Outlook for the next week – cool, showery and often quite windy

The dumbelling lows that I mentioned yesterday which seemed to be in orbit around the country over the weekend, are still present in the latest forecast charts from the GFS, but this time one of them pairs up with a newly developing low early next week that’s coming out of mid Atlantic, and extends the cyclonic sequence well into the middle of next week (fig 1). All I can say is that the outlook for the next week doesn’t inspire, and can be summed up as: cool, showery and often quite windy. Overall the pattern is very cyclonic in nature, and if these charts are correct we can forget about any more talk of drought, and any spells of drier, sunnier and warmer weather will be in short supply, and limited mainly to the southeast of the country, as they were yesterday.

Figure 1 – Courtesy of OGIMET

15 May briefing

Western Ireland saw the heaviest rain overnight, more specifically the higher ground of counties Kerry, Mayo and Donegal seeing accumulations of more than 75 mm (fig 1).

Figure 1 – Estimated rainfall totals from Weather Radar Images

Rain is holding the temperatures down in the southeast, but I notice that there’s much warmer air just across the Channel (fig 2) at 09 UTC.

Figure 2

There was a little bit of rain overnight in the southeast but not nearly enough, but the cold front will drag its heels this week though, and could take till Thursday to clear the southeast, and if the GFS model is correct, will produce a wet day on Wednesday across the south (fig 3).

Figure 3 – Courtesy of OGIMET

Many places still without rain this month

Many places across the British Isles, especially over Northern Ireland and Scotland are still without rain this month, as the dry spell that started in late March continues.

Figure 1

All change

Looking at guidance from the latest NWP generated from the GFS model shows that the weather is now on the change, with a more cyclonic southwesterly spell for this weekend and the early part of next week, before high pressure rebuilds in the mid Atlantic by the end of next week.  In fact the forecast for next Monday (fig 2) looks quite windy and wet, especially across the west, although the southeast does look like it will escape the worst of the rain.

Figure 2 – Courtesy of OGIMET

Having said that, the Met Office in their forecast charts for Sunday night don’t develop this feature quite so deeply (fig 3).

Figure 3 – Courtesy of the Met Office

Infamy, infamy they’ll all got it in for me…

This part of the southwest got well over an inch of rain last Sunday, and it looks like the same thing might well happen again this coming weekend, but it’s likely to be Saturday that sees most of the precipitation this time rather than Sunday (fig 1).

Figure 1 – Courtesy of OGIMET

Saturday looks like it will be particularly cold and wet day, with a moderate to fresh east northeasterly wind, before eventually high pressure pushes the warm front back south again as a cold front later in the day, according to the T+60 chart from the Met Office (fig 2). Although it will be cloudy further north is should remain dry, and over Scotland and Northern Ireland it looks sunny, and out of the wind in the west a very pleasant day. This just looks very similar to last weekend, and we are just going through a repeat cycle of it, believe it or not, the latest mid-range forecast from the GFS model does a very similar thing for the weekend after next, but that’s a long way away and forecasts from models beyond 5 days can be wildly out.

Figure 2 – Courtesy of the Met Office

Welcome rain on Sunday for some then high pressure bounces back

It seems that Sunday will be a wet day in southern and central areas, and that rain will be very welcome to the gardeners and House Martins there. How much rain they’ll get will probably be in the “not enough” category I would have thought (fig 1). May-day itself looks pretty wet over northern England but it should brighten up across the south by the looks of it. This of course raises the perennial question of why we have all our Bank holidays so early in the year.

Figure 1 – Courtesy of OGIMET

But during the course of next week according to the latest GFS model, the high pressure over cold northern Scandinavia will reassert itself and introduce another change in type and push all the frontal activity in western parts back into the Atlantic (fig 2). Thicknesses of less than 540 dam in April, with 15 knots of a chilly North Sea will not please any aspiring deck chair entrepreneur at Skegness though.

Figure 2 – Courtesy of OGIMET

Alexander Buchan strikes again?

