAL SATELLITE IMAGERY REVEALS THAT THE DEEP
CONVECTION IS RE-ESTABLISHED OVER THE LOW-LEVEL CIRCULATION CENTER.
TC 20S IS FORECAST TO TRACK WEST-SOUTHWESTWARD UNDER THE STEERING
INFLUENCE OF THE MID-LEVEL RIDGE ESTABLISHED OVER AUSTRALIA. THE
UPPER RIDGE CURRENTLY SITUATED OVER NORTHERN AUSTRALIA IS EXPECTED
TO MOVE OVER THE TIMOR SEA AND WILL PROVIDE MORE FAVORABLE OUTFLOW.
UNDER THIS MORE FAVORABLE ENVIRONMENT TC 20S IS EXPECTED TO
INTENSIFY THROUGH THE FORECAST PERIOD. MAXIMUM SIGNIFICANT WAVE
HEIGHT AT 180600Z5 IS 16 FEET. NEXT WARNINGS AT 181500Z5, 182100Z2,
190300Z3, AND 190900Z9.//

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