Major upper and surface lows 1 - 5 May

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JasmineStorm
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Major upper and surface lows 1 - 5 May

Post by JasmineStorm » Fri Apr 26, 2019 8:57 am

I thought we might as well create a thread to separate this event from the current April weather, as there is going to be plenty to discuss. As usual with these major synoptic scale systems, the upper low will call all of the shots. 120 hours out, models differ on the exact location of where the cut off upper vortex will be positioned. Most models are projecting the upper low to balloon north and assist in interacting jet streams around S.A. An associated moisture rich surface low could spawn anywhere from S.A, NSW or Vic around late Thursday in a currently unknown location. Plenty of downgrades and upgrades to come :)
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Rivergirl
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Re: Major upper and surface lows 1 - 5 May

Post by Rivergirl » Fri Apr 26, 2019 2:46 pm

Thanks JS. It's a pretty map :)

StratoBendigo
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Re: Major upper and surface lows 1 - 5 May

Post by StratoBendigo » Fri Apr 26, 2019 7:16 pm

Looks like a lottery. Anything from 0 to 50mm is possible...

flyfisher
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Re: Major upper and surface lows 1 - 5 May

Post by flyfisher » Sat Apr 27, 2019 4:30 pm

Downgrades - most models show the low further to the west and slipping south after that. BOM rainfall totals adjusted downwards too. Hopefully it wiggles back to a more favorable rainfall event for all - we really need a proper break.

StratoBendigo
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Re: Major upper and surface lows 1 - 5 May

Post by StratoBendigo » Sat Apr 27, 2019 6:30 pm

And then 00Z EC throws up a 60mm deluge for us...

Lottery.

Gordon
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Re: Major upper and surface lows 1 - 5 May

Post by Gordon » Sat Apr 27, 2019 6:48 pm

A mere 50mm Wed/Thursday for us :).

Sean
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Re: Major upper and surface lows 1 - 5 May

Post by Sean » Sat Apr 27, 2019 9:10 pm

Possible precip totals are up and down, up and down, but that usually means we're guaranteed something, so my hopes are rising

Handy 8mm yesterday, which will help anything that does fall to sink in.

Is this another of those 'autumn breaks' that seem to be our salvation? (the charts are looking good)

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Re: Major upper and surface lows 1 - 5 May

Post by hillybilly » Sat Apr 27, 2019 9:59 pm

Latest batch of Progs all look very good. Widespread 20-80mm falls. Devil will be in the details, but looks like a quite general state wide event, and quite cold as well so a proper winter spell :D Hoping this one jump starts our May total.

Macedonian
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Re: Major upper and surface lows 1 - 5 May

Post by Macedonian » Sun Apr 28, 2019 12:46 pm

After only 10mm april total at Macedon i hope this one comes off. It is getting bad out here.
I have faired a little better up high on the mountain but still the worst start to any year i have had here. Still only about 75mm ytd at my place and about 55mm ytd at work at Macedon. Yuk.

StratoBendigo
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Re: Major upper and surface lows 1 - 5 May

Post by StratoBendigo » Sun Apr 28, 2019 1:04 pm

I'm starting to believe we might do ok this week. Finally some convergence in the forecast models. 30-50mm would be very welcome...

JasmineStorm
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Re: Major upper and surface lows 1 - 5 May

Post by JasmineStorm » Sun Apr 28, 2019 1:07 pm

12.30pm mid level tropospheric water vapour image showing it is starting to come together.
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snowfall
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Re: Major upper and surface lows 1 - 5 May

Post by snowfall » Sun Apr 28, 2019 6:08 pm

Really hope it comes together. We need it! The models are still looking good, with EC looking the best for widespread rain in the latest run. No doubt there will be a few more ups and downs as we get closer to Wednesday, but so far so good. Some drizzle here this morning, but not quite enough to register in the gauge. Stayed mostly cloudy all day though, with a 15.5c maximum.

Sean
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Re: Major upper and surface lows 1 - 5 May

Post by Sean » Sun Apr 28, 2019 6:20 pm

It's crazy how long it's been since I've seen the word 'rain' mentioned in forecasts.

The whole state needs this. I'm not even looking at the charts now, scared it'll just disappear again

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Australis(Shell3155)
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Re: Major upper and surface lows 1 - 5 May

Post by Australis(Shell3155) » Sun Apr 28, 2019 8:40 pm

Damp here for the few sprinkles over the weekend.
Few good drops.
Hope this comes along nice and slow.
Could do with one of these every week for a few months..
hope I eat my words,.

JasmineStorm
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Re: Major upper and surface lows 1 - 5 May

Post by JasmineStorm » Mon Apr 29, 2019 8:49 am

First look at the rainfall projection for one of the local higher resolution models Access R. This is for round 1 up until 4am Thursday morning. Access R is cutting off a 2nd surface low around Kangaroo Island on Wednesday night. A look at an even higher resolution model Access C tomorrow night will give a better mesoscale view of the potential.
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StratoBendigo
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Re: Major upper and surface lows 1 - 5 May

Post by StratoBendigo » Mon Apr 29, 2019 9:26 am

AXS-R looks to be on the optimistic side. Both GFS and EC are suggesting 20-30mm, not 50mm for here.

Regardless, it's firming up to be the best rain since December.

JasmineStorm
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Re: Major upper and surface lows 1 - 5 May

Post by JasmineStorm » Mon Apr 29, 2019 5:42 pm

As expected, plenty of uncertainty on the exact positions of multiple cut off lows. One common theme though is that there will be interacting jet streams ahead of the first trough on Wednesday into Thursday. Winds @ 700 hPA are being projected at around 50 to 60 knots into Wednesday evening to support the launch of multicell clusters from the north west. With plenty of mid level moisture, there could be some very big isolated totals that most models won't be currently picking up. In my opinion the only model with a high enough resolution to pick up this cell potential is Access C (4km res), all the rest are just synoptic scale mathematical darts at a board.

stevco123
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Re: Major upper and surface lows 1 - 5 May

Post by stevco123 » Mon Apr 29, 2019 8:20 pm

Looks like 3 to 5mm in Melbourne metro (2mm in West, 4mm in east over the course of 16 hours. Mt Dandenong will get 15mm, Mouny Macedon 1mm and CBD 3mm.

Now save this post and get back to me on Friday :) :D :D :D
https://www.weatherlink.com/bulletin/53 ... 76dd68e8bc: for current weather updated every 2 minutes

QldTwister
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Re: Major upper and surface lows 1 - 5 May

Post by QldTwister » Mon Apr 29, 2019 9:09 pm

Access C is actully 1.5km res so lots of storm blobs in there tomorrow some isol heavy falls for sure.

Sadly feel like it be an east of Swan hill to Colac system, with West Vic and E SA missing out but east of there widespread 20-40mm with isol 80 to 100mm in the NE rages

Fun few days get excited
Bring on the heat and stroms

JasmineStorm
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Re: Major upper and surface lows 1 - 5 May

Post by JasmineStorm » Tue Apr 30, 2019 4:23 am

Yes, spot on QT...I typed out the old spec for Access C. Strangely the BoM still reference 4km but it's definitely 1.5km res. http://www.bom.gov.au/australia/charts/ ... cess.shtml

UK, new GFS upgrading for this area 50 to 100mm, EC 40 to 80mm. Their projected NW flow means potential rainshadowing south of the range into Melbourne. Looking forward to seeing Access C tonight :)

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