Subject: Indian-S: 1. Tropical Cyclone 28s (elaine) Warning Nr 006

From: SIU Weather Processor <[email-masked]>
Date: Thu, 18 Mar 1999 14:05:29 -0600

999
WTXS32 PGTW 182100
SUBJ:  TROPICAL CYCLONE WARNING
1. TROPICAL CYCLONE 28S (ELAINE) WARNING NR 006
   03 ACTIVE TROPICAL CYCLONES IN SOUTHERN HEMISPHERE
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   181800Z8 --- NEAR 21.4S7 111.3E6
     MOVEMENT PAST SIX HOURS - 150 DEGREES AT 08 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT
   RADIUS OF 050 KT WINDS - 055 NM
   RADIUS OF 035 KT WINDS - 140 NM SOUTHEAST SEMICIRCLE
                            110 NM ELSEWHERE
   REPEAT POSIT: NEAR 21.4S7 111.3E6
    ---
   FORECASTS:
   12 HRS, VALID AT:
   190600Z6 --- 22.9S3 112.7E1
   MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT
   RADIUS OF 050 KT WINDS - 055 NM OVER WATER
   RADIUS OF 035 KT WINDS - 140 NM SOUTHEAST SEMICIRCLE
                                   OVER WATER
                            110 NM ELSEWHERE OVER WATER
   VECTOR TO 24 HR POSIT: 135 DEG/ 14 KTS
    ---
   24 HRS, VALID AT:
   191800Z9 --- 24.9S5 114.8E4
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
   VECTOR TO 36 HR POSIT: 135 DEG/ 06 KTS
    ---
   36 HRS, VALID AT:
   200600Z8 --- 25.7S4 115.7E4
   MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
    ---
REMARKS:
182100Z2 POSITION NEAR 21.8S1 111.6E9.
TROPICAL CYCLONE 28S (ELAINE) HAS TRACKED SOUTH-SOUTHEASTWARD AT 08
KNOTS OFF THE NORTHWEST COAST OF AUSTRALIA OVER THE PAST 06 HOURS.
THE WARNING POSITION IS BASED UPON 181730Z0 ANIMATED INFRARED
SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED UPON SATELLITE
CURRENT INTENSITY ESTIMATES OF 75 AND 100 KNOTS. ANIMATED INFRARED
SATELLITE IMAGERY SHOWS TC 28S IS ELONGATING AND MUCH OF THE DEEP
CONVECTION IS BEING SHEARED TO THE SOUTHEAST. INDEED, UW-CIMSS SHEAR
ANALYSIS SUGGESTS TC 28S IS UNDERGOING MODERATE TO SEVERE VERTICAL
WIND SHEAR. ALTHOUGH TC 28S CONTINUES TO TRACK UNDER THE STEERING
INFLUENCE OF THE SUBTROPICAL RIDGE TO ITS EAST, A MODIFICATION IN
THAT RIDGE DUE TO AN APPROACHING TROUGH IS ALLOWING TC 28S TO
CONTINUE ON A MORE EASTWARD COURSE THAN PREVIOUSLY FORECAST.
TROPICAL CYCLONE 28S IS NOW FORECAST TO MAKE LANDFALL SOUTH OF
EXMOUTH BAY BY THE 24 HOUR FORECAST POSITION. TROPICAL CYCLONE 28S
IS FORECAST TO WEAKEN THROUGHOUT THE FORECAST DUE TO THE SEVERE
VERTICAL WIND SHEAR AND THEN INTERACTION WITH THE AUSTRALIAN
LANDMASS. NOTE, DUE TO THE HIGH WIND SHEAR ENVIRONMENT, THERE STILL
REMAINS A POOR PROBABILITY ALTERNATE FORECAST SCENARIO IN WHICH THE
CONVECTION IS SHEARED CLEAR OFF THE LOW LEVEL CIRCULATION BEFORE THE
LOW LEVEL CIRCULATION MAKES LANDFALL. UNDER THIS SCENARIO, THE
FORECAST TRACK WOULD ACTUALLY TURN WESTWARD ONCE AGAIN SINCE THE LOW
LEVEL FLOW IS MOVING WEST-NORTHWESTWARD. MAXIMUM SIGNIFICANT WAVE
HEIGHT AT 181800Z8 IS 20 FEET. NEXT WARNINGS AT 190300Z3 (DTG
190153Z9), 190900Z9 (DTG 190753Z5), 191500Z6 (DTG 191353Z2) AND
192100Z3 (DTG 191953Z8). REFER TO TROPICAL CYCLONE 29S WARNINGS
(WTXS33 PGTW) FOR TWELVE-HOURLY UPDATES. REFER TO TROPICAL CYCLONE
30S (VANCE) WARNINGS (WTXS34 PGTW) FOR TWELVE-HOURLY UPDATES.//
BT
#0006

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