Easterly Blast Prospect Thread :

ninebeanrows

It looks like Model Watching over the coming days may become a wee bit more interesting with a strong block forecast by the ECM and partially the UKM, the GFS is having none of it however.

The ECM has a corker of a Scandy/Russian HP by T+168hrs




UKM getting that way by T+144hr



It's all a long way away and probably not going to happen, but it's better than the persistent outlook of mild, bartlett synoptics that we have been fed lately.

darkman2

We will see. Right now it cold either turn much colder or much milder. Problem is the evolution we need is a very delicate one to achieve. A 100 miles the difference between very cold and cold, mild and cold, rain and snow......The charts are encouraging but we have seen this every winter for the last 10 years - the near miss.

isnt what we really need a blast of snowfall followed by a stable frosty system so we can enjoy the snow for a few days(how likely is that?), the possibility of snow there christmas night, had it come true, would have been quite pointless as it would have been soft snow and not lasted long.

What is it that all you snow lovers want? A picture or a few days of arctic weather

Thats FI.
It's worth watch though as it's only 3 days beyond the reliable.

The other problem is the continent has to be cooled first.
It's not a good sign when we are getting harder night frosts than Denmark for instance.
If a HP does verify,then thats the main part done.
I wouldnt worry about FI after one has established as they aren't that easily moved.
You need one for a solid week though before feeling it's effects goodo here as it has its work cut out to advect cold air even into near Russia first.
Moscow is only -2c today.
That needs to be down at -15 and blowing westwards across the continent for us to be in with a chance.
Theres no point in it stopping at the German border...

Trogdor

The ECM will be very interesting tonight, to see if it progs the high for the third time in a row. ECM ensembles are bunched more towards the cold from around the new year.
http://www.knmi.nl/exp/pluim/vijftiendaagse/index.html
Here's hoping...

trogdor

trogdor wrote: »

ECM ensembles are bunched more towards the cold from around the new year.
http://www.knmi.nl/exp/pluim/vijftiendaagse/index.html
Here's hoping...

They are but only between -5 and -8 850's which isn't good enough for sea level snow.
I wouldn't worry about that though.
Anything beyond 4 days on those yokes is pure speculation.
The main thing to concern ourselves with is getting that high established and oriented correctly for maximim advection of cold air.
If that happened you could easily see -10 or lower 850's appear out of no where near us as cold data so far unrecorded (because we haven't got there yet) gets fed into the NWP's.

Supercell

The potential is certainly there, I'm keenly watching the models as they output.
We are so overdue a proper easterly its not funny (it never was ).
If I was to lay money on it, my money is on a flabby euro high with conditions similar to last week. Frost is great and all that, but tbh in January I want sneachta as well.

Trogdor

Deleted User wrote: »

They are but only between -5 and -8 850's which isn't good enough for sea level snow.
I wouldn't worry about that though.
Anything beyond 4 days on those yokes is pure speculation.
The main thing to concern ourselves with is getting that high established and oriented correctly for maximim advection of cold air.
If that happened you could easily see -10 or lower 850's appear out of no where near us as cold data so far unrecorded (because we haven't got there yet) gets fed into the NWP's.

Actually, they are the surface temps for De Bilt in the Netherlands, but certainly we need to get the high established first before we start thinking about snow. Good ECM, with a brief Northerly at T+72
http://www.wetterzentrale.de/pics/Recm721.gif
Followed by a stong Scandy/Russian high again.
http://www.wetterzentrale.de/pics/Recm1441.gif
http://www.wetterzentrale.de/pics/Recm1681.gif
Further into FI and the Atlantic wins out, but there's not much point looking that far out.
http://www.wetterzentrale.de/pics/Recm2401.gif
EDIT: Check out the JMA:p
http://www.wetterzentrale.de/topkarten/fsjmaeur.html

trogdor

trogdor wrote: »

Actually, they are the surface temps for De Bilt in the Netherlands

Whoopsies you're right! I'm so used to looking at 850's in that format,I took one look and assumed 850's.
The colder bunch in that 50:50 split is quite encouraging though it's hard to interpret it.
It's better to see daytime temps in holland progged below -5c than night time temps and thats not easy..actually it's almost impossible to tell in such a micro format.

If only access to ecm ensembles were as public as GFS.

That said I still stand by my opinion on guess work made before a SH is in place.
Lets get it set up first(its far from nailed yet) and then lets see how the colder data impacts on the models.

