Potential for wind and snow (NW) 4th, 5th December - DISCUSSION ONLY

M.T. Cranium · 29-11-2011 12:07am #1

Models are increasingly pointing to the likely development of a very windy and cold period this weekend. Friday will see the gradual ramping up of a west to northwest wind in the 30-50 mph range but it will remain mild enough to prevent snow except perhaps on summits.

By Saturday, the parent low in the region near the Faeroes deepens further and colder air gradually works into the circulation as winds increase further to about 40-60 mph from the west-northwest. The snow line could come down in elevation especially across Donegal, Mayo and other parts of the north and west, to about 300m.

Then by Sunday further development takes place with the low transferring a deep centre southeast across Scotland into the North Sea. This will lead to severe gales in many parts of Ireland and Britain, and it will be cold enough for mixed wintry showers (at sea level, temps will be 3-5 C, at 300m near freezing) of hail and snow -- there could be some heavy snow amounts in northwest facing coastal regions similar to last December's Greenland express although it won't be quite as sustained or intense. As usual in these situations, the effects will be less dramatic towards the east and south but anyone planning to travel to the UK might want to consider the possibility of disruptions to road and air travel due to wind and local snowfalls. It looks particularly bad on the 18z GFS run for Yorkshire and East Anglia with a hurricane force storm in the North Sea. Winds over Ireland are likely to peak at around 50-70 mph given the model run and reasonable subjective tweaking of the output based on second-order factors (such as research energy peaks and sea surface temperatures).

This outlook may be revised rather substantially depending on the output of the more reliable 00z model runs. However, it has been "in the works" for several days and fits the developing global circulation which is seeing widespread intensification of zonal flow combined with an expanding arctic circulation of unusual intensity for this stage of the season.

This trend looks likely to reload around the 10th to 12th when more severe gales may develop at the full moon, with associated storm surge potential (just as a long-distance heads up).

darkman2 · 29-11-2011 1:19am

I fully agree with your forecast MT. A possibly widespread period of snow and strong winds cannot be ruled out especially on Sunday night all though how prolonged any rain to snow event may be is well open to question. There is a very nasty setup brewing next weekend and looks as though we will be on the polar front. Been watching this potential for a couple of days. Will make for interesting observing in the days ahead to see how this works out. Flooding looks possible aswell.

I just have to add this to the thread

only one · 29-11-2011 1:32am

darkman2 wrote: »

I fully agree with your forecast MT. A possibly widespread period of snow and strong winds cannot be ruled out especially on Sunday night all though how prolonged any rain to snow event may be is well open to question. There is a very nasty setup brewing next weekend and looks as though we will be on the polar front. Been watching this potential for a couple of days. Will make for interesting observing in the days ahead to see how this works out.

I just have to add this to the thread

What about us south east people?

darkman2 · 29-11-2011 1:37am

only one wrote: »

What about us south east people?

It depends on the track and depth of the system. It is too far out to be in anyway accurate about who gets what. But currently it looks a good bet for most even if temporary away from immediate west coasts. That's assuming the cold air is dragged down as quickly as forecast currently to interact with the cold front. Also there may be a period of sleet or snow for some (more likely in the North) ahead of the system. But it really is too far out to be accurate. It really is Sunday and Sunday night into Monday under the spotlight (144hrs away). It's not only any potential wintry weather but the wind potential too and flooding potential.

jimmy.d · 29-11-2011 1:45am

darkman2 wrote: »

It depends on the track and depth of the system. It is too far out to be in anyway accurate about who gets what. But currently it looks a good bet for most even if temporary away from immediate west coasts. That's assuming the cold air is dragged down as quickly as forecast currently to interact with the cold front. Also there may be a period of sleet or snow for some (more likely in the North) ahead of the system. But it really is too far out to be accurate. It really is Sunday and Sunday night into Monday under the spotlight (144hrs away). It's not only any potential wintry weather but the wind potential too and flooding potential.

dosent look like the south will get any looking at 144-hrs on snow check

cherryghost · 29-11-2011 1:52am

Some charts for Sunday

All charts except UKMO in agreement for this weekends weather.

maquiladora · 29-11-2011 2:01am

Finally some really interesting weather ahead.

sdanseo · 29-11-2011 2:05am

So basically, there's about a 1% chance of a blizzard in Dublin.

