Aleman

We still seem to get some people who get very gloomy about the prospects of seeing snow on the back of a short period of very warm weather or very low snowfalls yet historical records show snow levels can vary tremendously over short periods of time. Northern Hemisphere snow extent has a history of varying considerably away from its central trend from month to month: Rutgers University Climate Lab :: Global Snow Lab CLIMATE.RUTGERS.EDU Rutgers University Global Snow Lab The lesson is that regional weather can still cause massive winter weather events. We've even had articles explaining why unusually high levels of cold and snow in some places (e.g. Texas in Feb 2021 when Houston hit -12C and oil rigs in the Gulf of Mexico had equpiment freeze up) are still consistent with global warming and falling sea ice levels. So the prospects of snow in the UK have probably not really dipped a great deal despite warmer temperatures and lower sea ice. When weather systems can swing temperatures +/-10C or even +/-20C on rare occasions, and warming only amounts to a fraction of a degree per decade, there is still plenty of potential for an unusual weather system to bring weather to the UK that that will be so cold or snowy that it will cause massive disruption and damage. Indeed, statistically you can almost guarantee it will happen in coming decades, even if we continue to see a gradual reduction in numbers of moderate cold and snow events.

N. Hemisphere sea ice is building well at the moment but snow extent has fallen back. Significant snow is expected down the Rockies, possibly to the Mexican border this weekend, though, so that might get it back on track.

Following on from widespread snow across central and eastern Canada, the Canadian Archipelago seems to have seen a mini flash freeze and the surface temperature across northern Hudson Bay has dipped a bit. Presumably, snow has formed a freshwater slush that is is stopping warmer but denser saltwater upwelling from underneath - and the coldest areas (no upwelling) around coastal edges are now freezing solid.

After significant settled snow down from Nunavut down to the Great Lakes, climatereanalyser is showing light ice along coastal areas of North Hudson Bay proper. I'm guessing that, absent any milder weather soon, this will be a precurser to the first significant charted ice advances there in coming days, as measured by other sources/algorithms. A few more little bits of coastal ice appearing down Russian and Alaska into the Bering Sea now. Is this earlier than the recent normal? It feels early to me. Could be wrong. It is only little bits though and could be heavy snow that will melt back again rather than the onset of hard pack ice that will be sustained and advance. We shall see. NWS Alaska Sea Ice Program (ASIP) WWW.WEATHER.GOV

The temperatures were plummeting in Scotland last night before the cloud and rain arrived. Aboyne's new low for the season was -3.8C somewhere around midnight but had warmed to 7.0C at 6am. It looks like it would have been about -7C if it had not clouded over. Decoded synop reports WWW.OGIMET.COM

MIA - Icebreakers don't keep passageways open - they just get themselves and other ice class ships through where they otherwise could not go. They break and slightly disperse ice to leave a trail that refreezes behind them within hours. Even if each icebreaker were 10 miles wide, their wake would soon be ice again and would not show open water on charts/images. They do not keep anything open because it is quickly frozen again behind as a patchwork of new thin ice and broken thick ice - all mixed up in hazardous fashion. At this time of year, newer ice areas forming are snow slush or grease ice/frazil/nilas/shuga (non-snow formed ices). These are like sailing through differing grades of treacle before they eventually freeze into the hard stuff and so are not just open or closed as such. Such treacley areas don't always appear on ice charts but can slow a small vessel from 20 knots to 2, making it difficult to evade/outrun hazardous or colder weather, threatening fuel reserves and potentially leave a vessel trapped in solidifying ice. Slush and frazil can make a route impassable to small vessels even though not actually showing as ice until perhaps it thickens and hardens a few days later. Development of sea ice – Australian Antarctic Program WWW.ANTARCTICA.GOV.AU Learn about the different stages of sea ice development. I don't think anyone calls it the North Passage. It's known as the Northern Route or Northeast Passage. It's already likely been effectively closed for about 3 weeks at 110 degrees East, only a couple of weeks after it reluctantly opened at 170 East this year. It was only during this brief period that I saw any pleasure craft going through. There are still lots of vessels going through now but they are large commercial ice class vessels - cargo ships, tankers, barges and indeed icebreakers - that will only be slowed a little by slush and frazil, or even thin new ice. MarineTraffic: Global Ship Tracking Intelligence | AIS Marine Traffic WWW.MARINETRAFFIC.COM MarineTraffic Live Ships Map. Discover information and vessel positions for vessels around the world. Search the MarineTraffic ships database of more than 550000 active and decommissioned vessels. Search for...

