Your daily forecasts from Boards.ie weather forum (NO CHAT)

Avns1s

JohnSherwin90 wrote: »

Anyone got any tips for helping a diesel car to start in cold weather like this? Car doesnt sound great when first started the cold seems to get to it...:mad:

Motors Forum or Motors Tech Help forum >>>>>>>>>>>>

Sheba891

All tv forecasts seem to be showing a massive snowfall tonight?? Are they right??

M.T. Cranium

UPDATE _ Thursday 2 December _ 2040h
___________________________________

The forecast for later tonight and Friday is a difficult one, let's be clear about that ... at this point, I would say that most of Ireland will see 3-7 cms of snow from this front, and some places (most likely inland north to east) could see as much as 10-12 cms. There will also be some freezing drizzle or freezing rain mixed in, and this may be heavier in the inland south than elsewhere. Some places could get mostly this frozen type of precip. The whole mess could turn over to sleet for a while, and that's most likely near sea level and in places like Dublin city centre due to the local heat island raising temperatures by a degree or two.

Before this all arrives, some places will drop to -10 or even -12 C over the deep snow cover away from the coasts, before cloud spreads in and raises the temperature to about -4 C.

I will be updating this outlook as necessary, but for now, would say for most places, expect a medium-sized top up to existing snow, in some cases, new snow that will fall on bare ground, and in a few places, a heavy top-up ... perversely, the way this often works is that the deepest snow chills the surface layer the most effectively and thereby produces more snow locally than other places get.

What I will be watching for very carefully, is any sign of wave formation, which is partially anticipated in this (and probably other) forecast(s). If a well-organized wave developed west of about Clare tonight and tracked across the south, then this snowfall potential could increase to as much as 15-20 cms. So that is in the realm of possibility, I would say check back around 11 p.m. to midnight when updated model runs will be available and the front should be within radar range. The snow (or drizzle) should start on the west coast around 0300h.

TheMilkyPirate

M.T. Cranium wrote: »

What I will be watching for very carefully, is any sign of wave formation, which is partially anticipated in this (and probably other) forecast(s). If a well-organized wave developed west of about Clare tonight and tracked across the south, then this snowfall potential could increase to as much as 15-20 cms. So that is in the realm of possibility, I would say check back around 11 p.m. to midnight when updated model runs will be available and the front should be within radar range. The snow (or drizzle) should start on the west coast around 0300h.

I think this is what they meant on RTE weather just now when they said another front will pass over the south tomorrow night after this bringing snow to the south, would this be what they were talking about?

squonk

Thanks MT. I'm just wondering though, what's to stop this front mixing with the colder air and just producing sleet/cold rain at lower levels? I'm just a little bit skeptical for my neck of the woods, Skerries, which tends to have it's won little micro climate where, even today with streamers from the Irish sea giving falls of snow everywhere else with good accumulations, we merely got hail by the looks of it or at best a very sparse snow load. Could the Irish sea also have a modifying effect in eastern coastal regions? Thanks for all those great forecasts!

maquiladora

baraca wrote: »

I think this is what they meant on RTE weather just now when they said another front will pass over the south tomorrow night after this bringing snow to the south, would this be what they were talking about?

No that was something different, a cold front that could bring precip to the south later tomorrow night. The latest GFS however would make this rain rather than snow.

M.T. Cranium

All I can add is that systems like this are ideal breeding grounds for meso-scale surprise events, and the general experience with weak breakdown events in any climate is that they tend to produce less warming and more transitional precip than models like to depict. Cold air over deep snow cover is tough to shift especially when the mild air is this feeble to start with -- it's only 8/6 at the M6 buoy after a westerly wind shift. Clearly this "mild air" hasn't even managed to reach the same temperature as the ocean after three days, so it isn't much of a warm sector -- the first question to be answered is whether this system has any ability to produce much of anything, if that happens, it would probably be mostly snow and a little sleet, a little freezing drizzle.

pmccormack

Quick Question, Whats the difference between freezing rain/drizzle and Sleet/hail?

forkassed

Such a slow moving front can only aid the chances of snow fall with cold air undercutting...?

I'm in the suburbs of Dublin right by the coast and am hoping for a whiteout instead of the usual sleet fest to end this epic weather event.

forkassed

pmccormack wrote: »

Quick Question, Whats the difference between freezing rain/drizzle and Sleet/hail?

http://www.youtube.com/watch?v=OX9MVhPc-h0

Vizual Pics

MT what did you mean earlier about a wave in the system? Is this when the front breaks down and begins to mix with the colder air?

Vizual Pics

pmccormack wrote: »

Quick Question, Whats the difference between freezing rain/drizzle and Sleet/hail?

