Subject: Indian-S: Subj: Tropical Cyclone Warning

From: SIU Weather Processor <[email-masked]>
Date: Tue, 17 Apr 2001 15:31:48 -0500

WTXS31 PGTW 172100
SUBJ:  TROPICAL CYCLONE WARNING
IMMEDIATE DELIVERY REQ TO AMEMBASSY PORT MORESBY
1. TROPICAL CYCLONE 20S (ALISTAIR) WARNING NR 004
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   171800Z7 --- NEAR 11.4S6 128.7E8
     MOVEMENT PAST SIX HOURS - 245 DEGREES AT 11 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   RADIUS OF 035 KT WINDS - 050 NM SOUTH SEMICIRCLE
                            040 NM ELSEWHERE
   REPEAT POSIT: 11.4S6 128.7E8
    ---
   FORECASTS:
   12 HRS, VALID AT:
   180600Z5 --- 12.3S6 126.6E5
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   RADIUS OF 035 KT WINDS - 060 NM SOUTH SEMICIRCLE
                            050 NM ELSEWHERE
   VECTOR TO 24 HR POSIT: 250 DEG/ 13 KTS
    ---
   24 HRS, VALID AT:
   181800Z8 --- 13.1S5 124.1E8
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   RADIUS OF 035 KT WINDS - 080 NM SOUTH SEMICIRCLE
                            070 NM ELSEWHERE
   VECTOR TO 36 HR POSIT: 250 DEG/ 14 KTS
    ---
   36 HRS, VALID AT:
   190600Z6 --- 14.0S5 121.4E8
   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 - 100 NM SOUTH SEMICIRCLE
                            085 NM ELSEWHERE
   VECTOR TO 48 HR POSIT: 250 DEG/ 14 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   191800Z9 --- 14.9S4 118.6E6
   MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT
   RADIUS OF 050 KT WINDS - 045 NM SOUTH SEMICIRCLE
                            035 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 120 NM SOUTH SEMICIRCLE
                            110 NM ELSEWHERE
   VECTOR TO 72 HR POSIT: 250 DEG/ 13 KTS
    ---
   72 HRS, VALID AT:
   201800Z1 --- 16.7S4 113.5E0
   MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT
   RADIUS OF 050 KT WINDS - 070 NM SOUTH SEMICIRCLE
                            060 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 135 NM SOUTH SEMICIRCLE
                            125 NM ELSEWHERE
    ---
REMARKS:
172100Z1 POSITION NEAR 11.6S8 128.2E3.
TROPICAL CYCLONE (TC) 20S (ALISTAIR), LOCATED APPROXIMATELY 140 NM
WEST-NORTHWEST OF DARWIN, AUSTRALIA, HAS TRACKED WEST-SOUTHWESTWARD
AT 11 KNOTS OVER THE PAST 6 HOURS. THE WARNING POSITION IS BASED ON
171730Z6 INFRARED SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED
ON CURRENT INTENSITY ESTIMATES OF 35 AND 45 KNOTS. ANIMATED INFRARED
IMAGERY DEPICTS DEEP CONVECTION OVER THE APPARENT LOW-LEVEL
CIRCULATION CENTER. ANIMATED IMAGERY AND THE 200 MB ANALYSIS
INDICATES THE SYSTEM IS EXPERIENCING VERTICAL WIND SHEAR FROM
NORTHEASTERLY WINDS EQUATORWARD OF THE UPPER-LEVEL RIDGE AXIS. 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
CONDITIONS BY THE END OF THE FORECAST PERIOD. THE OVERALL
ENVIRONMENT FOR DEVELOPMENT INDICATES A SLOW INTENSIFICATION
THROUGHOUT THE FORECAST PERIOD. MAXIMUM SIGNIFICANT WAVE HEIGHT AT
171800Z7 IS 14 FEET. NEXT WARNINGS AT 180300Z2, 180900Z8, 181500Z5
AND 182100Z2.//

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