Temperatures climbed to 23°C (73°F) in London today, making for the UK’s warmest day of the year so far. As you well know, colder air is coming down and will wipe out this pleasant precusor of things to come by as early as tonight. The frontal boundary which seperated two very different air masses began to dive south today as expected and by tonight, where it was warmest, rains will fall and by mid-morning Friday, the Southeast will greeted by the same air mass which has kept Scotland, Northern Ireland, northern parts of the Rebublic and Northern England cool and unsettled. While it reached 23C today at St James’s Park, it may struggle to make 11°C tomorrow and by Saturday, highs around London could well hold at 9 or 10C.

I’ve been looking closely at the next 10-20 days and have tried to keep you updated as much as I can at what I am seeing for later down the road. There’s little if any change from my original idea and that is, that once the chill returns and we get that -NAO signal back, it may be tough to get out of it again. In other words, I hope you enjoyed the warmth in the Southeast for those lucky enough to have witnessed it because 21°C may not reach the UK till potentially the second week of May, at the earliest.

Here’s the ECMWF upper chart through next week.

Mon

Wed

Fri

While this weekend will see a pleasant but cold high pressure, bringing sunny but cool days and cold frosty nights, the next front forced to sink SOUTH thanks to ridging either side of the UK next week, should reinforce the chill and right through next week, I see little in the way of ‘westerly’ flow, just N or NW.

Notice in top two charts above the upper low which gets spun up at the base of the trough, this will bring unusually cool air into Spain and Portugal along with heavy, thundery rains and gusty winds. Some localised flooding is possible with even hill snow.

Further east, a strong and strong SW heat pump will bring a taste of summer from Rome up through Kiev and into Moscow next week with highs reaching the 70s all the way to the Russian capital.

Here’s a look at the latest May forecast off the CFSv2 – still looking rather chilly.

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Here’s why the model is picking up on this cold May coming…

NAO

The trouble is there’s still a plentiful reservoir of cold arctic air available across the North with an extensive snowpack covering the high latitudes. A much larger snowpack compared to normal will help maintain the arctic cold pool and when you’ve got an NAO and AO diving back into negative territory, that cold will come south.

Although any chill is greatly tempered by strong sunshine at this time of year, it doesn’t mean it can’t get chilly and it’s more about the level of departure from normal and how cold the nights get this late in the year.

In saying that, this type of pattern in recent days and weeks have produced some outrageous cold days and nights along with historic snows over North America, given what we’ve seen on the other side of the Atlantic, don’t be surprised to see some odd happenings in coming weeks if this pattern takes hold like I think it will.

AO

Below is the CFSv2 May through July temperature anomalies.

A rather cold look when combinning the upcoming 3 month period but when you break down these months, while May is quite cold looking, June is less cold, though still below normal but July remains average or ABOVE NORMAL over parts of the UK and Ireland.

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