Subject: Indian-S: 1. Tropical Cyclone 20s (alistair) Warning Nr 010

From: SIU Weather Processor <[email-masked]>
Date: Thu, 19 Apr 2001 02:58:07 -0500

WTXS31 PGTW 190900
1. TROPICAL CYCLONE 20S (ALISTAIR) WARNING NR 010
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   190600Z6 --- NEAR 16.8S5 120.9E2
     MOVEMENT PAST SIX HOURS - 230 DEGREES AT 15 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT
   RADIUS OF 050 KT WINDS - 035 NM SOUTHEAST SEMICIRCLE
                            025 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 075 NM SOUTHEAST SEMICIRCLE
                            055 NM ELSEWHERE
   REPEAT POSIT: 16.8S5 120.9E2
    ---
   FORECASTS:
   12 HRS, VALID AT:
   191800Z9 --- 18.5S4 118.8E8
   MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT
   RADIUS OF 050 KT WINDS - 035 NM SOUTHEAST SEMICIRCLE
                            025 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 075 NM SOUTHEAST SEMICIRCLE
                            055 NM ELSEWHERE
   VECTOR TO 24 HR POSIT: 225 DEG/ 11 KTS
    ---
   24 HRS, VALID AT:
   200600Z8 --- 20.0S2 117.1E0
   MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT
   RADIUS OF 050 KT WINDS - 030 NM SOUTHEAST SEMICIRCLE
                            025 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 070 NM SOUTHEAST SEMICIRCLE
                            050 NM ELSEWHERE
   VECTOR TO 36 HR POSIT: 225 DEG/ 09 KTS
    ---
   36 HRS, VALID AT:
   201800Z1 --- 21.2S5 115.8E5
   MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
   RADIUS OF 050 KT WINDS - 025 NM SOUTHEAST SEMICIRCLE
                                   OVER WATER
                            015 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 065 NM SOUTHEAST SEMICIRCLE
                                   OVER WATER
                            045 NM ELSEWHERE OVER WATER
   VECTOR TO 48 HR POSIT: 220 DEG/ 09 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   210600Z9 --- 22.6S0 114.5E1
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   RADIUS OF 035 KT WINDS - 055 NM SOUTHEAST SEMICIRCLE
                                   OVER WATER
                            035 NM ELSEWHERE OVER WATER
   VECTOR TO 72 HR POSIT: 190 DEG/ 07 KTS
    ---
   72 HRS, VALID AT:
   220600Z0 --- 25.2S9 114.1E7
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
    ---
REMARKS:
190900Z9 POSITION NEAR 17.2S0  120.4E7.
TROPICAL CYCLONE (TC) 20S (ALISTAIR), LOCATED APPROXIMATELY 100 NM
NORTHWEST OF BROOME, AUSTRALIA, HAS TRACKED SOUTHWESTWARD AT 15
KNOTS OVER THE PAST 6 HOURS. THE WARNING POSITION IS BASED ON
190530Z8 VISIBLE SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED
ON CURRENT INTENSITY ESTIMATES OF 55 AND 65 KNOTS. VISIBLE ANIMATION
DEPICTS AN ASYMMETRIC SYSTEM WITH A (APPROX) 110 NM CENTRAL DENSE
OVERCAST SITUATED OVER THE VORTEX CENTER. TC 20S IS FORECAST TO
TRACK SOUTHWESTWARD UNDER THE STEERING INFLUENCE OF THE MID-LEVEL
RIDGE ESTABLISHED OVER AUSTRALIA THROUGH 48 HOURS. AFTERWARD, THE
SYSTEM SHOULD BEGIN TO TRACK MORE SOUTHWARD WITH AN APPROACH OF A
MID-LATITUDE FROM THE SOUTHWEST. TC 20S HAS BEGUN ITS TRACK POLEWARD
OF THE SUBTROPICAL RIDGE AXIS AND BENEATH LIGHT TO MODERATE UPPER
WEST-NORTHWESTERLIES. THEREFORE, THE SYSTEM IS FORECAST TO MAINTAIN
CURRENT INTENSITY OVER THE NEXT 12 TO 24 HOURS BEFORE SHOWING A
SIGNIFICANT WEAKENING TREND THROUGH THE REMAINDER OF THE PERIOD.
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 190600Z6 IS 16 FEET. NEXT
WARNINGS AT 191500Z6, 192100Z3, 200300Z5 AND 200900Z1.//

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