During the night of Thursday into Friday the conditions in France and across the Channel look good for birds wanting to make a move (see chart below).
However, fast-forward to the same period on Friday going into Saturday and a front in the channel will have a blocking effect on birds heading north over the channel.
Of course it will depend on the actual timing of the front moving through. If it is a little late, birds could set off across the channel and be grounded on the south coast as they encounter the front. If it moves earlier than forecast birds might be grounded in northern France, unable to move until the front has passed.
So, what does this mean for the weekend?
As the spring progresses more and more birds will take advantage of any window in the weather. We should see pulses of arrivals that by now should include Swallows in particular as they do still seem thin on the ground. Yellow Wagtail, Tree Pipit and Redstart should also be a feature, along with Ring Ouzel, Cuckoo and House Martin.
A few Garden Warbler should join the Blackcaps, although it feels like there are still a lot of Blackcap to arrive too. Reed Warblers should also take advantage of quiet overnight weather and make it back to their reedbed territories.
Where are all the Wheatears? It is a little worrying that Wheatear is trailing well behind its historic average in BirdTrack. The purple arrow on the graph is where it should be, whilst the blue dots are where we are this spring. Hopefully, they are just held-up and will flood in as soon as conditions allow, but you have to wonder what sort of winter they have had.
BirdTrack reporting rate for Wheatear
On the rarity front, the warm southerly airflow we saw last weekend did bring a few overshoots with it in the shape of two or three Purple Herons, a Little Bittern, a couple of Western Subalpine Warblers, a Night Heron, a couple of Red-rumped Swallows and Woodchat Shrikes, two or three Black Kites and at least one Hoopoe. However, pride of place must go to the splendid male Rock Thrush that was found on St Martins, Isles of Scilly.
Rock Thrush courtesy of http://www.mpgoodeyphotography.com/apps/photos/