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Offline Paul Atkins  
#1 Posted : Wednesday, 21 August 2019 8:00:50 AM(UTC)
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Time is ticking and the Western Region 2019/2020 Cyclone Season is on its way. A Weather Forum to discuss what will happen this season?hat will happen this season?

Edited by user Tuesday, 10 September 2019 1:17:47 PM(UTC)  | Reason: Not specified

Offline @_yassified_shak  
#2 Posted : Wednesday, 11 March 2020 11:12:13 AM(UTC)
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Wonder who will win out here? local knowledge? one says yes, the other says no....

BOM

Potential Cyclones:

A tropical low was located near 12.1S 115.7E at 8am WST Tuesday, about 380km south of Bali and 970km north of Karratha. This system is forecast to move south towards the northwest of Western Australia throughout the week and lie near the west Pilbara coast by Friday morning. There is only a low chance of this system developing into a tropical cyclone, as conditions are broadly unfavourable for significant development. However, squally conditions and heavy rainfall are possible over the western Pilbara from later on Thursday as the system approaches.


Likelihood of this system being a tropical cyclone in the Western Region on:
Wednesday:Low
Thursday:Low
Friday:Low

JTWC:

2. REMARKS: THE AREA OF CONVECTION (INVEST 94S) PREVIOUSLY LOCATED
NEAR 11.0S 113.6E IS NOW LOCATED NEAR 13.9S 116.8E, APPROXIMATELY
523 NM NORTH-NORTHEAST OF LEARMONTH, AUSTRALIA. ANIMATED ENHANCED
INFRARED SATELLITE IMAGERY AND A 101352Z METOP-B 89GHZ MICROWAVE
IMAGE DEPICT A SMALL POCKET OF DEEP CONVECTION CENTERED OVER A
CONSOLIDATING LOW LEVEL CIRCULATION CENTER (LLCC). A 101239Z METOP-A
ASCAT IMAGE DEPICTS 30 KNOT WINDS IN THE NORTHERN PERIPHERY WITH
STRONGER WINDS TO THE SOUTH WITHIN THE DEEP CONVECTION. 94S IS IN A
FAVORABLE ENVIRONMENT FOR DEVELOPMENT
WITH LOW (<15KT) VERTICAL WIND
SHEAR, MODERATE POLEWARD OUTFLOW, AND WARM (30-31C) SEA SURFACE
TEMPERATURES. GLOBAL MODELS GENERALLY AGREE THAT 94S WILL SLOWLY
STRENGTHEN AS IT TRACKS SOUTH-SOUTHWESTWARD. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 28 TO 33 KNOTS. MINIMUM SEA LEVEL
PRESSURE IS ESTIMATED TO BE NEAR 1005 MB. THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS IS HIGH.
thanks 3 users thanked @_yassified_shak for this useful post.
Paul Atkins on 11/03/2020(UTC), DelBoy on 11/03/2020(UTC), 28degrees on 11/03/2020(UTC)
Offline DelBoy  
#3 Posted : Wednesday, 11 March 2020 11:23:01 AM(UTC)
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Thanks for pointing this out YS. My eyes were just looking at the Coral Sea and I didn't look in this direction!
Nice to see a decent trough across the top end.
Offline @_yassified_shak  
#4 Posted : Thursday, 12 March 2020 4:10:19 PM(UTC)
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Interesting, JTWC are calling it a cyclone, BOM are saying that it wont turn cyclonic?


JTWC:
112100Z POSITION NEAR 18.9S 115.7E.
11MAR20. TROPICAL CYCLONE (TC) 21S (TWENTYONE), LOCATED APPROXIMATELY
255 NM NORTH-NORTHEAST OF LEARMONTH, AUSTRALIA, HAS TRACKED
SOUTHWESTWARD AT 10 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED
INFRARED SATELLITE IMAGERY SHOWS THE CENTRAL CONVECTION IS SEVERELY
SHEARED EASTWARD, FULLY EXPOSING THE LOW LEVEL CIRCULATION CENTER.
THE INITIAL POSITION IS BASED ON THE ABOVE ANIMATION WITH HIGH
CONFIDENCE. THE INITIAL INTENSITY OF 35KTS IS BASED ON THE HIGH END
OF AGENCY DVORAK ESTIMATES OF T1.5/25KTS AND SATCON OF 42KTS.
ANALYSES INDICATE A HOSTILE ENVIRONMENT WITH STRONG (25KTS+) RELATIVE
VERTICAL WIND SHEAR (VWS) AND COLD DRY AIR ENTRAINMENT NEAR THE
SURFACE. TC 21S WILL CONTINUE TRACKING SOUTHWESTWARD ALONG THE
NORTHWEST PERIPHERY OF THE SUBTROPICAL RIDGE TO THE SOUTHEAST. THE
VWS IS EXPECTED TO ONLY GET WORSE AS THE CYCLONE TRACKS MORE POLEWARD
AND THE COLD AIR ADVECTION WILL NOT ABATE, LEADING TO DISSIPATION BY
TAU 12. THE WEAK REMNANTS WILL MAKE LANDFALL OVER LEARMONTH SHORTLY
AFTER TAU 24. THIS IS THE FINAL WARNING ON THIS SYSTEM BY THE JOINT
TYPHOON WRNCEN PEARL HARBOR HI. THE SYSTEM WILL BE CLOSELY MONITORED
FOR SIGNS OF REGENERATION. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 111800Z
IS 12 FEET.

