Cold Snap, T0-180Hours Only

K_1

patneve2 wrote: »

I just can't see that massive high pressure being eroded so quickly and easily, I am still confident of cold, maybe not as cold as what models were showing in previous runs but cold with possibility of snow nonetheless

Deja vu . . .anyone remember the posts all over here at Christmas 2010, insisting that the cold was too deeply bedded in to be swept away as quickly as the models were predicting?! Quickest thaw ever seen followed.

Kippure

Did the atlantic win out on the ECM tonight?

No it did not.:)

All is good.

Eastcoastryan

OK, this might sound silly but could this all work to our advantage?? surely if the Atlantic wants to push in and the cold wants to stay, isn't that where all our historic snowfalls have come from?? Warm v Cold?

K_1

I read this thread before looking at the models, and was disappointed. Then I looked at the models - whats all the panic about? We've got a set of dream charts on the big 3 (4?) up to about 90 hours, when it falls apart.

When was the last time anyone took a 96hr forecast seriously?

Isn't the general idea with FI to study the trend? The trend over the last few days has been epic cold, now we have one run where it falls apart and suddenly the whole forum needs prozac. :rolleyes:

snaps

Eastcoastryan wrote: »

OK, this might sound silly but could this all work to our advantage?? surely if the Atlantic wants to push in and the cold wants to stay, isn't that where all our historic snowfalls have come from?? Warm v Cold?

I could be wrong but its a battle of high pressures and not high pressure versus atlantic lows. I think its a battle between the Azores high and the central european high??? The azores high is the high pressure dragging up the mild south westerlys. Would be great to have that sitting there in the summer!!

K_1

snaps wrote: »

I could be wrong but its a battle of high pressures and not high pressure versus atlantic lows. I think its a battle between the Azores high and the central european high??? The azores high is the high pressure dragging up the mild south westerlys. Would be great to have that sitting there in the summer!!

No, there is only one major high pressure system at the moment, which is situated to the east of Scandinavia, almost where we want it. What happening in FI is that a shortwave feature (like a shallow low pressure) goes over the high, sinking it southwards and putting us in a south westerly flow (except the ECM which has it recovering to put us back in a favourable scenario).

nacho libre

K_1 wrote: »

Deja vu . . .anyone remember the posts all over here at Christmas 2010, insisting that the cold was too deeply bedded in to be swept away as quickly as the models were predicting?! Quickest thaw ever seen followed.

The crucial difference this time is deep cold will not have become embedded over Ireland, so the Atlantic's task is far easier. however, if you recall the year before 2010, it took the Atlantic a couple of attempts to get through. Further back in time the same thing happened. So it's not always the case that the Atlantic will sweep away entrenched cold at the first time of asking. It's very much depends on the angle of attack, among other factors.

rc28

K_1 wrote: »

I read this thread before looking at the models, and was disappointed. Then I looked at the models - whats all the panic about? We've got a set of dream charts on the big 3 (4?) up to about 90 hours, when it falls apart.

When was the last time anyone took a 96hr forecast seriously?

Isn't the general idea with FI to study the trend? The trend over the last few days has been epic cold, now we have one run where it falls apart and suddenly the whole forum needs prozac. :rolleyes:

Wise words. I really think people are overlooking what is coming over the next 5 days (coldest weather of the winter with some proper frosts at last). Beyond that truly is up in the air and still all to play for.

arctictree

OK, back to the more short term. Are we not looking at a major snow event for the east on Tuesday afternoon/evening?





Knife edge stuff. The wicklow mountains and maybe Dublin should be inline for a pasting??

ninebeanrows

arctictree wrote: »

OK, back to the more short term. Are we not looking at a major snow event for the east on Tuesday afternoon/evening?





Knife edge stuff. The wicklow mountains and maybe Dublin should be inline for a pasting??

Yes the ECM pumps up that low more than the other models and thus brings in the cold.

Interesting indeed, but most other models have this cold front further east.

One to watch and in the much more realistic timeframe!

nacho libre

Eastcoastryan wrote: »

OK, this might sound silly but could this all work to our advantage?? surely if the Atlantic wants to push in and the cold wants to stay, isn't that where all our historic snowfalls have come from?? Warm v Cold?

in a word. yes! the ideal scenario would be a front stalls, leading to somewhere in the country getting 48 hours of heavy snowfall. while there is less likelihood of forecasters being caught out nowadays, january 2009 was a recent example of this- some parts of the country had over 10 hours of snow.
there was one glorious example of unexpected frontal snowfall in the early 80s, which lead to significant snowfall in the east of Ireland. so while usually the cards don't fall in our favour, maybe next weekend they just might.

sdanseo

I know Icelandic charts are usually fairly reliable but seriously, a low (modelled differently on two charts for the same time) of 1014hPa? :rolleyes:

ninebeanrows

sdeire wrote: »

I know Icelandic charts are usually fairly reliable but seriously, a low (modelled differently on two charts for the same time) of 1014hPa? :rolleyes:

Yep we've been had!

