Subject: Indian-S: 02 Active Tropical Cyclones In Southern Hemisphere

From: SIU Weather Processor <[email-masked]>
Date: Mon, 7 Dec 1998 02:37:04 -0600

791
WTXS32 PGTW 070900
1. TROPICAL CYCLONE 06S (THELMA) WARNING NR 005
   02 ACTIVE TROPICAL CYCLONES IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   070600Z3 --- NEAR 10.0S1 131.0E5
     MOVEMENT PAST SIX HOURS - 205 DEGREES AT 02 KTS
     POSITION ACCURATE TO WITHIN 030 NM
     POSITION BASED ON EYE FIXED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT
   RADIUS OF 050 KT WINDS - 050 NM
   RADIUS OF 035 KT WINDS - 095 NM OVER WATER
   REPEAT POSIT: NEAR 10.0S1 131.0E5
    ---
   FORECASTS:
   12 HRS, VALID AT:
   071800Z6 --- 10.2S3 130.9E3
   MAX SUSTAINED WINDS - 100 KT, GUSTS 125 KT
   RADIUS OF 050 KT WINDS - 050 NM
   RADIUS OF 035 KT WINDS - 100 NM OVER WATER
   VECTOR TO 24 HR POSIT: 225 DEG/ 01 KTS
    ---
   24 HRS, VALID AT:
   080600Z4 --- 10.4S5 130.7E1
   MAX SUSTAINED WINDS - 115 KT, GUSTS 140 KT
   RADIUS OF 100 KT WINDS - 020 NM
   RADIUS OF 050 KT WINDS - 055 NM OVER WATER
   RADIUS OF 035 KT WINDS - 110 NM OVER WATER
   VECTOR TO 36 HR POSIT: 245 DEG/ 02 KTS
    ---
   36 HRS, VALID AT:
   081800Z7 --- 10.6S7 130.3E7
   MAX SUSTAINED WINDS - 120 KT, GUSTS 145 KT
   RADIUS OF 100 KT WINDS - 020 NM
   RADIUS OF 050 KT WINDS - 060 NM OVER WATER
   RADIUS OF 035 KT WINDS - 120 NM OVER WATER
   VECTOR TO 48 HR POSIT: 245 DEG/ 03 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   090600Z5 --- 10.9S0 129.7E9
   MAX SUSTAINED WINDS - 125 KT, GUSTS 150 KT
   RADIUS OF 100 KT WINDS - 020 NM
   RADIUS OF 050 KT WINDS - 060 NM OVER WATER
   RADIUS OF 035 KT WINDS - 130 NM OVER WATER
    ---
REMARKS:
070900Z6 POSITION NEAR 10.0S1 131.0E5.
TROPICAL CYCLONE 06S (THELMA) HAS REMAINED QUASI-STATIONARY IN THE
ARAFURA SEA OVER THE PAST 12 HOURS, BUT HAS DRIFTED SOUTHWARD AT 2
KNOTS OVER THE PAST 6 HOURS. THE WARNING POSITION IS BASED UPON A
070530Z5 VISIBLE SATELLITE IMAGE. THE WARNING INTENSITIES ARE BASED
UPON SATELLITE CURRENT INTENSITY ESTIMATES OF 65 AND 95 KNOTS.
ALTHOUGH TC 06S (THELMA) IS UNDER THE STEERING INFLUENCE OF THE
SUBTROPICAL RIDGE TO ITS SOUTH, ANIMATED INFRARED AND WATER VAPOR
SATELLITE IMAGERY INDICATE AN UPPER LEVEL TROUGH IS MITIGATING THE
STEERING EFFECTS OF THE RIDGE. APPARENTLY, THE TROUGH, WHICH
EXTENDS ACROSS THE EASTERN COAST OF AUSTRALIA AND DIGS NORTH
TOWARDS TC 06S (THELMA), IS CREATING ENOUGH WESTERLY FLOW NEAR TC
06S (THELMA) TO COUNTERACT THE EASTERLY WINDS ASSOCIATED WITH THE
SUBTROPICAL RIDGE LOCATED TO THE SOUTH. THIS MITIGATION EFFECT HAS
ALLOWED TC 06S (THELMA) TO DRIFT TOWARDS THE SOUTH. ACCORDING TO
THE NAVAL OPERATIONAL GLOBAL ATMOSPHERIC PREDICTION SYSTEM
(NOGAPS), THE TROUGH/RIDGE INTERACTION SHOULD AFFECT THE TRACK OF
TC 06S (THELMA) FOR AT LEAST THE NEXT 24 HOURS. BY THE 48 HOUR
MARK, TC 06S (THELMA) SHOULD TAKE A MORE WESTERLY TRACK AS THE
RIDGE TO THE SOUTH BEGINS TO HAVE SOME SWAY OVER THE COURSE OF TC
06S (THELMA). HENCE, THE FORECAST TRACK REMAINS SLOW TO
QUASISTATIONARY OVER THE NEXT 24 HOURS, BUT TENDS TOWARD THE SOUTH-
SOUTHWEST OVER THE 48 HOUR PERIOD. THE WIND RADII ARE BASED UPON
CLIMATOLOGY FOR AN AVERAGE SIZED SYSTEM BUT WERE SOMEWHAT REDUCED
DUE TO THE AVAILABLE SURFACE SYNOPTIC INFORMATION OVER NORTHERN
AUSTRALIA. UW-CIMSS DIVERGENCE CHARTS INDICATE THE UPPER LEVEL
ENVIRONMENT REMAINS FAVORABLE FOR FURTHER DEVELOPMENT, AND INDEED
TC 06S (THELMA) HAS DEVELOPED RAPIDLY OVER THE PAST 12 HOURS.
TROPICAL CYCLONE 06S (THELMA) SHOULD CONTINUE TO INTENSIFY, BUT NOT
AT SUCH AN ACCELERATED RATE, AS TC 06S (THELMA) SHOULD BEGIN TO USE
UP THE AVAILABLE SURFACE LEVEL ENERGY. MAXIMUM SIGNIFICANT WAVE
HEIGHT AT 070600Z3 IS 18 FEET. NEXT WARNINGS AT 072100Z0 (DTG
071953Z5) AND 080900Z7 (DTG 080753Z3).//

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