Spring / Summer 2010

[Milhouse]

Early next week should see the first proper spring like conditions over a wide area. Chances of widely reaching 10c still look slim but it could be the first time that there is a real sense of Spring in the air.

[Derp Patrol]

Feels like Spring already down here. The last few days have reached double figures, and it feels milder. Now all we need is a bit of sun and 15C and i'll be happy It's difficult to realise that right now the average temperature here should be about 10C, but we are struggling to reach that.

[summer blizzard]

While anologues are not really helping in regards to the summer at the moment, there are signs that things may not be so bad.

My own personal thoughts for this spring are that it will be fairly average, the warmest spell relative to average being the mid April to mid-May period, where hopefully we can breach 25C.

In regards to the immediate future, average to cool is what i think we will see, however sea surface temperature anomolies do indicate high pressure over or just west of the UK for the middle part of March.

In regards to the longer term prospects in relation to the sea surface temperature anomolies, the problem we have at the moment is warm air in the western Pacific leading to stratospheric warming over the Arctic, we need the Polar Vortex over western Canada to get blocking to our East/South, otherwise the tendancy will be for blocking to west of the UK.

In regards to summer, what is interesting to me, is that we have cold anomolies developing west of Irlenad, if we can keep a similar pattern in the central Atlantic, then once Europe warms and we see +ve anomolies mantiaining a Euro High, this could in theory give us a similar setup to that of 2006.

http://weather.unisys.com/surface/sst_anom.html

[lukemc]

Hi,

Although some have mentioned that very cold winters with a CET less than about 2 or 3C are statistically more likely to be followed by cooler summers (seasonal CET less that 15C), even if that is the case, I do think that the fact this winter was an El Nino one could alter the mechanics in a way that the coming summer would more likely to be warmer than average than if this was not an El Nino winter for example I know that this winter will come as one of the coldest winters where a moderate to strong El Nino was present so maybe a better comparison when trying to predict the conditions for the forthcoming summer will be those sub 3C CET winters where an El Nino was present and their following summers rather than sub 3C winters overall. This could especially be the case if the current El Nino pattern continues into the following summer without receding to neutral until late summer. Talking of that does anyone know if the cold winters of 1947 and 1955 which were followed by good summers where El Nino winters?

Luke

[LomondSnowstorm]

Hi,

Although some have mentioned that very cold winters with a CET less than about 2 or 3C are statistically more likely to be followed by cooler summers (seasonal CET less that 15C), even if that is the case, I do think that the fact this winter was an El Nino one could alter the mechanics in a way that the coming summer would more likely to be warmer than average than if this was not an El Nino winter for example I know that this winter will come as one of the coldest winters where a moderate to strong El Nino was present so maybe a better comparison when trying to predict the conditions for the forthcoming summer will be those sub 3C CET winters where an El Nino was present and their following summers rather than sub 3C winters overall. This could especially be the case if the current El Nino pattern continues into the following summer without receding to neutral until late summer. Talking of that does anyone know if the cold winters of 1947 and 1955 which were followed by good summers where El Nino winters?

Luke

I don't honestly believe tha we've had a cold winter in the last 60 years which coincided with a moderate-strong el nino - this is what makes me think this winter has been truly exceptional and not just a 'blip' either as some seem to think. http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears.shtml

54/55 was a weak-moderate and continuous la nina, not sure about 46/47 and in fact the only year with an el nino of any strength and a cold winter was 65/66.

[Snowyowl9]

Could be a long drawn out spring this year like 1996,I would like to see some snow in May this year though.

As for summer,I bet July will be the wettest month again.

[kold weather]

Yeah this winter more then any since the 60s have been soley down to one factor and thats the amazing -ve AO.

Such bouts aren't likely to go away anytime soon however it would be amazingly rare to get such a long lived AO to get it past 3-4 months, as would be the case by April. Wit hthe jet therefore to the south thus far I wouldn't be at all surprised to see a very period in the second half of the spring as the jet lifts northwards, we've already seen hints of that in the last 7 days of what will happen.

As for summer, thats a tough one, once the -ve AO declines the jet will come more into play again however I'd hate to make much of a call at the moment. Th eENSO signal should be negative so that doesn't give any real hints either. Interestingly the subtropicals are fairly cool whilst the tropics so any prolonged SW outbreaks may not be quite as impressive as some previous years either.

