Glastonbury Forecast 2010

[William of Walworth]

Just to add to the above pretty positive prospect overall (and once again, many many thankyous), the update (in written form) at midday today from the Met Office looked damned good also.

[Ben_Cambs]

From what I posted in the Model Output discussion, I think from the latest model output there is a chance of some showers towards the end of the festival (drop in the mean GFS ens) Though the ECM solution would keep a dry festival. Keep updated to Jackone's daily updates, they are very detailed, understandable to all viewers and an excellent read. :lol:

Edited June 17, 2010 by Snowman0697

[J10]

No time for a full update today, however daily updates will return tomorrow an will run until at least next Wednesday.

However this is a brief summation of today's models

GFS 00HZ and 06 HZ (variations on a very similar theme) High Pressure building up early next week, and initially keeping fronts to the west at bay, but low pressure may edge if from the west/south west from around Saturday onwards to give some rain.

GFS 12HZ High Pressure building up early next week, but not enough to dispel the chance of some showers initially moving in from the west, and more especially fronts skimming across southern parts of the UK from around Friday 25th onwards.

ECM Today keeps the High Pressure slighlty more robust for southern parts of the UK for next week,

. The ECM also models the low pressure slightly further north and this is good for Glastonbury, the 12HZ has the block slighlty weaker than the 00HZ however, still probably mostly fine for Glastonbury.

Synoptically the difference between GFS and ECM are slight, however these differences can make the difference between low pressure pushing in for Glastonbury later next week, or the block holding firm and drier weather ensuing, as a result there is still some uncertainty as to weather for the Glastonbury, especially towards the weekend. Unfortunately I will have to revert back to a 45% chance of a wet Glastonbury in light of the slightly less favourable outlook, especially from the GFS.

[J10]

This is the latest forecast, now fully completed.

GFS 00HZ A ridge of High Pressure builds across the UK for the early part of next week, giving settled conditions. However as this weakens, a weak area of low pressure is set to edge in from the west. The low pressure is then set to remain on top of the UK until the Sunday.

Detail is uncertain at the moment, but this done mean an increased chance of some rain, and more especially showers, which may be heavy and thundery, with temps in the low to mid 20s on Wednesday edging back during the festival.

GFS 06HZ A ridge of High Pressure builds across the UK for the early part of next week, giving settled conditions. However as this weakens, a weak area of low pressure is set to edge in from the west, before moving away to the east allowing a easterly than a northerly flow. This run would give the highest potential for rainfall for Thursday and more especially Friday, before clearing away across the weekend.

GFS 12Hz Synoptically very similar to that of the 00Hz, but perhaps slightly slower with the low pressure only reaching the UK by the Thursday.

On the ground, rain is likely to be restricted to scattered showers for Wednesday and Thursday, with perhaps more general rain or showers possible thereafter.

The ensembles agree with the basic theme of pressure dropping next week, however the main GFS run, does this more then the mean. The ensembles also show that CAPE levels are elevated for the festival period, although not off the scale, what this means is that some thunderstorms are possible.

The GFS unfortunately increases the potential for a wet festival, UKMO has a similar synoptic pattern to the GFS, and we now await tonight's ECM with interest.

ECM 00Hz High Pressure over the UK slowly edges away with low pressure pushing in from the west on Thursday, this lingering over the UK until Saturday before pressure picks back up on the Sunday.

ECM 12Hz High Pressure over the UK slowly edges away with low pressure pushing in from the west for Northern parts of the UK on Thursday. The low pressure deepens to cover all parts of the UK by Friday. Pressure builds up on the south, but again pressure lowering from the west on the Sunday.

So general agreement synoptically between the models, and on this basis, some rain seems likely on Thursday and Friday. Whether in the form of showers or more general rain, however we are still 5 days off from the festival and things can still change. On this basis, the odds of a wet festival now rise to 60%.

