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#1462178 - 20/04/2018 08:16 NSW - Coastal Showers and isolated storms - April 25th to 30th 2018 (inc. speculation about a late April ECL)
Kino Offline
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Registered: 10/08/2017
Posts: 2674
Loc: Wollongong, NSW, Aus
Ok time for a thread to speculate as models are in general agreement now as to a major ECL and rainfall event right along the east coast of NSW.

Summary so far:
- upper cold pool from the sw/w plus upper low
- east/ese/se flow & surface trough movies west
- deep ECL forms next weekend
- low develops northern NSW and moves sw along coast cradled by high to its east

ACCESS has oscillated between northern and central coast but persists with a deep ECL
EC initially was bullish, backed off to Tasman low feature but overnight has really ramped up with a deep ECL smashing Central Coast, Metro and Illawarra and persisting for days
GFS not keen but drags an unstable se’erly flow across the coast for a week
TWC WRF also likes a deep ECL forming north coast and dropping south

All models like substantial widespread rainfall accumulations.

Straws are locked and loaded.


Edited by Seabreeze (29/04/2018 23:36)
Edit Reason: title changed from "a few isolated storms" to "isolated storms"

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#1462179 - 20/04/2018 08:28 Re: NSW - Coastal Showers and isolated storms - April 25th to 30th 2018 (inc. speculation about a late April ECL) [Re: Kino]
Homer Offline
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Registered: 16/06/2007
Posts: 5990
Loc: Dural
Should be an interesting discussion this one. Thanks Kino.

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#1462181 - 20/04/2018 09:07 Re: NSW - Coastal Showers and isolated storms - April 25th to 30th 2018 (inc. speculation about a late April ECL) [Re: Kino]
GringosRain Offline
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Registered: 19/06/2007
Posts: 1625
Loc: Quorrobolong NSW
An important part of the agreeance in the models on this now is that the HPS moving in behind the trough which transitions the state on Anzac day, is able to strengthen a ridge underneath the developing surface low. Both Access and EC are showing this.

If that trough were to drag the developing surface low away to the SE then the event would quickly change to something much less significant and much faster moving.

The upper support will play a major role in who gets hammered the hardest.

Good time to be discussing, but probably Sunday before we get a real good level of certainty of the outcome. Probably EC current run is my pick. Access just seems too good to be true so dont want to get too enthused about it.

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#1462202 - 20/04/2018 11:16 Re: NSW - Coastal Showers and isolated storms - April 25th to 30th 2018 (inc. speculation about a late April ECL) [Re: Kino]
ashestoashes Offline
Weather Freak

Registered: 22/10/2017
Posts: 460
Loc: Voyager Point (South West Sydn...
Sorry to be a sceptic but EC is only keeping the coast well watered, with only the Northern tablelands receiving only a reasonable amount inland with 40mm. Outside of that Katoomba gets 30mm, even within Sydney and I live 20-25km from the coast. Also going on tropical tidbits it keeps heading up the coast dragging the cold pool and weakening to 1005hpa hardly a deep ECL.

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#1462203 - 20/04/2018 11:27 Re: NSW - Coastal Showers and isolated storms - April 25th to 30th 2018 (inc. speculation about a late April ECL) [Re: Kino]
Kino Offline
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Registered: 10/08/2017
Posts: 2674
Loc: Wollongong, NSW, Aus
When you have 2 large high's either side; 1005 is deep.

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#1462204 - 20/04/2018 11:28 Re: NSW - Coastal Showers and isolated storms - April 25th to 30th 2018 (inc. speculation about a late April ECL) [Re: Kino]
CoastalStorm22 Offline
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Registered: 10/07/2006
Posts: 2849
Loc: Lane Cove, Sydney, NSW
Oops, missed this thread earlier.

Well, the good news is the latest ECMWF weeklies is keen on a wet period between 23rd-30th.

