Theme for the week ahead
Mixed. Still dry for much of the time in the south, but generally deteriorating with increasing chances of rain pushing further south and east. Temperatures often close to the seasonal average, although still warm on some days in the south. No heatwave, and the prospects for the following week also look mixed with showers or longer spells of rain for many.    
Based on data from Sunday 25th July 2010. 

Overview 
High pressure ridging from the Azores towards the UK, but not building strongly enough to dominate the weather. Weather fronts will slice through the high, and by next weekend an increasingly well developed trough will probably be starting to influence the weather across Britain and much of western Europe. We'll be watching how this develops closely as it may well influence the weather during much of August and possibly September. 
Global Forecast System (GFS) analysis
The GFS is the computer model which we base our 16 day weather forecasts on.   

Mid week
The pressure chart for 4pm Wednesday shows the Azores high pressure building towards Britain, but not far enough north and west to produce sunny and very warm weather.         

The temperature chart for the same time shows close to average temperatures for the time of year. A lot still depends on the amount of cloud cover at this time of year. Even with cold upper level air from the north temperatures will rapidly rise if the sun shines.

 

The cloud cover chart for 4pm on Wednesday indicates there is likely to be quite a lot of cloud over the country during the middle part of the week. This is the main reason why the temperature are held down to average values on the chart above.     



Weekend 
By the weekend there are signs of showers or longer spells of rain increasingly affecting Britain as can be seen on the precipitation chart for 4pm Saturday. Confidence on this is quite low as often during recent weeks the amount of precipitation in southern areas has decreased as the forecast time has approached. We'll keep an eye on this during the week ahead.    

      

The jet stream chart below for 4pm Saturday shows a fairly typical set up with jet crossing Britain. Much of the time earlier in the year it was a long way south, but as is often the case it has headed north during the summer months. 

Issued 22/07/2010 (next scheduled update 25/07/2010)