By this time next week this may current heat wave may be just a distant memory, that’s according to the latest GFS forecast, as the British summer monsoon gets into full gear.
There’s quite a steep thermal gradient across the country this evening, with dewpoints as low as 6.4°C at Stornoway in the northwest, to as high as 19.3°C at Yeovilton in the southwest.
I count 26 stations with 30°C or higher today, and tomorrow, particularly in the southwest it may be even a little hotter again (fig 1). With temperature as high as 32°C, which they’ve been in the London area this afternoon, which could trigger one or two isolated thunderstorms in places.
2017, continues to move a little higher up the league table of warmest years to date (the 1st Jan to the 18th June), it’s now joint 4th and is within striking distance of both 1990 (0.02°C higher) and 2014 (0.15°C higher), and the way this current hot spell is going it could will go clear as the second warmest start to any year since 2007 before the week is out, in the daily mean temperature record that started in 1772. This is of course based on provisional values for this month from the Met Office.
This is a listing of the largest diurnal range across the British Isles, well to be precise the difference between the 18-06 minimum and yesterdays 06-18 maximum, I can’t plot the results on a map, so the table will just have to suffice for now (fig 1). Yesterday, Topcliffe in North Yorkshire, tops the list with a range of 18.7°C or 33.7°F.
At the opposite end of the table the minimum and the maximum on the Bealach Na Ba where both 7.7°C (fig 2).
After a fairly inauspicious start to June 2017, the last few days have really boosted this months sunshine totals, particularly across southern areas. Top of the league at the moment is Jersey with 186.7 hours (average 10.3 hours per day), now there’s a surprise, closely followed by Manston in Kent and Herstmonceux in Sussex.
A good degree of consistency between the UKMO and GFS models about how saturday will look at T+120 (figs 1 & 2). How accurate it will be is another thing entirely. Pressure is still forecast to be reasonably high across the south, 1000-500 hPa thicknesses are not far from 564 dm, but there is a fresh to strong westerly flow across the British Isles, with fronts driving in from the west, so things don’t look good for this current hot spell.