North American Weather (U.S.A & Canada)

[Roger J Smith]

Lesta, we might have a better idea in a few days time, the average at that time would be similar to London, highs of 6-9 C and lows near 2 C with little chance of snow but rain fairly likely. But that's just the long-term average. The pattern developing looks rather mild to me with such a large cold outbreak heading south into central regions of N America, this usually induces a strong SW flow in the east coast regions.

I came on to post this -- a huge ridge is developing this weekend over the eastern Pacific through western Alaska, apparently some sort of response to the dissipating ice anomaly because very mild air and high thicknesses are heading somewhat bizarrely for eastern Siberia, while polar air is flooding south towards Vancouver here. All of western Canada is already quite cold but will turn even colder before a massive storm develops and shoves the cold air back inland. This will lead to 15-30 cms of snow across most of BC and Alberta as well as the inland Pac NW states, this weekend coastal, and Monday in Alberta. A brief chinook may develop south of Canmore, Rich, but I think you'll get hit by 15-25 cms of snow as well. It could drop to near -30 C at times before this storm moves in (even here it may reach -3 C).

This ridge extends by the weekend past the North Pole slightly and could signal that later in the winter, extreme blocking patterns of a trans-polar nature may develop and shove anomalously cold air over the pole towards Greenland and Svalbard, even Iceland and Norway. This could be the recipe cold-and-snow-lovers have been awaiting but I don't think it can take effect for quite a while yet, if the ridge builds further east and shoves the cold air away from west-central N America this will be helpful in Europe's quest for winter weather.

But this is a very auspicious start, the only reservation I have is that it might be like 1987 and come all at once for just a brief spell. But I suppose many would settle for that as compared to any of the alternatives. http://nwstatic.co.uk/forum/public/style_emoticons/<#EMO_DIR#>/huh.gif

[WhiteFox]

Lesta, we might have a better idea in a few days time, the average at that time would be similar to London, highs of 6-9 C and lows near 2 C with little chance of snow but rain fairly likely. But that's just the long-term average. The pattern developing looks rather mild to me with such a large cold outbreak heading south into central regions of N America, this usually induces a strong SW flow in the east coast regions.

Looks like a cold spell coming up before then though. Many forecasts have been calling for a colder first half of December with a developing trough across the East followed by a milder second half.

The ensemble mean for the GFS shows this:

Having said that there is a lot of noise in the ensembles (steep drop next week; spot the cold front anyone?):

Experience tells me that the period Lesta is talking about can oscillate wildly. Around the same time last year (albeit slightly earlier) we had close to -20oC 850 air overhead and max temperatures of about -2oC with a fierce NW wind and blistering windchill. A couple of days later it was 13oC and fairly pleasant.

Roger is correct that the average max is 7oC in mid-December, with lows averaging 0oC.

[Coopsy]

A brief chinook may develop south of Canmore, Rich, but I think you'll get hit by 15-25 cms of snow as well. It could drop to near -30 C at times before this storm moves in (even here it may reach -3 C).

Roger, every storm that has hit the west and travelled through has pretty much died out here this winter, what is different this time to help the snow survive through the rockies to us in Canmore? will the chinook help with this or is there additional mositure coming in from the south?

I can feel each day has been getting colder here....current temps at 6:30pm is minus 16oC, gonna be a cold one tonight

[Roger J Smith]

I'm only John Smith when checking into certain hotels ... but in any case, latest output suggests that Sunday night into Monday very heavy snow across the Rockies and southern Alberta spreading north, potential for 20-40 cms in Calgary area, changing to sleet or freezing rain at times then slightly milder, main chinook will remain south but by Tuesday 1-3 C transitional air mass oozing north of Canmore to central Alberta, then front weakens and drifts back south late Tues into mid-week, more freezing drizzle or light snow then too.