[johnholmes]

for those worrying already about what the models are showing-take heart from this link

http://www.emc.ncep.noaa.gov/gmb/STATS/html/acz6.html

none are doing very well, UK Met apart, at 6 days!

[William of Walworth]

To JACKONE especially, and to all other contributors to this thread, thank you very much for all your work and thoughts.

Even on unwelcome developments!

We're off earlyish tomorrow (Sat 19th), we're Glastonbury Info Crew and will be on site very early, with no net access except on odd occasions from our friend's i-phone ...

At least it looks like being a good dry sunny and warm start (up to Wednesday?) on latest models. All we can hope for is those infernally hard to predict (and late, positive?) shifts in synoptic posiitoning, and that they benefit us festival dwellers.

It's that Somerset Shanty Town folks!

Monsoon or not? Who can tell...

I may be gone for some time ...

[khodds]

Me too! Thanks for the updates, I only live a few miles from the site but am working there from very early on thurs morning, first glasto in 5 years.. So praying for a dryish one, as the many I went to before that were always wet!

I shall be watching this post very closely!

[J10]

for those worrying already about what the models are showing-take heart from this link

http://www.emc.ncep.noaa.gov/gmb/STATS/html/acz6.html

none are doing very well, UK Met apart, at 6 days!

Indeed, and it would only take a slight beefing up of the High Pressure for the weak low pressure to be kept in the Atlantic.

[J10]

Here is today's analysis of the models out so far.

GFS 06Hz The low pressure to the west of the UK early next week, struggles to make much eastward progress. So with the possible exception of some very weak frontal rain on Thursday, the only precipitation until the Sunday, would be from showers, which do have he potential to be thundery again.

GFS 12Hz The low pressure to the North West of the UK early next week, struggles to push in again and it also tends to push in for Northern parts of the UK. Again the chance of some weak frontal rain early Thursday, then mostly until until the weekend, (but with the chance of some showers (potentially thundery again. However the 12Hz does point to a rather wet weekend, as the low pressure eventually edges in.

The GFS 12Hz are slightly better than the 06Hz, and certainly pressure is higher on the mean than the operational GFS run.

ECM 00Hz has the low pressure moving eastwards on Wednesday and Thursday but more especially for northern parts of the UK, meaning that Glastonbury would probably escape with a few showers, while pressure then builds in from the south for the weekend, so settling down again and with winds from the SE, probably also turning very warm.

ECM 12Hz again has the low pressure moving eastwards on Wednesday and Thursday but more especially for northern parts of the UK, with presusre over southern parts staying above 1020mb, meaning that Glastonbury would probably escape with a few showers at worst. Pressure builds in for Saturday, but perhaps finally turning unsettled form the west on Sunday.

The ECM pressure charts are from the following link.

http://www.meteogroup.co.uk/uk/home/weather/latest_model_forecasts/ecmwf/archiv/Europe/pmsl/2010061912/seethumb/ch/3d96e33ad3.html

UKMO tends to keep pressure over 1020mb across the UK for the Wednesday to Friday.

Summary

A few subtle changes today that mean the low pressure to the west of the UK is set to have less impact on the UK than originally thought, Its progress over the UK and especially to southern UK is less progressive than yesterday, and this improves the chance of a dry Glastonbury festival. On this basis the chance of a wet Glastonbury festival has been reduced to 45%.

This does not essentially mean a completely dry festival, however the chance of heavy downpours and prolonged rainfall are less than yesterday.

[Neil the Macc lad]

Thanks for that Jackone. It's unbelievable how much the forecasts have changed over the last 3 days. Hopefully things will continue to firm up tomorrow

[PompeyFC]

the GFS 00z is even better, each run seems to improve, could turn out to be half decent after all

[J10]

Thanks for that Jackone. It's unbelievable how much the forecasts have changed over the last 3 days. Hopefully things will continue to firm up tomorrow

Indeed things have changed a lot of recent days. there is always the potential for this especially when you have messy synoptic without dominant high pressures or deep areas of low pressures.