Given all the negative talk of late, I'll take those odds! :P

faktisperminute · 29-11-2011 2:06am

last year knock had heavy unexpected snow I think it could repeat again.

it was around 4/6c and was forecast for heavy rain but as soon as the heavy blowing wind came in sleet starting falling then slowly turned to snow and the temperature decreased to 0c

joe199 · 29-11-2011 2:18am

Really exciting period ahead finally! BBBBBRRRRRing it on!

mickger844posts · 29-11-2011 2:24am

Finally something of interest to get our teeth into. I don't expect any snow in Waterford but i'm jumping on the first Roller Coaster of the Winter

All aboard

Lucreto · 29-11-2011 2:52am

I doubt Naas will get any but it will be interesting on how it will turn out.

It was like the post I did a week to 2 ago now that the arctic geese have appeared and now a possible threat of snow.

I don't see it happening as Met Eireann has Friday as 12C.

edit: woot post 100.

Supercell · 29-11-2011 3:09am

Windy in Dublin with close to zero chance of snow, more interesting in the North West though, wish it was here!

Senna · 29-11-2011 3:22am

32 years living in Donegal and it's finally paying off:D

Huge amount of rain up here tonight and its been very mild. If there is snow and it lies (at any attitude) i cant see it lasting like last year.

mickger844posts · 29-11-2011 5:51am

0Z GFS showing rain for most of the country Monday with some Wintry stuff in the NW. Bottom chart shows snow potential over much of the country. Bit of a contradiction between the two

n

M.T. Cranium · 29-11-2011 7:38am

The 00z model runs are all generally weaker on the development over the weekend although this could be the start of a series of flip-flop changes so I wouldn't say that this scenario is off the table yet.

Harps · 29-11-2011 10:27am

Good to see the wind has been downgraded, the 18z would have been disastrous for Holland and Belgium!

Redsunset · 29-11-2011 11:04am

Realistic outcome for Monday as regard any sleet/snow.

WolfeIRE · 29-11-2011 11:35am

Monday at 9pm.

Snow depth and snow risk maps, provided courtesy of netweather

Snow/sleet confined to 300-400m above sea level. This may change in the interim.

At present, the first half of December looks like it will pan out being mild, cold, mild, cold, mild, cold i.e. an unsettled month but average to slightly below average temps for the month.

cherryghost · 29-11-2011 5:31pm

This afternoon's 12Z looks a bit better.

EDIT: Dew point isn't low enough thought. What Wolf says below

WolfeIRE · 29-11-2011 5:32pm

Snow potential in the latest GEFS run is restricted to high ground (above 300-400 metres) north of the Midlands. Certainly not looking any way as potent as it did last night. Where there are downgrades there can easily be upgrades regarding snow potential. An update from MT later will put everything right though......won't it MT?

munsterlegend · 29-11-2011 5:32pm

Have the latest charts any update on this? an upgrade/downgrade? or no great change?

maquiladora · 29-11-2011 5:50pm

Potential for severe winds seems to be dropping on every run.

pauldry · 29-11-2011 5:51pm

What a great thread title!!!

First snow of the season in Knock right now!!!!!!!!!!!!!

Ha ha

Only joking its hail

WolfeIRE · 29-11-2011 6:03pm

Downgrade, ML.

irish1967 · 29-11-2011 6:08pm

WolfeIRE wrote: »

Downgrade, ML.