[Coopsy]

Thanks for that Roger, will be an interesting few days for sure...minus 24oC overnight but no wind so feels quite pleasant

[johnholmes]

how about this you two

SNOW WILL BECOME WIDESPREAD THIS AFTERNOON AND THEN CONTINUE

THROUGH SATURDAY NIGHT. SNOW WILL BE HEAVY AT TIMES TONIGHT AND

SATURDAY MORNING. SNOWFALL ACCUMULATIONS FROM 1 TO 3 FEET ARE

EXPECTED BY LATE SATURDAY NIGHT. THE GREATEST SNOW ACCUMULATIONS

WILL OCCUR ON SOUTH AND SOUTHWEST FACING SLOPES...WHERE LOCAL

SNOW ACCUMULATIONS UP TO 5 FEET ARE POSSIBLE.

parts of Colorado

also this winter weather wtch with warnings of heavy snow

lots on here will be very jealous!

Edited November 30, 2007 by johnholmes

[Coopsy]

Now thats what I call a proper storm...I am moving lol

[Roger J Smith]

This is still looking quite impressive on the latest model run ... it's the classic situation where a strong low runs into a deeply entrenched arctic air mass and slowly loses its circulation but not before it dumps huge amounts of Pacific moisture over the Rockies and other ranges. I still think southern Alberta is going to get a heavy snowfall out of this from Sunday afternoon to late Monday, as well as most of southern BC, but it looks like here on the coast, we will get 10-20 cms on Sunday before it turns to rain late Sunday evening and then we can expect rain all day Monday with possibly 75 to 125 mms, so with 30 cms of snow on the local hills before that starts, massive amounts of floodwaters will be coming down the local rivers and creeks by Monday, there could be some pretty nasty mudslides and urban flooding from this. Into the BC interior it will be an ungodly mess because the mild air will have extra trouble scouring out the cold air trapped in north-south valleys so freezing rain seems quite possible on Monday. I would not be surprised if a lot of highways are closed across southern BC and Alberta at some point on Sunday and Monday.

The odd thing is that we had our only big snowstorm of last winter in late November here, after which it only snowed an inch or two a couple of times.

Somehow with this huge blocking high to our north I think we'll be seeing more snow this winter than in most of the past twelve that I have lived here, the only really snowy winter we had was 1996-97 but before I moved out here there were much snowier winters according to the climate data, not every year, but more often than in the past twelve years for sure.

Take care, Rich, it may become quite treacherous on the roads by Sunday there. But as you say, you can't beat the clear, cold weather for bracing conditions and fabulous views of the mountains. Friday was clear around here and the snow line is down to 400 metres now, the north shore mountains look quite wonderful against the blue sky with all this fresh snow on them.

[WhiteFox]

Big assed winter storm moving across the US right now. A very potent system indeed sucking up some very mild air and colliding with the much colder airmass as pointed out by Roger:

LLINOIS-OGLE-LEE-DE KALB-KANE- DUPAGE-COOK- INCLUDING THE CITIES OF... ROCKFORD...WOODSTOCK...WAUKEGAN... OREGON...DIXON...DEKALB...AURORA... CHICAGO 1054 AM CST SAT DEC 1 2007

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL MIDNIGHT CST TONIGHT...

A WINTER STORM WARNING REMAINS IN EFFECT UNTIL MIDNIGHT CST TONIGHT.

DAMAGING ICE ACCUMULATIONS AND STRONG WINDS LIKELY LATE THIS AFTERNOON AND EVENING.

SNOW AND SLEET...MIXED AT TIMES WITH FREEZING RAIN WILL OVERSPREAD NORTHERN ILLINOIS DURING THE EARLY TO MID AFTERNOON. PRECIPITATION WILL LIKELY TRANSITION TO ALL FREEZING RAIN BY EVENING. FREEZING RAIN WILL FALL RATHER HEAVILY AT TIMES RESULTING IN RAPID ACCUMULATIONS OF ICE ON TREES... POWERLINES... AND UNTREATED ROADWAYS.

