The criteria for each site were all contributed by local pilots, so should be accurate.

Forecast from Glidemet

Ridge Day Tool

Maybe a proper forecast tonight if I have time.

Forecast from Glidemet

Man your gliders

Forecast from Glidemet

Friday

Yes, today is going to be a reasonable day (though in comparison to previous month, it’s effectively great). Cumulus should be appearing around now, and south a line from the Severn to the Wash, reach 3,000 ft by 11 am. North of that it stays lower. In addition, north of that line, it will already be showing signs of spreading out. As we go into the early afternoon, spread-out develops south and east of London and in the west country, but in the good area, now boxed by Exeter-Minehead-the Wash-Ipswich, cumulus will remain good and by 1pm be 4,000+ ft, with 3-4 knot climbs beneath. However by 3pm, across the area, there will be areas of (cycling) spread-out forming. By 5pm, there’ll be a sea breeze line from Bodmin through to Lasham then down to Brighton, while elsewhere (in the “good” box) blobs of stratocumulus at 5,000 ft with sunlight and 2-3 knot climbs around them.

Hopefully that gives a flavour of the day. Flying wind 5-10 kt from the southwest, and no showers.

Forecast from Glidemet

Tuesday

The change to 2 km and 4 km grid resolutions is a significant. The model is now in the realm of “convection resolving”, particularly for the 2 km on-the-day forecast (4 km, for the “next day” forecast, is a bit borderline still, but a big improvement over the previous 5 km). This means that the model is capable of resolving the type and shape of cumulus clouds, although they will always appear to be a bit on the big side compared to reality (a model in the order of 500 m to 1 km would be needed to be fully accurate).

However, do not think (and I don’t suppose any of you would really but I’m just making sure) that the model is capable of saying there will be a cloud of shape x at time y over town z. It isn’t. What it is capable of is picking out areas of spreadout versus fine cumulus (best distinguished by using the “normalized surface sun” parameter). Spreadout will be fairly obvious, good cumulus will either be a spotty effect (separate small clouds) or simply blank (100% surface heating, i.e. no shade); spreadout will be large areas of greatly reduced insolation, perhaps with narrow areas of sunlight indicating the edges of larger stratocumulus clouds. Use “Cu Cloudbase where CuPotential >0” to see where (and when—-the model is actually pretty good on timing) cu actually should be, and where it will be mostly likely blue. The increased resolution means the model has better knowledge of high ground and forecast different amounts of cu at different heights accordingly. Wave will also be modelled better than ever.

It’s worth saying that right now, at the time of posting, RASP is currently down. Always check the the top of each map image to make sure it’s for the time and day you were expecting to see. Outages might happen from time to time for a week or two while Paul gets all the upgrades playing nicely.

If RASP UK is down you can always use the back-up service, Stratus, run by Darren Hatcher. Currently this still used the 4 and 5 km versions of RASP, and still uses the older RASPTable interface. There a lot of nice tools on Stratus though, my favourite being the excellent “RASP Quality Check” tool, or as I like to think of it, “how’s RASP doing?”. Interestingly the new Met Office site has a very similar Verification page.

Forecast from Glidemet

Big changes to RASP

Forecast from Glidemet

Taaalk to me!