[PompeyFC]

the bbc 5 day forecast artmidday looked sunny and warm !!!

6z played ball aswell

[J10]

I am now changing the format of the forecast from now on to try and nail down the weather on individual days.

Wednesday

The front is set to push eastwards towards The UK (more especially for Northern parts of the UK), but with higher pressure over southern areas, it should stay dry and fine over Glastonbury. There is the chance of some cloud, and as the front edges over later in the day GFS indicates the chance of light drizzle, but I think this risk is small. Maximum Temps hitting 23-24c.

Thursday

During the day, high pressure build up from the south west, and this will kill off any overnight drizzle, and it should turn increasing bright or sunny during the afternoon. CAPE Level are small as indicated under the ensembles section below, so showers are unlikely, Temps slightly cooler than Wednesday reaching up to 23c.

Friday

The ridge of high pressure is quite dominant today, and good agreement on a dry day with bright or sunny weather throughout, and with light winds it should feel very warm, don't forget your sun screen.

Temps again reaching up to 23c.

Saturday

Low Pressure again attempting to edge in from the west, and this is likely to mean more cloud than over the previous days of the weekend. GFS is indicating the chance of some rain, but not particularly heavy, and this may get downgraded closer to the time, as has been in the case over recent days. Temps hitting around 21c.

Sunday

Some differences in the model output, with GFS clearing the Low Pressure away to the East, with ECM keeping it close to the North West, so it is difficult to pin down the details at the moment. Sticking my neck I would say that mostly dry and cloudy is the most likely option at the moment, with temps probably around 20c.

Ensembles

Summary

Mostly Dry for Wednesday to Friday, perhaps a little rain and more cloud Wednesday night into Thursday. But general sunny for reminder of Thursday and Friday.

A little less settled over the weekend, with a chance of rain Saturday and perhaps Sunday, but really not amounting to much, and less than 5mm of rain is expected over the 5 day festival period at this stage. Temps warm in the low 20s and sunscreen is expected to be needed this week.

[PompeyFC]

mmmmmmmm............loving it.

cheers J.

[dancing daisy]

Thanks Jackone, great work as always.

Coupled with the Countryfile forecast I am cautiously optimistic for a scorching, m** free Glasto.

[danbailey80]

Thanks JACKONE, it's been great to have your help once again..If you could give us a mark out of 5 like you used to that be great!!...Are we a 2, (1 being completely dry, 5 being a washout)?....

[J10]

Thanks JACKONE, it's been great to have your help once again..If you could give us a mark out of 5 like you used to that be great!!...Are we a 2, (1 being completely dry, 5 being a washout)?....

on that basis a 2 is the most likely. Possibly not completely dry, but probably no need for wellies.

[Ian Fergusson]

Hi Jackone, Yup - Broad agreement, fyi, from UKMO-GM (plus ECM) perspective (i.e. looks dry and settled for the most part - yes, there's a Glasto rarity). A chance of very warm (even hot? i.e., 27C+) temps by the weekend; at least across into the SE and quite possibly into east Somerset too.... also still the potential for some showers / t-storms locally into late Sat / Sun given localised destabilisation / sea breeze convergence effects way beyond the resolution at this range of the various NWP products. We'll see. Main recent area of model divergence has been the evolution for Friday with that LP skirting up to the NW. But better agreement presently to hold it off that way. I'll dip into the next run of ECM's precip output and see if it varies. Glasto forecast blog went up earlier today at http://www.bbc.co.uk...2010-weat.shtml albeit I'm equally focused on blogging re Valencia prospects for the next F1-GP... one head in two places!!

