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Glastonbury Festival 2015 24 to 28 June - Forecast No 5



This is the 5th forecast blog for Glastonbury 2015.

The previous blog (Issued 10 June) was mostly positive.

IMO a definite trend is starting to emerge, which I will outline later, of course whether or not this is accurate, time will tell.

This forecast will be split into 2 main sources

[b]1. Prognostic Charts at 6-10 day and 8-14 day [from NOAA][/b]

The 6-10 day chart at this poll covers the immediate run up to the festival while the 8-14 day charts covers the festival period itself.
[b]6-10 day [/b]
[attachment=252942:610day.03 from 10 June.gif] [attachment=252947:610day.03 from 11 June.gif] [attachment=252946:610day.03 from 12 June.gif] [attachment=252990:610day.03 from 13 June.gif]

[b]8-14 day [/b]
[attachment=252943:814day.03 from 10 June.gif] [attachment=252944:814day.03 from 11 June.gif] [attachment=252945:814day.03 from 12 June.gif] [attachment=252993:814day.03 from 13 June.gif]

Both sets of charts are very positive with High Pressure over the UK in both cases, becoming dominant in the 8-14 day range which covers 21-27 June.

Interestingly today's charts (now published have dominant High Pressure over the UK, which slightly goes against the trend of the ensembles, slightly reducing the pressure over the UK.
[b]2. Ensemble Forecasts[/b]

[size=3][b]GFS Pressure Ensembles [/b][/size]

[b][size=3]11 June [/size][/b]
[attachment=252952:Ensemble Pressure 11 June 12Hz.png] [attachment=252948:Ensemble Pressure Anomaly 11 June.JPG]

[b][size=3]12 June [/size][/b]
[attachment=252978:Ensemble Pressure 12 June 06Hz.png] [attachment=252955:Ensemble Pressure 12 June 12Hz.png] [attachment=252958:Ensemble Pressure Anomaly 12 June.png] [attachment=252961:Extra Ensembles Pressure 12 June.JPG]

[b][size=3]13 June [/size][/b]
[attachment=252964:Ensemble Pressure 13 June 06Hz.png] [attachment=252974:Ensemble Pressure 13 June 12Hz b.png] [attachment=252966:Ensemble Pressure 13 June 12Hz.png] [attachment=252982:Extra Ensembles Pressure 13 June.JPG]

The pressure charts have a pattern to increase pressure over South Western parts of the UK, rising to an average of close to 1030mb by around the 17th June, It is then set to fall back to around 1020mb by the 22nd June. For the festival itself, the ensemble average pressure is just below, however with some runs, including the operational ones, turning things unsettled a bit.

[size=3][b]GFS Rainfall Ensembles [/b][/size]

[b][size=3]11 June [/size][/b]
[attachment=252953:Ensemble Rain 11 June 12Hz.png] [attachment=252950:Ensemble Rain Anomaly 11 June.JPG]

[b][size=3]12 June [/size][/b]
[attachment=252977:Ensemble Rain 12 June 06Hz.png] [attachment=252954:Ensemble Rain 12 June 12Hz.png] [attachment=252957:Ensemble Rain Anomaly 12 June.png]

[b][size=3]13 June [/size][/b]
[attachment=252962:Ensemble Rain 13 June 06Hz.png] [attachment=252973:Ensemble Rain 13 June 12Hz.png] [attachment=252965:Ensemble Rain Anomaly 13 June.png]

The General pattern is for a mostly dry spell of weather coming up, however there are some spikes in the ensembles indicaiong some moderate rainfall, however most runs are still dry.

[size=3][b]GFS Temperature Ensembles [/b][/size]

[b][size=3]11 June [/size][/b]
[attachment=252951:Ensemble Temp 11 June 12Hz.png] [attachment=252949:Ensemble Temps Anomaly 11 June.JPG]

[b][size=3]12 June [/size][/b]
[attachment=252976:Ensemble Temp 12 June 06Hz.png] [attachment=252956:Ensemble Temp 12 June 12Hz.png] [attachment=252959:Ensemble Temps Anomaly 12 June.png] [attachment=252960:Extra Ensembles Temps 12 June.JPG]

[b][size=3]13 June [/size][/b]
[attachment=252963:Ensemble Temp 13 June 06Hz.png] [attachment=252975:Ensemble Temp 13 June 12Hz.png] [attachment=252967:Ensemble Temps Anomaly 13 June.png] [attachment=252981:Extra Ensembles Temps 13 June.JPG]

Temps are forecast to be above average with 850hpa temps just below +10c.

[b]Summary [/b]

[b]Good [/b]
If the Glastonbury festival was a week earlier, there would be good confidence in a dry settled festival.
There is still decent confidence of a mostly settled festival, with the majority of ensembles keeping thing mostly dry. with a dry run-up to the festival meaning helping dealing with any rainfall that does fall.

[b]Bad [/b]
The one concern is that the settled weather ends sooner than expected, and some ensembles do show it turning unsettled for the festival.

Despite the concerns above, the current trend remains for the festival weather to be more settled, drier and warmer than average for the time of year. As such I give this festival a 3/10 rating at this time (0dustbowl, 10mudbath)

[attachment=252979:glasto Rating 13th June.JPG]

[b]Next Update [/b]

This will be published on Monday night, probably around 8-10pm.

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Thanks J10 for all your work once again this year, nice to see the forecast is so positive, the run up to the festival is just as important from a weather perspective as the festival itself, the really bad mud years have had a wet spell before and during the festival, looks like we should avoid that this year.

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