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And snow! Get ready for a wet n wild week at the White Pass. Mild temps, strong winds, plenty of precipitation. Trade those handwarmers for some GoreTex.
…but not just yet. The temperature inversion (see post below) has broken down amidst the recent North winds. Another few cold, clear days take us into the weekend, ahead of incoming weather and a change in the temperatures. A couple of great improvements from the December 24th forecast:
So expect same same weather for the next few days - cold temps, clear skies, light to modearate winds from the south and … ZERO precipitation.
As we move into the weekend we will probably see more unsettled weather, overcast skies, moderating temperatures and a little snow.
If you want to get out and ski, I’d strongly recommend SIMA, which seems somewhat protected from the cool temps
You could head down the Wheaton valley, also, as temperatures are a little milder. But I don’t think you want to ski there
At Mt Sima (1180m) 0700, 261217, We had clear skies, light Southerly winds and 0 precipitation. We received 0cm snow in the last 24hrs. Current height of snow 46cm. Temperature was -18 with 48% Humidity. Pressure was 1025 Mb with a falling barometer.
At Whitehorse airport (706m) 0700, 261217, We had clear skies, light Southerly winds and 0 precipitation. Temperature was -31 with 68% Humidity. Pressure was 1025 Mb with a falling barometer.
Have a great day, pray for snow. Steve
I’ll start the blog with some observations which tell a story…
At Mt Sima (1180m) 0700, 241217, We had clear skies, light Southerly winds and 0 precipitation. We received 0cm snow in the last 24hrs. Current height of snow 46cm. Temperature was -8.1 with 33% Humidity. Pressure was 1027 Mb with a falling barometer.
At Whitehorse airport (706m) 0700, 241217, We had broken cloud, light South Easterly winds and 0 precipitation. Temperature was -28 with 75% Humidity. Pressure was 1027 Mb with a falling barometer.
These observations shouldn’t come as a big surprise to those of us travelling in the mountains - it has been REALLY cold downtown, but as soon as you gain some elevation temperatures moderate. Yesterday I saw the most dramatic incarnation of this I’ve ever witnessed - as documented in the MIN report. -27 at the road, -4 at treeline.
The explanation, though initially counter-intuitive (it gets colder as you go up, right?) is pretty straightforward: Throughout the region we are seeing a widespread temperature inversion. A temperature inversion is simply where a layer of warmer air overlays a layer of colder air. This colder air will often have a significantly higher relative humidty, as in the observations above, as colder air cannot hold as much moisture as warm air. In turn this produces valley fog, or low level cloud (as in the image above).
These inversions have a number of causes, from Ground inversions (air cools by coming into contact with colder ground, this is what often gives foggy mornings) to Frontal inversions (air masses over-riding one another). They can often be quite persistent, as the cold air becomes trapped in valley bottoms and struggles to escape with a warm air ‘cap’ above it. Which brings us to…
Deja-vu: A high pressure to the North of us continues to dominate - expect Northerly outflow winds and steadily declining temperatures:
-45 for New Years Eve? Lovely. Ahead of rapid warming as a storm pushes into our area January 2nd (maybe - thats a long way out!).
I’ll be interested to see if the inversion dislodges with the expected weather between now and the new year. Staying high might keep you warmer. Expect 0 precipitation for the forecast period.
Hot Zone Report is out here
Two distinct storms in the past week brought a welcome refresh to our snow, and temperatures have dropped, meaning it certainly feels a bit more like winter.
A high pressure is building to the North of us - expect possible outflow winds and steadily declining temperatures:
Beyond that models are inconsistent with low confidence in the forecast. Likely see some weak weather move in on Monday with light snow in the White Pass, in Whitehorse this will probably just equate to gray skies. Isobars are broadly spaced amidst all this, and I wouldn’t expect anything too exciting between now and Boxing Day.
At Mt Sima (1180m) 0700, 211217, We had clear skies, moderate Westerly winds and 0 precipitation. We received 2cm snow in the last 72hrs. Current height of snow 46cm. Temperature was -8.6 with 52% Humidity. Pressure was 1033 Mb with a rising barometer.
First Hot Zone Report is out here
MIN from recent Log Cabin visit here
Stormin’: Expect unsettled conditions this weekend, with high winds (NOAA is predicting 50kmh + for the South Klondike) and moderate precipitation as a storm moves through our area. We should see clearing skies on Monday/Tuesday ahead of a much weaker storm arriving late Wednesday. Temperatures over the period will start to return to seasonal norms (expect -5 - -15 for the week).
NOAA has a weather advisory out for White Pass.
Snowfall amounts are tough for this one. I’m new enough to the region, and we have such a large and varied area that I’d take anything I claim here with a pinch of salt… So… For the first storm (Sat/Mon) NOAA (US weather) says 15 to 20cm for the pass. I think that’s optimistic, so I’ll say 10-15. GEM-LAM says 14.5. In town I’d say 10cm is quite possible (and with these wind speeds you’ll never prove me wrong muwhahahaha).
At Mt Sima (1180m) 0700, 151217, We had broken skies, moderate southwesterly winds and 0 precipitation. We received 5cm snow in the last 72hrs. Temperature was -2.6 with 56% Humidity. Pressure was 1006 Mb with a rising barometer.