Ian

[khodds]

Hi Jackone, Yup - Broad agreement, fyi, from UKMO-GM (plus ECM) perspective (i.e. looks dry and settled for the most part - yes, there's a Glasto rarity). A chance of very warm (even hot? i.e., 27C+) temps by the weekend; at least across into the SE and quite possibly into east Somerset too.... also still the potential for some showers / t-storms locally into late Sat / Sun given localised destabilisation / sea breeze convergence effects way beyond the resolution at this range of the various NWP products. We'll see. Main recent area of model divergence has been the evolution for Friday with that LP skirting up to the NW. But better agreement presently to hold it off that way. I'll dip into the next run of ECM's precip output and see if it varies. Glasto forecast blog went up earlier today at http://www.bbc.co.uk...2010-weat.shtml albeit I'm equally focused on blogging re Valencia prospects for the next F1-GP... one head in two places!!

Ian

If there was a "like" I would push it, cant wait!

[J10]

ECM 12 Hz this evening keen to put the low pressure even further north for the start of Glastonbury, and a slightly different resolution to the weekend with lower pressure to the south, perhaps the chance of a few T Storms over the weekend, perhaps imported from the continent.

[Nick F]

Certainly hint of height/pressure falls from the SW on the 12z ECM run Saturday and Sunday - so scope for perhaps some showers/storms to develop in the slack flow. 12z UKMO more anticylonic and dry. GFS showing height/pressure falls from the west, but any fronts moving in from the west look weak across the southern half of the UK so a dry picture too going into the w/e.

Hard to say at this stage with the model divergence with placing low pressure, but i'd say 70% staying dry atm, based on 12zs.

[Nick F]

Thursday and Friday looking essentially dry ... just an outside chance that a weakening cold front moving east on Thursday may give some cloud and light rain, pressure building in on Friday should bring a dry day. Some divergence into the weekend though, UKMO and ECM look essentially dry Saturday with high pressure, though 06z GFS shows lower pressure with height falls from the west and the risk of heavy showers developing both Saturday PM and during Sunday. ECM too shows pressure falling from the SW by Sunday PM, so chance of thundery showers later on Sunday. UKMO looks dry all weekend with ridging in control.

[J10]

This is the next update.

Wednesday

The models have very similar thoughts to yesterday. The front is set to push eastwards over more northern parts of the UK, but with higher pressure over southern areas, it should stay dry and largely sunny over Glastonbury. Hoewver there is the There is the chance of some cloud later in the evening, but it should stay dry. Maximum Temps hitting 23-24c.

Thursday

A rather cloudy start as the front edges very slowly across from, there may be a little rain or drizzle, but not really enough to wet the ground. During the day, it should turn steadily brighter with some sunny intervals possible to end the day. Temps slightly cooler than Wednesday reaching up to 23c.

Friday

The pressure build up slightly from the west, and despite the ECM 12Hz not increasing the pressure as much as the others, it should be a mostly dry and sunny day. With light winds it should feel very warm, don't forget your sun screen, temps reaching up to 23-24c.

Saturday

Even though we are a day nearer, there is no increase in certainty about Saturday's weather. There is no dominant weather pattern, with pressure around 1015mb. Frontal rain is unlikely and there is the chance of sunny intervals, however CAPE levels are high, and there is the chance of some thundery showers, temps around 23-24c.

Sunday

Another messy picture, GFS indicating low pressure from the west, with some rain, heavy and thundery in places. ECM keeps pressure slightly higher over the UK, but only at around 1016mb in the south, so the chance of some thundery outbreaks edging up from the south. Temps around 23-24c.

Ensembles

Summary

Mostly Dry and Bright or sunny for Wednesday to Friday, with more in the way of cloud Wednesday night and into Thursday morning.

A little less settled over the weekend, with the chance of some thundery outbreaks developing over the weekend, perhaps more likely on the Sunday.

85-95% chance of a dry first 3 days of the festival, 25-45% chance of some showers at some time over the weekend, with a small chance of some heavy rain and thunderstorms over the weekend.

[danbailey80]

So 1/5 for Wednesday-Friday

2/5 for weekend?........

Cheers Jackone, thanks always

p.s when are you going to join us all on the farm!?