April can be a month when you get a taste of spring, summer and winter, sometimes all in one day, so the latest forecast chart for next Wednesday (the 12th of April) from the GFS will come as no surprise (fig 1). A cold northerly with 1000-500 hPa partial thicknesses below 522 dam across the North of Scotland for a time, and if this forecast is right, then it will be the second time this year that one of Alexander Buchan’s singularities has been correct, the first time was noticeable in the CET series between the 6th and 12th of February. This cyclonic interlude is forecast to be short-lived, as high pressure returns for the Easter weekend in the south.

Poor eight day NWP forecasts

You may remember that I blogged about a change in weather type on the 17th of March, and contrasted the T+192 (8 day) forecast from the GFS model with the one from the ECMWF model, and commented about how totally at odds they were with each other. I promised that I’d look back, and examine the evidence, one of these solutions had to be wrong. Here are the two forecast charts, unfortunately the ECMWF is from a model run that is 12 hours later than the GFS.

Figure 1 – Courtesy of ECMWF

OK, so basically a large high pressure system (~1032 hPa) in the Celtic sea and an anticyclonic westerly flow across most of the British Isles from the ECMWF (fig 1).

Figure 2 – GFS courtesy of OGIMET

And from the GFS model a strong northeasterly type with lows over northern Germany (~990 hPa) and Biscay (~990 hPa), and a band of high pressure aligned SSW-NNE to the northwest of the British Isles (fig 2).

Figure 3 – Courtesy of the Met Office

Well, both models did very poorly. The ECMWF had the anticyclone too far to the southwest, with no sign of any easterly across northern France and English Channel. The GFS went overboard, with two overly vigorous lows, the one over northern Germany completely fictitious, and the other over Biscay misplaced entirely, so null points to both organisations.

How long will this high pressure stay?

How long will this high pressure stay around? Well the short answer to that – according to the latest NWP data from America – is not that long.

Image 1 – Courtesy of www.netweather.tv

The latest forecast run from the GFS courtesy of NetWeather has the high persisting till Monday of next week before pulling away to the northeast. We are then set for a cyclonic interlude for around a week, before high pressure returns in early April, and persists right through to the end of the forecast period (9th of April). If this forecast is anywhere near correct, the first few weeks of Spring may not be overly warm, but the dry anticyclonic theme looks likely to keep recurring as it’s done since last Autumn.

 

‘Tis neither good for man nor beast

Figure 1

According to the latest forecast charts (fig 3) it looks like we are in for a spell of cold easterly winds right through this coming weekend along the south coast and especially in the southwest. In fact it might not be till the middle of next week before that nagging easterly starts to veer round to the south. Today feels more like January than the middle of March in our part of Devon, and it reminds me of the old rhyme:

When the wind is in the east,
‘Tis neither good for man nor beast;
When the wind is in the north,
The skillful fisher goes not forth;
When the wind is in the south,
It blows the bait in the fishes’ mouth;
When the wind is in the west,
Then ’tis at the very best.

 

Figure 2

Hopefully the frontal cloud that’s spinning around the low might start to thin and break by Saturday and at least then we might get some sun, although the easterly will still be blowing. Further north things look more quiet under the influence of an anticyclone that’s firmly anchored over northern England, so there it will be more a case of sharp overnight frosts, followed by sunny days.

Figure 3

Still on course for a change in type

We’re still on course for a change in type during by the weekend as the low pressure complex slips away south and high pressure builds across the north of the country, and an easterly flow becomes established. This change may not last too long according to the GFS, but it will make a change to the cloudy, mild southwesterlies that we’ve had for most of March. The weather next week always looks more settled over the north, especially the northwest of Scotland than it does in the south, with strong easterly winds across the south.

Figure 1

I noticed that John Hammond mentioned warmer weather by the weekend on the 1 PM BBC forecast, this must be somehow connected to a pulse of warmer/less cold air being caught up by the easterly flow from the continent on Saturday.

Figure 2

I always thought that high pressure was synonymous with fine weather – well not according to the Met Office and their forecast chart for Friday at any rate, which has four separate occlusions draped across the anticyclone (1033 hPa) that’s centred over the British Isles.

Figure 3