Glidemet

I think, on balance, it’s worth pointing out that next week is going to see some very good weather as high pressure builds right over the UK. The first part will probably be better than the latter as it’s bound to steadily go blue as the inversion level steadily drops under the sinking air in the middle of the high, meaning thermals cannot reach high enough to form cumulus clouds.

I’m not posting this to rub salt in the wounds of those who are comps this week. More to suggest to those who might be able to take a few more short-notice days off work to do just that next week, as it might be the last chance for good quality thermal soaring this year.

But I can’t resist one little thing: in a post written three years ago I do say early September would be a good time to hold a competition. I believe one of the best Juniors of the last decade was indeed held that week (2002?). Yes I think the coming week last year was awful, but I stand by the statement: high pressure tends to build early September, often giving better weather than late August.

(Also, chart-watchers, look out for the ex-hurricane becoming an extremely deep low wandering around the mid-Atlantic next week. It’s normal for ex-hurricanes to come back out into the Atlantic this time of year, but it’s not often you’ll see a low that deep! It should go off towards Greenland, well away from us.)

A note on Friday seeing as I’m here: all still on track. It will continue to drizzle and rain all night, but it should dry up in the Bicester area around 5 am with sunshine by mid-morning. For Lasham stick about three hours on those timings. Even the top cover doesn’t look as if it will be as thick as it did previously. The wind will be a little high, about 15 knots, but I see every chance of at least a 300 being possible for most and even further for pundits.

Well, today (Thursday) is going to feature near continuous rain and drizzle from Wales through the Midlands (right over Bicester) and into East Anglia until well into the night. Areas south will be cloudy and still moist from time to time; to the north, from about Yorkshire up, considerably drier and brighter.

Much more interesting is what the forecasts for Friday are now showing. You’ll remember in my previous post that I said Friday looks quite good. In the intervening 24 hours some (not all) forecasts then suggested that Friday was going to be a scrub as well; now things are looking up again. Current indications are that the filling low that is following on behind the one over us today will lose its identity and run on the originally forecast track through northern France, resulting in an anti-cyclonic ridge over the UK (the intervening forecasts ran the low further north, over us). As a result southern counties will have a cloudy start while the south coast will have some rain as well. Through the morning the cloud will sink away southeastwards with the clearance maybe reaching the M4 by midday. To the north good cumulus will rise to 4,500-5,000 ft. There will be considerable top cover, but as we demonstrated at the Bicester Regionals even when there’s 8/8ths, if the air mass is unstable there will be usable thermals. Flying winds will be a good 15 knots or more from the northeast to start, but dropping quickly through the day.

Saturday looks a reasonable day: it would be plain good if not for the wind. An unstable but capped northwesterly air flow with plenty of cumulus at about 3,000 ft behind the Pennines in the north (a bit too damp on the western side), and up to 5,000 ft towards the southeast. However, the wind will be something like 15-20 knots. Risk of showers if you spend too long flying  .

Sunday will be in more or less the same flow but with a bit more cloud in it and a higher possibility of showers, and a same or stronger wind. Pretty marginal but some chance of a short task in the earlier part of the day.

Mainly for the benefit of the Juniors, and mainly because I forget stuff if I don’t write it down.

Synopsis is a parent low over southern Scandanavia which is extending a large wind field across northwestern Europe. As of midnight a trough was embedded in the system just north of Northern Ireland, probably just with a closed circulation, and with a central pressure of a rather unseasonable 994 mb. This is only adding to the wind gradient across Wales and most of England. (Pretty light winds up in Scotland). Upshot is winds of 25-30 knots from due west at flying heights, with a surface wind of just south of west at around 15 knots gusting to 25 knots.

The airmass is a good unstable returning maritime with no true inversion present, but a low enough temperature gradient that convection from 19-20 °C is stopped at about 12,000 ft. It’s about -4 to -5 °C up there, so easily cold enough to shower. Whether any clouds will actually grow that high before being blown apart is debatable, but it is already showering over Wales, down across Bristol Lulsgate ridge, and into the Lyneham area. These are only going to progress further east with help from the sunshine.