One has to remember that the sea does not freeze at -2C but snow landing is less dense and will only melt slowly or not at all. A light snow will prime the sea with a cold freshwater layer at the top that is less dense than brine, and a heavy snow will from a slush and then even build up to form a "dry" top layer. I think a widespread snow will sometimes cover an area that is getting close to freezing and then cause a flash freeze over that area. An area covered by slush will not show as ice in some models but can be seen on temperature maps as it stops upwelling of warmer water from underneath, accelerating the freeze process. When snowy depressions clear away, clear skies can then see a slushy area that has stopped upwelling flash freeze. This is not the only freezing mechanism - as sometimes there is no snow - but I expect heavy snow will sometimes help sea ice growth kick off or cause a spurt in the figures. I see the arm of the main ice pack has made contact with the ice growing out from Siberia (at 170East).

New ice growth at 64 degrees North in Russia (south of Bering Straight) seems early but there is snow right to the coastline there. It might be heavy snow that melts away again, though it was -30C last night not all that far west of there - about where it says 65N in the image..

More up North - Topcliffe's first negative: Minimum Temperature Last 24h 10/13/2022 at 12:00 UTC No.LocationStation IDAmount 1Aboyne (United Kingdom)03080 -2°C 2Redesdale (United Kingdom)03230 -2°C 3Eskdalemuir (United Kingdom)03162 -1.7°C 4Topcliffe (United Kingdom)03265 -1.3°C 5Cairngorm (United Kingdom)03065 -0.8°C 6Shap (United Kingdom)03225 -0.6°C 7Castlederg (United Kingdom)03904 0°C 8West Freugh (United Kingdom)03132 0.1°C 9Aonach Mor (United Kingdom)03041 0.4°C 10Aberdeen / Dyce (United Kingdom)03091 0.9°C 11Leeming (United Kingdom)03257 0.9°C 12Strathallan (United Kingdom)03144 1°C 13Warcop Range (United Kingdom)03226 1°C 14Keswick (United Kingdom)03212 1.1°C 15Mona (United Kingdom)03301 1.2°C Script courtesy of Michael Holden of Relay Weather. Data courtesy of Ogimet

You can see the pick up in the rate of extent expansion in the last few days. Full steam ahead!

-26C at Eureka (Northern Canadian Archipelago) last night. Ice is filling in those islands steadily now, which is not surprising with the recent drop in temperatures. I'd wondered about light ice showing after snows in Northeast Hudson Bay/Foxe Basin on climatereanalyser because the sea temperature looked much too warm but Canada's Sea ice Service is now backing it up even though it still looks a slightly too warm. There is also a little new ice around the islands at the Northwest inlet. This seems to be slightly early this year. Again, could it be something to do with the heavy snows in recent weeks? (Edit - once again, my images are linking with those of a previous poster when I click back on them - technical glitch?)

I missed the lows through the night but this takes in the temps at 8am yesterday, so there must have been plent of places seeing 0C. Minimum Temperature Last 24h 10/12/2022 at 08:00 UTC No.LocationStation IDAmount 1Benson (United Kingdom)03658 -1.1°C 2Shobdon (United Kingdom)03520 -0.9°C 3Pershore (United Kingdom)03529 -0.6°C 4Almondsbury (United Kingdom)03930 -0.5°C 5Exeter Airport No2 (United Kingdom)03844 -0.4°C 6Yeovilton (United Kingdom)03853 -0.1°C 7Hereford/Credenhill (United Kingdom)03522 0°C 8Pembrey Sands (United Kingdom)03605 0°C 9Sennybridge (United Kingdom)03507 0.7°C 10Bala (United Kingdom)03409 0.9°C 11Shawbury (United Kingdom)03414 1°C 12Bournemouth Airport (United Kingdom)03862 1.3°C 13Brize Norton (United Kingdom)03649 1.5°C 14Cairngorm (United Kingdom)03065 1.5°C 15Charlwood (United Kingdom)03769 1.6°C Script courtesy of Michael Holden of Relay Weather. Data courtesy of Ogimet

This one is a bit odd. Ice has appeared in the warm area of NW Alaska/East Bering. Maybe a scattered bit of the main ice pack has blown that way and built up at the coast? I've been hunting for webcams to shed more light but could find none.