This is what freezing rain is...and you know what the others are?

http://en.wikipedia.org/wiki/Freezing_rain

thetonynator

forkassed wrote: »

Such a slow moving front can only aid the chances of snow fall with cold air undercutting...?

I'm in the suburbs of Dublin right by the coast and am hoping for a whiteout instead of the usual sleet fest to end this epic weather event.

it won't be the end, there are more cold temps forecast for next week, not as cold but enough for the thaw to be very slow . .

forkassed

thetonynator wrote: »

it won't be the end, there are more cold temps forecast for next week, not as cold but enough for the thaw to be very slow . .

I realize that and its fairly evident on the ensembles.

I just have reservations about whether snow will occur tomorrow morning at lower levels by the coast in the east.

On the positive side i have never witnessed such a scenario where the front is coming in from the northwest so eastern areas are favoured .

Usually the cold spells are ended fairly abrubtly by a front coming in alot quicker from the southwest and Northern areas are favoured for snowfall.

M.T. Cranium

A wave in this case would be a low pressure centre forming in the trough and forcing any milder air to remain south of its track, rather than mixing further north ahead of a front.

Warm frontal waves are often tricky to forecast as models don't always catch them and once they form, they tend to slide easily around any entrenched cold air. Discussions of decades-old cold spells are full of references to mild air that never arrived (in the U.K. for the most part) and cold air that hung around -- so despite the advance in the models in recent years, we'll have to see how this plays out, the amount of warming shown on the most recent model run was not very impressive -- without the warm ocean around Ireland, there would be no chance of this even changing from snow to rain at all.

TheMilkyPirate

Snow reported in ballina, mayo from this front just now.

M.T. Cranium

Friday, 3 December, 2010
_________________________

TODAY ... Snow is likely to develop across most of eastern, central and northern counties this morning, while rain moves into the west and later south coast, and some sleet or freezing rain occupies a band between these zones, inland west and inland south. Various places may have changes of precip type, but in general, the snow will be heavier over existing snow cover in the east and inland north, and may reach 8-12 cms in places. Very slippery conditions will develop especially in the south and inland west due to sleet and freezing rain. Wind (WSW 20-30 mph) may become a factor in some places but the stronger winds may not mix down to the ground in all locations, and some dense fog may develop during this mixed precip event. Highs will be about -1 to +2 C for most, and a bit higher in coastal areas (to +5 C). Specifically for Dublin, expect some snow, mixing at times with sleet, and amounts dependent on elevation (3-7 cms). Conditions may become quite sloppy at low elevations and in the city centre. Some of the heavier snow is likely to be in a zone from Laois north to Westmeath and into Ulster.

TONIGHT will see most of this precip ending, with some light snow or sleet persisting, with fog patches becoming quite dense in some areas, cold with lows dropping back to -4 or -6 C inland, -2 C coastal areas. Winds near the west coast will become NNW 20-30 mph, and somewhat weaker northerly elsewhere.

SATURDAY will bring variable cloud, some patchy light snow or sleet, but also some sunny breaks, and moderate northerly winds, with highs of about 3 C.

SUNDAY will be a generally dry day with some sunshine, a cold start with ice fog developing in many areas, lows to about -6 C, then highs of about 2-4 C.

MONDAY will bring wintry showers in a northwest to north wind, and a temperature range from about -5 C to +3 C.

TUESDAY and WEDNESDAY are looking breezy, showery (sleet or snow mostly) and cool, although temperatures might recover a bit towards the west where highs of 5-7 C are possible. Further east it may stay closer to 2 or 3 C.

All through this period, some snow melt may occur, but I don't foresee all of the current snow pack melting in heavier snow areas, and there will be a certain amount of freeze-thaw activity leading to more ice at times.

The further outlook is for much colder weather to return ... I suspect that the models may begin to shift the Atlantic high west and allow in a renewed northerly perhaps faster than indicated, but in any case, the models have nothing but cool high pressure and then cold northerly weather patterns on offer. The main question is timing and balance between them. Just keep the time period 19-22 Dec in the back of your mind for some kind of winter storm potential.

Meanwhile, Thursday here was rather bland, cloudy with some hazy sun earlier, light rain more recently, and a high of about 7 C. It has turned a lot colder across most of central and eastern North America.

Watch for updates, and monitor the threads on the forum for information about the spreading snow, sleet, freezing rain and rain.

