Looks like a 'switch-flip' coming up mid-next week as AAM tendency heads sharply negative for a time but set against a high starting AAM anomaly; this is GWO stage 7-8 and corresponds to sluggish N. Atlantic westerlies but low heights to the W of the UK maintaining far enough north to prevent the resulting blocking high locating NW of the UK. A key difference to the typical Jan-Mar response, and something GFS took until today to fully adapt for.

Blocking NE or E of the UK with troughs out west struggling to make inroads, just doing enough from time to time to destabilise conditions with showers or thunderstorms the main source of rainfall in the UK (especially England).

That's the typical weak El Nino 'base state' from mid-late April to early-mid July. If it weren't for the complications that tend to arise, we'd be able to predict a warmer but not necessarily drier than average summer with good confidence for 2019.

 

From the evolution of that pattern, the latest two GFS runs give me final CET estimates of 8.9*C and 9.4*C, the former (06z) held back by a few more chilly nights (mins 2-5*C widely) managing to take place even as the warmer air established aloft.

 

Thinking longer-term again, I'll be really interested in how much we see the Azores High link up with the Scandinavian High this summer; ordinarily a Nino base state means a weak Azores High that has little direct influence, but there's an increasing amount of research pointing toward the reduced equator-pole temp gradient brought about by anomalously low low Arctic sea ice leading to a stronger Hadley cell, hence Azores High, and the sea ice area and extent is at record lows currently. Not only this, but low sea ice shows some (ancient) historical relationship with a stronger Scandinavian High too.

Last year we benefited from a super-strong Azores High regularly linking up with Scandinavian highs, thanks to low sea ice extent forcing combining with weak La Nina forcing; they both bring about the same response in the Azores High, and the low sea ice likely helped the Scandinavian highs to develop and persist too.

So what happens when it's a weak Nino pattern in place? Does the Azores High feature more than usual for the Nino base state and if so, does it work with, or against, the Scandinavian High which in theory should be exceptionally strong and persistent this May-July?

I look forward to finding out .

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Practically mid-month and it's 4.3C here up to today
Not surprising when only the 5th reached double figures and several nights have been well below -3

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A real contrast this month. A CET of just 4C yesterday with a similar figure expected today.

The CET mean will be down to just 6.31C by the end of today.

But some very warm weather now looks likely in the second half of the month. This has been on the cards for a while and is why I went for a high April CET notwithstanding the cold weather that was predicted in the first half.

The Easter weekend is currently looking stunning with a mean CET across the 4 days of 14C looking likely. Not record breaking from a date perspective but nevertheless very impressive for the Easter period. 

The question is will the warm weather hold on in the final week of the month. At the moment it looks like things will cool down somewhat but still stay above average. Currently a CET of 9.16C is forecast by the 28th. So we could get to 9.3-9.4C by the end of the month. If the very warm conditions were to persist a few days longer then a CET above 9.5C is not out of the question. 

Provisional Hadley data continues to be a good 0.5C above my calculations.

Met Office Hadley         7.1c.      Anomaly     0.3c.  Provisional to 13th.

Metcheck                      6.11c     Anomaly     -1.91c

Netweather                   6.88c     Anomaly     -1.23c

Mean of my 10 stations   7.34c.   Difference  -1.9c.   

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Thanks SC and GW!  From what you’re both saying, at the moment it looks like my 9.2c guess might have been a good one.  

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Thanks SC and GW!  From what you’re both saying, at the moment it looks like my 9.2c guess might have been a good one.  

Even my guess of 9.53°C might be starting to look like a really good estimate if that ends up bring right (hence the reason why I have been so relaxed until now, about the colder weather which is around just now).

 

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Even my guess of 9.53°C might be starting to look like a really good estimate if that ends up bring right (hence the reason why I have been so relaxed until now, about the colder weather which is around just now).

 

Yes, my glass is half full, but then it always is!  I hoped we might see some decent temps towards the end of the month, although we’re not there yet and a lot can happen in two weeks, especially when they’re in April!  But keep the faith John!   

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Good update GW.

To protect my 8.6c prediction I could do with a clean northerly in the closing days of the month to bring that projected CET down a little. There have been a few hints and as a result I remain confident it will land somewhere between 8.7 and 9.0c.

In the meantime lets enjoy the Easter warmth 

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Yes, my glass is half full, but then it always is!  I hoped we might see some decent temps towards the end of the month, although we’re not there yet and a lot can happen in two weeks, especially when they’re in April!  But keep the faith John!   