Still I'm not really a summer synoptic person because other then thunderstorms and the odd heatwave my attention tends to be turned to hurricanes, however for now I see an evolution thats warmer then average but not by a great deal and there will b quite a lot of variablity as well, still we shall see!

[Devon-Nelly]

I think Spring is going to be swings and roundabouts with a mostly cold first half at least with it being fairly unsettled and I think that this summer could possibly go either way this year , especailly if El Nino keeps up (but its abit early for summer yet)

It will be intreasting to see how this spring pans out i feel.

[Weathizard]

Is there any sites that do long term and I mean LONG term forecasts? I know they are pretty much useless but eh?

[Thundery wintry showers]

Could be a long drawn out spring this year like 1996,I would like to see some snow in May this year though.

As for summer,I bet July will be the wettest month again.

We are long overdue a northerly outbreak with widespread snowfalls in May- the last was in 1997. Only 2005 came close to producing one, and the northerlies of May 2005 were more notable for their frosts than their snow showers, which were largely confined to high ground. The 1990s were quite active for May snowfalls with widespread falls also in 1993 and 1995, and localised falls also occurred in 1992 (remarkable, considering how warm the month as a whole was), 1994, and the very cold one in 1996.

I doubt that we've reached the stage of global warming where widespread snow is impossible in May, given that it happened on the 2nd June in 1975 when Northern Hemisphere temperatures were only 0.5-1.0C lower.

Statistically there doesn't seem to be a significant link between the likelihood of May snowfalls and a cold early spring. It was certainly the case in 1996, but the May 1995 snowfalls occurred within a pattern of recurring switch-arounds, and the Mays of 1993 and 1997 followed on from consistently warm weather during March and April, especially so in the case of 1997. The warm sunny springs of 1948 and 1982 also had fairly widespread snow in May.

[kold weather]

I suspect TWS its thanks to in effect toppler northerly set-ups, a good shot from the north could give snowfall then quickly be ejected eastwards and a warm HP comes over the top, that would be a pretty decent set-up to have for May, though I have to admit I'd also like a plume in late May as well with thunderstorm risks.

[Milhouse]

Very much a high pressure dominated outlook from most of the models with only NOGAPS throwing a proper spanner in the works. Looks like a long overdue drying out of the ground is about to begin after the recent deluge.

[Nick L]

I notice that the Met Office haven't done a Spring forecast this year, and after their recent poor showings who can blame them?

[Thundery wintry showers]

I suspect TWS its thanks to in effect toppler northerly set-ups, a good shot from the north could give snowfall then quickly be ejected eastwards and a warm HP comes over the top, that would be a pretty decent set-up to have for May, though I have to admit I'd also like a plume in late May as well with thunderstorm risks.

From my recollections of going through the archives, most late spring snowfalls are associated with high pressure in the north Atlantic/Greenland with low pressure slowly filling out over Scandinavia giving a slackening northerly flow lasting for upwards of a few days- the classic example being early May 1979. In the May 1995 instance, the northerlies persisted for almost two weeks. Topplers are occasionally associated with them, but more rarely because in a toppler the cold air often doesn't get to establish for long enough before the high comes over.

The most usual source of "cold -> warm" switch-arounds doesn't involve a warm high coming over the top, but rather HP drifting across from the W or NW and then heading to the east or south-east allowing southerlies in - an extreme case occurred in early June 1975. The big switch-around in mid March 2005 was the most recent notable example that I remember. Switch-arounds of warm -> cold, as we saw in early April 2008 and repeatedly during the 1995 season, tend to have HP over and to the east of the UK giving warm sunshine, followed by LP transferring to Scandinavia and blocking transferring to the NW allowing northerlies in.

There are no hard and fast rules though- I think the warm -> cold switches of early Aprils 1968 and 1990 and May 1997 saw high pressure retreat allowing a deep low to replace it over Britain, and then the low drifted eastwards, and since pressure was also low over N Scandinavia, this allowed a very cold northerly flow in.

