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Author Topic: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs  (Read 17177 times)

oren

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #150 on: March 05, 2021, 02:21:45 AM »
I agree, and also think higher SWE in winter will not be making it into spring, as a general trend.
My past "research" into individual weather stations did not show much correlation of higher snow thickness in winter with a later melt-out date.
Certainly the inconvenience and potential spring flooding resulting from more winter snow are here to stay in many northern places.

Comradez

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #151 on: March 05, 2021, 03:23:12 PM »
According to Cryosphere Computing, NH snow cover extent now (3/4) has a quite substantial anomaly of -2.522 million km^2.

The weather looks to be exceedingly warm over the U.S. and northern China over the next 10-14 days.  Last year in Missouri we had several cold snaps that kept trees and bushes from budding until mid-April.  We may end up being a month earlier this year.  It is not forecasted to drop below freezing even once in that upcoming timeframe here. 

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #152 on: March 06, 2021, 04:26:12 PM »
According to Cryosphere Computing, NH snow cover extent now (3/5) has a whopping anomaly of -3.118 million km^2.

gerontocrat

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #153 on: March 07, 2021, 01:47:58 PM »
https://ccin.ca/ccw/snow/current

The images from Environment Canada show that as far as Snow Cover Extent (SCE) is concerned, the snowmelt season is underway, at least at lower latitudes.

It may be that in North America the Snow Water Equivalent (SWE i.e. mass) this is also in decline. But in Eurasia SWE is still increasing strongly.
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gerontocrat

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #154 on: March 10, 2021, 10:29:08 AM »
https://ccin.ca/ccw/snow/current

North America
The images from Environment Canada show that Snow Cover Extent (SCE) is concerned, the snowmelt season is well underway, at least at lower latitudes. It may be that in North America the Snow Water Equivalent (SWE i.e. mass) is now also in decline.

Eurasia
SWE is still increasing strongly. The maximum on the y-axis on the graph was increased.
SCE dithering.

click images to enlarge
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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #155 on: March 10, 2021, 08:08:31 PM »
Rockies and the Western Plains states are about to get hammered with snow. Extent should climb again in N.A.

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #156 on: March 10, 2021, 09:34:56 PM »
Rockies and the Western Plains states are about to get hammered with snow. Extent should climb again in N.A.

Yes, that is building up to be a massive winter storm.

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #157 on: March 12, 2021, 12:16:26 AM »
According to Cryosphere Computing, NH snow cover extent now (3/10) has an anomaly of -2.229 million km^2.

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #158 on: March 16, 2021, 03:11:54 PM »
Rockies and the Western Plains states are about to get hammered with snow. Extent should climb again in N.A.
The images and data from Storm Xylia are stunning
https://www.wunderground.com/article/storms/winter/news/2021-03-11-winter-storm-xylia-snow-records-since-fall-2020

Quote
Winter Storm Xylia has become the eighth storm since September to shatter major snowfall records in what has otherwise been a mild winter season overall in most of the United States.

Xylia buried Cheyenne, Wyoming, with 30.8 inches of snow March 13-14. Of that total, 22.7 inches fell on March 14, alone, which set a new record for the heaviest calendar-day snowfall in more than 135 years of weather records in the Wyoming capital, topping a 19.8-inch total from Nov. 20, 1979.

Although not a record, Xylia was the fourth-heaviest snowstorm on record in Denver (27.1 inches).

BUT
Because it covered such a small portion of the snow cover extent of North America, it only managed a small spike in the overall data and with little effect (so far) on the progress of snowmelt.

On the other hand, in EURASIA, snow cover extent loss pretty much stalled, while snow water equivalent, i.e. mass and depth, continued to climb and is several SDs above the average.

Could this delay snow cover loss in Siberia and as a consequence sea ice melt along the Russian coast?
or could it result in a sudden thaw and huge volume of water rushing down the rivers to the Arctic Ocean?
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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #159 on: March 16, 2021, 03:29:41 PM »
Quote
On the other hand, in EURASIA, snow cover extent loss pretty much stalled, while snow water equivalent, i.e. mass and depth, continued to climb and is several SDs above the average.

It would be helpful if we had a separate metric for the third pole. It looks like it has quite a bit of that snow.
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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #160 on: March 16, 2021, 04:21:45 PM »
Quote
On the other hand, in EURASIA, snow cover extent loss pretty much stalled, while snow water equivalent, i.e. mass and depth, continued to climb and is several SDs above the average.

It would be helpful if we had a separate metric for the third pole. It looks like it has quite a bit of that snow.
If you mean the Himalaya & Tibetan Plateau, that big block of purple never completely goes away. Attached  are snowmaps for Jul 2018, Aug 2019 and April 20.  As the map is supposed to show the deviation from the average, it is all a bit of a mystery to me.
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kassy

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #161 on: March 16, 2021, 07:03:06 PM »
It is versus some historical baseline so year round purple is not unexpected.
I just want two regions.  ;)
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wehappyfew

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #162 on: March 16, 2021, 09:18:20 PM »
I think gero's point is that the snow is spurious, an artifact of a imperfect sensor/algorithm.

The Tibetan Plateau experiences ~3 months of real summer with temps well above freezing almost every day, and night time temps above freezing on many days. Snow surviving year round in such a dry desert climate is highly improbable, despite the high altitude.

Glaciers in the Himalayas - sure - but those glaciers are shrinking, not growing, so I don't think there are any widespread positive anomalies vs baseline anywhere in the region.

