Munro Weather Forecasting

[kilima36]

Hi - Im quite new to climbing Munros and recently I've found quite a difference in the strength of the wind between the walk in and lower slopes to what I then expereince as I get closer to the summit. I climbed Ben Lomond last Sat and the wind was very strong at the top.

I'm used to checking BBC Weather for my normal day to day stuff but now that we're into autumn and approaching winter can I ask what weather forecasting you access when climbing.

I appreciate we are all different when considering personal risk as well as having different climbing experiences. I also appreciate the weather can be changeable and you do have the option to stop and turn back as well as some climbs being more exposed than others. But in regard to strength of wind do you have a mph and + that then stops you from starting that particular climb.

The reason I ask is that as we walked in another couple said words to the effect that we were 'brave' attempting the climb. I thought it a bit odd until we got closer to the summit and then appreciated the difference in the strength of wind. In essence I'd gone into the climb blind and therefore this became less enjoyable for my wife. We did mange to summit but I'm keen to be better prior aware and therefore more climb prepared to reduce avoidable risk and a potential burden on others e.g. MRT.

[kilima36]

Just seen the Saftey tab and weather forecasting options e.g. MWIS.

[Mal Grey]

Just seen the Saftey tab and weather forecasting options e.g. MWIS.

Hey

Yes, MWIS gives you a good idea of what conditions will be like on the summits. There's also an app that uses MWIS and others, plus stuff like avalanche info, that is very useful: MWUK (Mountain Weather UK).

I use both these, and the general weather forecasts from the Metoffice, XC Weather, BBC and yr.no. I look at others too, but those are my main choices.

Wind direction is also very much key, as you may climb the more sheltered side of a hill to come out into a real hoolie on the tops.

[jmarkb]

But in regard to strength of wind do you have a mph and + that then stops you from starting that particular climb.

For me, roughly speaking (for mean summit wind speeds, not gusts):

30-40 mph - OK, but I would avoid exposed scrambling terrain (e.g. Aonach Eagach, Liathach pinnacles).
40-50 mph - Mostly OK, but make route choices that avoid long distances on the tops and narrow ridges, and have the wind behind me if possible.
50-60 mph - Getting dubious - more careful route choices - avoid any steep, rocky or bouldery terrain where being blown over might cause injury. Think about doing short days, lower hills, easy grassy terrain or good paths, and sticking to the sheltered side of the hill if possible.
> 60 mph - Forget it - low level walks (or the tea shop) only!

[Mal Grey]

But in regard to strength of wind do you have a mph and + that then stops you from starting that particular climb.

For me, roughly speaking (for mean summit wind speeds, not gusts):

30-40 mph - OK, but I would avoid exposed scrambling terrain (e.g. Aonach Eagach, Liathach pinnacles).
40-50 mph - Mostly OK, but make route choices that avoid long distances on the tops and narrow ridges, and have the wind behind me if possible.
50-60 mph - Getting dubious - more careful route choices - avoid any steep, rocky or bouldery terrain where being blown over might cause injury. Think about doing short days, lower hills, easy grassy terrain or good paths, and sticking to the sheltered side of the hill if possible.
> 60 mph - Forget it - low level walks (or the tea shop) only!

I'm a bit wimpier than that these days! Though I have wild camped in gusting 60+, and was once crawling up the Drumochter hills when the Cairngorm weather station recorded a gust of 150mph...

I'd personally move each of your categories down 10mph, but that's for me these days when I'm older, and in the past we'd happily make attempts on rounded hills in any wind.

[Andy Milne]

The Met Office app (and website) gives you a forecast for most hills.
Type in the name of the hill you are looking at (not all the hills are shown, so look at a slightly higher but very close by hill) and it gives you wind speed plus gust speed for the summits, along with visibility, precipitation and feels like temperature.

MWIS covers such a large area, it is a good guide, but I have used this only to find it wasn’t as accurate as the met office forecaster.

[kilima36]

That's been really helpful and it is appreciated. I've downloaded MWUK, MWIS and the Met Office apps now and feel more prepared (mentally at least) for my climbing tomorrow west of Tyndrum.

Thanks jmarkb for your advice on wind speeds as that gives me a baseline to work from as I gain more expereince. Also thanks Mal Grey as I hadn't picked up on wind direction which was also confirmed by jmarkb. My route planning is very much at the early stages so again hopefully with more experience I can factor in different variables to inform my route choice.

