Potential Snowfall & Cold Spell Discussion (Wednesday/Thursday 30/12/09)

ninebeanrows

Jake1 wrote: »

WC, could I put upon you ,kind sir, to do the same for us westies? in Dublin

Thanks if you can

Following very similar trend.

Su Campu

Here's how I see today and tomorrow playing out.

The first half of today will be another repeat of yesterday - snow above ~600ft with isolated pockets at lower levels. The GFS and NAE both hint at a temporary stengthening of the thermal gradient this evening, giving a possible increase in precipitation rates, before the front finally starts to track southwards tonight/early hours of Thursday. As it does we will probably see some temporary backedge snowfall at lower levels, but skies will soon clear and a hard frost will set in in sheltered places.

As the front goes so too does the chance of precipitation, so we're really going from a situation of frontal precipitation to one of convective precipitation. As the wind backs to northeasterly tonight and tomorrow, we look to our northeast to see what will head our way.



The Lerwick and Albermarle soundings are a good indicator. They currently show a good snow setup, with temperature and dewpoint at zero or below, and good low level moisture and lapse rates.






As the Lerwick air is advected souwestwards it will lose a lot of it's moisture as snowfall over the Scottish highlands, so I expect northeast Ulster to be in a "snow shadow" tomorrow, as the airmass will not have enough of a sea track over the North Channel to generate sea-effect showers. But from northern Antrim around to Donegal should see some wintry precip.

For the republic we're looking at the Albermarle air to give us some excitement. With a northeasterly wind it has the longest sea track so I expect the east coast from Louth to south Wicklow to see wintry showers hitting early tomorrow morning. With a moderate northeasterly wind these should make it up to 50 miles inland, though dissipating as they do, and areas to the southwest of the Wicklow mountains may see slightly less.

There is the possibility of polar low development on Friday as a pool of sub -40°C H500 air tracks near Scotland. Depending on its exact locatoin though, it could dump its load over Scotland, but if it tracks forther west then northern parts could be in for it. Not certain at the moment though, but one to watch.

owenc

Weathercheck wrote: »

Following very similar trend.

what about us can we expect snow showers earlier or pretty much the same?

ninebeanrows

Jake1 wrote: »

I tell yis what, I wasnt expecting these strong winds.

Yes i would like to highlight again.

Some very high winds across the country today.

Notably as the low exits Southwest some sever gusts.

More concerningly for populated areas in Dublin.

Reaching a peak around 9pm this evening, sustained 45mph winds with gusts perhaps to 70mph.

gothwalk

Maynooth is wet and very windy this morning; temperature 3.9C with an overnight low of 2.6C. No further sign of sleet or anything other than cold drizzle and spitting rain.

ninebeanrows

Yes Su Campo,

I think we are beginning to see precip intensity already picking up as the thermal gradient tightens as the warm airmass attempts to head further north into the polar air.

Precipitation intensity will aid potential snowfall as the cold air pushes south this evening.

nacho libre

159 (71 members & 88 guests) Moderators : 4

Felixdhc, gothwalk, Su Campu, eskimocat, Josey Wales, dublincelt, andrewie, gerard65, Min, Weathercheck, owenc, MayoForSam, JanuarySnowstor, InKonspikuou2, JMSE, aaronm13, babe 2008, ravydavygravy, Nihilist21, blindjustice, munsterlegend, Jake1, Snoddy, Lex_Diamonds, jenzz, Stephen P, Graces7, burkieboy, PistolPete78, MollyZ, jam_mac_jam, trogdor, Ordinary man, opr, pebbles21, ronbyrne2005, .243, Abrean, Ted10, splish, civdef, Mr.Boots, towger, billy the squid, ltdslipdiff, youngblood, lucky-colm, IMBACKLATER, Wookie, howlinwolf, Gon10, Avns1s, Supercell, 1635barry, hoody, gnevin, swalsh, abitofacomedian, Discodog, Chicken Run, PauloMN, sushisushi, DOCARCH, joe316

if you forecast it they will come

Min

All I can see is a lot of ice once this current weather event is over.

burkieboy

MayoForSam wrote: »

Damp and very windy here in NE Galway, I don't expect that to change anytime soon.

So much for putting some fleece over my Griselinia hedge on Monday evening to try and save it from the frost, almost been blown off at this stage :rolleyes:.