It's always nice when the forecast has a nice warm spell coming up and that just happens to be what you want to get your prediction right

I call that a win-win

 

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 there's an increasing amount of research pointing toward the reduced equator-pole temp gradient brought about by anomalously low low Arctic sea ice leading to a stronger Hadley cell...

My limited understanding of this subject is that arctic amplification - ie a greater rate of warming in the arctic than elsewhere - tends to send the jet stream further South in the Atlantic because the region of strongest thermal contrast is shifted South. This would be bad news for our summers, and the recent run of six consecutive poor summers 2007-2012 is some evidence for this theory. There will of course be occasional good summers eg 2006, 2013, 2018 due to natural variability [eg solar]

Mods - I do not wish to derail the April discussion thread, but I thought it was a bit early to start a thread about prospects for summer 2019. I found Stormchaser's post interesting and therefore wanted to reply.

 

 

 

It's always nice when the forecast has a nice warm spell coming up and that just happens to be what you want to get your prediction right

I call that a win-win

 

  You’ll be pretty close too!

My guesses are always based on gut feelings and GW’s data, I’m rubbish with charts, and so far the month has behaved as I thought it might.  It just needs to warm up now for that win - win!  

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My take on the remainder of April is that whilst a warm up is likely for the third week, that this is likely to be stymied by the time we get to Easter Monday.  I predict  a much colder fourth week, possibly keeping the monthly CET closer to 8 than 9 c if the colder days can be accompanied by cooler nights too.  A very interesting month with many possible outcomes clearly possible.  A finish around 8.5c might be a compromise solution on offer today.  

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Met Office Hadley         6.9c.     Anomaly     0.0c. Provisional to 14th.

Metcheck                      6.07c    Anomaly     -1.95c

Netweather                   6.74c    Anomaly     -1.37c

Mean of my 10 stations  7.31c   Difference    -1.94c.

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Good update GW.

To protect my 8.6c prediction I could do with a clean northerly in the closing days of the month to bring that projected CET down a little. There have been a few hints and as a result I remain confident it will land somewhere between 8.7 and 9.0c.

In the meantime lets enjoy the Easter warmth 

I'll be fairly happy with that, Steve.

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Thanks for that detailed update GW 

 

For what it's worth, the GFS 18z of yesterday painted the warmest outcome to be modelled so far which gave me a final CET estimate of 9.4*C.

Bearing in mind GFS tends to undercook the maximums during Apr-May warm spells, sometimes by several degrees, it reinforces what's been said regarding the potential to finish some way through the 9s despite the cool first half.

That is, assuming the main trough stays west or southwest of the UK next week, so that diurnal mean temps stay up even during wetter spells.

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Met Office Hadley        7.0c.      Anomaly       0.0c. Provisional to 15th.

Metcheck                    6.23c      Anomaly       -1.23c

Netweather                 6.85c      Anomaly       -1.25c

Mean of my 10 stations    7.55c. Difference  -1.7c.        

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Met Office Hadley          7.2c.       Anomaly    0.1c. Provisional to 16th.

Metcheck                       6.43c      Anomaly     -1.58c

Netweather                    7.02c      Anomaly     -1.08c

Man of My 10 stations     7.62c.     Difference   -1.63c. 

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The longer term pattern appears to be moving away from a cooler and more mobile atlantic interlude in favour of a potentially warm and unsettled setup as low pressure disrupts to our south dragging up some humid SE'ly air.

This would significantly push the CET upwards in the final days of the month thanks to the possibility of mins close to double figures and maxes in the mid to upper teens.

The josling for supremacy in the league during the early part of the competition continues.

Those who predicted in the mid 9's look favoured.

Those who bravely forecast below 8.1c are in serious trouble as things stand currently. 

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Well it’s certainly changed today and the CET should rise nicely for a while.  It needs to average low teens for the rest of the month to end around my guess. 

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The longer term pattern appears to be moving away from a cooler and more mobile atlantic interlude in favour of a potentially warm and unsettled setup as low pressure disrupts to our south dragging up some humid SE'ly air.

This would significantly push the CET upwards in the final days of the month thanks to the possibility of mins close to double figures and maxes in the mid to upper teens.

The josling for supremacy in the league during the early part of the competition continues.

Those who predicted in the mid 9's look favoured.

Those who bravely forecast below 8.1c are in serious trouble as things stand currently. 

I'm starting to enjoy the way that this is going at the moment.

 

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