While April was drier than expected, the May pattern appears to be behaving as forecast with a much cooler and more unsettled regime with the Atlantic being the primary driver. Unlike Feb-Mar-Apr where a blocking high was dominant, that stone is gone and the atmosphere is much more free flowing and bringing up the rain deficits of the past 90 days.

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The expected ‘3 day 2nd surge of summer’ has not panned out as I don’t think you can call one day of 23 or 24C confined to the Southeast corner as the years 2nd surge of summer. Just like it was hard to break down the ridging last month, this month it’s hard to bring it back just like we saw with the El Nino of 2012 with that sudden turnaround from abnormal dry to wet.

In the video today I hint at the models showing another brief warmer and drier solution towards May 20 but when looking into newer runs and different models, a return of warmer, drier looks unlikely. The GFS operational shows a trough whereas the ensemble tries to build a ridge into the West of Europe day 5-10 but then it’s gone in the following 5 days. EPS control shows trough, not a ridge. Moral of this story is, this May won’t be remembered for long. It’s looking cooler and wet and as I’ve already stated, wet May’s often shape the summer.

GFS operational 50-day mean 500mb height anomalies Day 0-15

GFS ensemble

EPS control

CFSv2 is the outlier as it’s trying to show the UK positive returning week 2 through 4.

GFS ensemble has the NAO flat lining which supports a zonal/westerly flow from Atlantic into West Europe through the next 10+ days.

See today’s video for the discussion.

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