Features Of Cold Snaps From NW/NE Winds

[leicsnow]

I've been wondering what peoples views are of the features of cold snaps delivered by Northeasterly and northwesterly winds, and the comparison/contrast between them? I sort of have an idea, but can't explain it.

[leicsnow]

I think I may have worded this wrong lol maybe thats why no replies?

[leicsnow]

I've been wondering what peoples views are of the features of cold snaps delivered by Northeasterly and northwesterly winds, and the comparison/contrast between them? I sort of have an idea, but can't explain it.

[leicsnow]

Can anyone describe the difference and patterns between cold snaps coming from northeasterly and northwesterly winds? I kind of know but can't describe it. Personally I like nor'easter's better.

[Aaron]

Cold from the north west is rubbish, but cold from the north east owns all.

Simple

[leicsnow]

Cold from the north west is rubbish, but cold from the north east owns all.

Simple

Yeah, for some reason cold from the north-east seems fresher.

It also seems more consistent and longer-lasting.

[greybing]

this i no necessarily true ,cold from the north[n] west can pack a punch though tends not to last as long.

Edited December 7, 2011 by greybing

[Andy Bown]

Cold from the north west is rubbish, but cold from the north east owns all.

Simple

That's a rather simplistic view. Some of the best, most exciting heavy snowstorms I've experienced have come on a NW flow (although I agree frigid, long lasting cold is far more likely from the NE).

Had this week been several degrees colder then a narrow swathe of Somerset / SW Wiltshire / W.Dorset would have had pretty deep snow between Sunday evening and this morning. In an approximately 10 mile wide wedge a streamer of showers gave well over an inch of rain in that time.

And that leads me on to the theme of this thread. A feature of cold from the NW and NE is streamers of showers developing over the sea / coastline and heading inland to affect relatively narrow wedges of land.

[Alex95]

A NW wind is usually more marginal than a NE wind. In a NW flow, showers pepper Northern and Western Scotland, Northern Ireland, and usually North West England. Significant snow (say, >10cm?) at low levels is often reserved for Scotland early on the season, but as the Arctic gets colder it can affect other areas. On the 18th December last year Northern Ireland got over a foot in places, as did North West England late in the day, although that was from a prolonged spell of snow rather than showers. Sometimes, streamers form, such as the other day when showers ran from Merseyside to Norwich, but the showers are generally disorganized. Also, a NW flow usually only lasts a day or two, and is followed by milder westerly winds.

A NE flow is usually colder, and can last for several days or more, as it did in January 2010 and November/December 2010. Snow showers affect the North East at first, then gradually spread down the East Coast, affecting anywhere exposed to the NE wind. The deepest snowfall usually occurs in NE Scotland, and sometimes NE England - in January and Nov/Dec 2010 depths exceeded a foot in these areas. The showers usually start of as being disorganized, but they seem to gather together into slightly more prolonged areas of snow after a while in the North East especially. in a marginal NE'ly, the snow is wet, but often it is quite powdery in nature, especially if it lasts for several days and the cold air becomes entrenched across the country. The snow tends to affect Northern and Eastern areas, whilst places which aren't near windward coasts often miss out. Sometimes, a NE'ly gradually breaks down into milder conditions, whilst it can also be broken down during a battleground scenario as rain meets the cold air and turns to snow.

Away from Scotland, it is more common for a NE'ly to deliver significant snow to low levels in the NE than it is for a NW'ly to deliver significant snow the NW, but it depends on where you live as to which direction is more reliable for snow to come from.

[Wynn D Woo]

Back in November 2005, we were living in south Wales and received 6 inches from a NW'ly, whist lasted almost a week on the ground at 45m asl, whilst my parents in Gloucestershire also received a couple of inches a few days later. A potent NW'ly is just as good as a NE'ly imo.

edit, 2005 not 2006!

Edited December 7, 2011 by windswept

[Alex95]

Back in November 2006, we were living in south Wales and received 6 inches from a NW'ly, whist lasted almost a week on the ground at 45m asl, whilst my parents in Gloucestershire also received a couple of inches a few days later. A potent NW'ly is just as good as a NE'ly imo.

True, but what I was trying to say is that a NE'ly is nearly always potent with significant snow, whereas many NW'lies are marginal. 90% of NE'lies here deliver at least 5cm, and probably more than 50% deliver over 10cm, whereas I'm sure the figure would be lower for low lying areas of the NW from NW'lies.

