Summer Thoughts and Forecasts

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Summer Thoughts and Forecasts

Post by Admin1 » Wed May 30, 2012 10:32 am

I have picked up this forecast today from Matt Hugo, paints a good picture of the weeks ahead

"" Well it goes without question that the final week or so of May has produced some of the best weather of the year so far. Many areas have enjoyed the persistent effects of high pressure across the country, bringing some prolonged spells of very warm, if not hot, sunshine. Clearly a strong 'taste' of summer for many, however, it is all about to change and unfortunately timing with the onset of the first week of the first summer month.

So before looking forward, it is of worth to highlight and review why we have had such settled conditions. This will help give a comparison to the up-coming changes. The below is an analysis of the jet stream from this past weekend with information and comments as to why the weather has been settled and very warm;



If you compare the above image and analysis to the below image, which is the UKMO surface analysis chart on the 26th of May, you can see that a well established and large area of high pressure (1035mb) is centered just to the north and north-east of the UK and clearly maintaining very warm and settled conditions;

http://www.wetterzentrale.de/archive/20 ... 120526.gif

So, where do we go from here and why is the weather changing?...

Clearly to get a change in the weather we have to see the above synoptic patterns change and that is what is forecast to take place over the course of the opening week of June. High pressure is forecast to be replaced by lower pressure and more unsettled conditions and, as usual, this can often be seen and explained within the upper atmosphere;



Now transferring the upper analysis to lower levels and you can see this very well indeed. Using the GFS ENS (ensemble) mean as the example, note how by Tuesday the 5th of June low pressure is evident at surface levels to the east and north-east of the UK and the upper level low on the above image is directly related to that surface low pressure in the middle of the North Atlantic;



The natural progression here is for the surface low pressure in the central North Atlantic to head toward the UK from the west or south-west, as the minor ridge of high pressure in-between both systems is eroded. This is what is currently forecast to happen and I have high confidence in this event taking place given good model agreement and consistency within the forecast models for this to happen next week. So jumping ahead a few days and you'll note that by the middle and latter half of next week the low pressure to the west and south-west of the UK has moved up into the UK to bring a cyclonic pattern across the UK;



So, there we have it. From high pressure to lower pressure in approximately a week or so. Just to reinforce this prediction, find below 3 main forecast models GEM (Canadian model), GFS (USA, NOAA mode ) and the ECMWF (Reading, European model) . As you can clearly see despite some variations over the synoptic patterns, all 3 models by the middle and latter half of next week have low pressure affecting the UK;



As is often the case with the weather across the UK, it never stays the same for very long. I think many will admit and acknowledge that the weather of late really has been stunning and many have enjoyed it, particularly seeing that for a change the excellent weather persisted into this past weekend as well. However, given the above analysis it is safe to say the first official summer month is not going to get off to a good start and given the longer term analysis for the remainder of June I wouldn't expecting a 'flaming June' either at this stage across the UK.

It's a case of don't shoot the messenger, but get ready for a significant change in the weather over the next 7 to 10 days.. ""

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Re: Summer Thoughts and Forecasts

Post by Paul C » Thu May 31, 2012 10:33 am

Add into the mix now Ex TS Beryl ! - looks wet next week.

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Re: Summer Thoughts and Forecasts

Post by Carl M » Fri Jun 01, 2012 10:07 am

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Re: Summer Thoughts and Forecasts

Post by Paul C » Fri Jun 08, 2012 8:41 pm

Still nothing in the pipeline


Flamin’ June!…and not because it’s hot!
by Matt Hugo
Well the first official summer month is well and truly up and running and no doubt the phrase "flamin' June" has already been uttered up and down the country, but clearly not because of sunshine and heat, but because of torrential rainfall and very strong and unseasonal wind speeds!...

What isn't a surprise however, is the change to more unsettled conditions. At the latter half of May I took my usual look at the potential trends for the forth coming month and at that time there was a clear signal that the significant heat and sunshine that was evident during the latter stages of May would not continue into early June. This full discussion with thoughts for June can be found at the below link and in fact some of the forecast charts discussed at the time are matching the actual synoptic conditions of present day very well indeed!

http://matthugo.wordpress.com/2012/05/3 ... -pressure/

Today's blog is taking a more specific look or advancing on the above blog to provide some additional answers as to why the unsettled conditions are now present and how long they are likely to last.

As usual, one of the best places to start is the jet stream;



This jet stream pattern can then be followed down to more surface levels, which using the below surface chart clearly shows where the main area of low pressure is to the West and South-west of the UK;



Note how the Azores high pressure is being held well to the west and south-west of Spain and Portugal. This is a text-book sign that the jet stream is dominant just to the north of it and suppressing what is meant to be a feature of the weather much further north and east, affecting France and the UK during the summer, for example. It's clear to see that across the UK and also within the Central-North Atlantic low pressure is dominating the weather.

So is this likely to change...Again lets take a look at another jet stream chart but into next week;



As I have highlighted before, once you progress beyond a certain time period, it becomes important to look for broader trends in the synoptic evolution rather than the details. Just as a re-cap, troughs in the jet stream indicate unsettled and often cool conditions, whilst ridges signal higher pressure at surface levels and clearly warmer and drier conditions. Now unfortunately the variety of forecast models continue to signal a trough-type pattern across the UK until the middle of the month at the earliest with model agreement and also consistency. As a result we are likely to be 'stuck in a rut' now for some time with predominantly unsettled conditions dominating the weather.

The second half of June may well signal a change however. Some longer term forecast models and information do signal a pattern change with the jet stream changing to allow more ridging and hence higher pressure to affect the UK and one particular model, the GFS ENS, highlights this well;



Note how the Azores high pressure is being allow to build North-eastwards towards the UK in what is a perfect example of how the Azores high pressure can bring the UK some of it's best summer weather conditions, particularly if the high pressure builds across the UK and then becomes slow-moving as well. I did highlight within the last blog (link at the top) that the second half of June could well see an improvement in conditions and given the latest forecast data I stick by that prediction. So June could well turn out to be a month of two halves to say the least, the first being particularly poor, but with the potential for better weather in the second half.

I'll take a closer look at the second half of June and into early July later next week, but for the time being you'll have to keep the BBQ covered, the patio furniture fastened down and the summer shorts and t-shirts on standby, as low pressure is here to stay...

Regards to all,

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Re: Summer Thoughts and Forecasts

Post by Paul C » Tue Jun 19, 2012 9:53 am

http://matthugo.wordpress.com/2012/06/1 ... -analysis/

More thoughts !! - generally cool and wet summer to continue

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Re: Summer Thoughts and Forecasts

Post by Carl M » Tue Jun 19, 2012 10:19 am

Seems to be a trend of poor summers followed by warm ''Indian Summers'' :x
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Re: Summer Thoughts and Forecasts

Post by wmb » Sun Jul 01, 2012 4:19 pm

Carl M wrote:Seems to be a trend of poor summers followed by warm ''Indian Summers'' :x
Well one week of ridiculous warmth be it in March, May or the end of September. 6 years since we had a decent summery July, and is is soemthing like 9 yeasr since a decent summery August! Admittedly they had enough warm days to last a decade.

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