Amir Mohsen
متخصص بخش هواشناسی
Summer 2013 Forecast – Long range forecast Long range
Lewis
July 18, 2013
74
Summer 2013 Forecast
Here is our final summer 2013 forecast. Our forecast has been derived by studying historical datasets of various global circulations/indexes, and finding the periods most resembling the current state/projected states of these indexes through the summer. Overall the 2013 summer will likely be far less wet than that of 2012 (which, lets face it, isn’t difficult to achieve!), though it will portray the same characteristics in as much as we expect a predominantly unsettled summer. This isn’t to say there won’t be better, more settled periods. Indeed we have identified two such periods (one of them already having been picked up in our preliminary summer forecast). However, these are likely to be the exceptions rather than the rules.
It is, of course, also worth noting that the nature of long range forecasts are that specific details are difficult to provide. Here, we provide an oversight of what we feel the most likely conditions will be in terms of overall rainfall, temperature, and wind/flow direction. Overall, we expect rainfall to be around the seasonal average, whilst temperature is likely to finish around 1-2c below the long term average. Finally, it is worth taking note of the higher than usual rainfall we are expecting across the near continent. The risk of such deluges affecting the UK once again in a sustained manner is considered really rather low, but it is worth noting particularly if you are off to continental Europe at any stage this summer.
So, here it goes…
(Note: Images on the top are the 500mb Height Anomaly – a good indication of where higher and lower pressure is likely to set up, the images in the middle are Temperature anomaly – the difference from the long term average, and on the bottom are Rainfall anomaly)
Lewis
July 18, 2013
74
Summer 2013 Forecast
Here is our final summer 2013 forecast. Our forecast has been derived by studying historical datasets of various global circulations/indexes, and finding the periods most resembling the current state/projected states of these indexes through the summer. Overall the 2013 summer will likely be far less wet than that of 2012 (which, lets face it, isn’t difficult to achieve!), though it will portray the same characteristics in as much as we expect a predominantly unsettled summer. This isn’t to say there won’t be better, more settled periods. Indeed we have identified two such periods (one of them already having been picked up in our preliminary summer forecast). However, these are likely to be the exceptions rather than the rules.
It is, of course, also worth noting that the nature of long range forecasts are that specific details are difficult to provide. Here, we provide an oversight of what we feel the most likely conditions will be in terms of overall rainfall, temperature, and wind/flow direction. Overall, we expect rainfall to be around the seasonal average, whilst temperature is likely to finish around 1-2c below the long term average. Finally, it is worth taking note of the higher than usual rainfall we are expecting across the near continent. The risk of such deluges affecting the UK once again in a sustained manner is considered really rather low, but it is worth noting particularly if you are off to continental Europe at any stage this summer.
So, here it goes…
(Note: Images on the top are the 500mb Height Anomaly – a good indication of where higher and lower pressure is likely to set up, the images in the middle are Temperature anomaly – the difference from the long term average, and on the bottom are Rainfall anomaly)
June
500mb Height Anomaly – June – Summer Forecast 2013
2m Temperature – June – Summer Forecast 2013
Surface precipitation – June – Summer Forecast 2013June currently looks likely to provide a tail of two halves. If you notice in our top image, our 500mb height anomaly charts, which provide a rough indication of where areas of higher and lower pressure are likely to set up closer to the surface of the earth, there is a lot of yellow and green just to the South-West of the UK. We have to bear in mind that this chart is an average set-up for the whole of June. What this indicates is that higher pressure is likely to be rather close to the South-West of the UK at times, and our current expectation, which was also picked up during our preliminary summer thoughts, is that this high pressure is likely to take charge across the UK during the first half of June, settling things down, promising some sunshine, and the chance of some warmer temperatures. You will notice, however, that the predominant colour from our top image is blue, and this is indicative of lower pressure and more unsettled conditions making a comeback during the second half of June, providing some rainfall and cooler temperatures once again. Overall for the month temperatures are likely to finish below the seasonal average for June, despite the better weather early on, with rainfall around average – perhaps slightly below average across Southern and Western parts of the UK.
July
500mb Height Anomaly – July – Summer Forecast 2013
2m Temperature – July – Summer Forecast 2013
Surface precipitation – July – Summer Forecast 2013The most obvious feature from our top image is the huge area of blue/purple, indicating that lower pressure is likely to play a key part in our weather, anchored just to the East of the UK, and likely to bring a predominantly unsettled and cool month, with the wettest of the conditions likely across Eastern parts of the UK. There are indications that towards the middle of July, we may see a settled spell of weather once again, likely sometime between the 12-20th, but longevity of such a spell is uncertain, and once again the predominant story is one of unsettled conditions and cooler than average temperatures. We are not expecting copious amounts of rainfall still, with around average rainfall, though temperatures once again likely to finish below the long term average.
August
500mb Height Anomaly – August – Summer Forecast 2013
2m Temperature – August – Summer Forecast 2013
Surface precipitation – August – Summer Forecast 2013A largely similar picture to July is expected, with low pressure likely to dominate to the East of the UK offering a cooler than average and largely unsettled month. Once again we are not expecting copious amounts of rainfall such as the levels seen during the summer of 2012, with conditions more likely to be showery. During the final days of August, signs are there once again that we may see pressure rise from the South, settling things down somewhat. Temperatures once again expected to be below the seasonal average overall, with rainfall close to average.
The strongest signal through the summer period is for low pressure to stubbornly dominate just to the East of the UK, and this is why the signal for below average temperatures exists, with a notable higher than average rainfall anomaly persisting throughout across Mainland Europe. As mentioned previously, with the UK likely to straddle the boundary between low pressure to the East, and higher pressure just to the South-West of the UK, the main concern at present would be for a slight shift Westwards in the pattern, which may leave the UK open to another very wet summer as the rainfall anomaly across Europe ends up a little closer to the UK. However that is considered very low risk at present.
So overall a better summer than 2012 is expected with far less rainfall, though temperatures looking rather disappointing. As is the nature with long range forecasting the accuracy of this forecast is open to question. The pattern through May matched those projected from our initial summer thoughts published back at the start of April, and so on that basis at least part of our forecast has been vindicated. We will most likely re-visit this forecast, to ensure it is largely on track, during mid-July.
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