Victoria: Trough and Unsettled. April 17th-22nd 2010

[Karl Lijnders]

Looking like it is some way off but there is something brewing later in the weekend and early part of next week connecting to a trough and low pressure system moving in from the NW of the country.

At this very early stage there seems to be a sharpening of the trough and a stalling of the trough over the central west of the state and anywhere east of that point is likely to see showers and storms for many days a block sets up in the region. A potential TC in the Indian Ocean could also see this trough fuelled to continue the shower and thunderstorm actvity mainly over the ranges and C VIC.

Lots of changes likely but I think it is turning quite moist and thundery.

[johnno]

Yep had a feeling that we may possibily see this high go east of us Friday which will allow this system to develop over us later on the weekend into early next week.. EC has been quite solid about it with the remnants of the low West of us (near Perth) spreading into an Upper trough as it enters the Bight then it weakens SW of us but EC has been constant in showing the Upper trough strenthgning near SW Victoria and with the help of cold air from the West the Upper trough redevelops into an upper low Just West of us and isn't in any hurry to move either cos of the block.
With a High East of us and Surface trough west of us near the Western border it should enable good thundery weather to develop most of the state (Mainly Western and Central areas at this stage & some NE areas) it looks to me that EC has good rainfall anywhere from the Western border to as far East as the NE ranges it even has 80mm for Maryborough again (Sunday to Wednesday) at this stage but that would be re-evaluated as it gets closer. JMA and GASP are also showing this system so there is some agreement.

[droughtbreaker]

These sort of systems can end up very productive. Stalling upper feature for days in a blocking setup with N flow. Usually gets better as each day passes as more and more moisture is advected into the system. Would be great if this pattern comes off.

[Rhino]

EC really looking the good at the moment and OCF giving decent (15mm+) from Sun-Tues around here so looks ok, although a long way out yet but looking very interesting. Will be interesting for alot of cropping areas too, I think they like an Autumn break around Anzac Day, so could be spot on if they get a nice drink in those areas.

Rhino.

[Karl Lijnders]

Rainfall has reduced somewhat but still looks unstable and convective through the run from Sunday onwards.

Looks like this trend will continue beyond the outlook period.

[Twister]

Pattern looking interesting but forecasts and models changing everyday so there is no certainty at this stage about rainfall, showers and storms.
It is quite an interesting looking, almost summer like, pattern been proged with highs well south, and troughs hanging about and drifting through with light N NE winds should be VERY nice and warm with a hint of humidity about as well as a few clouds.

Enjoying summers attempt to hang on while its not hot at all mid 20s with chance of showers and thunderstorms and Ne winds in mid April is pretty good.

BTW the locusts plague up here is INSANE, they cover the roads, footpath, roof of everyones house and they are all flying about as well, driving around you almost have to have your wipers on and they could be here for weeks heres a pic.

http://mildura.yourguide.com.au/news/lo ... 00754.aspx

Our front place is like this and ALL Roads are covered like this if not worse have never seen anything like it.

[droughtbreaker]

Latest GFS looks to bring some fairly cold upper air in in the latest run. That's pretty much the key ingredient, as long as we get the cold upper pool and trough then the fundamentals for instability are put in place. Moisture shouldn't be an issue.

Certainly doesn't look like a completely dry outlook anyway. I would expect a stronger system associated with the passage of the next LWT to come through before the end of the month, could be very late in the month but at this stage the odds are pointing towards it happening.

Worth remembering that April is still a fairly settled and dry month for most parts of the state. Coastal areas and eastern ranges, including Melbourne metro I'm pretty sure have quite high April rain relatively speaking but here in west central and inland it is only around 5mm wetter than January on average. Most Aprils I remember locally have had long dry spells as a feature with decent rain events in between, sometimes very major rain events. Extended periods of showery days however does not feature strongly in my recollections. Of course some years it has happened but much less than we get in October/November (on the 'opposite side' of the year).

I understand that on the coast and east of the bay in particular, Dandenongs and eastern ranges, the bay and ocean is usually still relatively warm and this enhances showers a lot in April with the general SW biased flow. It didn't really happen that much with the system just passed although south Gippsland did alright. Could be a bit worrying for those areas as the upcoming potential system looks like a western half of the state event at this stage, particularly ranges so I understand where you are coming from there David. Still, we can hardly say we have had dry conditions prevailing so the concern for this month is not a great one IMO. Dry months are inevitable and can occur at any time regardless of short and long term climate patterns.

April 1976 is an interesting one to look up because it was a shocker here along with 1981, 1999, 1993 and 1997. Less than 20mm in all those months with several others less than 40mm total here.