Just to anticipate a few questions -- snow should arrive in Dublin and Wicklow around 0900h ... Cork is likely to start out with snow or sleet, turn to either freezing rain or a cold rain that will be just as bad on top of the frozen ground, then back to sleet ... Waterford looks more like a transition from snow to sleet to a brief period of freezing rain then back to snow ... similar for Wexford ... Limerick would be likely to see a bit of everything but may not get quite as much as the precip develops more further east ... Galway likely to see mixing by elevation and distance inland from the bay.

Stay safe if you have to travel.

Musicman2000

Just keep the time period 19-22 Dec in the back of your mind for some kind of winter storm potential.

Would this be a winter blizzard or more mild atlantic rain?

M.T. Cranium

Comments I make about distant potential events are based on research into trends and tendencies -- so all I can really say at this point is that a colder than average trend is likely through the month (although not as cold as recently for a while now) and a significant storm event is likely around that time (20-21 Dec) ... it is more likely to be a wintry storm than a mild storm but if it were to prove to be a mild event it would probably become very windy and pull down cold air rapidly as it departed ... but the current model runs are suggesting a colder period just before then and some sort of reload of the severe cold, so possibly a northeast wind streamer event would be favoured, perhaps enhanced by low pressure moving by to the south. Anyway it's a long way off and we have some active weather to consider in the next 24 hours, so here's an update on that.

UPDATE _ Friday, 6:00 p.m.
________________________

More wintry showers are likely overnight and through Saturday in a westerly flow turning more northwest to northerly on Saturday. Temperatures will fall back a few degrees and these wintry showers will take a variety of forms, with rain more likely in western counties, near the south coast and in city centre Dublin, while sleet or snow will be more likely in most other regions.

Except near the west coast where lows will remain 0-2 C, the overnight lows will fall to about -3 or a bit lower where it clears for a while and some very icy conditions are likely as slush freezes. A few places could see 1-3 cms of new snow but falls will not be widespread or very organized. During the day tomorrow the balance between rain and wintry types of precip will swing more to rain but there will continue to be a mix -- amounts of precip in any case will be fairly light, in the range of 2-5 mms which would give a few places (likely higher and well inland) 2-5 cms of snow.

The pattern beyond tomorrow remains about as predicted earlier and will be generally a bit milder than last week but not as mild as average -- this means a freeze-thaw cycle for areas that still have snow, some limited melting, and frequent returns to icy conditions especially outside the warmest part of the day (which is 1100-1500h).

thetonynator

M.T. Cranium wrote: »

Comments I make about distant potential events are based on research into trends and tendencies -- so all I can really say at this point is that a colder than average trend is likely through the month (although not as cold as recently for a while now) and a significant storm event is likely around that time (20-21 Dec) ... it is more likely to be a wintry storm than a mild storm but if it were to prove to be a mild event it would probably become very windy and pull down cold air rapidly as it departed ... but the current model runs are suggesting a colder period just before then and some sort of reload of the severe cold, so possibly a northeast wind streamer event would be favoured, perhaps enhanced by low pressure moving by to the south. Anyway it's a long way off and we have some active weather to consider in the next 24 hours, so here's an update on that.

I'm dreaming of a . . .

https://www.youtube.com/watch?v=PA45TnJQxhU

M.T. Cranium

Saturday, 4 December, 2010
_______________________________

TODAY ... Cloudy with some afternoon sunny breaks, continuing rather sloppy with temperatures just above freezing inland, to 4-6 C around coastal regions, possibly 6-8 C in the southwest. Widespread rather light showers of rain turning to sleet or wet snow over higher inland areas. Accumulations slight, 2-4 mms of liquid and in a few places 1-3 cms of snow (higher up, a bit more could fall). Moderate westerly winds turning more to northwest then north 15-20 mph.

Very slippery conditions will continue, with a slow thaw of lying snow at lower elevations, not much if any melt above 300m asl.

TONIGHT ... Clearing in some northern sections, mostly cloudy further south with a few remnant sprinkles of sleet. Some freezing fog developing as lows reach -5 C on average over snow, -1 C over bare ground. Light winds.

Icy roads and pavements may become quite treacherous in some parts of eastern and northern counties.

SUNDAY ... Variable cloud, some sunny intervals for most, only a few widely scattered light wintry showers, rather chilly again with highs of about 2-5 C.

MONDAY ... Cloudy with some breaks, more frequent wintry showers, hail, sleet and some snow prevalent, rain near coasts. Lows near -4 C and highs near 5 C on average (a bit cooler over remnant snow as a slow thaw continues).

TUESDAY ... Slightly colder again with flurries in Ulster, mixed wintry showers elsewhere, in a northerly flow of 15-25 mph. Lows near -5 C and highs near 2 C northeast to 7 C southwest.