Yeah I saw the jma.
Pity thats not the result of all the models.
I don't like the more southerly flow into Ireland on it though..

darkman2

Deleted User wrote: »

They are but only between -5 and -8 850's which isn't good enough for sea level snow

Actually I dont think this is accurate. It can and has snowed at -2 850 temp in the past and -5 is particularly effective when a front is pushing up against it. Its far more likely to snow in these circumstances with a Southeasterly or Easterly then sunshine and showers off the Irish sea - which can happen really at any temperature below -5 850's.

Also other factors have to be taken into account like air thickness. As far below 528DAM as possible is good. Surface cold and geopotential heights aswell. Wind direction and dew points. All these things have to come together all at the same time. Missing one element is the difference between snow and rain.


BTW cracking JMA this evening for those who have not seen it:



Good ECM up to 120hrs - very promising.

darkman2

darkman2 wrote: »

Actually I dont think this is accurate. It can and has snowed at -2 850 temp in the past and -5 is particularly effective when a front is pushing up against it.

It's probably as rare as hens teeth.

Its far more likely to snow in these circumstances with a Southeasterly or Easterly then sunshine and showers off the Irish sea - which can happen really at any temperature below -5 850's.

I'd have to strongly disagree.I'd say at a min you'd want to be below -5 on the 850's.
Then you need the other pieces aswell such as sub zero dew points and your thickness's.

Missing one element is the difference between snow and rain.

Well wasn't that the point I was making vis a vis the 850's!

BTW cracking JMA this evening for those who have not seen it

Yes it be eye candy.
Unfortunately as you probably know it's not professional forecasters model of choice in these islands and for good reason.

Good ECM up to 120hrs - very promising.

It's certainly excelent for the South East of the UK but need more tweeking for us.
Look at the isobar lines/air source feeding into Ireland on it...
North Africa was never renouned as a source of cold!
Sand maybe but not cold!

I wouldn't worry about it though as in my opinion 120 hrs is a bit flakey for reliance.
Give it another few days and if it keeps evolving the way it is, that track might be more south easterly at our end.
In fact anything could happen including disaster!

Supercell

I can't ever recall a south easterly that delivered snow unless it was at the backend of a proper easterly or north easterly and shortly turned to rain.

A SE in England might be great, but unfortunatly we don't have the continent a few miles off the coast of Wexford, just a lot of miles of warm sea.

This has potential, but i'm not getting excited at all yet, just a little interested!

darkman2

Only one thing to say to both of you:

Check out the archive charts for January 1982 - the big snowstorm.

Not only have you a Southeasterly but also temps little below -5 - in fact many places that got snow went above that at times.

darkman2

Deleted User wrote: »

It's certainly excelent for the South East of the UK but need more tweeking for us.
Look at the isobar lines/air source feeding into Ireland on it...
North Africa was never renouned as a source of cold!
Sand maybe but not cold!

but.........but.............thats not what im looking at. Im looking at the Atlantic and sussing out potential low undercutters - 1982 style:D;)

I remember january 82 darkman2 and as I recall the wind was straight easterly hitting that weather system off an already iced up UK.This was thanks to the position of the low of course that aided the UK sourced cold surface air feed staying over areas from south Leinster northwards.They weren't coming in off the Atlantic!They did to the south of the system alright which turned the snow to rain down in Cork and as far north as Rosslare!
I know this because it's the only time EVER that my bedroom window completely blocked up with snow.I got 10 days off school nipper that I was
I don't know what the 850's were but I'd imagine they were much better than -2c anyhow.


Anyhow this distraction aside-lets see what pans out!

Snowbie

darkman2 wrote: »

Only one thing to say to both of you:

Check out the archive charts for January 1982 - the big snowstorm.

Not only have you a Southeasterly but also temps little below -5 - in fact many places that got snow went above that at times.

darkman2 wrote: »

but.........but.............thats not what im looking at. Im looking at the Atlantic and sussing out potential low undercutters - 1982 style:D;)

Yes by the charts of yester year it does apperar to be a SE flow but in this case the atlantic brought the heavy snow here to the east but the snow fell aided by a direct east wind.

In particular this frontal cyclogenesis in '82,upper air was more a SE to south wind direction but surface winds had an undercutting gale easterly being sourced from an already bitter siberia,N europe and also helped by a cold UK at the time.

Snowbie

GFS 18z has potential but too far away to be excited about still.
It seems a repeat performance like the HP we just had.An azores high moving towards scandi(or as it seems) with positioning critical as usual.
So far im not considering this atm to be worthwhile.
Back to the model watching FI style.

darkman2

00z GFS has completely imploded on its 18z + 96hrs scenario and has gone with the ECM to an extent. Very promiing atm even though the 00Z never delivers for us. Fact is 1050+ hpa Scandi high is now progged meaning anything really!

darkman2

UKMO has ditched its output and gone with the ECM.

GFS falling into line nicely.

