Weather thread 2015

[Aragorn]

Rain Friday, Saturday, Sunday now. A couple of thunderstorms.

Seems to be pretty consistent with every forecast for the last week or so. Looks like were in for a lot of rain.

Don't talk wet quite literally. Most sites like accuweather are based on the GFS american model which updates every 6 hours. This far out it is trends only not what is likely to happen. I have seen weather models be nailed on for snow within 48 hours in the UK and yet slight last minute changes in the jet or orientation of highs and lows mean we miss out. Until next Friday at least we cannot be sure

[bennyhana22]

just a note - Metcheck was bang on the money in 2010

And they will be again.

(Just so long as today's forecast remains entirely unchanged up to and including 29 June)

Ben

[JoeyT]

They're falling over themselves on the netweather forum.

Looks like we are heading towards a nice long spell of high pressure thurs onwards next week!

[fur_q]

Afternoon all.

Anyone want to see some charts I knocked up showing probability of different rainfall scenarios for Pilton based on gfs ensembles?

[psychology]

Afternoon all.

Anyone want to see some charts I knocked up showing probability of different rainfall scenarios for Pilton based on gfs ensembles?

Yes

[fur_q]

Yes

Ok then

This data is scraped from the NOMADS Ensemble Probability Tool which basically allows users to query the GFS ensembles to determine probability of a selected set of weather conditions at a given location. Ive written a little R script that queries an ensemble run for multiple precipitation events (rainfall of less than 1mm/6hour and greater than 1,2,3,4,6,8,10,15,20&25 mm/6hour) at the location of the festival this is then graphed as below.

The X axis represents the probability of the event occurring as a percentage, the Y the Y axis represents the rainfall amount queried for 4 each day

The blue bar represents the last available ensemble run and the black + * x show the same results from the previous 3 ensemble runs, Ive put these here as the give an indication of confidence in the forecasts, i.e. if the models are constantly showing the same outputs we can be more confident in their predictions than if they keep fluctuating wildly.

Only Wednesday to Friday so far as gfs doesn't go beyond that point.

[FuzzyDunlop]

They're falling over themselves on the netweather forum.

Looks like we are heading towards a nice long spell of high pressure thurs onwards next week!

That means rain by the week after

Edited June 12, 2015 by FuzzyDunlop

[windy_miller]

Ok then

This data is scraped from the NOMADS Ensemble Probability Tool which basically allows users to query the GFS ensembles to determine probability of a selected set of weather conditions at a given location. Ive written a little R script that queries an ensemble run for multiple precipitation events (rainfall of less than 1mm/6hour and greater than 1,2,3,4,6,8,10,15,20&25 mm/6hour) at the location of the festival this is then graphed as below.

The X axis represents the probability of the event occurring as a percentage, the Y the Y axis represents the rainfall amount queried for 4 each day

The blue bar represents the last available ensemble run and the black + * x show the same results from the previous 3 ensemble runs, Ive put these here as the give an indication of confidence in the forecasts, i.e. if the models are constantly showing the same outputs we can be more confident in their predictions than if they keep fluctuating wildly.

Only Wednesday to Friday so far as gfs doesn't go beyond that point.

If I'm reading these correctly, this means that there is a 90% chance of less than 1mm of rain?

Edited June 12, 2015 by windy_miller

[fur_q]

If I'm reading these correctly, this means that there is a 90% chance of less than 1mm of rain?

Yes that's what the data is currently suggesting

[devonhammer]

Yes that's what the data is currently suggesting

That is great work. I'm guessing this is using slightly old GFS data because they now have data out to Sunday lunchtime.

Latest GFS run is in and currently has high pressure from Monday which hangs around and blocks any lows for over a week. It starts to break down, but is hanging in there until at least the Sunday lunchtime of the festival. Looks like a low might spin in on the Monday after the festival, but nothing more than showers until then.