Latest sat image shows the front has indeed progressed further north than expected (bringing mild air with it). As soon as it starts to move back down, then the temps should start to drop. Plenty of showers to the NW too.

Classic polar low (comma-shape) can be seen to the north of Norway, now if only one of those could form just south of Iceland.....

I am expecting some serious snow to arrive just as most of us as returning to work and school next week, sod's law.

Just a low pressure you see to the north of norway as yea can see in the fax charts below!!!

http://www.meteociel.fr/modeles/ukmo2.php?carte=2000&ech=0

ninebeanrows

The weather is currently deteriorating quickly here this morning.

Gales and driving rain.

Not pretty, and pretty cold too

nacho libre

Su Campu wrote: »

There is the possibility of polar low development on Friday as a pool of sub -40°C H500 air tracks near Scotland. Depending on its exact locatoin though, it could dump its load over Scotland, but if it tracks forther west then northern parts could be in for it. Not certain at the moment though, but one to watch.

if it does track further west,will the low maintain its strength and eventually spread southwards?

hoody

Had a covering of snow this morning in Loughrea, very wet underfoot though. Currently melting off a bit, aided by some very wintry rain/sleet. Wind is getting up too.

Min

The circulation is really getting going now, rain/sleet pushing in from the south east.
Looks rotten.

Tactical

Min wrote: »

All I can see is a lot of ice once this current weather event is over.

Imaging if we did get a little snow before the cold sets in, there would be no thaw and any snow could remain around for a few days at least

Think positive.

Su Campu

nacho libre wrote: »

if it does track further west,will the low maintain its strength and eventually spread southwards?

If it can avoid Scotland then it could get a clear run at the North. I'd like to see a more northerly airflow to allow that to happen - at the moment it's looking like it will be a little too northeasterly for my liking. Polar lows only last 1-2 days though, and die out quickly as they hit land, so while it could be a snwfest in the northern half of the country, that may not be the case further south.

jenzz

nacho libre wrote: »

159 (71 members & 88 guests) Moderators : 4

Felixdhc, gothwalk, Su Campu, eskimocat, Josey Wales, dublincelt, andrewie, gerard65, Min, Weathercheck, owenc, MayoForSam, JanuarySnowstor, InKonspikuou2, JMSE, aaronm13, babe 2008, ravydavygravy, Nihilist21, blindjustice, munsterlegend, Jake1, Snoddy, Lex_Diamonds, jenzz, Stephen P, Graces7, burkieboy, PistolPete78, MollyZ, jam_mac_jam, trogdor, Ordinary man, opr, pebbles21, ronbyrne2005, .243, Abrean, Ted10, splish, civdef, Mr.Boots, towger, billy the squid, ltdslipdiff, youngblood, lucky-colm, IMBACKLATER, Wookie, howlinwolf, Gon10, Avns1s, Supercell, 1635barry, hoody, gnevin, swalsh, abitofacomedian, Discodog, Chicken Run, PauloMN, sushisushi, DOCARCH, joe316

if you forecast it they will come

Nacho - weve been camped here since December 21st...... Thats longer than the cold spell itself

burkieboy

nacho libre wrote: »

if it does track further west,will the low maintain its strength and eventually spread southwards?

That low does head for us it hits us on saturday as a weak front il show you the fax charts for it just click one after another and you will see the track it makes!!!!!

http://www.meteociel.fr/modeles/ukmo2.php?ech=0&carte=2000

http://www.meteociel.fr/modeles/ukmo2.php?ech=48&carte=2000

http://www.meteociel.fr/modeles/ukmo2.php?ech=72&carte=2000

http://www.meteociel.fr/modeles/ukmo2.php?ech=96&carte=2000

jenzz

Tactical wrote: »

Imaging if we did get a little snow before the cold sets in, there would be no thaw and any snow could remain around for a few days at least

Think positive.

Im not gonna be greedy I dont want snowfest - just a little covering so I can take my pictures thats all !!!!!!!!!!!!!!!!!!!!!!!!!!!!