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#1462206 - 20/04/2018 11:29 Re: NSW - Coastal Showers and isolated storms - April 25th to 30th 2018 (inc. speculation about a late April ECL) [Re: GringosRain]
Kino Offline
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Registered: 10/08/2017
Posts: 2674
Loc: Wollongong, NSW, Aus
Originally Posted By: GringosRain
Good time to be discussing, but probably Sunday before we get a real good level of certainty of the outcome. Probably EC current run is my pick. Access just seems too good to be true so dont want to get too enthused about it.


Agree; just we've had zero to talk about lately grin

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#1462207 - 20/04/2018 11:29 Re: NSW - Coastal Showers and isolated storms - April 25th to 30th 2018 (inc. speculation about a late April ECL) [Re: CoastalStorm22]
Kino Offline
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Registered: 10/08/2017
Posts: 2674
Loc: Wollongong, NSW, Aus
Originally Posted By: CoastalStorm22
Oops, missed this thread earlier.

Well, the good news is the latest ECMWF weeklies is keen on a wet period between 23rd-30th.



Cheers Coastal - would love to see some of those blue anomalies hey.

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#1462208 - 20/04/2018 11:32 Re: NSW - Coastal Showers and isolated storms - April 25th to 30th 2018 (inc. speculation about a late April ECL) [Re: Kino]
Kino Offline
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Registered: 10/08/2017
Posts: 2674
Loc: Wollongong, NSW, Aus
Note overnight run of ACCESS pushes it north again; so timing of the building high & ridge critical to keeping the convergence near us (and resultant rainfall).

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#1462217 - 20/04/2018 12:20 Re: NSW - Coastal Showers and isolated storms - April 25th to 30th 2018 (inc. speculation about a late April ECL) [Re: Kino]
Homer Offline
Meteorological Motor Mouth

Registered: 16/06/2007
Posts: 5990
Loc: Dural
There are some good maps being posted in the Day to Day South East QLD thread as well.
They are just as desperate for a bullseye as we are!

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#1462224 - 20/04/2018 12:45 Re: NSW - Coastal Showers and isolated storms - April 25th to 30th 2018 (inc. speculation about a late April ECL) [Re: Kino]
Homer Offline
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Registered: 16/06/2007
Posts: 5990
Loc: Dural

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#1462230 - 20/04/2018 13:11 Re: NSW - Coastal Showers and isolated storms - April 25th to 30th 2018 (inc. speculation about a late April ECL) [Re: Kino]
GringosRain Offline
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Registered: 19/06/2007
Posts: 1625
Loc: Quorrobolong NSW
Originally Posted By: Kino
Note overnight run of ACCESS pushes it north again; so timing of the building high & ridge critical to keeping the convergence near us (and resultant rainfall).


If you have a look at day 10 though- (29th) there is another trough between the 2 highs. good chance it would be dragged back south again in that scenario from day 11 onwards. Way too far out for anything other than speculation though.

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#1462257 - 20/04/2018 16:55 Re: NSW - Coastal Showers and isolated storms - April 25th to 30th 2018 (inc. speculation about a late April ECL) [Re: Kino]
Kino Offline
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Registered: 10/08/2017
Posts: 2674
Loc: Wollongong, NSW, Aus
Updates are in and still looks good. But - Sunday is the key day IMO. If it still looks this good then game on.

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#1462258 - 20/04/2018 16:55 Re: NSW - Coastal Showers and isolated storms - April 25th to 30th 2018 (inc. speculation about a late April ECL) [Re: Kino]
Mega Offline
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Registered: 03/02/2003
Posts: 7258
Loc: Maryborough, Wide Bay, QLD
You can see the difference in the upper levels between EC & GFS @ 120 hrs - GFS quickly takes the upper trough / low offshore while EC keeps it stronger, slow moving and has it smack-bang over SEQ/NE NSW from Mon-Wed. GFS solution would more than likely develop a trough or low out to sea keeping the heaviest falls offshore while EC would see this low or trough develop closer to the NSW coast. ACCESS-G this afternoon still onboard and very much agrees with EC up until about Wednesday. After that it gets tricky and kind of pointless to bother even speculating on.