[johnno]

Expect another sub 20c today in Melbourne the BOM are out of their mind thinking today will get to 21c so it should be 4 in a row after the 25745 day record of over 20c.

[Anthony Violi]

The system has just been put back s few days, it will still come and deliver decent rains for us.

[Rhys_34]

With everyone talking about this string of days where the maximum has exceeded 20C+ has anyone noticed that Melbourne has also had the same amount of days where the minimum hasn't gone below 10C? Surely that must be a record as well!

[rikjpool]

Lots of high cirrus here tonight. Had a nice sundog. Unfouruantly i was stuck in the car so these where the Best i could come up with.

.

[Karl Lijnders]

Hi Rhys,

I beleive DJ could let us know whether that is a record but on current trends it would not suprise me.

Rik!! Loving the picture!! Nice and crisp!!

This system is looking very tentative with most models throwing the trough too far west and weakening it on our doorstep here in C VIC. But US has got the trough moving a little further east and dropping reasonable falls. In the balance but should see some resolution in the next day or so.

Not completely writing it off but I am loosing interest fast.

[Blackee]

It's a bit of a worry Karl.
On the flipside, we should all enjoy the last stunning weekend of weather!!
Around 25c, good day to be out gardening, or in my case painting!!

[Anthony Violi]

It will come..around 10 days time we should see a big system. The only difference is its pushed it back 3 days.

[droughtbreaker]

I wouldn't be putting 100% faith in EC either. Sure it is by far the better performed model, but there is significant divergence between it and GFS atm and it is still at least 4 days until the beginning of the upper trough is expected to arrive or at least approach western VIC. The general pattern is OK, I expect it to arrive eventually as Anthony says and then the next major system some time towards the latter stages of the month.

On another issue, can we trust BOM with temps for the next 7 days given the baffling cock up they made of the last few days? 20C, 20C, 21C ended up 18C, 18C, 18C, and it was bleeding obvious that these temps would occur (sub 5C 850T may translate to low 20s in the middle of Jan but not the middle of April ) and that we would be under cloud for most of the time. I think a few guys at the BOM have forgotten about Southern VIC's 'anticyclonic gloom' starting at this time of year. The cloud will persist as long as flow is onshore, even if we are near the centre of a high. It is a well known fact of our weather at this time of year and becomes more prominent as we get closer into winter. Then again, the forecast is 100% derived from the automated system with pretty much zero input from forecasters. The BOM forecast for the next 7 days can be viewed by clicking on a location on the 'graphical forecast' on the BOM website. There is never any difference between the graphical forecast output and what BOM forecasts so local knowledge from senior forecasters goes out the window.

If you want to get a better forecast you have to hear it straight from the forecasters mouths on ABC radio or some other network that has crosses to the BOM.

[Anthony Violi]

And luckily forecasting has improved as has model output apparently. Believe it if you like, but i certainly dont. The whole method of following EC actually highlights how pathetic models can be. Simply by not following the old rule of looking out the window, and using some common sense. 20 years ago when i abused Ward Rooney, it was understandable. Now its just getting worse..

[thunderhead]

Hi everyone - just joined this forum. Pardon my ignorance but what is an EC and why shouldn't I put my faith in it?

[Jake Smethurst]

I still think this system is likely to occur, for at least western Victoria anyway. A few showers and storms with it from Sunday.

[Jake Smethurst]

Andrew, even though the new forecast system follows EC most of the time, the forecasters can edit the parameters as they wish allowing the forecast to differ from the actual model itself. So the forecasters 'views' can still be used in a forecast, they just have to edit the model basically. I learnt all this when I did work experience there, but just for a bit of insight, the forecasters actually prefer (as would I) the old way of doing it before the new system came into place. But still, the forecasters are able to edit the forecasts as they wish, and from what I believe the Vic state forecast is still manual anyway.

Regarding the up-coming trough. I still think it will happen, at least for western Victoria, with afternoon convection and isolated showers/storms from Sunday ahead of a bigger event that Anthony is talking about latter in the period.

And welcome thunderhead EC (or ECMWF) is a computer model, it predicts variables for weather allowing a forecast to be derived from it. Generally, you should not put faith in any model, including EC, as they are used only as a guide, and cannot accuratley forecast correct variables at extended periods. Hope that helps mate.

[johnno]

Latest 00z UKMet has some thundery weather/showers/rain covering most of the Western half of the state to as far east as Geelong late Saturday into Sunday morning with 10-20mm at this stage, I find it bit hard to believe but the fact at 1 time or another models have juggled the idea of this happening keeps me fairly interested in this system at this stage.