First Hot Zone Report is out here
A resilient ridge (more on that later) has built over the Pacific West coast. This is maintaining unseasonally warm air and dry conditions from California right up to Vancouver Island and deep into the BC interior. Locally we are sitting in a South/South Westerly flow at the top of this ridge.
Locally this means unseasonally warm conditions, with moderate to strong winds. BUT while the unseasonably warm temperatures across the territory have some lamenting (or celebrating) the end of winter before Christmas, the ridge may actually be a blessing in disguise for us Northerners. Multiple storms and low pressure events in the Aleutian gulf are blocked from their usual southerly path, and instead channeled right into our backyard:
So, for the forecast (from now until Wednesday): Expect moderate southerly winds, peaking Monday morning, unsettled conditions, with a brief break overnight into Tuesday and light precipitation. Temperatures will cool over the forecast period. White Pass may see quite intense precipitation with up to 20cm of snow over the coming days.
At Mt Sima (1180m) 0700, 081217, We had broken skies, moderate southerly winds and 0 precipitation. We received 0 snow in the last 24hrs, with very light rain briefly yesterday morning. Temperature was +2.1 with 45% Humidity. Pressure was 1008 Mb with a falling barometer.
Ski hill open this weekend, and conditions yesterday were fantastic. Particularly given our absence of snow anywhere else, come spin some laps!
Have a great weekend! Steve
The weather isn’t super interesting at the moment: It was COLD, then it warmed up, it’s going to go back to being cold for a day or two, then very warm (like + temps.). We’ll get a bit of precip. but not much. That being said, do you wanna hear about Surface Hoar? I know I do…
Last night built some really spectacular surface hoar on open aspects at 1180m:
Erm, lovely, so what does that mean?
Well, surface hoar is fancy words for frost. It sure is pretty. But what is it, and why is it important? Well, here’s the nerd stuff on Surface Hoar. But, if you can’t be bothered with that, here’s the ‘Cole’s notes’ (TM):
Surface Hoar forms on cool, clear, humid (relatively), calm nights by water vapour condensing on the surface of the snow. It generally needs clear skies (i.e. not in forested areas, no cloud cover) to form. And it builds these beautiful feather or wedge like structures on the surface of the snow.
But should you care? It depends. Surface Hoar is not a problem. Until it is a problem. On its own, Surface Hoar is pretty benign. But, if conditions remain calm until more precipitation falls, the new snow will layer on top of those pointy Surface Hoar structures. Spatial variability is key - in one area, Hoar may not have developed, in another, it may have been knocked down by wind, but, in a third, it may have grown and then seen layered snow on top. Herein lies the problem: The Hoar layer will support the snow (think about putting playing cards on end and then stacking a baking sheet on top of them). However, impart a force laterally to this baking sheet (snow) (like a skier or whatever…) and the Hoar layer may collapse, like the playing cards in the analogy. And like this…
Depending on a number of factors, buried Surface Hoar can become a persistent weak layer in a snowpack, that is difficult to detect, and may linger for a long time. Ever heard a ‘whumpf’ when travelling on snow? That could have been a buried Hoar layer collapsing.
Argh! Now I’m scared!
Right? Well, don’t panic just yet… Instead, if you’re travelling in the mountains in the next few days, look for this pesky beast. Where is it? Where isn’t it? Get those MIN reports in here. Even if you’re out walking the dog in town, take a look at spots where Surface Hoar grows fast (besides creeks is a classic), so you can better identify it in the backcountry. And let’s see what the next weather system gives us.
At Mt Sima (1180m) 1200, 011217, We had clear skies, calm winds and 0 precipitation. We received 0 precipitation in the last 24hrs. Temperature was -9 with 79% Humidity. Pressure was 1006.5Mb with a rising barometer.
Have a great weekend! Steve
Well, the charts say one thing, the forecast says another… Low pressure in the gulf of Alaska will see cloudy skies, unsettled conditions and light precipitation prevail through the day
Where it gets interesting is Sunday:
Which I think looks like: Clearing skies, SW winds. The forecasts seem to think N winds and continous cloud cover. Who will win!?
Currently it is -19 at the airport (77% RH), under an overcast cloud deck, with light Northwesterly winds.
As predicted the last system deposited snow across our region, and was accompanied by good transport winds. Widespread scouring in ‘fetch’ areas and pressed, wind affected snow in ‘lee’ terrain was observed at treeline yesterday. If you are venturing out into the mountains this weekend keep that in mind. Caution should certainly be excercised on lee aspects (broadly SE in this storm, but be aware that local terrain features may change that). Quick windslab definition here.
Well, it’s still cold. Which is better news than what’s about to happen down south:
An ‘atmospheric river’ has taken aim at the BC/WA coast. They can expect record breaking temperatures and up to a foot of rain! With 3000m freezing levels.
Up here we will continue to see frigid temps and light precip. but, heck, at least we don’t have to worry about flooding.
Expect clearing skies and no precipitation for today. It’ll remain cold. From Wednesday onwards we maybe start seeing some more interesting weather - the 500mb suggests unsettled conditions for the passes and even town:
But looking at the ‘Precipitable Water’ for the same period is less optimistic:
This confused picture is reflected in the weather model precipitation amounts. In summary: