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A Winter's Tale

Colder Spell Discussion

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Spring is a time of contrasts and because of that you can get some interesting weather and more often than not some nice weather. 20C and sunshine, and sunshine and snow showers become equal in my preferences for April weather aswell as your typical, changeable but often pleasant Spring weather so it seems that we're going to see the two different ends of the Spring weather spectrum within two weeks - hopefully prevailed by sunny, near average and showery conditions before warmth returns. But anyway, unlike summer and winter where you either get what you want or not want, in Spring - most of the time what you get is pleasing whether it's warm, cold or seasonal - Spring is a very special time indeed.

It seems very likely that April 2012 will be much colder than 2011 and a repeat of any of last year's record breaking early warmth was reserved for March but perhaps later on in April and certainly into May we'll see a return to summer weather aswell as keeping nice late Spring-like conditions.

So like the week gone bye, this coming week will be interesting (although not quite as spectacular) and there are quite a few things we need to look out for:

- Big Temperature Contrasts - Aboyne enjoyed 23C this week, 3C max is possible at times next week there.

- Low Temperatures - When was the last time April temperatures were so low - how does it compare to other years, a real taste of winter?

- Frosts - How low can it go, how it would affect plants and nature and whether it's more than what you'd expect for a April.

- Snow - Some possible snow events, April could be just as snowy as any of the past few months in places and when was the last time the UK had an April snow event and how would this year raknk?

- White Easter - Been a while since we've seen a white easter, could we see one this year and what could it be like?

- The long term - Can high pressure sustain itself further west, could we expect more northerlies for the rest of the month?

So this week and next week could well emphasise what Spring is great for and I sure hope that we'll look back at this Spring with good things to say, not only about the warmth and cold but the other weather that Spring brings too. Let's see how it works out!

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Slight downgrade of uppers on the 12z ECM which could be crucial, -8c or less would definately do the trick but anything -7c or greater would be very marginal, i was more bullish about the potent spell in a week or so time shown on the GFS and on ECM runs a 2 days ago but the ECM does not want to know anymore.

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For proper cold in April you need a long drawn northerly arctic flow with tightly packed isobars, ideally a strong low pressure system and very active cold front moving into the N Sea to pull down those cold uppers.

The upcoming week will bring cold uppers, but the flow doesn't look like being that tight with slacker winds and less of an active frontal attack, but if we do see a sluggish front under low cloud temps will struggle to reach mid single figure maxima which will make for cold conditions.

The classic cold spells of Aprils' gone by have been courtesy of long fetch northerlies and the polar front/trough strung out over the country - with heights well out to the west and therefore a north/northeasterly feed and enabling shallow low features to develop in the flow helping the cold to maintain its icy grip. Late April 1981 was a classic case in point, some exceptionally cold maxima and heavy snowfalls.

Conditions could later next week evolve into something akin to a proper cold wintry blast for April, but we really need those mid atlantic heights to ridge further away to the west - the closer they are, the harder it will be to pull the trough our way and keep the cold uppers locked in place.

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For proper cold in April you need a long drawn northerly arctic flow with tightly packed isobars, ideally a strong low pressure system and very active cold front moving into the N Sea to pull down those cold uppers.

The upcoming week will bring cold uppers, but the flow doesn't look like being that tight with slacker winds and less of an active frontal attack, but if we do see a sluggish front under low cloud temps will struggle to reach mid single figure maxima which will make for cold conditions.

The classic cold spells of Aprils' gone by have been courtesy of long fetch northerlies and the polar front/trough strung out over the country - with heights well out to the west and therefore a north/northeasterly feed and enabling shallow low features to develop in the flow helping the cold to maintain its icy grip. Late April 1981 was a classic case in point, some exceptionally cold maxima and heavy snowfalls.

Conditions could later next week evolve into something akin to a proper cold wintry blast for April, but we really need those mid atlantic heights to ridge further away to the west - the closer they are, the harder it will be to pull the trough our way and keep the cold uppers locked in place.

