From a builders pov, wet finger in the air, rain before 7 ends before 11 and all that

I'll go for a changable September with hopefully a few thunderstorms thrown in and October, an indian summer... November wet & windy mild. Probably all wrong but what the ell...

I've been very happy with this summer, especially as pointers were for this summer to be one of the worst

http://modeles.meteociel.fr/modeles/cfs/run1m/cfs-0-1074.png?06

CFS is throwing out a lot of charts like this for late September and a large part of October.

Factor in a tendency to give the Atlantic too much energy, and the resultant bias towards taking energy NE, and this could be read as indicating a strong chance of seeing higher than normal pressure to the NE rather than somewhere over Russia.

Just thought I'd post this as an example of how human input can attempt to account for systematic errors in the computer models

Not much going on in this thread

Might as well give a detailed recap of September so far, which has been a month of marked transitions:

We began with generally low heights around the pole and also to our NW i.e. across Greenland. Conditions were very warm under a ridge from the Azores, with the broad pattern similar to that of July and August.

Before too long, however, a strong storm system flattened our ridge of high pressure and managed to push into Scandinavia. This coincided with rising heights across the pole as the polar vortex split - the two events are likely related, with the PV energy providing fuel for that strong storm.

The storm system remained as a strong trough feature for 4-5 days, and kept the door open for further Atlantic systems to sweep across from the west, interchanging with very brief ridges. Temperatures were some way below average for much of the time, with only a brief exception in the south. During this time, heights were rising to our NW and there was the real threat of Arctic air streaming south to bring exceptionally chilly conditions to the UK.

I believe that we would have ended up at the mercy of high pressure to our NW slowly toppling towards the UK, had it not been for Humberto's arrival on the scene;

Humberto was a major game changer as his remnants became the focus for a large area of low pressure not far from the Azores. The models originally had a lot of energy racing NE, leading to something like the scenario outlined above, but as it turned out they were barking up the wrong tree. The fact that the energy has remaiend largely to the W and SW of the UK has resulted in a weak ridge across Europe which, in combination with the trough, has allowed warm air from the south to win out over Arctic air being pulled down by the continued presence of an Arctic/Greenland High.

In the near future, that Arctic/Greenland High looks to be falling apart as a bit more energy comes into the jet from America. That also serves to send the trough near the Azores eastward, but it looks likely to be met with strong opposition as the ridge across Europe builds north in response to the Arctic High drifting through the Svalbard area. Potentially, a true high-latitude block could form, but that requires the Atlantic not to ramp up too much, which at this time of year is not something you'd tend to bet on!