Forecasts for Cold Snaps/Spells and Snowy Weather only.

Trogdor

darkman2 wrote:

LOL!!!!!!!!

Real height rises over GL in the reliable timeframe:

http://www.wetterzentrale.de/pics/Rtavn1561.png

which leads to this;)
http://85.214.49.20/wz/pics/Rtavn1921.png
I've been optimistic so far this winter thinking that we'd get something good. I know the only reliable thing at the moment is the northerly this weekend which could still change i suppose:p but i think what it leads on to could be very interesting indeed

Snowbie

Ok lets hope the models upgrade further and keep up with height rises.A bit away from certainty atm but the best output we have seen so far.
Tuesday/wedensday cant come quick enough for it to be a defo.

Edit: DM that HP seems to want to park over us than over GL in the 18z.Still on this run to give a northerly but not artic influence yet.Needs positioning in Greenland to give us the artic blast.
0z should be interesting.

arctictree

Wow - look at the chart for Wed 24th:

http://www.wetterzentrale.de/pics/Rtavn2161.html

A strong easterly at the end of Jan?!!

How accurate are these anyway in your experience?

A

SpitfireIV

arctictree wrote:

Wow - look at the chart for Wed 24th:

http://www.wetterzentrale.de/pics/Rtavn2161.html

A strong easterly at the end of Jan?!!

How accurate are these anyway in your experience?

A

That link doesnt work for me, but seen as its over a week away I wouldnt pay much attention to it, could all change.

ninebeanrows

Wahooooooooooooooooo

Salvation at last for cold and snow lovers salvation at last..

Couldnt have seen this coming from around the tightest of bends last week but thats why the weather is so god damn good. You just dont know what ya gonna get!

This 12z is by a some way the best output of this winter, no doubt the usual cautions must be beared but the models have been homing in on this synoptic for some time but it is just getting better and better with each run.

Cold northerly next weekend turning easterly towards the New Week - fanbloodytastic:D

time for a few good ole

darkman2

Right this deserves its own thread. Ive just seen some of the best charts in years. Will post on this etraordinary upcoming cold spell later;)

Gonzo

about time we all deserve a decent dollop of snow here, we are so overdue an 80s style whiteout, I know it prolly wont happen but it wud be so cool... 6 inchs plus and the news reports 'do not venture outside unless you really have to' wud be a gud start I think:) I can only dream but maybe just maybe we get lucky this time around!

ninebeanrows

I wouldn't say the best in years Darkman i've seen better charts last year and the year before - last year they didnt materialise but the year before they do.. You need really exceptional charts to bring a good snow around here and a load of luck -- we have near exceptional charts at +160hrs and we dont know what our luck is yet...

Long time to go - charts are extremely good but not amazing at this stage:)

Takeshi_Kovacs

I dunno, i'll believe in the snow when i see it lying out side my front window, until then, it is all speculation..
though with the rain that fell today, you would have some serious amount of snow if it had been a lot colder. But what are the odds that if we do get a cold blast, that we will get dry weather with it?

lucernarian

I'm going to deliver a dose of pessimism now: this "irrational exuberance" will leave us all depressed. Look at it this way, we are depending on some supercomputers to basically predict the future. We will get cold weather and we will probably see snow within the next two weeks, but those in the pale should not get excited.

I remember at one stage last year that the ECMWF had a roaring NEely for us at 120 hours out but the next run collapsed the whole trend like a house of cards. The greenland high that we did have, delivered primarily to Donegal, and not much by historical precedent.

From those charts, I can't see how Donegal/north coast of Ireland could fail to get snow of some description from Sunday morning onwards but precipition and its path is a biatch to predict as we all (should) know. It's like pinning the tail on the ass, blinfolded. I'm particularly concerned by the positioning of the Atlantic High, and I feel its position is treacherous. We are very close to dry, cold days appearing on the charts. This particular coin is still in the air.

I have my fingers crossed, but until this coming Thursday arrives, I am reading these as a probable lack of data from the Atlantic Ocean and refuse to look at them as anything but fantastical tripe.

Here we go again!:)

darkman2

Should say snow showers are expected on Wednesday especially in the west and north.

Supercell

The 12Z ensembles are just bloody brilliant , every run seems to be getting colder which is a fantastic trend, and also looks like there will be precipitation around, especially on Monday which looks like being the peak cold day right now.