Yes it also it needs to be a long sausage shaped high ridging all the way up into greenland that just sits there, that would be just the ticket, rather than a half baked one that ends up with the uppers being moderated, it has shown on some runs lately but i would have to say the ECM is likely to be near the mark now.

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Looks like we are reliant on the short term, no cheer in the medium term from the 18z im afraid, HP just not looking like migrating to Greenland, too close to us for a full on blast, still we could be in for some suprises at short notice this week though so eyes down for next few days, it will be interesting when the snow potential midweek comes into NMM and NAE range.

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I'm just hanging out for Tuesday into Wednesday down here on the coast......

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I don't think there is now any doubt about the type of weather pattern from now well into April. Over the last week the 3 500mb anomaly charts have slowly, and at times erratically, moved towards the same type of upper pattern. The detail obviously has to be stitched on and the synoptic 2x or 4x daily outputs will change.

Overall a colder and more unsettled spell of weather is going to take over. Quite a shock to many areas after the 'summer' of last week. Typical April/spring weather though with wild swings from one type to the other as the hemisphere moves into its summer mode.

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The sluggish airflow means that snow probably won't be particularly widespread, but nonetheless following the frontal system on Tuesday there will be sleet, snow and hail showers spreading from the north, and overnight Tuesday/Wednesday wintry showers (mostly of snow) will probably continue near North Sea coasts, giving a thin covering for some. The model outputs then suggest a scattering of sleet/snow showers across the country on Wednesday, though convection probably won't be particularly intense due to the advancing high pressure.

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Some accumulations to low levels in Scotland and an absolute pasting for the highlands, it will be interesting to see the exact track it is likely to take as it moves south, so eyes down for the 12z NAE and in particular, the 18z.

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=ukuk&MODELL=nae&MODELLTYP=1&BASE=-&VAR=prty&HH=42&ZOOM=0&ARCHIV=0&RES=0&WMO=&PERIOD=

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Any snow that does fall I would be very surprised to see it accumulate, even across the higher parts given the strength of the sun at this time of year. Although thermal lag is still a few weeks behind, the strength of the sun is now as similar to what it is in September. Typically 'april showers' with embedded hail pellets is what i'm watching out for myself.

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Correct me if I'm wrong but the snow is supposed to fall overnight, not during the day..

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Any snow that does fall I would be very surprised to see it accumulate, even across the higher parts given the strength of the sun at this time of year. Although thermal lag is still a few weeks behind, the strength of the sun is now as similar to what it is in September. Typically 'april showers' with embedded hail pellets is what i'm watching out for myself.

I think the point is that it won't be a 'sunshine and showers' situation so there will be little if any sunshine. More a case of overcast skies, continuous precipitation and an increasingly cold NE wind . With the temperature falling steadily as the precipitation moves south I wouldn't be at all suprised to see at least a thin cover above 300m or so from Derbyshire/Staffordshire northward; probably several cm at places as high as the Cat and Fiddle.

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I think the point is that it won't be a 'sunshine and showers' situation so there will be little if any sunshine. More a case of overcast skies, continuous precipitation and an increasingly cold NE wind . With the temperature falling steadily as the precipitation moves south I wouldn't be at all suprised to see at least a thin cover above 300m or so from Derbyshire/Staffordshire northward; probably several cm at places as high as the Cat and Fiddle.

What do you think chances are for sothern hills tuesday evening and night as it looks like fairly good timing although id be happier if it was delayed another few hours to make it all in the night.

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Certainly for the highlands a snow cover but on low ground very doubtfull i think.

Dewpoints are above 0c untill the rain almost passes through,especially further south.

http://www.wetterzen...s/Rtavn6610.png

http://www.wetterzen...cs/Rtavn664.png

Some hilly parts of N.England-Penines,Peaks etc likely will see a cover but most places i would guess rain, sleet or possibly wet snowflakes more likely as the colder uppers dig in before it dries out under rising presuure.

