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#38075 - 08/05/2009 17:05 Re: Looking towards the next substantial rainfall for SE Australia??
Johnoo Offline
Member

Registered: 23/11/2006
Posts: 8610
Loc: From: Where it forgot to Rain....
Here we go.. EC is so violtile lately its unreal its now downgraded by at least 70% next week makes the system weak with a new incoming high behind it just like someone already mentioned in here. GFS still looks fairly good but guysss still a long way to go before this is a done deal. Anyhow we should get a few showers at least better than nothing I suppose.

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#38076 - 08/05/2009 17:46 Re: Looking towards the next substantial rainfall for SE Australia??
ROM Offline
Meteorological Motor Mouth

Registered: 29/01/2007
Posts: 6628
Relax Johnoo!
If I [ and Mantis ] am right and the springs are just starting to get active and that is still to be verified as I posted in the Spring's thread, then about the very end of this month or first week in June will see the big break.

The small black ants are also just getting very active but as one of my more cynical family members says about ants, they are just taking advantage of the soft going to clean out the nest after the last rain!

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#38077 - 08/05/2009 18:41 Re: Looking towards the next substantial rainfall for SE Australia??
ColdsnapIII Offline
Meteorological Motor Mouth

Registered: 19/01/2007
Posts: 6500
Loc: Mount Macedon, VIC
What I'm worried about is how one model (EC) can have another big high coming in with just the odd weak front brushing through Eastern VIC and GFS can place us bang in the westerlies with cold and unstable airstream with embedded fronts and rain.

Almost complete opposite scenarios. This gives me absolute zero confidence in the models atm to the point where they are not even worth looking at until they at least come into some sort of convergence with the outputs.

If the Elders website is suggesting a more active period with the LWTs over the SE I guess GFS could have some credibility there but it is so hard to tell.

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#38078 - 08/05/2009 19:03 Re: Looking towards the next substantial rainfall for SE Australia??
BOM99 Offline
Weatherzone Addict

Registered: 23/08/2004
Posts: 4645
Loc: Australia
Yes, not often there is this much discrepency between EC and GFS. Now they are fairly close only until about 96 hours, beyond that they may as well be forecasting for different planets. In a nutshell we know "nothing" about the end of next week.

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#38079 - 08/05/2009 22:14 Re: Looking towards the next substantial rainfall for SE Australia??
ColdsnapIII Offline
Meteorological Motor Mouth

Registered: 19/01/2007
Posts: 6500
Loc: Mount Macedon, VIC
It's only one run but now GFS is lining up with EC with further high pressure dominance for most and no significant rain events or systems are likely now for the next 180 hrs.

Not saying it won't come back with future runs but it it is a bit ominous given GFS was out on its own and now lining up with EC, obviously EC was on the money.

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#38080 - 08/05/2009 23:05 Re: Looking towards the next substantial rainfall for SE Australia??
BOM99 Offline
Weatherzone Addict

Registered: 23/08/2004
Posts: 4645
Loc: Australia
Yes, quite right coldsnap2, I just saw those 06Z models and could not believe what I saw, I really did not expect GFS to come in line with EC quite that fast. Cannot waite for the next episode, although I would tend to think that our chance is gone now.

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#38081 - 09/05/2009 14:56 Re: Looking towards the next substantial rainfall for SE Australia??
pete28 Offline
Weatherzone Addict

Registered: 08/01/2007
Posts: 1114
Loc: Christchurch, New Zealand
Yeah snowmi it was looking fairly good there for a while, shame it has downgraded so much...with no substantial rainfall on the horizon and Melbourne's rainfall since the start of the year only sitting at 94.2mm, it got me thinking that this would have to be very close to the driest first 4 months of the year in Melbourne's history? Can anyone confirm this?

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#38082 - 09/05/2009 15:07 Re: Looking towards the next substantial rainfall for SE Australia??
Johnoo Offline
Member

Registered: 23/11/2006
Posts: 8610
Loc: From: Where it forgot to Rain....
After having a good think I'm with GFS on this one it has been very consistant In the main runs (00z and 12z model runs I tend to ignore the 06z and 18z runs guys as it doesn't have all its input information) Where EC has been all over the place going from huge cut off lows to weak fronts it is way to volitile so it will be something inbetween and I think GFS has hit the nail on the head it will be roughly what its showing so its still looking fairly showery to me.
Since Christmas EC has been way off the boil GFS been much better, perhaps last year and the year before EC was the better known model but so far this year GFS has been doing alot better.