WEDNESDAY ... Breezy and milder especially in the southwest. Scattered showers in gusty W to NW winds. Variable cloud and mixed showers elsewhere, warming rather restricted in northeast, so highs in a range from about 4 C northeast to 10 C southwest.

THURSDAY-FRIDAY ... Yet another brief cooling interval Thursday on strong northwest to north winds, flurries, but quickly turning milder again during Friday. This topsy-turvy weather pattern will have the freeze-thaw cycle on full throttle and some road damage is likely as deep frost comes out of the ground gradually. Snow melt will continue rather slowly and will not be complete especially in wooded areas and on higher ground.

FURTHER OUTLOOK ... Around the weekend of the 11th-12th it should once again start to turn colder but this time perhaps in a much more organized northerly outbreak that may return temperatures to near freezing. Remember, we're keeping a close watch on the period 19th-22nd for a winter storm.

I hardly noticed, but today was partly cloudy and mild here with a high near 7 C. It continues rather cold further east and there was a heavy lake effect snowstorm near Buffalo NY, but otherwise not too much happening, just a dry cold pattern although not too extreme.

I plan extensive rest this weekend (having been through the weather wars all week) so you may have to hunt for scraps from the weather forum although I imagine the resting impulse will be quite widespread there too. :cool:

Have a good weekend and watch for ice. I imagine there will be more of these snow slides from flat roofs as well.

yachtsman

Thanks

Thanks MT, love reading your forecasts.

irish147

19th-22nd for a winter storm.
would be nice

Caitriona

I know it's a very basic question, but what exactly is involved in a wintry storm? Would there be more snow? (Sorry, I'm only a beginner here)

M.T. Cranium

Just my way of saying the period could produce a storm with wintry weather conditions, so yes snow likely to be involved, but we'll have to wait about two weeks for the details to become clearer. My research shows that in Dec and Jan the full moon is often a time for a strong low pressure system and as the pattern looks cold (after perhaps a slightly milder period mid-month) putting it together I speculate on a wintry storm for the days in that period, 19th to 22nd. The full moon is precisely at 0813h GMT on the 21st, if visible in Ireland you would see it setting around 0730-0800h on 21 Dec as it enters a growing eclipsed state; where I live, if it's clear we'll see a lunar eclipse around midnight (20-21 Dec local time).

Sponge Bob

While temperatures were above zero with rather nice sunshine in the west today a very sharp frost has already set in as I type. As the air was still the ice from friday night melted but did not dry out owing to the lack of a drying breeze.

The grit was washed off the roads in most areas by yesterdays rain and has not been replenished. At 4pm the sun went down and the roads and footpaths were pretty uniformly wet everywhere at that time.

By around 8-9pm this evening there will be a serious ice covering absolutely everywhere it rained yesterday. Be very very careful out there tonight and tomorrow morning unless you are on a road you know to have been gritted since the rains on friday.

HornyDevil

M.T. Cranium wrote: »

where I live, if it's clear we'll see a lunar eclipse around midnight (20-21 Dec local time).

where you live is Vancouver . . . . Canada

hmmm

Tae laidir

The National Weather Service in the US are indicating a strong La Nina event around now and lasting throughout the winter.
Do you think this is significant for us?

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.html

M.T. Cranium

The La Nina effect factors into most long-range forecasts that have already been made, but to be honest the range of past conditions in Europe in La Nina winters covers almost the entire range of possibilities, so for somebody to say "this will be one of those La Nina winters" means very little away from the source region. Even here on the west coast of North America, I think we can only rule out the mildest third of outcomes, and deal with the other two thirds, so either very cold or near normal, and with snowfall, about the same thing, it's unlikely to be one of those snow-free winters we sometimes get here, but as to very snowy or just average, all that's in play (from the starting point of saying it's a La Nina winter).

I tend to use a lot of other factors in my long-range forecasting and figure that these will be built into the La Nina signal anyway. All La Nina means is that water temperatures in the equatorial Pacific will be cooler than average. This tends to be balanced by a warm bubble of sea surface temperatures in the mid-latitudes near the middle of the vast Pacific (near the IDL). That's the more relevant factor because it tends to favour ridge development into Alaska, something that then favours cold air coming south into central North America. But you can see that if that's just a broad general picture, the variations in it are significant. How strong will that ridge be? How many times will it break down? A month's climate often depends on a few singularities and not on the background pattern. Consider November 2009 in Ireland, a month that will be remembered mostly for two days of very heavy rainfall.

And this month is already heavily influenced by three days of extreme cold and locally heavy snow, even if the rest of the month proved bland and near normal, that's what people would remember and also those stats would have a heavy influence on the final figures for the month.