Am very very happy to see at least the possibility of snow finally and in January, in recent years we've been seeing charts like this in blooming March which has too powerful sun to allow a proper cold spell.

Fingers and toes crossed that the trend continues and doesn't melt away at 72 hours!

Snowbie

To_be_confirmed wrote:

I'm going to deliver a dose of pessimism now: this "irrational exuberance" will leave us all depressed. Look at it this way, we are depending on some supercomputers to basically predict the future. We will get cold weather and we will probably see snow within the next two weeks, but those in the pale should not get excited.

I remember at one stage last year that the ECMWF had a roaring NEely for us at 120 hours out but the next run collapsed the whole trend like a house of cards. The greenland high that we did have, delivered primarily to Donegal, and not much by historical precedent.

From those charts, I can't see how Donegal/north coast of Ireland could fail to get snow of some description from Sunday morning onwards but precipition and its path is a biatch to predict as we all (should) know. It's like pinning the tail on the ass, blinfolded. I'm particularly concerned by the positioning of the Atlantic High, and I feel its position is treacherous. We are very close to dry, cold days appearing on the charts. This particular coin is still in the air.

I have my fingers crossed, but until this coming Thursday arrives, I am reading these as a probable lack of data from the Atlantic Ocean and refuse to look at them as anything but fantastical tripe.

Here we go again!:)

Good post TBC,
Everybody take note of this it is to the point and it says it all.
Im not knocking our overdue cold,christ knows i want it too but we have to be honest with the ensembles of which the HP is of the utmost significance.If on a track towards GL we need it to go.If over us blah.

Ah exciting times ahead over the next few days.:)

Villain

Umm I go away for a few days and come back to these charts! It does seem awful far out to be getting excited about though, surely the atlantic will kick this cold snap back before we see any white stuff? Or perhaps the I'm just being negative for once hoping it will prove me wrong

fatherdougalmag

Is there not a bit more confidence behind this snap seeing that multiple models are showing the same coldness?

arctictree

Hmmm - charts on wetterzentrale seem to be changing quite a lot.

Monday still looks like the coldest day with not much change for Tue/Wed although the strong easterly seems to replaced by a north easterly.

I'd say we'll know for sure on Wednesday this week.

A

Snowbie

Use this thread to post on forecasts from any Met Organisation on the possibility of snow from more than one day out and beyond.Use model detail(GEFS,ECM etc) if and when you can to explain the posibilities.

Post on snow events that are presently happening or are certain to happen in this country within 24hr peroid [thread=2055023550]here[/thread]

This is to seperate a forecast for snow and an imminent type snow event.

darkman2

May aswell start with the ensemble chart on this thread:




Ive decided not to post charts from the models for the time being until we get over the more uncertain period and also so as not too build up too much expectation. Until then check out the ensemble chart ive just posted. As you can see really good agreement for a marked drop in temperature from the 20th. Where the average starts to rise is well into FI and should not be taken much notice of atm. Clear indication there of a very cold period of weather from this weekend. Indeed by the 22nd temperatures will be hardly getting above freezing on that chart. After that it could go anywhere from an Easterly to a Southwesterly. Fingers crossed for the former:D

Snowbie

Continue the discussion here

http://www.boards.ie/vbulletin/showthread.php?t=2055041562

Snowbie

Right,a good start may it continue.Bit of BB trouble atm whats the 18z doing with our High pressure

Trogdor

Each run seems to upgrade each this cold snap which is making me happier and happier the only downside is that it can downgrade just as fast but the change in the charts has been amazing it's gone from zonal to easterly in 36 hours. If the wind were to pick even a slight easterly component it should be good for the east coast with a feed of showers:D
P.S.18z doesn't start to come out for another hour yet

lucernarian

As this run progresses, the Greenland High is weakened but it might hold off further into the Atlantic. This is just based on what looks likely and fits into the pattern - nothing really scientific in my method so this could be crap.

I'd also say that higher precipitation will be a feature of this run.

Edit: after looking at the t+120 chart, there's a definite increase in precipitation:p The Icelandic low in the run which is much stronger this time is the one forecast to hit us next weekend.

ninebeanrows

They say a week is along time in politics-



Somebody pinch me... is this January 2007 or have i been taken to some fantasy planet...