Thanks again for all your advice

[simon-b]

The Met Office app (and website) gives you a forecast for most hills.
Type in the name of the hill you are looking at (not all the hills are shown, so look at a slightly higher but very close by hill) and it gives you wind speed plus gust speed for the summits, along with visibility, precipitation and feels like temperature.

MWIS covers such a large area, it is a good guide, but I have used this only to find it wasn’t as accurate as the met office forecaster.

Agreed, this is a useful service from the Met Office. Also worth pointing out it's usually the name of the summit that's given, which can be different for the name of the hill commonly used. So eg for Ben Wyvis type Glas Leathad Mor, and for Liathach type the names of the individual summits, etc.

[jmarkb]

Agreed, this is a useful service from the Met Office. Also worth pointing out it's usually the name of the summit that's given, which can be different for the name of the hill commonly used. So eg for Ben Wyvis type Glas Leathad Mor, and for Liathach type the names of the individual summits, etc.

It's useful, but it is worth noting that, unlike MWIS and the Met Office mountain area forecasts, the hill-specific forecasts are automatically derived from the computer forecast models with no human intervention, and I would not recommend using them on their own, or reading too much into differences between nearby hills of similar height. The wind and temperature forecasts are likely to be reasonably OK, but the precipitation and especially visibility forecasts should be taken with a fair pinch of salt.

[Scraggygoat]

Knock 10mph off the suggested rule of thumb given above, it’s easy to overestimate the winds strength, or conversely underestimate its affect.

Also MWIS tend to overestimate winds speed, skewing perception, they have swallowed the mountain safety shilling being very conservative and cried wolf too often. In time you will learn to recalibrate / adjust. But for now read and consider them, & compare with other forecasts.

Given its now nearly winter don’t forget as soon as you get snow, spindrift or hail in your face carried on the wind it’s painful even at lower speeds; Goggles are good, but goggles can’t help if the ground is slippy, either soaking wet or partly iced / frosty where if caught by a gust you might get blown over when normally you’d be fine.

On the met office website search/look for specialist forecasts this will give a regional detail for the next day by height and outlook for the following days. There is also a map link so you can get forecasts for a number of predetermined summits.

[al78]

Also MWIS tend to overestimate winds speed, skewing perception, they have swallowed the mountain safety shilling being very conservative and cried wolf too often. In time you will learn to recalibrate / adjust. But for now read and consider them, & compare with other forecasts.

How do you know they have a high bias? Have you compared their forecasts with the limited mountain weather station observations?

[Scraggygoat]

Yes I have, and you also have to consider that they commonly forecast for the worst outcome in their large geographic areas which overall means for the majority of the forecast area they will be high. But MWIS would counter argue if that speed has occurred anywhere within the forecast area they were correct.

If you ask a group of regular Scottish hill goers or MRT you will likely get the same opinion. That doesn’t mean we ignore it, but you will find it’s a widely held opinion .

[jmarkb]

Knock 10mph off the suggested rule of thumb given above, it’s easy to overestimate the winds strength, or conversely underestimate its affect.

Fair comment, especially for the relatively inexperienced, and for smaller, lighter people who will suffer the effects of the wind more noticeably.

It is quite instructive (and fun!) to measure actual windspeeds on the hill with a wee hand held meter like this: https://www.skyview.co.uk/products/jdc-skywatch-xplorer-1-jdc-xpl-1

[al78]

Yes I have, and you also have to consider that they commonly forecast for the worst outcome in their large geographic areas which overall means for the majority of the forecast area they will be high. But MWIS would counter argue if that speed has occurred anywhere within the forecast area they were correct.

If you ask a group of regular Scottish hill goers or MRT you will likely get the same opinion. That doesn’t mean we ignore it, but you will find it’s a widely held opinion .

Fair enough. A forecast that covers a region isn't the same as a forecast for a point, so a peak wind speed forecast for the Cairngorms will likely occur on Cairngorm summit or one of the other 4000'ers if it validates. There is also uncertainty on the forecast so a deterministic forecast is the most likely outcome, not a guarenteed outcome. I would expect occasionally for the forecasts to underestimate the peak wind speed, since uncertainty goes in both directions.

[davekeiller]

I'd broadly agree with the wind speed suggestions above.
I can stand up in 60mph wind, but wouldn't really be able to walk very far in it.

As to MWIS forecasts, they probably do err on the side of caution with wind speeds. Wind is more likely to keep you off the hills than precipitation, low cloud or poor visibility. If the forecast says 60mph wind and it's only 50, then you'll make a safe decision. If it's the other way around, you're more likely to get into difficulty.