SNOW AND SLEET ACCUMULATIONS OF 1 TO 3 INCHES ARE POSSIBLE THIS AFTERNOON... PARTICULARLY ALONG THE WISCONSIN BORDER. HOWEVER...OF MUCH GREATER CONCERN IS EXPECTED DAMAGING ICE ACCUMULATIONS. ONCE THE PRECIPITATION CHANGES TO FREEZING RAIN...ICE ACCUMULATIONS OF ONE QUARTER TO ONE HALF INCH WILL BE COMMON...WITH SOME LOCATIONS PICKING UP ONE HALF INCH TO ONE INCH OF ICE ACCUMULATION BEFORE TEMPERATURES RISE ABOVE FREEZING.

SOUTHEAST WINDS WILL INCREASE TO 20 TO 30 MPH WITH SOME GUSTS APPROACHING 40 MPH THIS EVENING. ICE ACCUMULATING ON TREES AND POWERLINES WILL WEIGH THEM DOWN MAKING THEM EXTREMELY VULNERABLE TO THE STRONG WINDS AND LIKELY RESULTING IN POWER OUTAGES. THIS IS A POTENTIALLY DANGEROUS SITUATION...THE POTENTIAL EXISTS FOR WIDESPREAD AND PROLONGED POWER OUTAGES ACROSS THE WARNING AREA.

IT ONLY TAKES A SMALL AMOUNT OF ICE ACCUMULATION ON UNTREATED ROADWAYS TO MAKE TRAVEL NEARLY IMPOSSIBLE. THE STORM IS QUICKLY APPROACHING AND PREPARATIONS FOR THIS WINTER STORM SHOULD BE RUSHED TO COMPLETION. PERSONS IN THE WARNING AREA SHOULD BE PREPARED FOR THE POSSIBILITY OF SEVERAL DAYS WITHOUT POWER. STOCK UP ON NON-PERISHABLE FOODS... FLASHLIGHTS...BATTERIES...AND MEDICATIONS IN THE EVENT OF PROLONGED POWER OUTAGES.

A WINTER STORM WARNING MEANS SIGNIFICANT AMOUNTS OF SNOW... SLEET... AND ICE ARE EXPECTED OR OCCURRING. STRONG WINDS ARE ALSO POSSIBLE. THIS WILL MAKE TRAVEL VERY HAZARDOUS OR IMPOSSIBLE.

I'm travelling to Chicago tomorrow; could be some delays I'm thinking!

[WhiteFox]

Snow has now changed over to freezing rain through the centre of the storm:

[Coopsy]

Once again it looks like the storm that hit BC will not be affecting us here in southern Alberta. Forecastors go with a few flurries. Thats been the story of the winter so far here.

Roger, how did you fair...bet its been a messy day or so for you there...are you into the rain yet or is it still snow?

[Roger J Smith]

Rich, there was about 3 inches of packed powdery snow on the ground here at 0730 when I first looked out ... it had not snowed much overnight ... now it is coming down in very large flakes and looks to acccumulate another 2-3 inches by noon, at which time I think it may turn over to ice pellets or freezing rain. Then heavy rain is coming tonight and Monday so a rapid thaw will set in.

As for the forecast for southern Alberta, I think that may be underestimating the potential here, but I see the GEM precip panel cuts off the accumulating snow on the Alberta side of the Rockies, possibly the computer output has factored in low and mid level wind directions and failed to find upslope potential, but a look at the 24h prog shows a wave running along the front just south of Calgary overnight and with winds likely to back from SSE to ENE during this event, I would not be too surprised if the "flurries" heavy up to steady snow and 3-6 inch accumulations, although no blizzard by southern Alberta standards, the winds will only be 30-50 km/hr at worst. Canmore of course is at the confluence of two valleys and local orographics are complicated. I would think there might be 1-3 inches in town and 3-6 on some slopes, 6-12 inches over towards Lake Louise though, as heavy snow is expected through the east Kootenay region of s.e. BC ... also would watch for a period of freezing drizzle later Monday making roads very slick around the area.

It will be interesting to see what actually happens, Alberta weather is notoriously difficult to predict (even for me, he said running for cover) ...

Oh, I just wanted to add for the benefit of UK readers who may not be that familiar with N American geography, the storm that White Fox is talking about is a separate low over the western Great Lakes region, the ones we're talking about are coming in from the Pacific in several waves today and tomorrow. There's a big cold high in between the two. Parts of southern Ontario are expecting an inch of ice accumulation from freezing rain later today -- that's a nasty kind of weather I am glad to have left behind, we seldom get more than a thin glaze of ice here, it always moves through too fast to accumulate.

