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

From: SIU Weather Processor <[email-masked]>
Date: Wed, 31 Mar 1999 08:34:01 -0600

999
WTXS31 PGTW 311500
1. TROPICAL CYCLONE 31S (FREDERIC) WARNING NR 015
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   311200Z7 --- NEAR 17.6S4 91.7E7
     MOVEMENT PAST SIX HOURS - 255 DEGREES AT 08 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 140 KT, GUSTS 170 KT
   RADIUS OF 100 KT WINDS - 035 NM SOUTH SEMICIRCLE
                            030 NM ELSEWHERE
   RADIUS OF 050 KT WINDS - 090 NM SOUTH SEMICIRCLE
                            070 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 180 NM SOUTH SEMICIRCLE
                            150 NM ELSEWHERE
   REPEAT POSIT: 17.6S4 91.7E7
    ---
   FORECASTS:
   12 HRS, VALID AT:
   010000Z1 --- 17.9S7 89.9E6
   MAX SUSTAINED WINDS - 150 KT, GUSTS 180 KT
   RADIUS OF 100 KT WINDS - 035 NM SOUTH SEMICIRCLE
                            030 NM ELSEWHERE
   RADIUS OF 050 KT WINDS - 090 NM SOUTH SEMICIRCLE
                            070 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 180 NM SOUTH SEMICIRCLE
                            150 NM ELSEWHERE
   VECTOR TO 24 HR POSIT: 250 DEG/ 10 KTS
    ---
   24 HRS, VALID AT:
   011200Z4 --- 18.6S5 87.9E4
   MAX SUSTAINED WINDS - 130 KT, GUSTS 160 KT
   RADIUS OF 100 KT WINDS - 030 NM SOUTH SEMICIRCLE
                            025 NM ELSEWHERE
   RADIUS OF 050 KT WINDS - 080 NM SOUTH SEMICIRCLE
                            060 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 170 NM SOUTH SEMICIRCLE
                            135 NM ELSEWHERE
   VECTOR TO 36 HR POSIT: 240 DEG/ 11 KTS
    ---
   36 HRS, VALID AT:
   020000Z2 --- 19.7S7 86.0E4
   MAX SUSTAINED WINDS - 115 KT, GUSTS 140 KT
   RADIUS OF 100 KT WINDS - 020 NM SOUTHEAST SEMICIRCLE
                            015 NM ELSEWHERE
   RADIUS OF 050 KT WINDS - 070 NM SOUTHEAST SEMICIRCLE
                            050 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 160 NM SOUTHEAST SEMICIRCLE
                            120 NM ELSEWHERE
   VECTOR TO 48 HR POSIT: 230 DEG/ 13 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   021200Z5 --- 21.4S7 83.9E0
   MAX SUSTAINED WINDS - 100 KT, GUSTS 125 KT
   RADIUS OF 050 KT WINDS - 060 NM SOUTHEAST SEMICIRCLE
                            045 NM ELSEWHERE
   RADIUS OF 035 KT WINDS - 140 NM SOUTHEAST SEMICIRCLE
                            105 NM ELSEWHERE
    ---
REMARKS:
311500Z0 POSITION NEAR 17.7S5   91.3E3.
TROPICAL CYCLONE 31S (FREDERIC) HAS TRACKED TOWARDS THE WEST-
SOUTHWEST AT 8 KNOTS DURING THE PAST 6 HOURS. THE WARNING POSITION
IS BASED ON 311130Z9 SATELLITE IMAGERY. THE WARNING INTENSITY IS
BASED ON SATELLITE CURRENT INTENSITY ESTIMATES OF T7.0 (140 KNOTS).
TC 31S (FREDERIC) HAS INTENSIFIED CONSIDERABLY AND RETAINED A WELL-
DEFINED 24 NM EYE. THE FORECAST PHILOSOPHY FROM THE PREVIOUS
WARNING REMAINS ABOUT THE SAME.  THE SYSTEM HAS CONTINUED UNDER THE
STEERING INFLUENCE OF THE SUBTROPICAL RIDGE TO THE SOUTH, BUT IS
APPROACHING A WEAKNESS IN THIS RIDGE. FURTHER EROSION OF THE RIDGE
BY THE SYSTEM COUPLED WITH THE SYSTEMS SELF PROPAGATION AND AN
APPROACHING MID-LATTITUDE TROUGH IS EXPECTED TO ALLOW TC 31S
(FREDERIC) TO BEGIN TAKING A MORE SOUTHWESTWARD TRACK THROUGHOUT
THE FORECAST PERIOD. ATMOSPHERIC CONDITIONS ARE FORECAST TO REMAIN
FAVORABLE FOR FURTHER DEVELOPMENT DURING THE NEXT 24 HOURS. AFTER
THIS PERIOD, TC 31S (FREDERIC) IS EXPECTED TO ENCOUNTER INCREASING
VERTICAL SHEAR WHICH SHOULD BEGIN WEAKENING THE SYSTEM THROUGHOUT
THE REMAINDER OF THE FORECAST PERIOD. MAXIMUM SIGNIFICANT WAVE
HEIGHT AT 311200Z IS 34 FEET. NEXT WARNINGS AT 010300Z4 (DTG
010151Z8) AND 011500Z7 (DTG 011351Z1).//
BT
#0001

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
To unsubscribe from WX-TROPL send e-mail to [email-masked] with
"unsub wx-tropl" in the body of your message.  For help with the
WX-TROPL or WX-TALK discussion groups write to [email-masked] or see
http://www.inlink.com/~landmb/intro.html.  For more information on
tropical weather products, see the NCEP Products Homepage at
http://www.nhc.noaa.gov/nhcprod.html.