So far .....

megatron989 · 29-11-2011 6:22pm

I'm hoping for snow but really I think Jan is the month for us! Only 4 or 5 weeks away and we could be shlipping and shliding all over the gaff lads!

aurora 527 · 29-11-2011 6:24pm

mickger844posts wrote: »

Finally something of interest to get our teeth into. I don't expect any snow in Waterford but i'm jumping on the first Roller Coaster of the Winter All aboard

Push over, coming aboard:D

snaps · 29-11-2011 6:43pm

pauldry wrote: »

What a great thread title!!!

First snow of the season in Knock right now!!!!!!!!!!!!!

Ha ha

Only joking its hail

I reported it earlier on a different thread. Was speaking to a few folk that had been through there mid afternoon and there was some wet snow up at the airport. Croagh Patrick also had snow on top earlier.

Mayo_Boy · 29-11-2011 6:45pm

Whats the latest scenario with the weather for the weekend? Still a chance of sleet/snow or has it changed?

TheMilkyPirate · 29-11-2011 6:52pm

Mayo_Boy wrote: »

Whats the latest scenario with the weather for the weekend? Still a chance of sleet/snow or has it changed?

Bit of a downgrade so far today, But the latest model is rolling out later tonight so we'll see how that goes.

M.T. Cranium · 29-11-2011 6:56pm

The 12z runs seem about on par with the 06z and if anything it looks a bit colder for Sunday night and Monday so, all things considered, we are seeing the sort of model performance that often leads to a cycle of upgrade-downgrade. I suspect there will be a drift back towards a stronger wind scenario and at the moment I would estimate the chances of seeing snow in some parts of the northwest as about 30-40% on Wednesday night into Thursday morning, and 50-70% on Sunday night into Monday. Amounts are not likely to be very significant on the current maps but 1-3 cms here and there sort of thing with 5-10 cms possible on higher slopes.

The Wednesday night potential is partly based on convection in a strong frontal passage, so it could be a brief burst of thunder-snow. This would be around 2300h to 0200h from the current guidance.

As always, this reduces to very small potential in the 80% of Ireland east and south of about Roscommon with the exception of some very high summits as may become evident the day after the event if skies cleared.

But there will be the possibility of thunder and hail or even snow pellets as the freezing level will be down around 300-500 metres at times.

irish1967 · 29-11-2011 7:02pm

And the rollercoaster begins...

A severe weather warning has been issued for Donegal for the next few days with forecasts for heavy rain, sleet, snow and winds of up to 110kph.

The warnings come as the first real taste of winter bites in Co Donegal.

This afternoon we have had reports of heavy sleet in Falcarragh, Downings, Kilmacrennan and Termon.

And according to Met Eireann and BBC forecasters much more is to follow in the next few days.

Worried islanders on Tory, afraid of being cut off from the mainland, had supplies flown out to them this morning.

Vital supplies including foodstuffs such as milk and bread as well as fuel was taken onto the island by the rescue helicopter based at Sligo.

With heavy seas and strong winds forecast, it is feared that boats will not be able to access the island for a number of days.

A spokesman for Met Eireann said stormy conditions are certainly forecast beginning from later today.

“It will get a lot colder and windier in the coming hours across the North West.

“We still do not know how cold it will get just yet but temperatures are already plunging.

“We are expecting very strong winds of up to 110 KPH and more rain.

“Temperatures are getting much colder and because of that there is a strong possibility of snow in places.

“We have already had reports of sleet in many places across Donegal and that looks likely to continue,” said the spokesman.

Many roads around Termon and Kilmacrennan are reported to be white with heavy sleet this afternoon which could turn to snow this evening.

Donegal County Council is currently on standby and may be forced to send out gritters if the temperatures continue to plummet.

Pangea · 29-11-2011 7:19pm

irish1967 wrote: »

And the rollercoaster begins...

Thanks, where did you get that from btw?
Heres a bit on Highland.
http://www.highlandradio.com/2011/11/29/met-eireann-warns-of-winds-of-up-to-110km-per-hour-to-hit-donegal/

Pangea · 29-11-2011 7:24pm

News just in, RNAG said it is snowing in Letterkenny town.