[reef]

From my recollections of going through the archives, most late spring snowfalls are associated with high pressure in the north Atlantic/Greenland with low pressure slowly filling out over Scandinavia giving a slackening northerly flow lasting for upwards of a few days- the classic example being early May 1979. In the May 1995 instance, the northerlies persisted for almost two weeks. Topplers are occasionally associated with them, but more rarely because in a toppler the cold air often doesn't get to establish for long enough before the high comes over.

The most usual source of "cold -> warm" switch-arounds doesn't involve a warm high coming over the top, but rather HP drifting across from the W or NW and then heading to the east or south-east allowing southerlies in - an extreme case occurred in early June 1975. The big switch-around in mid March 2005 was the most recent notable example that I remember. Switch-arounds of warm -> cold, as we saw in early April 2008 and repeatedly during the 1995 season, tend to have HP over and to the east of the UK giving warm sunshine, followed by LP transferring to Scandinavia and blocking transferring to the NW allowing northerlies in.

Yes, for late Spring snowfall a NNE flow sourced from the Svalbard area with relatively low thicknesses seems to be a key factor. This presumably helps because the zero degree level is then rather low, so you get a large temperature gradient when you take into account the temperature close to the surface helped by solar heating aswell. This leads to the exciting temperature drops during showers as a combination of the solar heating being cut off and downdrafts from shower clouds mean it can be 8-10C one minute and several degrees colder and snowing the next.

Hopefully we'll have a few switcharounds this spring. Last year's homogenous mild weather was very boring indeed.

[Thundery wintry showers]

The point re. thicknesses is a good one, and one that I missed in my above analysis. I recall a couple of sources (I can't remember exactly where, unfortunately) suggesting that the 2nd June 1975 snowfalls were heavily assisted by low thicknesses, resulting in dramatic falls in temperature during the showers- it is often forgotten that maxima were widely between 10 and 13C, and 850hPa temps around -4C, on the day itself, so some of those temperature drops must have been quite dramatic.

The best recent example in Cleadon that I remember was the 8th April 2006- temperatures reached 8C that day, but during a heavy shower the temperature fell to 0.6C with very large snowflakes, and again, the upper air looked quite marginal on the face of it but the low pressure and low thicknesses assisted the snowfall.

It's probably a large part of the reason why topplers tend not to deliver many late snowfalls, because thicknesses are often relatively high nearer to the high pressure, even though both the surface and upper air may be relatively cold.

[Bottesford]

Hopefully we'll have a few switcharounds this spring. Last year's homogenous mild weather was very boring indeed.

Likewise I hope it's not homogeneously cold either - like this winter has been! I would certainly prefer a sharp changeable spring - flipping from cold to warm (pref very cold to very warm and back) before settling down into a warm to hot & dry summer...

[k19]

Is it ever interesting? Is there thunderstorms much in spring? I have lived all these years and never actually decided what weather belongs to what season ( apart from snow and ice- generally winter)

[glosteroldboy]

So what is the average/least amount of rainfall for March? Looks very dry almost everywhere for the next 7 days with total precipitaion accumulations being nothing across most of the country, guess that can all change though into the 2nd half of the month?!

http://expert.weatheronline.co.uk/daten/proficharts/en/2010/03/04/basis00/ukuk/rsum/10031106_0400.gif

[SteveB]

Likewise I hope it's not homogeneously cold either - like this winter has been! I would certainly prefer a sharp changeable spring - flipping from cold to warm (pref very cold to very warm and back) before settling down into a warm to hot & dry summer...

That sounds just about perfect, and when Autumn starts we switch back to cold cold cold.

[Thundery wintry showers]

Is it ever interesting? Is there thunderstorms much in spring? I have lived all these years and never actually decided what weather belongs to what season ( apart from snow and ice- generally winter)

Thunder frequency is generally quite low in March, but it increases by April, and by May it is comparable to that of the three summer months.

Snow in March is about as frequent as in December, but tends not to stick around for as long because of the stronger sun. In April, snow is about as common as it is in November, while snow in May is traditionally a little more common than in October but the last decade has turned that on its head.