The precip chart is from this mornings ECM, while temp from this evenings ECM.

Reckon should be pretty similar though, maybe the precip a wee bit further south.

ninebeanrows

Here is the T54 PRECIP

Even better

arctictree

sdeire wrote: »

I know Icelandic charts are usually fairly reliable but seriously, a low (modelled differently on two charts for the same time) of 1014hPa? :rolleyes:

Sorry, updated the precip chart. Still a lot of precip around though. And AFAIK it is the ECM.

ninebeanrows

arctictree wrote: »

Sorry, updated the precip chart. Still a lot of precip around though. And AFAIK it is the ECM.

Would be nice for Wicklow, and even a few miles off the east coast as your travel northwards.

Redsunset

As it pulls away and the wrap around of colder air has a greater influence





Anyway that could be so much different in later run but something to throw the eye on for sure

Eastcoastryan

redsunset wrote: »

As it pulls away and the wrap around of colder air has a greater influence





Anyway that could be so much different in later run but something to throw the eye on for sure

Will we be under colder air at that stage? I'm assuming night-time would be better in terms of low level snow!!?

Redsunset

Yeah better chance to lower levels.Be like back edge snow. More than likely change though, KEEP WATCHING TIS ALL WE CAN DO:D

Redsunset

Maybe ye have seen this but here is the official MetOffice blog.
Should be good for updates on the situation in front of us

http://metofficenews.wordpress.com/

pistolpetes11

Im only doing these vids out till 144hr even at that I have prob gone into FI

ECM 12Z

https://www.youtube.com/watch?v=W84WhA7BPhE

GFS 12Z

https://www.youtube.com/watch?v=cfKW9Sn8s-o

Deep Easterly

nacho libre wrote: »

january 2009 was a recent example of this- some parts of the country had over 10 hours of snow.

It was Jan 2010 Mr. Mayo!

yorlum11

gfs-2012012912-1-90.png

I mean we would be happy to get here by next Friday,where does it go wrong from here and what would be best to keep it all moving westward?

Im a newbie to all this and trying to get a handle on it.

aboyro

Can i be so bold as to ask a question about that high pressure of 1050mb's. what is known to be the highest high recorded over europe/siberian??

Tom Cruises Left Nut

Right nearly 18z time.

Will the pub run give us some eye candy ? Answers on a postcard ! :pac:

Tom Cruises Left Nut

aboyro wrote: »

Can i be so bold as to ask a question about that high pressure of 1050mb's. what is known to be the highest high recorded over europe/siberian??

From Wikipedia:

The highest barometric pressure ever recorded on Earth was 1,085.7 hectopascals (32.06 inHg) measured in Tonsontsengel, Mongolia on 19 December 2001

pistolpetes11

yorlum11 wrote: »

gfs-2012012912-1-90.png

I mean we would be happy to get here by next Friday,where does it go wrong from here and what would be best to keep it all moving westward?

Im a newbie to all this and trying to get a handle on it.

Hard to show off that chart ,

But we dont want the high pressure to sink into Europe ,

Ideally it would place over Scandinavia or move towards Iceland.

On most of the tonights models there is too much energy in the northern arm of the jet stream , which in turns send a low pressure system toppling over our high and pushing our the HP into Euro which in turn allows the atlantic /milder air to come across us.

Redsunset

I can't help but admire the sheer depth of cold pouring out from Siberian all the way across to Europe.:D
Also this is Tuesdays chart from 12z GFS and we certainly got a chance of snow then.

nacho libre

Deep Easterly wrote: »

It was Jan 2010 Mr. Mayo!

I can't even remember things from a couple of years:o

While the entrenched cold air helped no end, the track sw- ne over the country was crucial. Had it been west - east, things could have been different. I remember yourself and redsunset at the time predicted there would be snow, despite met eireann saying no.

Su Campu

We had two stations on the Finnish-Russian border report sea-level pressure of 1061.3 hPa at 09Z this morning, the highest of the winter so far. The stations were at 181 and 223 m.

Just a word on these high pressures, especially the one in Mongolia, which was taken at an altitude of 1750 m. They were not actually recorded in the sense that that was the pressure at the barometer at the time. They are calculated from station pressure and virtual temperature over the past 12 hours, so in very cold conditions, where the rate of change of pressure with height is greater, extrapolating station pressure down to sea level will yield very high figures. At high altitude stations, this calculation becomes very unreliable, and for this reason many high-altitude synop reports only report station pressure.

The same goes for Ojmjakon, which at 750 m has been reporting sea level pressures way above what the models are analysing, and I suspect the models are programmed to disregard the sea level calculation in such case, only taking the station pressure.

In the case of today, the stations along the Finnish-Russian border are relatively low down, and the station pressures were still relatively high (around 1030 hPa), so this is truly a strong anticyclone. How strong it will be against the Atlantic systems will be one to watch, however, as the supply of high geopotential northwards gets cut off during the week.