Jan-Feb : The model search for more cold

Snowbie

Darwin wrote: »

blackbriar - I think I see what you are saying...I'm still a bit confused about the origins of the forecast cold snap on Wed night/Thursday - the charts show an area of LP blowing atlantic westerlies (mild wet weather?) with an area of HP positioned over the bay of biscay.

The origin of the westerly was polar,but in this instance it is a returning polar maritime air. Its not a direct arctic blast but the air is not being modified too much to cause the usual cool westerly,so a very cold westerly is in the making. The HP to our south is moving NW so the winds will arc more to a WNW direction helping to draw in the colder air

Another example is,if a LP traveled down from the north,straight down from arctic regions and was off our western seaboard,what you would have is a SW or S'ly wind but it be very cold as it is a RPM(returning polar maritime) and you would get snow to more southern windward areas as the air has not got sufficient time to heat up or modified.

Snowbie

Snowbie wrote: »

Another example is,if a LP traveled down from the north,straight down from arctic regions and was off our western seaboard,what you would have is a SW or S'ly wind but it be very cold as it is a RPM(returning polar maritime) and you would get snow to more southern windward areas as the air has not got sufficient time to heat up or modified.

Thats a much better explanation of the possible outcome of what is being hinted at , depending on the orientation of the iberian high once it heads north westwards into the atlantic.

nacho libre

but if the high is moving north westwards will this not mean pressure will become too high for any sort of snow event over most of Ireland bar a few showers in the north and north east?

Snowbie

nacho libre wrote: »

but if the high is moving north westwards will this not mean pressure will become too high for any sort of snow event over most of Ireland bar a few showers in the north and north east?

With this situation atm,no as its up against a strong arm in the jet. The HP is not too close to Ireland for the cold blast on Thursday,plus the pressure gradient is tight across the northern atlantic track so showers will be blown from a long stretch across to us.

Whats significant is a Jan 3/4th snow in Meath and Louth is possible from Mizen head to Malin head inland,but be hard to tell where at the mo. The east could get a rouge shower if the wind remains strong but just inland west can see merging snow showers and several cm's. These showers would also be heavier than what was experienced in the east 3 weeks ago due to the longer track and more moisture content.

Now if the HP stays put over biscay or slightly west(which i think it will for now) thursday looks short but significant and then the HP comes closer for the weekend and with Black Briar too mentioning positioning of the HP for later,as i said before a LP could could travel down a NW airstream to make things more interesting if our HP moves off more west.

Villain

Lads I'm heading to Stockholm on the 1st of Feb what would think I'll see in the way of weather?

ninebeanrows

Check out this for a chart, more like a mid summer chart.



Wrt Stockholm, really cold air is expected to push into Scandanavia towards February and set up shop.

Danno

Jeez WC, yesterday (Monday) was supposed to have been the most depressing day of the year... stop continuing the pain man!

So when can I open a "winter is over thread"???

Snowbie

Danno wrote: »

Jeez WC, yesterday (Monday) was supposed to have been the most depressing day of the year... stop continuing the pain man!

So when can I open a "winter is over thread"???

I'd keep that on hold for a second Danno. Have you seen whats progged for the end of the month/start of Feb. A nice potent NNE'ly from 00Z GFS. FI i know but in accordance with this thread its the best output in awhile for cold.

Heres similar from tonights ECM.

http://www.ecmwf.int/products/forecasts/d/getchart/catalog/products/forecasts/medium/deterministic/msl_uv850_z500%21Wind%20850%20and%20mslp%21192%21Europe%21pop%21od%21oper%21public_plots%212008012312%21%21chart.gif

I don't think I can recall a High in this position bringing a Northeasterly before but its a different kind of northeasterly in that it's really a Northerly artic source.

Brrrrr!

FI of course

Gonzo

the way things have been turning since the middle of January, I want to Roll on Summer!!! in all honesty.....if we havent had a major snow event between now and end of February then roll on Summer to the max....

arctictree

OK - Still FI, but this time next week seems to turning much cooler.

http://www.wetterzentrale.de/pics/Rtavn1681.html

(Fri and Sat look like crackers but thats really pushing it into FI...)

Looks like we could have a good few dry days between now and then. Especially in the east...

A

Gonzo

excellent stuff, i could do with some dry days regardless of temperature, im sick of all the wet and muck.

http://www.wetterzentrale.de/pics/Rtavn1921.html

if that happened we would have at least 6 inchs of snow from Irish Sea snow showers.

ninebeanrows

ECM is satisfactory this morning.

ECM @ 168hrs............... this is the type of chart we need to verify to save our winter.

Villain

I'm due in Stockholm for that, if that chart came off what would I be looking at WC?

Weathercheck

Weathercheck wrote: »

ECM is satisfactory this morning.

ECM @ 168hrs............... this is the type of chart we need to verify to save our winter.

Yeah lovely that *if* it happens.
Twould safely deliver snow to Galway anyway as it's a proper feed of Polar and not a roundabout one.
Even Dublin would see snow from that.
We here in the Southeast would most probably see nothing or very little including longfield and artictree I'm afraid unless a disturbance moves south which has happened in a set up like this in the past.
I can recall one where it surprisingly started snowing even town here for a few hours.
Very little settled but it was pleasant winter weather and the hills got very white.