Spring is associated with more "episodic" weather patterns due to a traditionally weaker Atlantic, so dramatic switch-arounds are more likely than at any other time of year. High pressure increasingly tends to be a source of dry sunny weather rather than "anticyclonic gloom" because of the strengthening sun, and southerlies can increasingly bring hot thundery plumes. Westerlies bring the usual mix- bright & showery from polar maritime air, cloudy & warm & drizzly from tropical maritime air but some sunshine towards the SE. Northerlies still tend to be bright and showery during the spring months- cloudy northerlies don't become particularly common until we reach the summer- but easterlies become increasingly associated with low cloud and suppressed daytime temperatures, with the exception of some anticyclonic/easterly types in May which can be sunny and warm except for the east coast.

As for a variable spring leading into a hot dry sunny summer, quite a lot of hot dry sunny summers do follow on from that progression- as well as the oft-mentioned example in 1995, I think there were some quite notable contrasts in those of 1947, 1955, 1984, 1989 and 1990, and also more recently 2006. 1989 and 1990 are rightly remembered for a lot of warm sunshine, but in 1989 there was the contrast between the warm March & May and the cold wintry April, and in 1990, April had numerous contrasting episodes. However it doesn't always work- Spring 1983 was mostly cold, cloudy and wet throughout. 1983 did, however, illustrate that it is possible to get a very thundery May.

[lukemc]

Hi,

Talking of the prospects for the coming summer, wasn't the winter of 2005/06 rather cold and "blocked" with a rather cold first half to spring and the fact that in some respects we just missed out on a severe winter similar to the one we have just had (it was quite a severe winter in parts of Mainland Europe and 2006 was a hot summer here and on the continent to). And I also remember that the Met Office actually forecast a cold winter that year so they almost got it right (was winter 2005-06 the coldest since 1995/96 at the time or 1996/97?) And we know that that winter was followed by warm to very warm summer so it goes to show that a blocked continental type winter can be followed by a similar type summer.

Luke

[Derp Patrol]

Thinking of that 2006 summer makes me happy.. that is my ideal summer.

In July, my nearest station recorded:

12 days above 30C

10 days above 25C

The rest above 21C

Max temperature: 35C

Average Max: 28.3C

Average Low: 15.8C

Average temp: 22.05C

While the average low temps were only about 1.5C above average, the max temp was 5.5C above average.. which is what matters

Back to the Spring prospects, I'm looking forward to the blossom. My cherry tree looks beautiful for 2 weeks when it does blossom. Lasy year it was fully blossomed on the 1st April, I'm not sure about this year, although all of the trees around here have their 'buds' out, and it looks like they are going to spring to life soon!

[Milhouse]

Oh, i do hope we are in for another 2006 type summer. Thats the last time i experienced proper heat i.e temperatures approaching 30c in very little wind. The last 3 summers have had their moments but they have been all to brief (not existent as was the case in 2007) or affected by an onshore breeze which keeps the east coast several degrees cooler. Finding it hard to sleep comes with a hot summer but i will definately take that if it means we get plenty of warm sunny evenings where it doesnt drop below 20c until it gets dark. I hate having to wear an extra layer in summer even in the evenings, it should be the season for shorts and t-shirt most of the time.

[reef]

Oh, i do hope we are in for another 2006 type summer. Thats the last time i experienced proper heat i.e temperatures approaching 30c in very little wind. The last 3 summers have had their moments but they have been all to brief (not existent as was the case in 2007) or affected by an onshore breeze which keeps the east coast several degrees cooler. Finding it hard to sleep comes with a hot summer but i will definately take that if it means we get plenty of warm sunny evenings where it doesnt drop below 20c until it gets dark. I hate having to wear an extra layer in summer even in the evenings, it should be the season for shorts and t-shirt most of the time.

Last summer actually wasnt that bad at all around here. The 4th warmest since 1976 in fact. July was wet but June and August were very dry. It had more rainfall than 2006, but then again in that summer August was wet too. I think many people see that summer through rose-tinted glasses due to the exceptional July. The problem in hoping for another month like that was that it was so extreme for this country that even if the climate continues to warm we probably wont see one like that or warmer for many years.

In reality, we've actually been spoilt in the last 20 years for summers. The average temperature of the season from 1989-2009 was some 0.5C above the 1971-2000 mean (and here its actually 0.7C above). Its easy to forget that summers with means in the 14s werent too uncommon before then. If we can manage the coldest winter for 30 years, then theres no reason we couldnt manage a similar summer. Im not saying we will of course, but it would certainly bring some perspective!