Stunning charts tonite just immense.. getting better all the time too..
How long will it last

boardsdotie

darkman2 wrote:

May aswell start with the ensemble chart on this thread:




Ive decided not to post charts from the models for the time being until we get over the more uncertain period and also so as not too build up too much expectation. Until then check out the ensemble chart ive just posted. As you can see really good agreement for a marked drop in temperature from the 20th. Where the average starts to rise is well into FI and should not be taken much notice of atm. Clear indication there of a very cold period of weather from this weekend. Indeed by the 22nd temperatures will be hardly getting above freezing on that chart. After that it could go anywhere from an Easterly to a Southwesterly. Fingers crossed for the former:D

I always wanted to understand this model. Is this true ....

Ignore all other lines except for the thick red line, as this is the average of all runs ?

lucernarian

Having seen the run up to t+168, I'm going to leave it at that. I'm pretty pleased, though the polar jet is doing some curious things on the chart 1 week ahead which I can't tell the significance of. I also notice heights are rising more strongly near/over Scandanavia. The +174 chart identifies an individual high pressure cell at this stage. This looks like a much better chart for long term prospects.

The HP positioning is not as good for those in the pale as the wind direction is much more of a northerly/northwesterly bearing as a consequence of the HP being a little further south. But the amount of small LPs at the beginning of events is terriffic for Ireland as a whole!!! There could be spells of light wintry precip. as early as Saturday evening!

*takes off dunce cap*

Those LP systems are lovely but the change between the two runs is startling. The first LP that hits us is developed totally different on this run. It can very easily change again. It's impossible to tell who will end up with the rain and who will get the snow and if the cold air will reach our shores before or after the rain has passed.

It's still very borderline...

Trogdor

boardsdotie wrote:

I always wanted to understand this model. Is this true ....

Ignore all other lines except for the thick red line, as this is the average of all runs ?

Sorry about going OT but the red line is the average temperature of the last 30 years. The white line is the average of all the runs and the blue is the control run that is displayed in full detail. The precipitation is on the bottom of the graph and 850hpa temp on the top.

EDIT: been keeping an eye on Wednesday's cold blip since last week and there is definately a bit of potential there too:D

boardsdotie

trogdor wrote:

Sorry about going OT but the red line is the average temperature of the last 30 years. The white line is the average of all the runs and the blue is the control run that is displayed in full detail. The precipitation is on the bottom of the graph and 850hpa temp on the top.

Thanks for that

Is there a plot on this graph where the precipitation meets the temp that predicts snow.

Trogdor

boardsdotie wrote:

Thanks for that

Is there a plot on this graph where the precipitation meets the temp that predicts snow.

OT again, sorry:o
Not really from this chart. There are so many different factors that have to be right to get snow that's it's very difficult to forecast. On this chart there is only temp and precip so it's not that great for predicting snow. To forecast snow the main variabes are the 850hpa temp which needs to be below -5C generally
http://85.214.49.20/wz/pics/Rtavn1802.png
the air thickness which needs to be below 528dam generally
http://85.214.49.20/wz/pics/Rtavn1803.png
and obviously the precip and
ground temp althought as i said there are many, many more aswell
http://85.214.49.20/wz/pics/Rtavn1804.png
http://85.214.49.20/wz/pics/Rtavn18017.png
they can all be found at
http://www.wetterzentrale.de/topkarten/fsavneur.html
and for just a snow prediction chart as i posted in a differnt post above you can go here http://www2.wetter3.de/animation.html
and click on niederschlagsstaerke und-form is the slide down box. Pink is snow and blue is rain

darkman2

boardsdotie wrote:

I always wanted to understand this model. Is this true ....

Ignore all other lines except for the thick red line, as this is the average of all runs ?

The white line is the average of the runs currently being displayed. The red line is what we should expect this time of year. (its the average over 30 years)

lucernarian

The 06z GFS looks good for 5 days of quite cold weather in a very unstable airstream. It starts off with NWely winds and finishes off with NEely winds so there should be something to please everyone in that run.

ECMWF is not very good at all to be honest. It portrays just what I feared: Atlantic HP forcing the LP away from us and then it moves right over us, or close enough to prevent extra convective showers or troughs from approaching us. What I saw on the ECMWF is something to be looked at before we get the snow shovels out.

http://www.wetterzentrale.de/topkarten/fsecmeur.html