No point in salivating over it yet as it may never happen or verify as a one or two day wonder.

hawkwing

meteireann
Turning very cold by Tuesday night, with severe frost, but mostly dry. Early indications suggest that it will remain bitterly cold through Wednesday, Thursday and Friday, with severe frost at night and a risk of wintry showers.

also the cnn long range for dublin and belfast looks cold from tuesday on,winter is coming back:cool:

Supercell

Next week is looking interesting for us.
I reckon there could be snow even in the east looking at the ensembles, whether it will be cool enough for settling snow is too early to tell - definitely my eyes will be glued to the charts over the next few days.

arctictree

Charts looking good, Met.ie mentioning wintry showers late next week, steady as she goes....keeping calm....

A

Danno

The 18z run is coming out now. Up to Friday next week so far (at the time of typing). Quite alot of borderline situations after Tuesday night...

Paddy.1

ECM 00hrs downgrades cold snap for next weekend:
http://www.wetterzentrale.de/wz/pics/Recm1921.gif

Still looks like the north and north east could sqeeze a little something out of it up til then.

ninebeanrows

Paddy.1 wrote: »

ECM 00hrs downgrades cold snap for next weekend:
http://www.wetterzentrale.de/wz/pics/Recm1921.gif

Still looks like the north and north east could sqeeze a little something out of it up til then.

Not really just the cold has moved up to the 120/144/168 charts!!


Looking at the ECM and GFS which are very similar, it looks like a 3 day intense blast of cold air, i say intense because the cold air we are tapping into is reallllllly cold.

We are talking about ice days for Thursday/Friday/Saturday of next week
with widespread snow showers.

Gonzo

theres a risk of the cold weather lasting till Tuesday 5th February but the main cold will be Wednesday to Saturday of next week if things work out the way we hope.

darkman2

he snow potential starts Wednesday night really. In factthe risk of more prolonged sleet or snow wednesday night. Gets colder from then on. We cant ignore the fact that some quite marginal situations are coming up. ATM it looks on the right side of marginal generally.

I'm not unconvinced that this will be good for Galway across to Dublin and North of that line but also good for West Munster.
There is unlikely to be anything more than Frosty days and nights , a very cold wind,low negative dewpoints etc but mainly dry weather south and East of that line-with maybe a few snow showers breaking through.
Unless you get a polar low which will do two things,it will make for a snow fest in the high risk areas I've mentioned but would likely breach that area to give some snow fall further south ie even into the southeast but not much and probably not settling except on the higher ground.

The air mass seems likely to be unstable enough for polar lows with varying degree's of ooomph but you will not know of their existance `up to 36hrs prior to their forming.

I'm not expecting ice days out of this in coastal areas by the way.

The above is said assuming todays data verifies which it mightn't though with such ensemble and cross model support,it more than likely will in some shape or for but is just as likely to turn into a one or two day wonder nearer to the time,if some as yet unseen (around these parts)system from nowhere heads out of the states and buggers up the track of the polar air.

lucernarian

36 hours would be a very very remarkable forecast for a PL. The shallow low on 3rd January (I don't think it can be called a polar low) was spotted by myself not even 2 hours before it reached here and it was spotted by the Met Office 3 hours beforehand. It seemed to have gone unnoticed by Met Éireann themselves.

And polar low or not, the southern half of the country will experience nothing disruptive I think. It looks like the far north of the country can't lose however!

There'll be showers boys, and lots of them! The question is, where will they accumulate? IF there's a Polar Low at some time, experience tells me that the "oomph" will die off after Monaghan town or thereabouts;)

to_be_confirmed

Those shallow lows and polar lows are not the same beast
I said within 36hrs for to see polar lows which means within 36 hrs of the event or during the 36hrs of the event more like.
You'll commonly see them form 24hrs upstream from you in a disturbed enough polar low.
I'm not as confident (yet) as to the amount or distribution of showers.
They could end up in fact being everywhere tbh.

to_be_confirmed wrote:

And polar low or not, the southern half of the country will experience nothing disruptive I think.

Also the Xmas (2004 started on the 26th iirc) snow came from a similar air source though more correctly a faux westerly arising out of a northerly thatbecame a NW flow aswell at time.
That caused a good 4-6 inches of disruption to west cork and Kerry which is about as far south as you can get on this island

Cornilius

I guess il be heading to my girlfriends house in belfast next week! How much snow are we talking? They are getting very excited across the water judging by the forums are they expecting worse conditions over there?

If I say it here cornillus it's bound not to happen
But you should see snow! and potentially a lot if a trough heads down the narrow north channel.

Paddy.1

GFS 12z now upgrades cold snap to last into next weekend:

http://theweatheroutlook.com/twodata/gfs/12_168_mslp850.png

I think GFS is just playing with possibilty rather than surety. If ECM does not come on board later then I think we are looking at a return to the present conditions sooner rather than later.

Agree with Black Briar that shower distribution is hard to pin point at the moment, though at this stage north Connacht, Ulster and North Leinster look favoured.

Supercell

I'm starting to become optimistic, a possible snow fest may be on the way if those lows track as forecast currently.
If it pans out as forecast right now should be about 10-15 cm of snow here by Thursday at least.