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#38083 - 09/05/2009 18:09 Re: Looking towards the next substantial rainfall for SE Australia??
petethemoskeet Offline
Weatherzone Addict

Registered: 13/08/2003
Posts: 1256
Loc: toowoomba
Latest GFS looks the goods for E Vic with 10 to 15 mils
on fri/sat and snow on the alps and maybe a flurry or two on the NSW Central Tablelands on Sun morning

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#38084 - 09/05/2009 18:34 Re: Looking towards the next substantial rainfall for SE Australia??
ROM Offline
Meteorological Motor Mouth

Registered: 29/01/2007
Posts: 6628
Just for info, Ed Berry in his latest "Atmospherics Insights" says [again! ] that the numerical models have been and will continue to struggle as well as having the usual seasonal transitional problems that always arise during during this time of the year, also known as the "zone of unpredictability".

Berry heads this weeks update; Atmospheric MAYhem!

So don't expect much improvement in the accuracy of the various model's output for some time yet.

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#38085 - 09/05/2009 19:05 Re: Looking towards the next substantial rainfall for SE Australia??
Mega Offline
Meteorological Motor Mouth

Registered: 03/02/2003
Posts: 6551
Loc: Maryborough, Wide Bay, QLD
Quote:
Originally posted by Johnoo:
After having a good think I'm with GFS on this one it has been very consistant In the main runs (00z and 12z model runs I tend to ignore the 06z and 18z runs guys as it doesn't have all its input information) Where EC has been all over the place going from huge cut off lows to weak fronts it is way to volitile so it will be something inbetween and I think GFS has hit the nail on the head it will be roughly what its showing so its still looking fairly showery to me.
Since Christmas EC has been way off the boil GFS been much better, perhaps last year and the year before EC was the better known model but so far this year GFS has been doing alot better.
Same for us northerners Johnoo...It's hard to take much notice of EC lately because it keeps throwing up a different scenario with every run, whereas GFS seems more consistant on a run to run basis.

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#38086 - 09/05/2009 19:19 Re: Looking towards the next substantial rainfall for SE Australia??
ColdsnapIII Offline
Meteorological Motor Mouth

Registered: 19/01/2007
Posts: 6500
Loc: Mount Macedon, VIC
Well, considering that, I still don't like the look of GFS. The fronts progged for next week are not 'standing up' and the high pressure ridge is still the dominant feature. Under that scenario the same places would get the bulk of the showers or rain, i.e. coastal, Dandenongs, some Eastern or SE suburbs of Melbourne, South Gippsland, Otways etc. and of course TAS. Very little inland from that despite the rainfall progs atm.

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#38087 - 09/05/2009 23:47 Re: Looking towards the next substantial rainfall for SE Australia??
justcruising Offline
Member

Registered: 28/07/2007
Posts: 632
Loc: Elsternwick 3185
Andrew,

The question was posed by a wise man on another forum many years back..

He stated: What is more important, the position of the highs or the position of the low?
Initial thoughts and reactions tend to be - surely the position of the low or the fronts right?

Upon more consideration and analysis it became apparent that for Melbourne to receive the type of weather we like (snowy, cold and wet) it is actually more important for the high pressure systems to be in the right place.
Lows can be fickle and minor position changes can result in both little rainfall and a lack of cold temps.

If a high remains anchored in the right position (which I believe to be south of WA) low pressure systems continue to form and develop and cold fronts continually develop and pass us by. The 8th-18th August last year is a particularly good example and the best my bad memory can recall.
Melbourne received only 24 odd mm but this came over 10 days of consecutive days of rainfall/showers!

Please all readers check out the archive charts for this epic 10 day event here: http://www.bom.gov.au/nmoc/MSL/index.shtml
Notice lows, cut off lows and cold fronts continue to form and dominate our weather in a prolonged cold west/south west/southerly nature?

Stats here: http://www.bom.gov.au/climate/dwo/200808/html/IDCJDW3050.200808.shtml

Now I personally believe in hindsight Melbourne was a little hard done by to only receive the amount of rain that it did.
Once again many of the fronts lacked a little intensity and resultant rainfall was not as impressive as it could/should have been.
I'm sure many places fared exceptionally well.

Anyway in summary I tend to hope for some slower moving well positioned high pressure systems as really they force clearing phases much earlier. Particularly higher migrating highs allow westerly jetstream conditions and consecutive fronts just roll on by.
If you think a little further you realise that almost all of our "better" weather scenarios rely on the inherent position of a high pressure system..

A fair bit of this post has a more winter/cold snow focus but my point is still quite relevant for summer too.

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#38088 - 09/05/2009 23:55 Re: Looking towards the next substantial rainfall for SE Australia??
chill out Offline
Weather Freak

Registered: 20/10/2007
Posts: 138
Loc: Pascoe vale South (ex Wodonga)
hey guys, just interested to know if in the past it has happened/ how often it happens that a dominant high becomes stationed over west aus and we cop front after front with good rain (similar to what is progged on GFS for next weekend). Does this ever happen to us?
Similar to what happens in NZ when we have a big high stationed over us and they seem to get some nice systems.
Reason I ask is that I have only really followed the weather since about 2005 & so used to seeing us destroyed by highs, can/do the highs ever work to our advantage if they are situated nicely? Or do they always move on & eastward with a dismal few mm before they camp over us for 7+ days at a time?

