Has somebody broken the Met Office weather model?

[Ammonite]

I experienced a similar situation this morning in the Southampton area. A look at the last hours observations suggested to was going to absolutely chuck it down in a few minutes but the forecast for the next hour indicated no rain. Sure enough it chucked it down.

 

[franksingleton]

I experienced a similar situation this morning in the Southampton area. A look at the last hours observations suggested to was going to absolutely chuck it down in a few minutes but the forecast for the next hour indicated no rain. Sure enough it chucked it down.

The web page is more informative than the app for the immediate future.

 

[dunedin]

Well somebody has definitely broken the BBC Weather website model for today and tomorrow says
Hurricane force winds of over 8,050 mph

 

[Boathook]

Mine gives a wind speed gust 15027 for today and tomorrow down south !

 

[Hermit]

Have they been reading this thread?

 

[franksingleton]

Most unprofessional. Serious weather prediction should be left to professionals.

 

[Supertramp]

Notwithstanding that this isn't a good day for forecasts, this is an example of the dilemma which seems to have become more common to me this season.

These are extracts of this weekend's Met Office forecast for Abersoch (N Wales).


The dilemma is the scale of difference between (average?) wind strength in knts and the gusts. On my own I would sail and deal with it (at anchor somewhere safe). For inexperienced crew it could turn into a scary endurance mission.

On several occasions this year I have sailed in similar wind forecasts sometimes encountering the lower figure and on others the higher figure (sustained).

I sense that the UK wind (West side at least) this season is genuinely varying by such extremes and that the models struggle to deal with the volatility.

 

[Boathook]

Same with the inshore forecast. Seems to always be a spread of 2 forces, ie 3 to 5, 2 to 4, etc.

Below is the latest inshore forecast.

Selsey Bill to Lyme Regis
24 hour forecast: North or northeast, veering southeast later, 2 to 4. Slight or moderate, becoming smooth or slight. Showers at first. Good.

Outlook for the following 24 hours: Southeast 3 to 5, veering west 4 to 6 later. Smooth or slight. Mainly fair. Good.

 

[lustyd]

BBC Weather app forecasts hurricane force winds

Well, at least the BBC have noticed

 

[franksingleton]

Notwithstanding that this isn't a good day for forecasts, this is an example of the dilemma which seems to have become more common to me this season.

These are extracts of this weekend's Met Office forecast for Abersoch (N Wales).
View attachment 184075View attachment 184076

The dilemma is the scale of difference between (average?) wind strength in knts and the gusts. On my own I would sail and deal with it (at anchor somewhere safe). For inexperienced crew it could turn into a scary endurance mission.

On several occasions this year I have sailed in similar wind forecasts sometimes encountering the lower figure and on others the higher figure (sustained).

I sense that the UK wind (West side at least) this season is genuinely varying by such extremes and that the models struggle to deal with the volatility.

Thank you for this. I have been hesitating to suggest that some of the examples of strong gusts quoted earlier in this thread were, in fact, quite possible. When there is deep convection, stronger than normal gusts are always a possibility. I have no idea whether this is a climate change effect or not, I have no idea. It could well be normal variability.

 

[franksingleton]

Same with the inshore forecast. Seems to always be a spread of 2 forces, ie 3 to 5, 2 to 4, etc.

Below is the latest inshore forecast.

Selsey Bill to Lyme Regis
24 hour forecast: North or northeast, veering southeast later, 2 to 4. Slight or moderate, becoming smooth or slight. Showers at first. Good.

Outlook for the following 24 hours: Southeast 3 to 5, veering west 4 to 6 later. Smooth or slight. Mainly fair. Good.

There is nothing at all unusual in these forecasts. These are 24 hour forecasts. If you think that these unusual, then your memory must be extremely short.

 

[franksingleton]

Earlier in this thread there was some excitement about predicted gust speeds being possibly too strong. There were comments that there were apparent differences between gust speeds on the Met Office app and those shown on UKV as provided by third parties. I and others raised these matters with the Met Office but never got any definitive response.
My suspicion was that we had been through a period with some extreme convection when extreme gust speeds were possible. The differences between various presentations of the same data remain a mystery.

Does anyone still suggesting that forecast gust speeds are still over predicted? Are the Met Office app gust speeds still not consistent with the UKV output.

