April CET

[stewfox]

About the warmest April so far, I mentioned earlier in the thread that in 1778, April stood at 10.9 after the 13th, and ended up at 8.2 C. There were no more days above 10.0 that month.

But there is no suggestion in the relaible time frame (ie next 10 days) of such a cool down.

[damianslaw]

But there is no suggestion in the relaible time frame (ie next 10 days) of such a cool down.

Perhaps not but we could see a marked cooldown just after easter if heights build to the NW bringing much colder nights - I think this is the direction heights will eventually end up with the weakened polar vortex. Whether it will take until May before this happens remains to be seen, but yes I agree we are definately in a position to challenge April 2007. When was the last time a monthly CET warm record fell in the space of four years? and why has April consistently returned mild CET after mild CET it seems the most difficult month to record a below average CET? even more so than September.

[Milhouse]

it seems the most difficult month to record a below average CET?

Careful, you'll encourage NEB.

[Optimus Prime]

The run of warm Aprils could have something to do with the run of the cold winters being experienced right now.

The 1960s had generally cold winters but Aprils were generally mild averaging 8.2c for the decade (against the 7.9c average) and so blocked winters may have some kind of butterfly effect into providing Aprils with blocked weather which, given the time of year results in warm weather.

Perhaps the greatest example were during the 1940s. Winters were often very cold. Aprils, however were exceptionally warm aside from 1941 (6.4c) and there were a total of 4 with a CET at or greater than 10.0c, 3 in a row from 1943 and 1945 (almost 4 with 1946 averaging 9.9c) the average for that decade was a whopping 9.3c.

Edited April 15, 2011 by Optimus Prime

[Roger J Smith]

Just to clarify, I wasn't suggesting any marked cooldown, I was just answering the question, what was the highest value of CET through 13 days. The other part was what happened in 1778.

[TonyH]

Unless GFS is correct with its very warm Easter I feel the 2007 record will be intact but a close one (hopefully by 0.2c too low)

Edited April 15, 2011 by Tonyh

[Scorcher]

Looks like this will most likely end up as another exceptionally warm April- to go with 2007 and to a lesser extent, 2009. We really have had an amazing run of Aprils if you also include the warm Aprils of 2003 and 2004. We have also had several notable early warm spells in these months when you think back to 2003 and 2007 and now 2011 which was more notable for how early it was than the very high temperatures. The consistent sunshine and warmth of this upcoming week seems very reminiscent of 2007. The question is will the record go? It's certainly a possibility now.

[Tom D]

Looks like this will most likely end up as another exceptionally warm April- to go with 2007 and to a lesser extent, 2009. We really have had an amazing run of Aprils if you also include the warm Aprils of 2003 and 2004. We have also had several notable early warm spells in these months when you think back to 2003 and 2007 and now 2011 which was more notable for how early it was than the very high temperatures. The consistent sunshine and warmth of this upcoming week seems very reminiscent of 2007. The question is will the record go? It's certainly a possibility now.

Let us not forget April 2008, when we had snowfall here early in the month.

https://picasaweb.google.com/dupplawt/Snow6thApril2008?authkey=Gv1sRgCOSlh9DlnqyzGw#

[Milhouse]

So we are 11.2c to the mid point in the month. Whether the record is broken depends on if the second half of the month is warmer than the first. It is definately possible.

[AderynCoch]

I'm definitely out of it now. I need the second half to average 5.8C!

[The PIT]

I wonder if we'll beat our driest ever spring 1993 just 55.3mm so far we have 23 mm.

[Terminal Moraine]

I wonder if we'll beat our driest ever spring 1993 just 55.3mm so far we have 23 mm.

Are you sure that wasn't 1990, Pit? We had 91.6mm in 1990, the driest spring on record, but there was 225.6mm in 1993.

I'm wondering if we're going to beat 2007 as the warmest spring on record the way things are going.

[Weather-history]

So we are 11.2c to the mid point in the month. Whether the record is broken depends on if the second half of the month is warmer than the first. It is definately possible.

If the second half is as warm as the second half of April 1893, then the CET will be in the high 11s.

[sebastiaan1973]

Over here in the Netherlands De Bilt recorded till 16 april 11.0c. Which makes it the third warmest month. Just behind 2007/9. April 2007 is by far the warmest april month in 3 centuries, it has a average temperature of 13.1c.

[Weather-history]

It would be pretty exceptional that the 2nd coldest of a particular month is followed just 3 months later by possibly the warmest of a particular month.