Were very close to a very cold spell of weather.;)

http://www.wetterzentrale.de/pics/brack4.gif

darkman2

darkman2 wrote: »

Fact is 1050+ hpa Scandi high is now progged meaning anything really!

Only if it starts creeping into the tv forecasts which would want to be soon.
You don't see the ECM ensembles so you don't know the probability attached to it.

Snowbie

0z is fantastic for an easterly with all models agreements.Not nailed yet in reliable time frame but tantalizingly close.
Friday next week has a similar setup to Jan '82 for us here,but too far away to be believed.

Great runs and best of the winter so far.

maquiladora

Interesting times ahead. It's looking good so far. Keep your fingers crossed....

I'd like to see the nitty gritty closer up though if this pans out at all.
You could have an Easterly that way out west with us has a long sea track and enough modifying to bring rain/sleet.

Country file will be well worth watching on BBC one on Sunday for some actual UKMO forecaster thinking.

nacho libre

i'm not going to get my hopes up about this. let's see what the bbc weather for the week has to say about it on Sunday.

It looks nice chartwise especially for the East of the country (what with the potential for Irish sea showers) but you need negative dewpoints.
A feed down through Russia and across Europe and up through the UK would do that.

You need that feed to run for 4 or 5 days for it to bite though.

You need the UK to seriously freeze up.It was having ice days in january 1982(and throughtout all the classic SH 80's snowy spells) for instance and this helped us a lot as our ground level gale force easterly was feeding in that icy surface air so fast it hardly had any time for modification on the Irish sea.

None of the above is reliaably forecastable as you are looking at a week to 10 days away.
The models will show you the nice eye candy but they will fail with the particulars as its too far out yet.
My advice is to keep looking at t96 and less and if thats playing ball-we're good to go
What happens afterwards may or may not go our way,it will be a nowcast situation as these things always are.

Whilst I know they didnt have the tools that they have now,the tv forecast on the evening of start of the 82 4 day blizzard (yeah 4 days non stop with thunder and lightning) didnt expect what was coming and talked of snow in munster and south leinster with drifts on hills.
This area had 10 to 15ft drifts at Sea level,roads blocked for over a week and drifts on the hills up to the tops of the trees in the woods...thats 40 ft!
I'm not expecting to see that once in a lifetime experience again but if I do,I won't complain too much (for the first few days anyhow,it gets kind of not nice when the shops run out of bread and other foods which they did).

Snowbie

Yep good post Black Briar and i fully agree.
We have to get the ingredients spot on for this one or any potential cold spell, if we where to see snow at sea level.

Although as we all know the charts look promising and if they go inline well thats step one needed.
SST's(Irish Sea)wll have an affect of modifying the air temp both above the sea and coastal regions.
850mb temps preferably below -8c,-10 be my choice of seeing any chance of settling snow.
Dewpoints 0c or below but with the above 850mb temps(-10c) this would have ground temps at 1c and below anyway.
Wet bulb temps again below 0.5c.

So,it would snow for sure and stick even on the beach with the above but it can snow with higher 850 temps at around -5c but dews and wet bulb have to be near the 0c mark for any chance of snow to settle in the heavier precip.

From a east direction,the dews would get low enough but we need a strong wind blowing so no modification of air temps and dewpoints as Black Briar said and just like it occured in the infamous spell of Jan '82.

All sounds so simple,as if.

Edit: The above is true for coastal areas,a few miles inland it becomes less particular and for the mountains.

Snowbie

Snowbie wrote: »

Edit: The above is true for coastal areas,a few miles inland it becomes less particular and for the mountains.

Agreed.
I know they don't want to hear it from a being jinxed point of view but if this flow is strong enough and goes beyond 4 days or more then anywhere above 500ft and more than 3 miles inland could see a fair bit of Irish sea shower settled snow.
For those of us on the coast we need that extra bit of ingredients and all to come right.

At least these synoptics are in early january,I couldn't think of a better time frame (now to mid feb) for them to come off if they do.

maquiladora

12z looks ok......

Ok...it looks more than ok, it looks very good indeed....

It's an absolute beaut!
Snow heaven were it to pan that way especially in the East but not exclusively.

-10 850's penetrating all of Ireland from the East a week today.
The pentration that far west should virtually endure negative dew points.

If I saw the below at t36 or less I'd be happy



And the lp heads SE allowing that cold air as far west as it wants to go.

maquiladora

Deleted User wrote: »

It's an absolute beaut!
Snow heaven were it to pan that way especially in the East but not exclusively.

Fingers crossed all the way now.....

Let's see what UKMO has to say...

ninebeanrows

Absolutely corking 12z run from the GFS