One by one, other sources have been coming into line with the sparse new ice seen growing out from coastlines by climatereanalyser 11 days ago after heavy snows started. I'm putting the slower reaction down to differences in how their algorithms pick up grease ice and snow slush before further snows add enough fresh water that it eventually freezes solid. It's appearing in the areas hinted at by temperature maps, too. It's now become so cold that open sea will start to freeze up in peripheral areas even without snow. It was a much colder -24.0C at Eureka yesterday and similar over the central main ice pack on the Russian side of the North Pole. It was -10C around edges of the main ice pack. There is still snow in forecasts, though, too, so sea ice expansion looks like it's about to step up a gear.

This highlights some good progress in the last week.

Looks like lot of snow for the top of Ben Nevis this week - 38cm - though with lots of rain too, so maybe not much settling? Imagine if it came through 1 or 2C colder than expected, and the 80mm+ of rain came through as snow, too. Another 80cm+ of snow would then take it to 4 feet of snow in total ! Of course, it might equally come through a bit milder. Ben Nevis Weather Forecast (1344m) WWW.MOUNTAIN-FORECAST.COM Ben Nevis, Grampians, Scottish Highlands, United Kingdom Mountain weather forecast for 1344m. Detailed 6 day mountain weather forecast for climbers and mountaineers.

Snow extent is off to a flying start this year. It's already reached 1/4 of its normal winter peak.

Another source is showing some of the sea ice climatereanalyser had growing from coastal edges a few days back after snows. Ice has started to build out from both the Siberian Coast and Alaskan Coast. NWS Alaska Sea Ice Program (ASIP) WWW.WEATHER.GOV

Zoom in and see bays freezing over as ice starts to grow out from Russian coastal areas towards the main pack. The temperature map hints at where it is happening without having to zoom in as much. Snow landing on the white areas might settle if it is heavy or there is no wind after - or it might melt but quickly refreeze if the temperature drops.

If we look at the ice charts, lots of areas of have seen new ice infilling. It's not all new ice, though. I think it's areas of 10%-90% old ice that have seen their overall % jump after heavy snow. There was scattered ice in all these pink "new ice" areas before the heavy snows. I think this ties in with all the light ice amongst the Canadian Archipelago I highlighted a few days back on climatereanalyser that was not being picked up by other sources and still isn't. I have said in previous years that sudden ice formation seems to start with snow that some sources pick up in bits as they happen and others show as a flash freeze a few days later. Temperature maps often seem to be a giveaway of snow settling on sea that some sources are not recording as ice. It might depend on the parameters for ice in their model. Snow drops the surface temperature and sits on the surface as freshwater slush that stops warmer saltier denser water churning up from underneath. When the low passes and high restablishes itself, you then get a sudden freeze - but it's actually a freshwater/brackish slush that's freezing up rather than straight salty sea. It's not the only freezing mechanism, of course. The sea will freeze without snow. Snow often helps it along on some occasions - and there's been a lot dropped in the last couple of weeks with all the lows.

All the lows looks to be having an effect. They churn up warmer water below, releasing moisture and creating snow, raising the air temperature while they are at it but it drops back again after. There's been lots of snow lately. We have a big jump in ice registered here after snows:

Benson -0.3C Rostherne +0.5C

The main pack has recontacted Russian mainland at 100 degrees East so Laptev might ice up quickly now. This was one of those areas that seemed to have a sudden appearance of light ice after snow but the main pack also drifted that way recently under prevailing winds.

Topcliffe 0.7C this morning so should be a few seeing frost on cars, etc. My garden has a southern aspect, though, and not here quite yet with 4.9C.

If you step back and forth over the last couple of days, DMI's volume map shows rather less ice than climatereanalyser but also shows ice increasing in a few areas, particularly the N/NW coast of Greenland into the northern Islands of the Canadian Archipelago, with the bonus of a bit of main pack infill. It seems to suggests the oddly large amount of new ice shown yesterday on climatereanalyser in the Canadian Archipelago might not be a glitch - though other sources have yet to fall in line. More significant snows are expected over this area over the next couple of days with air temperatures running below -5C, sea surface temperatures below 0C and even little bits of leftover ice floes from last year scattered about - so very ripe for sea ice formation. DMI Modelled ice thickness OCEAN.DMI.DK