Edited December 2, 2007 by Roger J Smith

[johnholmes]

tks for that Roger, maybe a map of the areas of interest to the two of you, could add even more interest for some of us this end with rather shaky N Merican/Canadian geography?

[Coopsy]

Rich, there was about 3 inches of packed powdery snow on the ground here at 0730 when I first looked out ... it had not snowed much overnight ... now it is coming down in very large flakes and looks to acccumulate another 2-3 inches by noon, at which time I think it may turn over to ice pellets or freezing rain. Then heavy rain is coming tonight and Monday so a rapid thaw will set in.

As for the forecast for southern Alberta, I think that may be underestimating the potential here, but I see the GEM precip panel cuts off the accumulating snow on the Alberta side of the Rockies, possibly the computer output has factored in low and mid level wind directions and failed to find upslope potential, but a look at the 24h prog shows a wave running along the front just south of Calgary overnight and with winds likely to back from SSE to ENE during this event, I would not be too surprised if the "flurries" heavy up to steady snow and 3-6 inch accumulations, although no blizzard by southern Alberta standards, the winds will only be 30-50 km/hr at worst. Canmore of course is at the confluence of two valleys and local orographics are complicated. I would think there might be 1-3 inches in town and 3-6 on some slopes, 6-12 inches over towards Lake Louise though, as heavy snow is expected through the east Kootenay region of s.e. BC ... also would watch for a period of freezing drizzle later Monday making roads very slick around the area.

It will be interesting to see what actually happens, Alberta weather is notoriously difficult to predict (even for me, he said running for cover) ...

Oh, I just wanted to add for the benefit of UK readers who may not be that familiar with N American geography, the storm that White Fox is talking about is a separate low over the western Great Lakes region, the ones we're talking about are coming in from the Pacific in several waves today and tomorrow. There's a big cold high in between the two. Parts of southern Ontario are expecting an inch of ice accumulation from freezing rain later today -- that's a nasty kind of weather I am glad to have left behind, we seldom get more than a thin glaze of ice here, it always moves through too fast to accumulate.

Thanks Roger, thats a great analysis of the current conditions. I will be intrigued to see how we end up. Its about minus 18oC at the mo and cloudy. You may be right about the upsloping, but I have found in the past 3 years that Canmore often happens to be the snowless capital of towns around here. If it comes in from the west it seems to stop just on the edge of the National parks about 5 miles away, if it upslopes, Exshaw, about 15 miles to the east get slammed and we get flurries. Its a strange geogrphic location to say the least...incidentally I have just spoken to a friend in Nelson, he says the flakes are huge, the snow really heavy, easily a foot has fallen since yesterday. Nice for the skiers for sure

[WhiteFox]

tks for that Roger, maybe a map of the areas of interest to the two of you, could add even more interest for some of us this end with rather shaky N Merican/Canadian geography?

Having trouble finding anything, but Roger is of course correct. The storm which hit the Midwest yesterday and is on the doorstep of the East Coast entered stage left in Southern California bringing some much needed rain to Arizona and New Mexico before picking up strength and heading up towards Michigan. Some strong WAA associated with this storm:

As a result, the forecast temps for places like Chicago are:

Yesterday: 1oC

Today: 9oC

Tomorrow: -1oC

For New York:

Today: 1oC

Tomorrow: 7oC

Tuesday: 2oC

Incidentally, this Low is projected to pass over the East coast and reform near Connecticut before zipping up North East towards Maine. Accumulations of several inches are forecast for New England with a foot or more possible in parts of Southern Vermont and New Hampshire.

Edited December 2, 2007 by WhiteFox

[Roger J Smith]

This will give you folks some idea of where we are ...