In 1947, the coldest February was followed 5 months later by the then warmest August on record.

In 1915 and 1916, the 2nd coldest November on record was followed a month later by the warmest January on record which in turn was was followed 4 months later by the joint 2nd coldest June on record.

In 1817, the 2nd coldest October on record was immediately followed by the then 3rd warmest November on record.

In 1795, the coldest January on record was followed 7 months later by the then 2nd warmest September on record.

[North-Easterly Blast]

It would be pretty exceptional that the 2nd coldest of a particular month is followed just 3 months later by possibly the warmest of a particular month.

In 1947, the coldest February was followed 5 months later by the then warmest August on record.

In 1915 and 1916, the 2nd coldest November on record was followed a month later by the warmest January on record which in turn was was followed 4 months later by the joint 2nd coldest June on record.

In 1817, the 2nd coldest October on record was immediately followed by the then 3rd warmest November on record.

In 1795, the coldest January on record was followed 7 months later by the then 2nd warmest September on record.

For a low April CET, you would need frequent high pressure over Greenland drawing in northerlies / north-easterlies across the UK, or frequent low pressure moving across the south originating from a polar maritime source near Greenland.

I have been looking through the archives, to see what is a favourable pattern prior to April to lead to a cold April. My conclusion is that, 1989 is one of the very few instances where a cold April has followed the whole first quarter of the year being well above average. Generally, the ideal pattern to lead to a cold April is one or more of the first three months in the year (Jan, Feb, Mar) being below average. Like 1986, 1983, 1978, 1977, 1970, 1969, 1966, 1958, 1956, 1951, 1941, 1936, 1932, 1922, 1917, 1908 etc all had one or more below average months in the Jan, Feb, Mar period, some of which were notably so, ala Feb 1986, Mar 1970, Feb 1969, Feb 1956, Jan 1941, the whole of the winter months and the March of 1916-17, and these led to cold Aprils. Generally I would say that no colder than average month in the Jan / Feb / Mar period is not favourable for a cold April.

My analysis is that "pear shaped" winters like 2010-11, hardly ever lead to significant cold spells in the spring, so from this it would appear that a cold spring month in 2011 was unlikely after how pear shaped the winter was. (A pear shaped winter is one that starts with a good cold spell early on but deteriorates into nothing / rubbish), albeit 2010-11 is certainly by a long way the most extreme case of a pear shaped winter since the CET record began in 1659.

I am of the belief that a winter that is cold overall, with cold spells spread through the winter period, is the most ideal pattern to lead to a cold April, or a cold March or even a cold May.

Right from the start of the cold spell in late Nov, winter 2010-11 never felt right to me, or how it should be. To get such extreme cold so early was totally unprecedented - two weeks of ice days and widespread snow in late Nov / early Dec, and no winter that was "severe" overall (CET less than 2*C), has ever seen extreme freeze ups set in late November and persist through much of the winter, and to me the early freeze up that we had in 2010 always looked a bad omen for getting a winter that is cold overall or for the most part. Personally I would say that the best pattern for a cold winter overall is a fairly mixed spell of weather pre Xmas, then severe cold setting in close to the Xmas period, of which severe cold that sets in around that time has a better chance of being maintained through the winter, as severe cold spells in late Nov / early Dec rarely persist.

[Optimus Prime]

I am of the belief that a winter that is cold overall, with cold spells spread through the winter period, is the most ideal pattern to lead to a cold April, or a cold March or even a cold May.

Despite the fact the 1940s and 1960s dispute that argument? Seems your view on all this comes across as being quite religious.

Anyway, about this month it does look it is virtually certain this will be come in as the warmest on record. Quite a decent chance it will break the 12.0c barrier too. A 4.0c or more above average month likely.

Edited April 17, 2011 by Optimus Prime

[reef]

If the temperatures shown on the GFS 6z were to come to fruition, then we would be sat on a provisional 12.1C at the end of the month. Thats 0.9C above the record set in 2007 which itself was 0.6C above the previous record.

It would be a value every bit as impressive as May 1833.

[Thundery wintry showers]

Yes, I don't think we are yet certain of the record (the last week of April is still out in FI and could turn cooler from the east for instance) but the odds are looking pretty favourable for another record warm April. Despite a cloudy first week, it could well end up among the sunniest on record as well.

[Milhouse]

If the temperatures shown on the GFS 6z were to come to fruition, then we would be sat on a provisional 12.1C at the end of the month. Thats 0.9C above the record set in 2007 which itself was 0.6C above the previous record.

