Subject: Indian-S: 1. Tropical Cyclone 18s Warning Nr 009

From: SIU Weather Processor <[email-masked]>
Date: Sat, 6 Feb 1999 15:18:46 -0600

563
WTXS31 PGTW 062100
SUBJ:  TROPICAL CYCLONE WARNING
1. TROPICAL CYCLONE 18S WARNING NR 009
   01 ACTIVE TROPICAL CYCLONE IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ONPN,)NEYRAGE
    ---
   WARNING POSITION:
   061800Z5 --- NEAR 18.3S2 108.8E7
     MOVEMENT PAST SIX HOURS - 270 DEGREES AT 08 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 - 300 NM SOUTHWEST QUADRANT
                            090 NM ELSEWHERE
   REPEAT POSIT: 18.3S2 108.8E7
    ---
   FORECASTS:
   12 HRS, VALID AT:
   070600Z3 --- 18.3S2 107.1E9
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   RADIUS OF 035 KT WINDS - 300 NM SOUTHWEST QUADRANT
                            090 NM ELSEWHERE
   VECTOR TO 24 HR POSIT: 270 DEG/ 08 KTS
    ---
   24 HRS, VALID AT:
   071800Z6 --- 18.3S2 105.5E1
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   RADIUS OF 035 KT WINDS - 300 NM SOUTHWEST QUADRANT
                            090 NM ELSEWHERE
   VECTOR TO 36 HR POSIT: 270 DEG/ 08 KTS
    ---
   36 HRS, VALID AT:
   080600Z4 --- 18.3S2 103.9E3
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   RADIUS OF 035 KT WINDS - 275 NM SOUTHWEST QUADRANT
                            080 NM ELSEWHERE
   VECTOR TO 48 HR POSIT: 270 DEG/ 08 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   081800Z7 --- 18.3S2 102.3E6
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   RADIUS OF 035 KT WINDS - 250 NM SOUTHWEST QUADRANT
                            070 NM ELSEWHERE
   VECTOR TO 72 HR POSIT: 270 DEG/ 08 KTS
    ---
   72 HRS, VALID AT:
   091800Z8 --- 18.2S1 99.0E8
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   RADIUS OF 035 KT WINDS - 250 NM SOUTHWEST QUADRANT
                            070 NM ELSEWHERE
    ---
REMARKS:
062100Z9 POSITION NEAR 18.3S2 108.4E3.
TROPICAL CYCLONE 18S HAS MOVED WESTWARD AT 8 KNOTS OVER THE PAST 6
HOURS. THE WARNING POSITION AND INTENSITY ARE BASED ON A
COMBINATION OF 061730Z7 INFRARED SATELLITE IMAGERY ANALYSIS WITH
CURRENT INTENSITY ESTIMATES OF 25 KNOTS, A MICROWAVE IMAGER PASS
(061310Z1), AND A PREVIOUS MICROWAVE SCATTEROMETER PASS (060241Z3).
THE SCATTEROMETER PASS INDICATED A 40 KNOT MAX WIND WITH 35 KNOT
WINDS EXTENDING 300NM SOUTHWEST. ANIMATED INFRARED SATELLITE
IMAGERY INDICATES INTERMITTENT CONVECTION REMAINING WELL WEST OF
THE LOW-LEVEL CIRCULATION CENTER (LLCC) AND MODERATE TO STRONG
VERTICAL WINDSHEAR. THE PREVIOUS MICROWAVE DATA INDICATED THE LLCC
REMAINS WELL EAST OF THE CONVECTION. TROPICAL CYCLONE 18S IS
EXPECTED TO CONTINUE TO TRACK WESTWARD UNDER THE STEERING INFLUENCE
OF THE SUB-TROPICAL RIDGE TO THE SOUTH. TC 18S IS EXPECTED TO
MAINTAIN INTENSITY AS IT MOVES WESTWARD OUT OF THE STRONGEST SHEAR
ENVIRONMENT. SHEAR IS STILL FORECAST TO REMAIN MODERATE THROUGHOUT
THE PERIOD. THE WIND RADII WAS EXTENDED SOUTHWESTWARD TO INCLUDE
THE GALE FORCE WINDS CAUSED BY THE INCREASED PRESSURE GRADIENT
BETWEEN TC 18S AND THE HIGH PRESSURE AREA SOUTH. THIS AREA IS
EXPECTED TO DECREASE AS THE SYSTEM MOVES FURTHER WESTWARD. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 061800Z5 IS 15 FEET. REFER TO WWIO31
PGFW FOR ADDITIONAL SEA HEIGHT INFORMATION. NEXT WARNINGS AT
070300Z0 (DTG 070155Z8), 070900Z6 (DTG 070755Z4), 071500Z3 (DTG
071355Z1) AND 072100Z0 (DTG 071955Z7).//

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