As expected, meteorological autumn opened right where summer ended with a September featuring very changeable and frequently cool conditions thanks to firm Atlantic influence.

September temperature anomaly so far.

August was below normal.

Why the cool, damp disappointing summer? Low over high aligned west-east shows a firmly Atlantic pattern.

While the westerlies where the main driver in September’s opening 20 days, it looks as though that westerly flow and subsequent low pressure systems shall become deflected as we end the month thanks to a powerful Scandinavian blocking high.

GFS ensemble 5-day mean 500mb height anomaly

Is there any change for October?

I honestly do not see the somewhat blocky, more settled regime holding much into October. Most models see the dominant Icelandic trough returning keeping the Northwest of Europe unsettled with perhaps a few named storms on the cards through particularly the second half of the month.

CFSv2 for October

500mb height anomaly

Precipitation anomaly

Temperature anomaly

FEATURED IMAGE CREDIT: Justin McLean‏ @Jup_84

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