Glidemet

From what I could see (satellite from above and webcams from below the high cloud) there was quite low cumulus to the west, but it was blue to the east. RASP had forecast an area where the inversion level was was higher, high enough for high cumulus, but it looks like the inversion never lifted sufficiently.

A single “pulse” type thunderstorm (quite rare) fired at 4pm west of London when surface heating became sufficient to over come the inversion and allow a thermal to access the unstable free atmosphere above. This developed quickly and tracked northwest producing some 60 lightning strikes and radar returns at the top of the scale at one point, indicating quite heavy hail. A second storm, smaller but equally intense, formed between Reading and Oxford about ninety minutes ago (as of writing). Isolated storms of this nature can be powerful as they feed on the energy trapped in the boundary layer, and have no other cells nearby competing for this resource.

Tomorrow (Saturday) is proving tricky to forecast in the light of today. RASP paints a picture of a much higher inversion over a much wider area, but today’s performance has to be born in mind. There’s also a clear signal for more widespread shower formation. I’m going to go for cumulus at around 4,000 ft over an area of southern and central England, from east Dorset to West Sussex and north to roughly the Wash—Bristol Channel, with showers bubbling up from 4pm. Flying winds light, around 10 knots, from the southeast (less at surface). The southwest and Wales will see more general cloud and more showers.

Sunday will a distinct (but still light) easterly flow (and will also be the hottest day yet this year—-25C inland). Not keen on forecasting for that day until seeing how tomorrow goes (and there’s a cirrus signal in there too), but it will certainly be soarable, as will be Monday and Tuesday.

Small site updates
There’s now an “Other” section on the left where you’ll find the Java Web Start link to NOTAM-Map (I meant to put that in before but forgot), and also links to pollen and UV forecasts—-useful for the hayfever sufferers amongst us (including me!) and for knowning when it’s extra-important to where sunblock :-).

The latest satellite images now show the thick frontal cloud beginning to crawl in from the southwest as the cloud mass battles the high over the North Sea. Tomorrow (Friday) the thickest cloud should get just a little bit further, bringing patchy drizzle as far east as the Cotswolds, before moving back west in the afternoon. Patches of cirrus from the top of the front are likely to be gently carried further east across much of England on light upper-level winds, reducing insolation in areas through the day.

Surface dewpoints are forecast to be higher tomorrow, so cumulus should form in favoured areas of central and southern England (not East Anglia, where it will be definitely be “low and blue”), though elsewhere it’ll be blue. Cloud bases may be as low as below 4,000 ft in the Dorset—Gloucestershire area, and as high as 5,500 ft east to a line Wash—Beachy Head, though I feel there’s a fair amount of uncertainty in those figures.

Flying winds lighter than today—-10-15 knots—-and surface winds will be very light, both from the southeast.

Saturday looks like being a good soaring day with a good chance of decent cumulus, while Sunday will also be soarable, but be blue. Monday also looks promising.

Ahhh, you know it’s summer when the terminator is in the southeastern corner of the 8pm Met Office vis sat image. That and the fact it’s really warm.

But it you look at that image you’ll also be seeing a socking great wedge of cloud to the west. Happily this will stay roughly where it is for tomorrow (Thursday), with only the far southwest being afflicted by top cover. For the rest of England it will be a mainly blue day to 4,500 ft, lower to the east and down to the south coast. In Wales there’ll be cumulus to 5,000 ft, and there might also be scrappy cumulus over the Thames Valley or slightly south at 4,000 ft or so. Flying winds 15-20 knots from the southeast.

Friday sees the front creep into England, though the east should remain sunny and potentially soarable, though the air might be damper by then giving lowish cumulus. Saturday sees the front being pushed back west and so may well be soarable. Sunday and Monday similar.

No “early outlook” this week as it would be something of a misnomer! Nice to see a flight from Usk today, I was beginning to wonder if there was anyone there…

Tomorrow (Wednesday) will see a fair bit more cumulus around than there was on Tuesday, though East Anglia will remain blue in the southeasterly flow (some 15 knots at height). Scattered cumulus should start from noon at around 4,000 ft and then rise to over 5,500 ft in central areas by late afternoon (risk of going blue), and a bit less west into Wales and south to the coast. Showers, possibly quite heavy, will pop up in Wales (but they’ll be moving towards the Irish Sea away from England).

Thursday will see a little bit of cloud from a front creeping into southwestern England and western Wales, but further east there’ll be soaring, though again rather blue in the east. Friday sees the front progress east resulting in a cloudier day. Saturday looks promising with the front currently projected to move back west (much like as happened on Monday). Sunday also looks soarable.

Today indeed proved to be a weak blue day. I probably over-forecasted it a bit :-(.

Tomorrow (Sunday) looks cloudy for almost everyone all day. The far east—-perhaps Essex and Kent—-might get enough insolation for soaring for a while, but that’s it. Quite heavy rain from an incoming cold front will spread east during the afternoon. The movement of this front is now quite uncertain and it looks like it could halt over England on Sunday night and actually start going west on Monday. Currently persistent light rain is forecast all Monday :-(.

Tuesday, as is normal for the day after a Bank Holiday, looks good.

Expect variable amounts of cirrus around tomorrow (Saturday). It’s quite hard to tell exactly what effect that will have on the soaring but generally there should be cumulus to around 5,000 ft over Oxfordshire and areas north and east, with bases dropping to closer to 3,000 ft over East Anglia. In the quadrant southwest of Oxfordshire expect it to go blue (and it may well go blue elsewhere too). Wales is likely to be quite cloudy all day and a bit damp at times. Wind 10-15 knots from the south at the surface, 15-20 knots at height.

Sunday generally a cloudy day and wet in the west. Monday still sees the guilty front moved to the eastern half of the country with decent soaring behind.