GFS + 120hrs: https://www.tropicaltidbits.com/analysis/models/gfs/2018042000/gfs_z500aNorm_swpac_21.png

EC +120hrs: https://www.tropicaltidbits.com/analysis/models/ecmwf/2018042000/ecmwf_z500aNorm_swpac_6.png

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#1462263 - 20/04/2018 18:09 Re: NSW - Coastal Showers and isolated storms - April 25th to 30th 2018 (inc. speculation about a late April ECL) [Re: Kino]
CoastalStorm22 Offline
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Registered: 10/07/2006
Posts: 2849
Loc: Lane Cove, Sydney, NSW
Latest EC looks awful IMO.
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#1462274 - 20/04/2018 21:21 Re: NSW - Coastal Showers and isolated storms - April 25th to 30th 2018 (inc. speculation about a late April ECL) [Re: Kino]
GringosRain Offline
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Registered: 19/06/2007
Posts: 1625
Loc: Quorrobolong NSW
yeah EC looks terrible now. Drags the low away with the trough. Worst possible scenario really...and all too often the one that wins...

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#1462276 - 20/04/2018 21:27 Re: NSW - Coastal Showers and isolated storms - April 25th to 30th 2018 (inc. speculation about a late April ECL) [Re: Kino]
ashestoashes Offline
Weather Freak

Registered: 22/10/2017
Posts: 460
Loc: Voyager Point (South West Sydn...
Yes that's what i believe as well because the ridge in the Tasman washes out too quickly and it ends up as strong east Tasman low, but we shall see tomorrow morning. BOM is still going for a decent event still with some areas in NE NSW receiving around 100+ mm according to the rainfall map. Although the GFS 06z run is still going for a huge system for the mid north coast around Taree even though there is no landfall of the low so SST probably will play a factor.
Interesting on the BOM synoptic 4 day chart they have a trough extending from of the mid north coast all the way to Papua New Guinea .


Edited by ashestoashes (20/04/2018 21:31)

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#1462280 - 20/04/2018 22:04 Re: NSW - Coastal Showers and isolated storms - April 25th to 30th 2018 (inc. speculation about a late April ECL) [Re: ashestoashes]
Mega Offline
Meteorological Motor Mouth

Registered: 03/02/2003
Posts: 7258
Loc: Maryborough, Wide Bay, QLD
Originally Posted By: ashestoashes
Interesting on the BOM synoptic 4 day chart they have a trough extending from of the mid north coast all the way to Papua New Guinea .


Yep, this is the first phase which has the potential to produce heavy falls along the MNC & N Coast if it were to come off. A no brainer really considering where that flow is originating from as you pointed out (east of PNG). Second phase (Wed night onwards) is what I gather others here are referring to as being downgraded...which is true, but to be fair anything more than 5 days out is always fantasy land in the world of weather modelling.

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#1462286 - 20/04/2018 23:02 Re: NSW - Coastal Showers and isolated storms - April 25th to 30th 2018 (inc. speculation about a late April ECL) [Re: Kino]
Steve777 Offline
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Registered: 20/10/2011
Posts: 4429
Loc: Artarmon (Sydney North Shore)
The models agree that something will happen next week. It's just that they're not quite sure exactly what, or where.

It hasn't rained in Sydney for 24 days, a longish dry spell. The current BOM forecast seems to be predicting 'normal' rain for late next week.

I think the heat has finished for the season. In the last few days, and looking at the forecast, the weather's gone from being 3 months behind the calendar to just one, so that's Autmunish, sort of, even if it's still shorts and T shirts weather.

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#1462298 - 21/04/2018 04:25 Re: NSW - Coastal Showers and isolated storms - April 25th to 30th 2018 (inc. speculation about a late April ECL) [Re: Kino]
Long Road Home Offline
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Registered: 08/10/2007
Posts: 8597
Loc: Northern Beaches Syd
GFS is all guns blazing in it's new run for the Hunter, with a bullseye of near 300mm for Newy.

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