..........................x

............................x

.............................x--^^^------------------------------^\^---------------

..............................x--^^^-------BRITISH COLUMBIA--^^-------------

...........................x..x--^^^----------^--------^----^----^\^--------ALBERTA

.........................xxx..x--^^^---------^---------^----^----^|^----------------

..........................xxx..x--^^^----------^--------^---^-----^|^Rich--Calgary

...........................xxx..x--^^^----------^-------^----^-----^|^--------------

............................xxx..xRJS--^---------^---Nelson--^------^!^------------

..............................xxx..x___________________________^!____________

................................xx..x-----^---------------|---|------------^--------------

...................................x..x----^---------------|---|--------------^------------

.............................xxx...x-----^----WA-------|---|-----------------^----------

.............................x.^.x..x----^---------------|ID-\---------MT------^--------

..............................x.^..x------^--------------|------|-------------------^------

..............................x

...............................x

When you go inland from Vancouver, you go through the Cascades or as they are known north of here the Coast Ranges, quite a high mountain range with volcanic peaks among the lot, then over an extensive high plateau (1600 m asl) into the Okanagan valley of south central BC (this is where Kelowna is located), then through several more mountain ranges before you reach the Rockies. There is one range west of Nelson which is not as high as the others, the Monashees, but they get first crack at the moisture so some good ski resorts like Big White Mountain, then you encounter the Selkirks, the Purcells (two parallel ranges with Kootenay Lake between them) and finally the Rockies which form the border between BC and Alberta, then run down through Montana.

The geography is pretty complicated because various rivers rise in eastern BC and flow out of the country into the northwest US, then back into Canada later on, like the Kootenay River. It starts just over the Rockies from where Rich is located, flows well south of the border into Montana and Idaho, then back up into Canada near Nelson, and joins the Columbia River, which starts in almost the same pond as the Kootenay River and flows in a sort of mirror image the other way north and west through Revelstoke. It flows down through the Arrow Lakes which are man-made reservoirs, then into Washington and out to the sea. The last part of it forms the border between Washington and Oregon states. Then the Fraser River drains most of central BC, taking in the Thompson River which gathers all the drainage from the mountains of central BC north of Kamloops. The Fraser cuts a deep canyon through the Cascades near Hope and then has a large coastal plain to the east of Vancouver here, and this all leads to some meso-scale weather patterns based on outflow winds through the narrow openings -- quite often there can be 70-100 km/hr winds blowing from the northeast out of all the coastal fjords and the Fraser valley as well when an arctic high battles with an offshore storm. Last night we were seeing winds like that blowing down Howe Sound which is just around to the northwest of Vancouver, but a few miles away the winds can be much, much lighter, so strange micro-climates exist all over the place in BC and Alberta.

The east Kootenay valley lies between the Rockies and the Purcells in far eastern BC, then the West Kootenay region is a series of other valleys between all the other ranges. To the west of that is the drier and lower Okanagan valley, so the geography of BC is quite complex and there are all sorts of mountain ranges to grab some of the Pacific moisture before the Rockies get their turn. The heaviest snowfall zones are around 100 kms north of Nelson in an area known as Kokanee, and then north of there in the Revelstoke area of the Selkirk-Purcell ranges which merge around there into one range. The Rogers Pass on the Trans-Canada Highway runs through there routinely gets six to ten foot dumps of snow, but the Rockies west of where Rich lives, get lesser amounts, still quite a good snowfall regime around Lake Louise near the BC-Alberta border (in Alberta though), and as Rich says, Canmore is a bit of a snow doughnut area with less snow than all points around, as it lies in an east-west valley intersected from the south by a north-south valley, so a lot of upslope potential is lost there.

Edited December 2, 2007 by Roger J Smith

[debs]

Hiya Peeps,

We had snow here yesterday with more forcast today. From the point of view of a recent immigrant to this nation I am over the moon. Temps were at -4 (not as low as other parts of Canada I know but low enough to freeze ass) and they got down further overnight to -10. Windchill made it feel -22. My hubbies beer had turned to slush...he'd left it in the car overnight and just opened it this afternoon .....hubby thinks its great and wants to sell it commercially.....anyone interested .

Reports indicate that this could be a traditional canadian winter and alot colder than previous winters.....here's hoping.

Anyway I thought I post a couple of photos.

