Advice on accurate weather forecasts

[christopherwalkin]

Hi all!

I'm planning Ben Wyvis on Sunday (18/8/19) and I'm just wondering which website people use to get their forecasts from?

I'm hoping the weather stays fine, but I'm getting conflicting results from various websites.

Thank you!

[SummitStupid]

Loads of nerdy weather stuff here:

https://www.walkhighlands.co.uk/Forum/viewtopic.php?f=1&t=90408

but otherwise just have faith in MWIS.

[mynthdd2]

MWIS every time

[Marty_JG]

I use MWIS and so far it has at least a 50/50 success rate.

[Fractral]

I tend to look at both MWIS and the Met Office Mountain Weather pages (and their summit specific forecasts, but those are usually only usefully accurate a day in advance). If they agree then they're probably right; if they disagree then I tend to go with the optimistic one.

[Coop]

I tend to look at both MWIS and the Met Office Mountain Weather pages (and their summit specific forecasts, but those are usually only usefully accurate a day in advance). If they agree then they're probably right; if they disagree then I tend to go with the optimistic one.

As above

[johnscot55]

Just try and get as much info as possible. I google "mountain name"weather and open all the main results I get (met office, mountain-forecast.com, etc) and compare, see who agrees etc. Also MWIS which is more area info. Just remember none of them 100% accurate. Take last Saturday (10th), Ben Nevis was supposed to have wind, rain, poor visibility and possible thunder storms, none of which happened.

[davekeiller]

I find MWIS to be the most reliable, although it's worth looking at the met office too. Looking at a surface pressure chart can also be helpful - it can give an indication of why the forecasters are making their predictions and can give an idea of how changeable the weather might be and whether you're likely to be on the edge of bad weather.

[mynthdd2]

......am assuming MWIS gets the basics from the Met Office then tweaks a few extras in eg effect of altitude etc as for example Met Office ‘wind chill’ is defined at a 2m height?

[jmarkb]

......am assuming MWIS gets the basics from the Met Office then tweaks a few extras in eg effect of altitude etc as for example Met Office ‘wind chill’ is defined at a 2m height?

MWIS likely uses other model data as well at the Met Office (for example the US-based GFS model, whose output is all freely available, unlike the Met Office). There is quite a lot more to it than just taking a low-level forecast and adjusting for altitude, especially for cloud bases. There are ruls of thumb

I'm surprised that it's not universally known that the Met Office issue a mountain specific forecast -https://www.metoffice.gov.uk/weather/specialist-forecasts/mountain - I guess it's not that easy to find by browsing their website, and it's not available on their phone app.

What sets the MWIS and Met Office mountain weather forecasts apart from anything else is that a human forecaster is involved, and not just an algorithm.

[al78]

I used a combination of MWIS and the Met Office when I was up in Fisherfield back in June. It helps to obtain different forecasts, as this will give an idea of the uncertainty. Sometimes local knowledge will be useful as well. When I was at the campsite in Poolewe, I had two conflicting forecasts for the day I set off across Fisherfield, one rain most of the day, one dry until the evening. The man who runs the campsite said it would be dry until about 3pm, and that turned out to be the most accurate. The thing to remember is that the weather in Scotland is heavily modified by the orography, and weather can vary considerably over very modest distances. This small scale variability increases the uncertainty. Most weather forecast models can't directly resolve down to sub km scales required to model orographic induced flow directly. Looking at the surface pressure maps will give a general overview. If a low pressure system is sat over you, the weather is going to be unsettled, and potentially wet.

[iain_atkinson_1986]

Use a combination of MWIS, Met Office and BBC News. Controversially I find the BBC to be the most accurate. Just use the satellite map as close to the walk as possible and if there's a lot of blue you'll get wet.

[christopherwalkin]

Thanks so much for all your helpful replies everyone! These will most definitely come in handy.

I think it's going to be a bit rainy for my first Munro (Ben Wyvis) on Sunday though by the looks of it. Best pack my swimming cap!