The bad forecast yesterday looks very much like an outlier. Probably put in just to keep the Nal's spirits up.

Edited June 12, 2015 by devonhammer

[fur_q]

Yes there seems to be a bit of a lag on probability tool, 12/6 00z was the latest available at 5pm

Will try and update daily between now and next week

Edited June 12, 2015 by fur_q

[neil999]

That is great work. I'm guessing this is using slightly old GFS data because they now have data out to Sunday lunchtime.

Latest GFS run is in and currently has high pressure from Monday which hangs around and blocks any lows for over a week. It starts to break down, but is hanging in there until at least the Sunday lunchtime of the festival. Looks like a low might spin in on the Monday after the festival, but nothing more than showers until then.

The bad forecast yesterday looks very much like an outlier. Probably put in just to keep the Nal's spirits up.

Excellent, so trends are showing a washout is pretty unlikely atm, im always pretty happy with anything bar a massive washout as a bit of rain and mud is always cope-able

[devonhammer]

Here's a picture showing the rain that will likely hit on the Monday after the festival. Obviously still way to far out for any certainty:

[yehbutnobut]

That is great work. I'm guessing this is using slightly old GFS data because they now have data out to Sunday lunchtime.

Latest GFS run is in and currently has high pressure from Monday which hangs around and blocks any lows for over a week. It starts to break down, but is hanging in there until at least the Sunday lunchtime of the festival. Looks like a low might spin in on the Monday after the festival, but nothing more than showers until then.

The bad forecast yesterday looks very much like an outlier. Probably put in just to keep the Nal's spirits up.

So when are we officially to start celebrating and allowed to get even more excited that the weather is going to be bang on...? Or would it still be tempting fate at this point???

[justperfect]

I don't give a shit if we get hit by a tsunami on the Monday

[psychology]

Looking good

[General Lee]

I don't give a shit if we get hit by a tsunami on the Monday

very true!

[CiaranMc]

So when are we officially to start celebrating and allowed to get even more excited that the weather is going to be bang on...? Or would it still be tempting fate at this point???

Just as you drive out the gate on the Monday morning after the festival I'd suggest...

[parsonjack]

So when are we officially to start celebrating and allowed to get even more excited that the weather is going to be bang on...? Or would it still be tempting fate at this point???

Monday 29th June.

[fur_q]

So when are we officially to start celebrating and allowed to get even more excited that the weather is going to be bang on...? Or would it still be tempting fate at this point???

My impression from years of glasto weather watching is that the gfs model tends to be a relatively good predictor of the next two weather systems that will be affecting the uk, so I really think we new to wait for this weekends low to clear off before we will get a more accurate prediction.

[FuzzyDunlop]

You can't take the reports that seriously yet. 2 days ago it was a washout

Edited June 12, 2015 by FuzzyDunlop

[Migraine]

Over at the Daily Mail headquarters they are currently sacrificing a vegan to the rain gods. No rain = no picture of two girls with an umbrella splashing in the deepest puddle on site.

[frostypaw]

My impression from years of glasto weather watching is that the gfs model tends to be a relatively good predictor of the next two weather systems that will be affecting the uk, so I really think we new to wait for this weekends low to clear off before we will get a more accurate prediction.

It says something when one's understanding of the weather around pilton and the forecasting models reaches 'meta' proportions.

Not sure it's a bad thing, but there's a boundary been crossed for many of us

[devonhammer]

My impression from years of glasto weather watching is that the gfs model tends to be a relatively good predictor of the next two weather systems that will be affecting the uk, so I really think we new to wait for this weekends low to clear off before we will get a more accurate prediction.

I was thinking exactly this while walking the dog in the rain. By Wednesday we should have an idea of how the high pressure is progressing and whether it's likely to hang around.

[CiaranMc]

This is the most stressful thing ever.

I've never been before and I'd only love my first time to be one of those halcyon dry years that (nearly) everyone loves.

Edited June 12, 2015 by CiaranMc