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#38089 - 10/05/2009 01:15 Re: Looking towards the next substantial rainfall for SE Australia??
ColdsnapIII Offline
Meteorological Motor Mouth

Registered: 19/01/2007
Posts: 6500
Loc: Mount Macedon, VIC
Everything's out of whack atm. We have a huge low sitting over NZ and the progs suggest another large low or LWT set to surge through NZ after the current one passes. What this does is blocks the highs once they get to us and tends to centre them over the Bight or over us. The highs are moving swiftly towards us from WA and then hit a brick wall at VIC.

The position of the high pressure ridge is still in transition to the winter pattern and is sitting close to our latitude atm, perhaps just starting to show signs of migrating north of us. At this time of year, late Autumn, we rely a lot on cut off lows, 'standing up' cold fronts interacting with NW moisture bands and with Nly flow ahead of the system etc. It is not until mid winter that we tend to see a lot of rain coming up from the S/SW as unstable air in the westerlies affects us and the high pressure ridge weakens and migrates north.

Basically the way I see it for now is we need cut off lows and strong upper troughs/LWT to affect us for decent rain, particularly inland. We are not seeing this at all and have the 'default' pattern of high pressure ridge over us and westerlies over TAS.

Simply put, nothing is happening for us atm and really it is continuing the pattern for most of the year so far, our weather is just way too stable and lacking variability atm.

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#38090 - 10/05/2009 01:16 Re: Looking towards the next substantial rainfall for SE Australia??
ColdsnapIII Offline
Meteorological Motor Mouth

Registered: 19/01/2007
Posts: 6500
Loc: Mount Macedon, VIC
Quote:
Originally posted by chill out:
hey guys, just interested to know if in the past it has happened/ how often it happens that a dominant high becomes stationed over west aus and we cop front after front with good rain (similar to what is progged on GFS for next weekend). Does this ever happen to us?
Yes it does and that's what we are constantly looking out for here in the SE when we get the LWT over us and WA gets the slow moving highs. Also good for cold outbreaks when we have the high stationed that far west for an extended period.

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#38091 - 10/05/2009 14:16 Re: Looking towards the next substantial rainfall for SE Australia??
Power Storm Offline
Member

Registered: 08/12/2007
Posts: 3594
Loc: Simpson South, Southwest Victo...
I agree Andrew, that the highs are showing signs of slowly migrating further north. It will be great when they have, allowing strong substantial fronts through.

GFS is looking okay to me atm, and I agree with it at this stage. EC has been all over the place which is what I mentioned in another thread several days ago.

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#38092 - 10/05/2009 16:03 Re: Looking towards the next substantial rainfall for SE Australia??
BOM99 Offline
Weatherzone Addict

Registered: 23/08/2004
Posts: 4645
Loc: Australia
Those cold fronts are going to be awfuly marginal now, almost nothing in it.

Also it is worth noting that EC was the first to suggest a non event last Thursday while GFS was still showing a strong front with an ECL on Friday, but now of course GFS has come in to line with EC.

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#38093 - 11/05/2009 09:30 Re: Looking towards the next substantial rainfall for SE Australia??
---- Offline
Meteorological Motor Mouth

Registered: 25/11/2002
Posts: 5786
memory is a funny thing, which is why its not reliable to rely on it, especially me LOL.
So with that in mind I cannot remember such a time when my/our weather is so completely dominated by blocks. Strong powerful barely moving highs for weeks, small interludes often weakened by new ridges moving in quickly, then the return of the blocks for more weeks before the next interlude. Barely any flow through at all. Often even the rain bearing systems we do get are the result of a block, just a teeny bit more in our favour one. But no real significance in the rains. The last 12 months at least by my memory (refer to my first line here LOL) have behaved this way. People kept saying " its normal at this time of year" as a attempt to rationalise the crap conditions, but this time of year turned out to be the whole year (and then some it seems)
Is it my flawed memory and cynical nature or has our weather always been constantly dominated by blocks and stalls? What happened to fronts followed by a high that moves east followed by other fronts and the odd NW cloudband interaction, then more flows with odd blocks and much weaker fronts especially over summer and autumn but good general eastwards flow.
smile

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#38094 - 11/05/2009 10:56 Re: Looking towards the next substantial rainfall for SE Australia??
BOM99 Offline
Weatherzone Addict

Registered: 23/08/2004
Posts: 4645
Loc: Australia
Exactly my thoughts right now Hilsrain, I too tend to think that this is just too many blocks to be normal.
Bring back the El Nino I say, we seemed to get good strong westerlies with plenty of cold fronts embedded in 1980.
All the La Ninas seems to do is cause these easterlies that just bring coastal showers.

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