It would be a value every bit as impressive as May 1833.

Agreed, that would be absolutely astounding to beat the previous record by almost 1c. Interesting times ahead indeed.

[stewfox]

For a low April CET, you would need frequent high pressure over Greenland drawing in northerlies / north-easterlies across the UK, or frequent low pressure moving across the south originating from a polar maritime source near Greenland.

I have been looking through the archives, to see what is a favourable pattern prior to April to lead to a cold April. My conclusion is that, 1989 is one of the very few instances where a cold April has followed the whole first quarter of the year being well above average. Generally, the ideal pattern to lead to a cold April is one or more of the first three months in the year (Jan, Feb, Mar) being below average. Like 1986, 1983, 1978, 1977, 1970, 1969, 1966, 1958, 1956, 1951, 1941, 1936, 1932, 1922, 1917, 1908 etc all had one or more below average months in the Jan, Feb, Mar period, some of which were notably so, ala Feb 1986, Mar 1970, Feb 1969, Feb 1956, Jan 1941, the whole of the winter months and the March of 1916-17, and these led to cold Aprils. Generally I would say that no colder than average month in the Jan / Feb / Mar period is not favourable for a cold April.

My analysis is that "pear shaped" winters like 2010-11, hardly ever lead to significant cold spells in the spring, so from this it would appear that a cold spring month in 2011 was unlikely after how pear shaped the winter was. (A pear shaped winter is one that starts with a good cold spell early on but deteriorates into nothing / rubbish), albeit 2010-11 is certainly by a long way the most extreme case of a pear shaped winter since the CET record began in 1659.

Small point CET Jan 2011 was below average.

I am sure there is no correlation

[North-Easterly Blast]

Small point CET Jan 2011 was below average.

I am sure there is no correlation

Looking at the most recent 1971-2000 average, Jan 2011 may have been 0.5 below average, but looking at earlier sets of averages it was even fractionally above by 1951-80 and 1941-70 standards. It is always useful to look at earlier sets of 30 year averages to see how a month compares with more historical standards other than just the most recent 30 year mean.

Before any arguments, Jan 2011 was a little below average by most recent standards yes, but it was an AVERAGE month by historical standards. On top of this, the colder conditions that occurred at times during Jan 2011, in particular during the second half of the month, were largely due to a mid-latitude HP sat close to the UK giving surface cold rather than a flow of deep cold Arctic air, so despite the CET looking average or even marginally below, it was still a pretty snowless month due to the lack of proper cold synoptics (northerlies / easterlies).

Agreed, that would be absolutely astounding to beat the previous record by almost 1c. Interesting times ahead indeed.

This April is just turning into such a ludicrously warm month. April 2007 was really the equivalent of a March like 1938 or 1957, but if we beat April 2007 this month it makes we wonder and fear that we are entering a new era of sustained exceptional warmth a la 2006/2007, given how mild February was too. The 12 months from May 2006 to April 2007 were just absolutely ridiculous - virtually the "warm" equivalent of 1740.

Will we ever see a cold April again? We just don't seem to be able to get northern blocking and / or cold polar maritime zonality to give us cold weather in April any more - all we seem to be able to get now is high pressure sat over the UK, refusing to ever move north of the UK to let cooler airflows in.

Edited April 17, 2011 by North-Easterly Blast

[Thundery wintry showers]

Will we ever see a cold April again? We just don't seem to be able to get northern blocking and / or cold polar maritime zonality to give us cold weather in April any more - all we seem to be able to get now is high pressure sat over the UK, refusing to ever move north of the UK to let cooler airflows in.

We are able to get it, we just haven't had it sustain for long enough to deliver a significantly colder-than-average April.

[North-Easterly Blast]

We are able to get it, we just haven't had it sustain for long enough to deliver a significantly colder-than-average April.

April 2008 managed a cold spell from the 5th to 19th, but it didn't last beyond this and things just returned to above average after this, and in fact that month the first four and last ten days were quite warm.

After winter 2009-10 had been cold overall, and a more spread out winter too, I really thought that the chance of a cold April last year was better than it had been for many years, but hopes were dashed again. You only have to look at records, and cold winters overall but more spread out ones, and even colder than average Jans / Febs / Mar are often a favourable pattern to lead to a cold April. Sadly after a favourable pattern last year, a cold April still failed to materialise. This makes me ask the question more, will a cold April ever pop up anywhere?

[Thundery wintry showers]

I thought Mr_Data already answered that question at least once?