The sustained thaw of recent days has been steadily weakening the ice that had kept it’s wintry grip on Loch Morlich for 94 days and alas the overnight gales coupled with rising water levels eventually fractured the weakened ice and within hours the Loch was open and choppy, once the ice fractured the wind and increasing waves accelerated the break up.

^Loch Morlich remains ice bound at dusk on Thursday.

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^But by late morning the Loch was free from the grasp of winter.

Sad in a way that the Loch did not remain frozen for another week to break the 100 day mark and it will seem slightly strange to look down from the ‘Gorm for the first time in three months and not see the white frozen expanse below.

The bit of good news for snowsports though is that the air temperature was back below freezing at the Summit late afternoon and dew points are below 0c and it’s dry, plus the wind is moderating. Snow should be setting up firm higher up and drying out and crunching up lower down - the thaw for now has relented.

Adam Watson reports that by the afternoon snow had stopped thawing and was firming up about 150-200ft above the car park level at Glenshee and at 2600ft the ground was still frozen where snow free. Frozen ground is as good as a base in that any new snow falling sticks straight away, it might almost be the Spring Equinox, but spring can stay on hold just now, we’re hopefully not yet done with winter 2010.

Well so says the sign at the door to the Meall Odhar Cafe…

Meall Odhar Cafe Sign.

If your sliding around CairnGorm Mountain (or any of the areas for that matter) this weekend, stop and have a look around and think what your sliding on, what does this terrain usually look like, what’s under my feet in summer?

Just how much snow might be under you feet will depend where you stand, gullies, burns and other terrain depressions will likely have the most, but let’s consider the Coire Cas Gunbarrel,  the T-bar track to be exact. Both of these photos though looking up from a different position and angle show the same tower of the Cas T-bar up-line nearest the camera.

Coire Cas Gunbarrel - going up the Cas Tow on Wednesday 3rd March:

Cas Gunbarrel on Wed 3rd March

The small orange roundels that give the tower number give a fixed point of reference, this allows the height from roundel to top of tower to be measured in each photo, giving a scale factor that means it’s possible to assess the relative portion of the tower still visible in the above photo.

On the photo below the red-line gives a representation of the snow surface level on the top photo:

Cas Gunbarrel on 11th December 2009

The snow fence up the track side is approximately 5ft and the tower base height is around 2ft on the uptrack side. Given these bits of info and from comparing the tower to the skiers in the top photo, an estimate of 10ft/3m depth on the tow track at that point would not seem unreasonable.

Will try and measure the roundel to snow surface height on this tower accurately in the coming days and rephotograph it - this will allow the above estimate to be verified with a more accurately calculated depth and will continue to monitor it.

Trying out the wordpress interface over a mobile gprs connection on Alvie Estate (of interest for a website I’ll be working on in the near future). You’d expect a basic html form to load in a few seconds, but the wordpress wysiwyg editor took over 4 minutes to load! Back to the drawing board for this one perhaps?

OK so nothing of much interest here as this is all uber geek gibberish, however some clear spells around Strathspey now, promising for Saturday.

Earlier in the Season I posted up that for Scotland as a whole, the December and January combination was the coldest such combination since Scotland wide records begun in 1914.

As 1st March is the official start of the meteorological spring in the UK and is used as such for climate data the provisional Scotland wide figures are now available for winter 2009/10.

Winter 2009/10 has been the coldest winter in Scotland since 1962/63 and surpasses 1979.

The provisional average temperature for the whole of Scotland for Dec, Jan and Feb 2009/10 is +0.24°c, the 1971/91 average is +2.7°c and the provisional figure is just +0.08°c above 62/63.

Following winter 2008/09 the Met Office had the following to say:

http://www.metoffice.gov.uk/corporate/pressoffice/2009/pr20090225.html

“The cold weather has been in contrast to the run of very mild winter temperatures that have been recorded over recent years.

Natural variability of climate means that the UK will continue to see spells of colder weather at times. Although, if it had not been for the general warming already observed in global temperatures, this winter may well have been even colder.

Peter Stott, Climate Scientist at the Met Office, said: “Despite the cold winter this year, the trend to milder and wetter winters is expected to continue, with snow and frost becoming less of a feature in the future.

The famously cold winter of 1962/63 is now expected to occur about once every 1,000 years or more, compared with approximately every 100 to 200 years before 1850.”

Did you forget Valentines Day? Never mind, I forgot to post this on the day in question as well….

The 14th of February also marks the point of Thermal Mid Winter for Northern Scotland, the point when the rolling 30year average temperature at the 850mb height reaches it’s lowest level. Sea temperatures around Scotland are usually also lower than early in the winter, so cold air gets less modification as it passes over the sea towards us.  However this can mean less convective snow showers bubbling up over the sea as it requires colder air aloft to generate the same temperature gradient as earlier in the winter, this is part of why we’re getting bluebird days and not the repeated dumpage of late December from the current weather pattern.

As we move through the last couple of weeks of the official UK meteorological winter (in reality the astronomical definition of 21st Dec to 21st March is perhaps more useful for Highland Scotland) we start to move into a period where the Atlantic is traditionally quieter - the chances of big Atlantic storms starts to diminish. Hopefully the Atlantic hasn’t been saving itself up all winter so far!

As the days lengthen so the potential for convective showers start to increase, remember the April (Snow) Showers of 2008.  Dare we even hope for a 2001 or 2008 like spring after the season so far?

Wednesday 3rd February will mark another significant milestone in winter 2009/10, seven weeks of consecutive snow lie at even relatively low altitudes in places such as Aviemore. Indeed even here in Central Inverness, you need to go back the same 7 weeks to find a time when the immediate surrounds has been completely snow free and there is a light dusting of fresh this evening as well.

At least some patches of snow on the ground for 7 weeks at ~10m above sea level in Inverness… 7 days of snow lie is quite rare consecutively for low levels!

It’s now officially the coldest December and January period for Scotland as a whole since Scotland wide records begun in 1914. What about the Coldest Winter? Well we’re still a good bit short of the coldest recorded 2 month period and February would need to make the festive period look quite benign to get close the coldest winter record.

However, could this be the fabled Hale Winter everyone was talking about 2 or 3 years ago?

Fresh Snow in Aviemore.

Overnight a period very wet snow / sleet was followed by a sudden drop in temperatures, freezing the wet sticky snow solid to the anemometers on our CairnGorm weather stations at the SSC Hut and the Sheiling.

The Weather Stations were de-iced on Friday afternoon and should remain spinning freely while the temperature remains well below freezing. Problems usually occur when temperature is just around freezing and precipitation falling followed by a drop in temperature.

Iced up Anemometer at the SSC Hut.

De-icing the Sheiling Tow AWS.

Unfortunately the Glencoe webcams are off-line this weekend. This is due to a recurring hardware problem affecting communications, replacement parts are due to arrive on 1st Feb and it is hoped to have the Access Cam and SSC Hut cams back online by the middle of next week, in plenty time for the following weekend.

OK, this is just one distant chart from a suite of some 20 ensemble members from the GFS model, but it’s something pretty special none the less. Complete reversal of the mid latitude zonal winds, Easterly from one side of the chart to the other screaming across the UK.

If such a scenario were to happen it wouldn’t so much be weather, more a complete breakdown of the fundamental laws of physics! Did the Earth’s direction of rotation change?