Still haven't made a snowman yet...snows quite dry.

TTFN

[johnholmes]

must have cost a fortune to get all that flour everywhere!

[Roger J Smith]

It comes out of helicopters, I think John ... you can see them dumping it all over my street here (almost live photo) ...

[Nick F]

Certainly some very cold air at 850mb and at the ground over Western Canada today:

... and a very steep temperature gradient developing by late tomorrow as that low arrives off BC trying to introduce milder air - a big snow producer by the looks of it on the cold side of the front!

[Cookie]

must have cost a fortune to get all that flour everywhere!

brillaint!

some gud pics btw

[Coopsy]

Well well, just as I stopped typing my last message at around 1pm the snow started. 5 hours later and it has stopped. Its not particularly heavy, we have had about 2 inches so far, but its persistent and if it carries on through the night, which it may well do if this is due to the upsloping effects, then we could be looking at totals of 6 inches by morning, nothing spectacular from the Rockies perspective, but impressive to a Brit.

[Roger J Smith]

Snow kept on pounding down in those huge flakes I photographed, until 5 pm, at which point there must have been 15 cms or so, but now it is raining and about 1 or 2 C, on the way up to 10 to 12 C some time tomorrow -- it will all sadly melt rather quickly, at least I hope it does because I don't fancy driving at 0700 in anything other than totally melted snowfall and wet roads, can handle that but they don't have the equipment around here to handle widespread icy roads. Retiring from that very soon, thank goodness ... so I can get into even more trouble on the internet than ever before.

Well Rich, if you managed to get two inches out of part one of this storm, then part two could be heavier than I was speculating, because there is some quite heavy activity over the BC interior on radar tonight, heading your way.

The ski resorts must be in fabulous condition at this early stage, too bad for the very local ones around Vancouver they are going to get the rain up to their elevations tomorrow, that won't be much of a problem for all the rest though.

[Coopsy]

Roger, its pepping up alot more now, much heavier snow now, approx 2 more inches have fallen in the past 2 or so hours, so i guess we are up to 4 inches. All roads are totally covered. Been an interesting drive from the movies tonight. Guess the snow ploughs will be out in the morning

[WhiteFox]

Hiya Peeps,

We had snow here yesterday with more forcast today. From the point of view of a recent immigrant to this nation I am over the moon. Temps were at -4 (not as low as other parts of Canada I know but low enough to freeze ass) and they got down further overnight to -10. Windchill made it feel -22. My hubbies beer had turned to slush...he'd left it in the car overnight and just opened it this afternoon .....hubby thinks its great and wants to sell it commercially.....anyone interested .

Reports indicate that this could be a traditional canadian winter and alot colder than previous winters.....here's hoping.

Anyway I thought I post a couple of photos.

Still haven't made a snowman yet...snows quite dry.

TTFN

Hi Debs,

Glad to see you're enjoying the NE winter up there! It's unlikely that you'll be able to make any snowmen; a feature of the snow over here (away from the NW) is that it tends to be very dry and powdery. Not even any good for snowballs!

Looks like staying unsettled for you up there. The storm forming off the NE US tonight looks like hanging around almost bang on top of New Brunswick for 36 to 48 hours. Most PPN seems to be funnelled into Northern New England and Maine, hence the 12 inch+ snow forecasts, but it looks like there should be some more up your way.

Going forward, I don't think I've seen such wide disagreement in the ensembles at such a short range for quite some time. Certainly many forecasts were going for a cold start to December with a switch to milder mid-month. However, looking at the ensembles it looks like the GFS cannot pick a trend at all!

Just look at Chicago:

A clipper system looks to bring snow through Tuesday into Wednesday, but after that all we can say is that it is likely to warm up, but after that you may as well roll a dice!

I'm in Chicago now (my 11am flight from NY was cancelled due to weather) and I reckon that it was the bumpiest ride I've ever had. For about half the flight even the air crew had to sit down! Normally they fly at about 34000, but due to the upper level winds we had to fly at 24000. Given the strength of the storm and the mixing of airmasses I'm not surprised it was so bumpy!