mountain forecast comparison

Mon, Dec 4, 2006

I’ve been using Geoff Monk’s Mountain Weather Information Service now for the last three years and found it to be a pretty damn good resource. It certainly beats spending a fortune phoning an advice line or even, in the old days, getting a fax. On my ML training, we compared it against other forecasts and it can be a little on the more doom side of gloom. It sometimes errs on the side of armageddon. The BBC Radio Scotland outdoors forecast was the most reliable and many a time I’ve huddled in a tent at 7pm, to get the forecast for the following day. But that’s only to be expected as it’s an up to the minute forecast, whereas MWIS comes out at 4pm. 3 hours doesn’t really make that much difference though.

For beginners though, MWIS is a good resource. It even describes the effects that the predicted weather will have on you. It also has a two day extension so you can plan the weekend and also a week long look at what’s coming.

Now, the Met Office want in on the act and are preparing to bid for a new funded service. So I decided to take a look and see what the differences were. When I first heard it though, I couldn’t help thinking it was the result of desperation on behalf of the Aberdeen Met Office, which was almost closed. Are they eyeing up MWIS to add to their portfolio to justify their existence? I don’t know but their forecast is here if you want to follow along.

The first problem I encountered was getting the North West Highlands forecast. The Met Office (MO) don’t have one. The Met Office have 5 areas in the forecast. MWIS have 5 for Scotland alone, plus another 3 for England. So that’s a tick for MWIS. Straight away I have an inferior forecast. The MO have just sliced Scotland down the middle, east/west. So I now get to share the Cuillin/Torridon forecast with the Arrochar Alps. That’s helpful, not!

The next issue is the MO only issues forecasts for daylight hours but to be fair the MWIS one doesn’t state the hourly range, so we’ll call that a draw. No ticks awarded.

The general summaries are different however. The MWIS North West Highlands gives a summary of UK mountain weather for that day, which I’ve always found pretty pointless when I want a NW forecast. The MO summary is a summary for the West Highlands, i.e. the forecast area. So although it’s too large to be of much use, it’s less broad than the MWIS and so it wins here. A tick for MO.

Now the forecasts start to diverge. MO, covering the whole of western Scotland says the wind will be gusting 70mph. MWIS, covering the NW Highlands, is more precise at 90mph. That’s a 20mph difference! I could just about hang on at 70mph, as I did this morning trying to get the car door shut but at 90mph I’d stay in the pub. So that’s a tick for MWIS. I’m presuming that each forecast is equally professional and any discrepancies are due to coverage and therefore granularity of the forecast.

The same goes for cloud cover. The MO forecast is just too big to tell me local conditions. For example, today MO are forecasting 900 - 1100m cloud base, falling to 600m in rain. MWIS saying bases will be at 400 - 700m lifting to perhaps 900m. So MO are saying a lot of Munro tops will be clear while MWIS is saying the opposite. Another tick for MWIS.

The visibilities differ, though only slightly. In keeping with the more hand waving forecast of MO, they say “good becoming moderate … poor in snow”. MWIS says “widely very poor … near zero in snow”. Slightly more quantative. Poor and near zero and quite different things when you’re tired and wandering about the hill looking for the way down. But they’re almost the same. A tick each I think.

Next comes temperature and wind chill. MO don’t give the wind chill. They just say “severe wind chill” What does severe mean? MWIS quanify it - “will feel closer to -17 in wind”. Also MO don’t actually give the temperature. They say “temperatures at or near freezing at 900m”. MWIS say “1C at 900m”. MO say the freezing level is 900 - 1100m, MWIS says 1050m. So a tick for MWIS for being slightly more accurate and less hand-wavy.

The outlook from MO is poor. They condense everything into three headings so it’s even less use for the NW highlands and the day after is just as poor. There’s just not enough information. If you’re heading into the hills for the weekend, you can take the Friday MWIS forecast with you and you’ll have an equally detailed forecast for Sat/Sun. With MO, you’d have to get to a computer! So that’s a big tick for MWIS.

Finally, MWIS provides a longer weekly outlook, which MO doesn’t have. So another tick for MWIS.

And what’s the score?

MWIS : 7, Met Office : 2

The Met Office forecast covers a far too large area to be of any real use, for me anyway.

That’s quite a discepancy. No doubt others will come to different conclusions but I know what I want, having had it for the last 3 years and the Met Office aren’t going to give me what I want. That’s plain to see, or not, depending on the forecast.