However, I know full well that NW winds can sometimes be very good.

Edited December 7, 2011 by alza

[Thundery wintry showers]

It's no accident that the potent NW'lys of the past two winters, and the one on the 25th November 2005, all occurred with a pronounced Greenland High and low pressure to the N/NE, i.e. a generally northerly type but with the configuration of lows and highs being right to give us a north-westerly. This is because the Arctic air only has to travel a short distance over the Atlantic and thus modification is relatively low.

North-westerlies associated with a generally westerly type, aka "cold zonality", tend not to deliver widespread snowfalls to low ground away from Scotland and Ireland because further south and east the cold Arctic air has too long a track over the Atlantic. The most potent instances, such as in Januarys 1978 and 1984 and early March 1995, are capable of delivering sustained snow cover from the north Midlands northwards and short-lived snow cover even in the south, but those are pretty rare. Short-lived snow cover across northern England and the high ground of Wales and the Midlands, such as on 16 February 2000 and 23 February 2002, is fairly common though.

North-easterlies are traditionally more potent because they pick up arctic continental air, which is the coldest airmass source of the lot, and I generally think of the north-east as being the snowiest wind direction taking the UK as a whole, not just NE England. Even so, I think it's an exaggeration to suggest that 90% of them deliver at least 5cm to the Newcastle area (even on fairly high ground) as sometimes we get issues with modification from old depression cores which turn them marginal too.

[leicsnow]

I think the recent north-westerly also followed this theme, as pretty much everywhere from the North Midlands up received some snow, and the south none.

[Lynxus]

I always think of NW'erlies as wetter and more violent.. If It brings enough cold, Then these are the times you get nasty blizzards along with terrible windy conditions.

NE'erlies I always think of being colder and crisper with less wind and less snow. Just generally frosty and colder ( Snowy on the east )

I think this is due to the amount of land the air has to pass over on a easterly and bringing us drier air. Unlike from the north and west.. Plenty of water to be picked up..

Just my thoughts. , This is how I see it..

[Alex95]

It's no accident that the potent NW'lys of the past two winters, and the one on the 25th November 2005, all occurred with a pronounced Greenland High and low pressure to the N/NE, i.e. a generally northerly type but with the configuration of lows and highs being right to give us a north-westerly. This is because the Arctic air only has to travel a short distance over the Atlantic and thus modification is relatively low.

North-westerlies associated with a generally westerly type, aka "cold zonality", tend not to deliver widespread snowfalls to low ground away from Scotland and Ireland because further south and east the cold Arctic air has too long a track over the Atlantic. The most potent instances, such as in Januarys 1978 and 1984 and early March 1995, are capable of delivering sustained snow cover from the north Midlands northwards and short-lived snow cover even in the south, but those are pretty rare. Short-lived snow cover across northern England and the high ground of Wales and the Midlands, such as on 16 February 2000 and 23 February 2002, is fairly common though.

North-easterlies are traditionally more potent because they pick up arctic continental air, which is the coldest airmass source of the lot, and I generally think of the north-east as being the snowiest wind direction taking the UK as a whole, not just NE England. Even so, I think it's an exaggeration to suggest that 90% of them deliver at least 5cm to the Newcastle area (even on fairly high ground) as sometimes we get issues with modification from old depression cores which turn them marginal too.

Maybe, but I bet if you list all the NE'lies with sub -5 uppers in the last 20 years the majority will have delivered 5cm. It tends to be direct easterlies which have more of a risk of being modified - Jan 3rd 2008 was quite poor in my location, but I was simply referring to direct NE'lies.

I always think of NW'erlies as wetter and more violent.. If It brings enough cold, Then these are the times you get nasty blizzards along with terrible windy conditions.

NE'erlies I always think of being colder and crisper with less wind and less snow. Just generally frosty and colder ( Snowy on the east )

I think this is due to the amount of land the air has to pass over on a easterly and bringing us drier air. Unlike from the north and west.. Plenty of water to be picked up..

Just my thoughts. , This is how I see it..

The showers don't tend to penetrate as far inland with NE'lies, but there is often more snow associated with them.

Edited December 7, 2011 by alza

[greybing]

For me a north westerly element to a northerly or easterly [east around Scotland from very cold direction ,curves to a northerly on land or on the sea of western

Scotland.Then as air comes to the north west a kink in the isobar over the north sea and then a North westerly flow from coast.Manchester can get hit then,my area is too bad for the best snow directions ,though in a straight eastrely ,my low level area of south Manchester can be very dry ,clear and freeze a lot.The odd snow shower adds to the severe cold...................