BOM:

Potential Cyclones:

A tropical low was located near 19.4S 114.9E at 11am WST Thursday, about 250km northwest of Karratha and 290km north northeast of Exmouth. This system is forecast to move south southwest towards the northwest of Western Australia and lie near the far west Pilbara coast late Thursday evening, and just to the west of Exmouth early Friday morning. This system is unlikely to develop into a tropical cyclone, however squally conditions and heavy rainfall are possible over the far western Pilbara from later on Thursday as the system moves by. A Severe Weather Warning has been issued and for more details refer to http://www.bom.gov.au/products/IDW21037.shtml

The low is expected to weaken on Friday, however moisture from the low is expected produce areas of rainfall over southwestern WA on the weekend.


Likelihood of this system being a tropical cyclone in the Western Region on:
Friday:Very Low
Saturday:Very Low
Sunday:Very Low
Offline Orebound  
#5 Posted : Thursday, 12 March 2020 7:25:53 PM(UTC)
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Originally Posted by: @_yassified_shak Go to Quoted Post
Interesting, JTWC are calling it a cyclone, BOM are saying that it wont turn cyclonic?


JTWC:
112100Z POSITION NEAR 18.9S 115.7E.
11MAR20. TROPICAL CYCLONE (TC) 21S (TWENTYONE), LOCATED APPROXIMATELY
255 NM NORTH-NORTHEAST OF LEARMONTH, AUSTRALIA, HAS TRACKED
SOUTHWESTWARD AT 10 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED
INFRARED SATELLITE IMAGERY SHOWS THE CENTRAL CONVECTION IS SEVERELY
SHEARED EASTWARD, FULLY EXPOSING THE LOW LEVEL CIRCULATION CENTER.
THE INITIAL POSITION IS BASED ON THE ABOVE ANIMATION WITH HIGH
CONFIDENCE. THE INITIAL INTENSITY OF 35KTS IS BASED ON THE HIGH END
OF AGENCY DVORAK ESTIMATES OF T1.5/25KTS AND SATCON OF 42KTS.
ANALYSES INDICATE A HOSTILE ENVIRONMENT WITH STRONG (25KTS+) RELATIVE
VERTICAL WIND SHEAR (VWS) AND COLD DRY AIR ENTRAINMENT NEAR THE
SURFACE. TC 21S WILL CONTINUE TRACKING SOUTHWESTWARD ALONG THE
NORTHWEST PERIPHERY OF THE SUBTROPICAL RIDGE TO THE SOUTHEAST. THE
VWS IS EXPECTED TO ONLY GET WORSE AS THE CYCLONE TRACKS MORE POLEWARD
AND THE COLD AIR ADVECTION WILL NOT ABATE, LEADING TO DISSIPATION BY
TAU 12. THE WEAK REMNANTS WILL MAKE LANDFALL OVER LEARMONTH SHORTLY
AFTER TAU 24. THIS IS THE FINAL WARNING ON THIS SYSTEM BY THE JOINT
TYPHOON WRNCEN PEARL HARBOR HI. THE SYSTEM WILL BE CLOSELY MONITORED
FOR SIGNS OF REGENERATION. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 111800Z
IS 12 FEET.

BOM:

Potential Cyclones:

A tropical low was located near 19.4S 114.9E at 11am WST Thursday, about 250km northwest of Karratha and 290km north northeast of Exmouth. This system is forecast to move south southwest towards the northwest of Western Australia and lie near the far west Pilbara coast late Thursday evening, and just to the west of Exmouth early Friday morning. This system is unlikely to develop into a tropical cyclone, however squally conditions and heavy rainfall are possible over the far western Pilbara from later on Thursday as the system moves by. A Severe Weather Warning has been issued and for more details refer to http://www.bom.gov.au/products/IDW21037.shtml

The low is expected to weaken on Friday, however moisture from the low is expected produce areas of rainfall over southwestern WA on the weekend.


Likelihood of this system being a tropical cyclone in the Western Region on:
Friday:Very Low
Saturday:Very Low
Sunday:Very Low


Different classification criteria. 1 minute wind analysis via JTWC (versus 10 min) often sees them classified a bit earlier. BoM also use persistence forecast that requires an extended period of observational data above warning thresholds. Remember that JTWC is not an official WMO recognized agency, more just for asset protection so can be a bit loose in its forecasts.

A few clips from the last WA TC...

Edited by user Thursday, 12 March 2020 7:29:32 PM(UTC)  | Reason: Not specified

thanks 1 user thanked Orebound for this useful post.
Paul Atkins on 13/03/2020(UTC)
Offline 28degrees  
#6 Posted : Tuesday, 19 May 2020 4:58:41 PM(UTC)
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Hi folks
This could be interesting

Tropical Tidbits
98S GENESIS004
https://www.tropicaltidbits.com/storminfo/

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