 

[Chiara’s slave]

I feel it has been an odd season for wind, we have indeed noticed the gusts, you tend to feel them more on a multi. We’re sailing next week, just a short trip for a club lunch. Comparing all the forecasts available as you do, the met office are a stand out. Same base wind, give or take, but this time they are alone in giving big gusts. 15 gusting 26. (Mph) ECMWF, which I thought was theirs, gives 11 gusting 16 kn. That is a fairly big discrepancy. Is there an explanation for that, I appreciate one is marine and one is not, but I haven’t noticed it being like that before.

 

[Snowgoose-1]

Earlier in this thread there was some excitement about predicted gust speeds being possibly too strong. There were comments that there were apparent differences between gust speeds on the Met Office app and those shown on UKV as provided by third parties. I and others raised these matters with the Met Office but never got any definitive response.
My suspicion was that we had been through a period with some extreme convection when extreme gust speeds were possible. The differences between various presentations of the same data remain a mystery.

Does anyone still suggesting that forecast gust speeds are still over predicted? Are the Met Office app gust speeds still not consistent with the UKV output.

Thanks for taking the matter up with the Met Office.
On the East Coast , I am still finding the gusts are too highly forecasted.

 

[lustyd]

ECMWF, which I thought was theirs

ECMWF has always been a separate organisation. MET is a UK organisation whereas ECMWF is European cross government (The European Centre for Medium-Range Weather Forecasts) albeit based in Reading.

 

[franksingleton]

I feel it has been an odd season for wind, we have indeed noticed the gusts, you tend to feel them more on a multi. We’re sailing next week, just a short trip for a club lunch. Comparing all the forecasts available as you do, the met office are a stand out. Same base wind, give or take, but this time they are alone in giving big gusts. 15 gusting 26. (Mph) ECMWF, which I thought was theirs, gives 11 gusting 16 kn. That is a fairly big discrepancy. Is there an explanation for that, I appreciate one is marine and one is not, but I haven’t noticed it being like that before.

There are some pre-conceived ideas about gusts that are ill-founded. I would not regard 15 with gusts to 26 as unlikely. I have seen actual reports of gusts being twice the average wind. Given the quality of Met Office scientists, I suspect that their gust forecasts should no be disregarded. A good source of latest actual data is Meteociel - Observations des rafales de vent en Royaume-Uni en temps réel. Select a location to get a table of recent data.
I did this just now and happened on Sligo Airport. See the image attached. Gusts nearly double the mean wind!

 

[franksingleton]

ECMWF has always been a separate organisation. MET is a UK organisation whereas ECMWF is European cross government (The European Centre for Medium-Range Weather Forecasts) albeit based in Reading.

Correct. ECMWF is, in effect, owned by (mainly) European weather services. There are exchanges of staff through secondments and, sometimes full time.
The countries involved are shown on ECMWF

 

[franksingleton]

At 00 UTC today, Tiree reported wind of 20 km/hr with gusts 45 km/ht. Some of you would have poured scorn on that had it been a forecast

 

[Ammonite]

I don't think anyone is saying that is extreme, just that there are seemlingly a lot more F2 gusting F6 and F3 gusting F7 type forecasts than there used to be, which are often not reflected in the other models and not in sites like predict wind that use the metoffice data. For example, the metoffice site is showing gusts to F9 on Saturday lunchtime for Portsmouth and the U and U2 models are showing F5/F6 on predict wind for the same period. Unfortunately I don't know if this is just a timing difference when it comes to updates on this occasion

 

[dunedin]

At 00 UTC today, Tiree reported wind of 20 km/hr with gusts 45 km/ht. Some of you would have poured scorn on that had it been a forecast

No, not considered unusual (a) in the stormy weather system passing today (b) in Tiree, one of the most exposed / low lying and hence windiest locations in the UK, (c) in October.

But still doesn’t explain the sudden change in the UKHO gust forecasts in July / August in more sheltered locations such as the Clyde.

Yes there are alsoways some risks of gusts. But it is a waste of expensive super computers to have a next day forecast for weeks on end with wind forecast such as 6-8 mph gusting 20-26 mph.
As noted, I could print that on a laminated sheet of paper and use that as a daily forecast and be accurate 80% of the time. But equally no use to man or beast - certainly not a sailor considering whether to venture out.

Incidentally, what is the definition of a gust forecast - the strongest instantaneous gust, even if just for a second or so (which may be captured as Wind Max on my boat instruments), or some sort of percentile to avoid over distortion?