JanuarySnowstor · 29-11-2011 7:27pm

Can I just put on record here that I very much disagree with the thoughts of this thread.
First of all the 18z last night was the only run that gave us severe wind.
Secondly conditions next Monday look very borderline, even for high ground. Of course either way it an 18hour event at most.

Next......

irish1967 · 29-11-2011 7:28pm

Donegal's busiest road was flooded last night at an area called 'The Dry Arch'.

29-11-2011 7:31pm

One of my top ten weather fantasie's would be , to stay on Tory during a major storm, in a cottage with a big turf fire roaring. With all the supplies I needed for a month. Just hibernate.:)

Would be heaven.

irish1967 · 29-11-2011 7:32pm

Pangea wrote: »

News just in, RNAG said it is snowing in Letterkenny town.

Getting tweets of very large hail in Letterkenny but none of snow yet.

jimmy.d · 29-11-2011 7:32pm

Pangea wrote: »

News just in, RNAG said it is snowing in Letterkenny town.

anyone got pictures would be nice to see might ease the craving

HeidiHeidi · 29-11-2011 7:33pm

Jake1 wrote: »

One of my top ten weather fantasie's would be , to stay on Tory during a major storm, in a cottage with a big turf fire roaring. With all the supplies I needed for a month. Just hibernate.:)

Would be heaven.

+1

irish1967 · 29-11-2011 7:34pm

Jake1 wrote: »

One of my top ten weather fantasie's would be , to stay on Tory during a major storm, in a cottage with a big turf fire roaring. With all the supplies I needed for a month. Just hibernate.:)

Would be heaven.

If you are staying for a month I suggest you bring two

Pangea · 29-11-2011 7:35pm

irish1967 wrote: »

Getting tweets of very large hail in Letterkenny but none of snow yet.

Yeah who knows one weather report contradicts the other

Harps · 29-11-2011 7:42pm

Pangea wrote: »

News just in, RNAG said it is snowing in Letterkenny town.

No snow, just a crazy hail shower, looks exactly like snow outside now though with everything all white

29-11-2011 7:46pm

Jake1 wrote: »

One of my top ten weather fantasie's would be , to stay on Tory during a major storm, in a cottage with a big turf fire roaring. With all the supplies I needed for a month. Just hibernate.:)

Would be heaven.

I have a relative with cottage at Lough Swilly, that will have to do:)

sillymoo · 29-11-2011 8:00pm

M.T. Cranium wrote: »

The Wednesday night potential is partly based on convection in a strong frontal passage, so it could be a brief burst of thunder-snow.

:eek: :eek: :eek:

thomasj · 29-11-2011 8:06pm

Jake1 wrote: »

Jake1 wrote: »

One of my top ten weather fantasie's would be , to stay on Tory during a major storm, in a cottage with a big turf fire roaring. With all the supplies I needed for a month. Just hibernate.:)

Would be heaven.

I have a relative with cottage at Lough Swilly, that will have to do:)

I spent 3 weeks of my youth in the gaelteacht in falcarragh. IMO the best view of the atlantic that there is is in falcarragh!

I never got the chance to get the boat from there to tory. Promised myself i would. I will go back and do so maybe before the year is out!

Rodar08 · 29-11-2011 8:28pm

Thunder and lightening in Buncrana!! Woohooo!!

Long rumbles too!

Harps · 29-11-2011 8:31pm

Passed 5 miles north of me of course :mad:

Disgusted looking at the radar, still thunder and lightning but well in the distance. Sounds like an amazing storm, almost a constant rumble!

Pangea · 29-11-2011 8:50pm

Thunder and Lightning here too

h57xiucj2z946q · 29-11-2011 8:52pm

Pangea wrote: »

Thunder and Lightning here too

Sure is! wherever the feck you are...

Potential for wind and snow (NW) 4th, 5th December - DISCUSSION ONLY

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