Graces7

jenzz wrote: »

Nacho - weve been camped here since December 21st...... Thats longer than the cold spell itself

Su Campu

burkieboy wrote: »

That low does head for us it hits us on saturday as a weak front il show you the fax charts for it just click one after another and you will see the track it makes!!!!!

http://www.meteociel.fr/modeles/ukmo2.php?ech=0&carte=2000

http://www.meteociel.fr/modeles/ukmo2.php?ech=48&carte=2000

http://www.meteociel.fr/modeles/ukmo2.php?ech=72&carte=2000

http://www.meteociel.fr/modeles/ukmo2.php?ech=96&carte=2000

I don't think that's what I'm talking about. A polar low is a sub-synoptic scale system (ie. much smaller than the one shown). If one is to develop it will do so on the western flank of that low.

If you're trying to pick one out on a satellite picture then look for something resembling a hurricane, as they are very similar systems, believe it or not! Some polar lows even have an eye!

Snoddy

Watching and waiting. Very cold here , raining and howling winds couple of bins on the loose

jenzz

Graces7 wrote: »

Im just making sure someone keeps Grace company - wouldnt want her here all alone !!:D:D

eskimocat

nacho libre wrote: »

159 (71 members & 88 guests) Moderators : 4

Felixdhc, gothwalk, Su Campu, eskimocat, Josey Wales, dublincelt, andrewie, gerard65, Min, Weathercheck, owenc, MayoForSam, JanuarySnowstor, InKonspikuou2, JMSE, aaronm13, babe 2008, ravydavygravy, Nihilist21, blindjustice, munsterlegend, Jake1, Snoddy, Lex_Diamonds, jenzz, Stephen P, Graces7, burkieboy, PistolPete78, MollyZ, jam_mac_jam, trogdor, Ordinary man, opr, pebbles21, ronbyrne2005, .243, Abrean, Ted10, splish, civdef, Mr.Boots, towger, billy the squid, ltdslipdiff, youngblood, lucky-colm, IMBACKLATER, Wookie, howlinwolf, Gon10, Avns1s, Supercell, 1635barry, hoody, gnevin, swalsh, abitofacomedian, Discodog, Chicken Run, PauloMN, sushisushi, DOCARCH, joe316


So we have 88 guests lurking too, lol Come on Guests sign up and get a free ride on the rollercoaster here!!!:D:D:D:D

nacho libre

Su Campu wrote: »

If it can avoid Scotland then it could get a clear run at the North. I'd like to see a more northerly airflow to allow that to happen - at the moment it's looking like it will be a little too northeasterly for my liking. Polar lows only last 1-2 days though, and die out quickly as they hit land, so while it could be a snwfest in the northern half of the country, that may not be the case further south.

ah yes the polar lows i remember came from the iceland direction. so if i'm not mistaken what you're saying is coming from the north east it will likely lose its energy quicker as it hits land,whereas that is not the case with a polar low coming from Iceland.

Supercell

Check out the UK Met radar images for the last hour, there is clearly showers over southern Scotland/Northern England tracking in a SW direction....it begins!

burkieboy

Su Campu wrote: »

I don't think that's what I'm talking about. A polar low is a sub-synoptic scale system (ie. much smaller than the one shown). If one is to develop it will do so on the western flank of that low.

Iwas pointing out that its not a polar low as someone said it just a low pressure!!

jenzz

Supercell wrote: »

Check out the UK Met radar images for the last hour, there is clearly showers over southern Scotland/Northern England tracking in a SW direction....it begins!

Blow some jack frost over me first - Temp 5.2 & Dp 3.2

burkieboy

nacho libre wrote: »

ah yes the polar lows i remember came from the iceland direction. so if i'm not mistaken what you're saying is coming from the north east it will likely lose its energy quicker as it hits land,whereas that is not the case with a polar low coming from Iceland.

I remember that one it formed of the mountains of iceland and push south!!!

nacho libre

burkieboy wrote: »

That low does head for us it hits us on saturday as a weak front il show you the fax charts for it just click one after another and you will see the track it makes!!!!!

http://www.meteociel.fr/modeles/ukmo2.php?ech=0&carte=2000

http://www.meteociel.fr/modeles/ukmo2.php?ech=48&carte=2000

http://www.meteociel.fr/modeles/ukmo2.php?ech=72&carte=2000

http://www.meteociel.fr/modeles/ukmo2.php?ech=96&carte=2000

thanks. those last two charts look very good. if they are realised, the north will derfinitely get plastered but hopefully if it remains windy it will help push the showers further south without them dying out.

nacho libre

burkieboy wrote: »

I remember that one it formed of the mountains of iceland and push south!!!

was that the infamous polar low of 2000?