Model Outooks: Winter 2008/2009

daviddwyer

Hi Snowaddict

What does this all mean.... are we back on track....or just going in a different direction. Please tell me..... WILL THERE BE SNOW?

Danno

Right, anything else beyond a week is huff and puff at this stage. What the run 18z shows is quite encouraging indeed. A true greenland high that is built high up in the atmosphere with plenty of warm air rushing up the NW passage. A splitting Polar Vortex that is centred over lapland with it's secondary centre in Denmark. This opens a floodgate of NE'ly cold air that will rush down over Ireland and Scotland before being deflected westwards by shortwaves running from mid Atlantic, off the south of Ireland and up the english channel. These shortwaves will be very interesting to see how they react with the cold air when it hits them... IMHO a very good run, and I have a strong inkling that as the week progresses, we will see the cold air arrive a few hours sooner and the whole scandy vortex shunted about 100 -> 200 miles further west meaning that the secondary low will be located somewhere in the mid North Sea off Newcastle, UK.
If this happens, then a snow shower fest could spark off in the Irish sea and affect eastern Ireland over the weekend, especially when the deep arctic air comes down.

Snowbie

Danno wrote: »

The Greenland high is much stronger with thicker air and much more WAA than earlier runs. A low to our SW, a low to our NE come Saturday.

The missing element of WAA (warm air advection) of recent runs but then this run does not have a retro in GL. Really quite an opposite run again but in terms of cold much better than the 12z.

From here on in, i would stick with palpatations from the ECM both for good and bad. GFS is good in the short term and does not do well with blocks. I hope we can all see the difference in the last 4 runs or 24hrs, it has painted a clear pic of GFS past T+96, its hopeless and not consistent.

ECM ftw.

snowfan

The UTV weather has just stated that things will get colder by the 2nd January with Polar air streaming down over Ireland

Could be interesting.......:)

Snowfan

arctictree

j1979p wrote: »

Not a good 18z at all

I beg to differ.

The 18z is a cracker and floods cold air down over Ireland from the NE at t+180

Again, this is knife edge stuff. The real interesting stuff is still in FI and note that there was a significant change on this run at t+120.

Pangea

lol @ this going back on favour of a cold spell, its hard to keep up

Danno

The theme is right, but the detail is not in it to be honest... as ever more runs are needed. There will be more detail in upcoming days, but for the moment the GFS is on the right track and I think it will be a building process from here on in. I predict further upgrades... just my gut feeling, but I have said this since 23rd December and I genuinely believe that this first half of January will be more cold and severe than anything since 1995 or 1991.

snowfan

Danno wrote: »

but I have said this since 23rd December and I genuinely believe that this first half of January will be more cold and severe than anything since 1995 or 1991.

What is this based on Danno ? Gut feeling ? Or do you think these cold spells are cyclical and Ireland is due a good cold blast now?

Snowfan

Danno

I would say its a bit of everything really. Genuine gut feeling, I am encouraged by this winter's patterns and I feel that we are waay overdue a stern blast of snow.

Villain

The models are changing rapidly, Brian Gaze on TWO reckons the 18z is missing data?

I don't know the charts look good tonight to me but my ability to read charts is low to zero, the problem with the kind of setup I can see is where the mild meets the cold air, a few hundred miles east and all we get is sleet and rain a few more hundred miles west and we could get serious snow fall but looking at charts over 100h for that kind of detail is like looking for a Virgin in Coppers.

Or maybe I'm reading it all wrong?

Danno

Nope, you are fairly spot on Villain. As I have said the theme is there, the detail isn't, but it is of encouragement to know that the main run was a mild one, all the others are colder.

It does seem that some critical data is still missing from tonights run according to TWO, but I suspect that the amount is far less than what has been missing since December 24th.

My 2c.

snowfan

Villain wrote: »

The models are changing rapidly, Brian Gaze on TWO reckons the 18z is missing data?

I don't know the charts look good tonight to me but my ability to read charts is low to zero, the problem with the kind of setup I can see is where the mild meets the cold air, a few hundred miles east and all we get is sleet and rain a few more hundred miles west and we could get serious snow fall but looking at charts over 100h for that kind of detail is like looking for a Virgin in Coppers.

Or maybe I'm reading it all wrong?

This would be my nightmare scenario and has happened so many times in the past

Ireland undergoes a cold period

Then when the rain hits the west coast, it crosses Ireland as rain but once it hits Britain it falls as snow...typical!

If this happens again, I will be having a word with the man above!

Danno

The reason for that happening is the fetch of the wind involved. Usually a front coming in from the west is preceeded by south winds, coming in over Tramore Bay they get a lot of heat from the sea and mixes with the cold air over here causing snow to fall as rain.

In England, they have France to thank for keeping their air cold when the same southerly winds hit there.

However, when we get the atlantic coming in from the southwest, this causes the winds to back more east or southeast, suddenly the landmass of England and Wales becomes a helping hand for keeping the air travelling over us cold enough to cause the snow to fall all the way to the ground as snow.

In the second scenario above, either of two things can happen - 1: The southwesterly becomes established and the snow is only a two or three hour event; 2: The front stalls or retreats back into the Atlantic or down to the bay of biscay... every snow lover in Ireland's dream! In this situation only Devon and Cornwall and maybe pembrokshire join in the fun as the rest of the UK stay sunny and dry, but very cold.

snowfan

Thanks Danno,

Very informative!

I never knew that was why rain fell over Ireland in such a scenario, now this makes sense

So lets hope then we get a cold pool of air over Ireland with rain coming in from the south west....might give us some snow !