What is a streamer and can Manchester ,low level ,[south west] experience these.

[Wynn D Woo]

I always think of NW'erlies as wetter and more violent.. If It brings enough cold, Then these are the times you get nasty blizzards along with terrible windy conditions.

NE'erlies I always think of being colder and crisper with less wind and less snow. Just generally frosty and colder ( Snowy on the east )

I think this is due to the amount of land the air has to pass over on a easterly and bringing us drier air. Unlike from the north and west.. Plenty of water to be picked up..

Just my thoughts. , This is how I see it..

Exactly, a NE'ly is often colder but it just doesnt deliver much or any snow more often than not, whereas the NW may be more marginal but even wet marginal snow is better than none at all.

In the end no surprise Eastern folk back the NE'ly the western based folk back a NW'ly.

[Aaron]

NE'ly will bring far more snow then a NW'ly... for us easterners

[Thundery wintry showers]

I think that taking the UK as a whole, north-easterlies deliver more widespread snow on average because they tend to be colder. Shower activity tends to be similarly widespread in both cases, but near windward coasts, a wintry mix tends to result whenever the word "marginal" creeps in, and in sheltered areas, precipitation is less likely to be heavy enough to produce snow cover, and temperatures are less likely to be low enough to allow a thin snow cover to withstand daytime sunshine.

The most potent north-westerly blasts, even when associated with Arctic northerly types, will rarely deliver any advance on -10 to -12C at the 850hPa level, while a deep north-easterly is capable of bringing 850hPa values of -15C or lower across from Scandinavia.

The archives do contain some examples of north-easterly outbreaks with 850hPa temperatures around -5C which struggled to bring widespread snow cover in north-east England (20th/21st February 2006 for instance), usually on occasions when Scandinavia was anomalously warm. but generally anything -8C and below will be near-guaranteed to give at least 5cm to the Newcastle area. The same applies to places like Carlisle and Manchester from a north-westerly but getting such a cold airmass is harder from that direction.

However the above analysis takes the UK as a whole- for most of Ireland, northern and western Scotland and NW England, and upland parts of Wales, a north-westerly is the better bet. I hesitate to include south-west England in this as north-westerlies are heavily modified by the time they reach the south-west, while on the 2nd February 2009 a generally north-easterly flow sent snow showers right across from the North Sea to Exeter.

[leicsnow]

Oh and why are north easterlies more common in late Winter and Spring rather than in early Winter? From my experience that is when they tend to happen.

Edited December 7, 2011 by Tellow

[Weather-history]

One thing that the NWly has over the NEly is how many times has a polar low hit the UK on a NEly compared to a NWly?

[Alex95]

Oh and why are north easterlies more common in late Winter and Spring rather than in early Winter? From my experience that is when they tend to happen.

The polar vortex tends to be stronger early on in the winter I think, and when it becomes slightly displaced (as it is at the moment) we can get cold zonality from the NW. If it weakens later on in the winter there can be more of a chance for northern blocking to take hold, or for low pressure to move into Continental Europe.

One thing that the NWly has over the NEly is how many times has a polar low hit the UK on a NEly compared to a NWly?

That's a good point, although there have been examples of one forming in a NE'ly. Jan 2003 is a good example, caused a whopping 3 inches of snow in the South East somewhere and the M1 got blocked

[Andy Bown]

What is a streamer and can Manchester ,low level ,[south west] experience these.

A streamer is a line of showers that develops over the sea or on the coast and heads inland, or over any body of water. This is a constantly repeated occurence when the conditions are right for development (normally under LOW pressure with wind blowing from water to land). Generally they develop due to the difference in temperature between the sea and the land.

They are very regular through the Cheshire Gap, from the Bristol Channel and, in cold Easterly set ups, from the North Sea and River Thames.

[Les Penniston]

A streamer is a line of showers that develops over the sea or on the coast and heads inland, or over any body of water. This is a constantly repeated occurence when the conditions are right for development (normally under LOW pressure with wind blowing from water to land). Generally they develop due to the difference in temperature between the sea and the land.

They are very regular through the Cheshire Gap, from the Bristol Channel and, in cold Easterly set ups, from the North Sea and River Thames.

I believe it was a streamer that cancelled the Lincoln christmas market last year, they can be hit and miss because unfortunately it missed us.

Les