Convective cloud bases themselves are actually quite good, 4,000-5,000 ft. However this wind, with little directional shear, is going to put a lot of wave influence (if not wave itself) across England, so there’s going to be large areas, across the wind, where the air is going down fast, and other areas of booming, if very rough and broken thermals.

So, windy as ‘eck with rough, broken thermals that will sometimes push up at perhaps 5-6 knots but sometimes will be replaced with big areas of sink, combined with showers rushing through. It won’t street in these conditions—-the wind is too strong, and the wave influence will break anything up.

A little look ahead—certainly Wednesday and probably Thursday are off the cards as another low tracks across southern England, bringing more rain. But Friday, Saturday, and Sunday look much better with good air and much lighter winds. Could be three good days.

The only flight on the ladder (later update—-a couple of flights now posted from England, so it was a bit soarable, at least in places). It’s safe to say that yesterday was one of my poorer forecasts, and honestly, it was probably avoidable. Lots of top cover, in the form of both dense cirrus and areas of altocumulus castellanus, turned up, and I didn’t give enough thought to that possibility so didn’t look for it. While the airmass lower down did generally behave as expected, the sun was pretty weak in most places today putting paid to useful thermals. Still, at least it’s a nice evening for a beer and a barbeque.

Tomorrow (Sunday) generally cloudy with some showers in the north and east, and most other places cloudy (if a bit cooler than today). The southwest is the only place where there might be good conditions.

After that a low pressure system stays all too close to the UK for pretty much the week, bringing cloud and occasional rain most days  .

Interesting day today, it looked cracking through the window, if a little slow to get going, but that was just one spot and from the ladder it sounds like it wasn’t necessarily representative.

Tomorrow (Saturday) looks another interesting day too. Cumulus will start to form first in the northwest and west (i.e. Wales and the southwest), and appearing further and further southeast as time goes on, (later edit that might not be in the email) although there’ll be a fair bit of cirrus floating around, which isn’t helpful.

In the southwest expect bases to top out 3,500 ft with sea air encroaching the north of the peninsula. Wales sees bases to 3,500 ft from late morning going to over 4,500 ft in the afternoon—-good. The Northwest is a similar story but not as strong—-bases about 2,500 ft to start going to 4,000 ft in places but staying stubbornly lower in others. Northeast goes to 3,500 ft a little later.

So, midlands and the rest of the east and south, cumulus should appear to 1W by midday and 1E by early afternoon, generally at 3,500 ft at 1W (and down into Kent), going up to 4,500 ft towards Tibbenham. The cumulus will remain at roughly this height or slowly rise, and generally shouldn’t go blue or spreadout. The only thing it will probably do is overdevelop in England west of 1W (not Wales), with showers possible by evening. Winds generally light southerly but check the F214 on the morning.

Sunday, as everyone seems to know, thundery showers. However they now look much less developed, and much further east, than data I saw earlier suggested. Maybe even only up the Channel and off the east coast, and while a low was forecast to develop, current data isn’t so developmental. However it will be a warm, damp airmass, so expect low spreadout stratocumulus rather than soarable conditions. Sorry.

Next week looks rather unsettled with low pressure never far, though the odd (probably somewhat brief) window for soaring should present itself.

Just quick like. Today (Thursday! I mean Thursday!) blue to 3-3,5000 ft over most areas except the following where cumulus from late morning is more likely: northwest of a line Bath to Yeovilton to Exeter to Barnstaple, and all of Wales: bases at around 3,000 ft rising to 4,500 ft in many areas; northest England (Yorkshire up) bases to 3,500 ft (some sea air seeping in the Vale of York between the Pennines and the North York Moors), and the best conditions today will be in the northwest of England, where cumulus bases should be over 4,000 ft from noon for the rest of the afternoon. Good for places like Edensoaring (whose Twitter feed I added to the “Latest news” section on the left a week or two back).

I noticed, by spotting several gliders flying past from the vague direction of Booker, that the comp season has started. Some time today I hope to get the “latest comp news” section working again, if I can remember how to do it!