SF

Snowaddict

Hey again all.

Its difficult to keep up with somewhat unreliable internet access at the moment in lands far away, but the 18Z ensembles are certainly much better than the 12Z ones.

That is the key for me. The mean drops below -5 on the 5th of January, and remains below right out until the end of the run.

Furthermore, the operational was not on its own with its very wintry output.

However, nothing is certain yet again and we need to see the setup at T+72 before any real excitement can kick in.

Either way, I agree completely with Danno's feelings on January. This is slightly off topic but the United States is experienceing record warmth in eastern and mid western parts at the moment. Several of the past severe cold spells included this setup, notably Feb 1991.

This is far from set in stone at the moment, but very very good ensembles. However, the main cold onset it still outside of the much more reliable timeframe.

Regards,
SA.

Pangea

Everywhere seems to be predicting that the cold snap will last until mid january
http://www.guardian.co.uk/weather/2008/dec/29/health-warning-cold-weather-met-office

Danno

http://www.wzkarten.de/pics/MT8_Dublin_ens.png <<< Snowfest 5th January according to tonight's ensembles.

Pangea

Danno wrote: »

http://www.wzkarten.de/pics/MT8_Dublin_ens.png <<< Snowfest 5th January according to tonight's ensembles.

Wow, It dont get more complicated than that, the bit i do understand is the word snowfest from your post *does a jig.

j1979p

arctictree wrote: »

I beg to differ.

The 18z is a cracker and floods cold air down over Ireland from the NE at t+180

Again, this is knife edge stuff. The real interesting stuff is still in FI and note that there was a significant change on this run at t+120.

I must have been looking at the 12z cos I had another look and I see what u mean! Not bad but still too far in FI I think to be worth getting overly excited. We've seen how fickle these models can be

Pangea

Got to give SA credit here, pretty much spot on, this is ur post on the 19-12-2008, 10:46 ,Im sure there is other people with other accurate posts but I came across SAs and thought id give him props on it. We are quick to complain when outlooks dont fair out the way we were told but we are even quicker forgetting about old outlooks that are correct.

Snowaddict wrote: »

IMO, the GFS operational 06Z run is a major upgrade in the more reliable timeframe, and certainly for that ever dreaded FI.

A Greenland high of 1064 mb is develops on this run... And just look at what follows.

The positioning of the high is much much better IMO. Of course this is only one run, but its another one in which things are definately trending in the right direciton.

On Xmas and Stephen's day, we miss out on an easterly by about 350-400 straight line miles. Its that close to be honest. And as the run develops its simply fantastic.

I mean, we are covered in a cold to very cold airflow from about the 28th onwards on this run, and just look at what develops at the end of it.

I don't care that these are in FI, they are simply FANTASTIC. Furthermore, there is a clear trend for cold from T+180 onwards. Just look at that chart below.

Its a classic, no doubt about it. Sorry but I had to get excited when seeing this run, because it is truly a classic.

Just take a look at this chart, and the ten that go before it, by the end of this run Ireland is gripped by a severe wintry outbreak into the New Year.

A big health warning attached to it though, this is FI and is subject to substantial change and I would assume that this will be a cold outlier in the main...

Danno

Seen this over on TWO -
10 to 15cm snow anyone?

*WARNING* This may or may not happen.

Supercell

Supercell wrote: »

All eyes on that channel low modelled on for next Monday night, slight changes in position of that will make massive changes to our weather here, one to watch in upcoming runs I think.

*Ahem*, one to watch, going to be a nowcast situation right up till Monday I reckon but does represent our best chance of something decent in the shortish term.

kerry1960

Danno wrote: »

Seen this over on TWO -
10 to 15cm snow anyone?

*WARNING* This may or may not happen.

From an IMBY point of view all i can say is fcek it , yes fcek it .........away in Prague all next week and could miss out on this ........grrrrrr :mad:.

Pangea

kerry1960 wrote: »

From an IMBY point of view all i can say is fcek it , yes fcek it .........away in Prague all next week and could miss out on this ........grrrrrr :mad:.

lol i feel for u man ,dam hateful il save u a snowball in my freezer :P

danni2

Well nice to see upgrades from earlier runs, lets hope this continues.

kerry1960 you will probably have a better chance of seeing snow in Prague, it's much colder there then in Ireland.

kerry1960

danni2 wrote: »

Well nice to see upgrades from earlier runs, lets hope this continues.

kerry1960 you will probably have a better chance of seeing snow in Prague, it's much colder there then in Ireland.

Not wishing to sound too picky but given the choice i'd take the snow in Kerry ahead of the cold in Prague .........did i just say that ........:D.

danni2

kerry1960 wrote: »

Not wishing to sound too picky but given the choice i'd take the snow in Kerry ahead of the cold in Prague .........did i just say that ........:D.

Yep you said it:D

Anyway you may not be missing anything after all, the 00z has downgraded again:mad:

JanuarySnowstor

Well ive given up on N/W mainly because of the incessant ramping of late. The models there are ignored if mild and treated as 100% when showing cold.
As for Ireland I cant remember in my lifetime such boring weather the last 3 weeks. Cold but not cold enough. Might aswell be mild:cool:

snowfan

Hey JS ,

I totally agree - the weather for the past week here in Dublin has been boring.

Grey every day with highs of 4 to 6oC. One night we had a severe frost but the other nights the temp hovered between 1oC and 3oC

God bring on the decent cold! You are right, with this type of weather it might as well be mild !

SF

200motels

Here's the latest model for next Sunday. Not bad but how reliable are these models? They seem to change on the hour.