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I tend to agree with Phil's assessment of the frontal precipitation- probably rain/sleet at low levels, though at Terminal Moraine's elevation snow is certainly possible.

However I think recent posts are underestimating the potential for a "sunshine and snow showers" setup on Wednesday, particularly as the GFS has now joined UKMO in showing a pretty stiff north to north-easterly airflow, which should bring a fair number of showers inland off the North Sea as well as a scattering of homegrown ones. There is a substantial possibility of parts of eastern Scotland and north-east England waking up to a snow cover that morning, though it will probably melt swiftly in the sunshine in between the showers. With daytime max temperatures progged at 4 to 7C across the country (allowing for the GFS's traditional underestimations) and dewpoints well below zero most of us should see snow in those showers.

The GFS also hints at an area of more persistent precipitation coming back into East Anglia on Wednesday although it is also tied in with slightly warmer air so might well give rain/sleet rather than snow.

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All the road warning signs on the A9 in Perthshire are now showing snow warnings for Monday.

It was 16C on my car temp gauge there today though.

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The thing to note here is that the Met office are suggesting accumulations possible above 200m, so it only needs a very small overestimation of temps, thicknesses, etc, by the models to bring a lot more people into the equation, ive seen these type of marginals deliver before, im quietly confident of seeing lying snow in my location, the 18z NAE will be interesting.

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I've seen many forecasts that say snow will be exclusive to high altitude locations above 200m, and then ends up snowing down to lower levels below 100m..

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I've seen many forecasts that say snow will be exclusive to high altitude locations above 200m, and then ends up snowing down to lower levels below 100m..

Agreed. its such a fine margin, it doesnt matter if the models and forecasters are 100m out with the snow level usually because, 500m instead of 600m or 800m instead of 900m does not affect many people but 100m instead of 200m brings a huge area into the equation.

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Met Office are saying 2-5cm at lower levels in Scotland. Is this likely?

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Met Office are saying 2-5cm at lower levels in Scotland. Is this likely?

Yes, its almost a certainty that some places in scotland right down to low levels will see lying snow, with the uppers being projected, of course this does not mean everywhere will see it though.

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Yes as some have said 200m isn't the be all and end all.

I've seen heavy lying snow at 100m with these types of setups while it can also go tits-up with rain and the odd flake even at this elevation.

The last time the Meto forecast snow for 300m+ we ended up with 14cm (Feb 2011).

post-8968-0-80028100-1333305846_thumb.pn

All to play for. Certainly the hilly areas of the northern half of the pennines -close to the Scottish boarder- looks to get a pasting. This area might miss out on the heaviest of the percipitation, ideally we need the heaviness further west as it tracks south east. GFS snowfall totals show quite alot of snowfall with lying snow almost anywhere.

post-8968-0-23174000-1333307828_thumb.pn

Wouldn't be surprised if there are reports of falling snow in London. Nothing substantial like but I would say most places would see some snowflakes come Thursday.

five day forecast looks chilly

post-8968-0-07499100-1333307994_thumb.pn

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Yes as some have said 200m isn't the be all and end all.

I've seen heavy lying snow at 100m with these types of setups while it can also go tits-up with rain and the odd flake even at this elevation.

The last time the Meto forecast snow for 300m+ we ended up with 14cm (Feb 2011).

post-8968-0-80028100-1333305846_thumb.pn

All to play for. Certainly the hilly areas of the northern half of the pennines -close to the Scottish boarder- looks to get a pasting. This area might miss out on the heaviest of the percipitation, ideally we need the heaviness further west as it tracks south east. GFS snowfall totals show quite alot of snowfall with lying snow almost anywhere.

post-8968-0-23174000-1333307828_thumb.pn

Wouldn't be surprised to see falling snow almost anywhere, even the city of London could see something wintry.

five day forecast looks chilly

post-8968-0-07499100-1333307994_thumb.pn

are you showing the photo that has 14cm on it?

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February 2011 is a great example of the Met Office forecasting settling snow only for areas above 300m, only for snow to settle at the heart of Leeds City Centre..

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