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #163 on: March 16, 2021, 11:45:04 PM »
I think gero's point is that the snow is spurious, an artifact of a imperfect sensor/algorithm.

The Tibetan Plateau experiences ~3 months of real summer with temps well above freezing almost every day, and night time temps above freezing on many days. Snow surviving year round in such a dry desert climate is highly improbable, despite the high altitude.

Glaciers in the Himalayas - sure - but those glaciers are shrinking, not growing, so I don't think there are any widespread positive anomalies vs baseline anywhere in the region.
Last summer's excessive snowfalls across the Himalayas were firmly supported by very negative surface temp anomalies in the region, in fact, they were the coldest they had been in decades.

kassy

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #164 on: March 17, 2021, 04:07:55 PM »
Where do we find a series of absolute values of snow that go back to the reference year?

PS:
The plateau is a high-altitude arid steppe interspersed with mountain ranges and large brackish lakes. Annual precipitation ranges from 100 to 300 millimetres (3.9 to 11.8 in) and falls mainly as hail.

Permafrost occurs over extensive parts of the plateau.


So the accumulations reported might be on the interspersed mountains (what is the pixel resolution of this product?).
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oren

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #165 on: March 17, 2021, 04:10:27 PM »
Or the product could be wrong. It never seemed very reliable to me, especially in the Tibet region.
A way to circumvent this would be to locate specific weather stations which measure snow depth, and plot their long term trend.

Paul

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #166 on: March 18, 2021, 01:34:13 AM »
Does increased snow thicknesses slow down snow melt? Think I read on here in the past, it has little to no difference at all?

I am interested whether the last 2 months of below average temperatures means the snow pack is colder and make it more resilient to melt just like colder ice is more resilient than 'warm' ice. Also whether those colder air temperatures mean a slower warm up over parts of Siberia and give a negative feedback that way.

That said, I think temperatures were below average in 2013 and April saw rapid snow cover retreat so it might not make much difference regardless?

Still on a weather POV it is fascinating how the start of 2020 and 2021 is at opposite end of the scale when it comes to temperatures.

vox_mundi

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #167 on: March 18, 2021, 02:19:26 PM »
Observed Snow Depth Trends In the European Alps: 1971 to 2019: Alpine-Wide Study Shows Snow Cover Declining
https://phys.org/news/2021-03-alpine-wide-declining.html

For the first time, a study coordinated by Eurac Research has collected and systematically evaluated snow data from more than 2000 measuring stations in Italy, Austria, Slovenia, Germany, Switzerland and France. Up until now, studies had been limited to individual areas in the Alpine region and been based on data from, at most, a few hundred measuring stations.

The results, published in The Cryosphere, have made it possible to reliably describe snow trends at up to 2,000 meters above sea level. Higher than that, there are too few measuring stations to be able to extract reliable information for the entire Alpine region. This consistent data set spans five decades and was created through the collaboration of more than 30 scientists from each of the Alpine states.

The data shows that snow is unevenly distributed and does not decrease everywhere to the same extent. In the Southern Alps, which already have less snow than their northern counterparts, snow depth below 2000 meters decreased more than in the Northern Alps. Regional trends sometimes differ considerably, but decadal variability is similar throughout the Alpine region: the 1970s and 1980s were generally snowy, followed by a period of snow scarce winters in the late 1980s and early 1990s.

Since then, although snow depths have increased again to some extent, they have not reached the level of the 1970s. And everywhere, there is less snow in spring, as Crespi points out: "While in winter, there is a wide range of variation in trends depending on location and altitude, even with isolated increases in snow at higher altitudes, in spring, almost all the stations recorded decreases." Below 2,000 meters, the snow season decreased by 22 to 34 days during the last 50 years, and snow on the ground tends to appear later in winter and disappear earlier as spring approaches. This is a direct result of climate change, as Matiu explains: "In this study, we did not look explicitly at the formal attribution, but it is clear that snow melts earlier and faster due to higher temperatures and that precipitation occurs as rain rather than snow."


Time series of mean monthly snow depth averaged by 500 m elevation bands. The rows indicate elevation band and the columns the months. The small numbers at the top of each panel denote the number of stations included in the average.

Michael Matiu et al, Observed snow depth trends in the European Alps: 1971 to 2019, The Cryosphere (2021).
https://tc.copernicus.org/articles/15/1343/2021/
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The Walrus

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #168 on: March 18, 2021, 06:33:43 PM »
That is a nice summary.  I wonder how recent snow melt compares to earlier years.  I am not surprised that levels have not returned to the cold times of the 1970s.

gerontocrat

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #169 on: March 19, 2021, 11:59:30 AM »
It is my contention that at this time of year as long as daytime temperatures are above zero, snowmelt will occur and snow cover extent reduce, even though night temperatures are well below zero.

So I reckon Canada below 60 degrees North is going to lose a lot of snow in the next few days.
Also Eastern Europe and lower latitudes in Siberia?

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #170 on: March 20, 2021, 01:57:19 AM »
It is my contention that at this time of year as long as daytime temperatures are above zero, snowmelt will occur and snow cover extent reduce, even though night temperatures are well below zero.

So I reckon Canada below 60 degrees North is going to lose a lot of snow in the next few days.
Also Eastern Europe and lower latitudes in Siberia?

Surely it depends on ground temperatures and just how long temperatures are above zero for? If the temperatures are only above zero for only a limited amount of time, then any snow melt will be limited?

gerontocrat

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #171 on: March 21, 2021, 10:48:32 AM »
It is my contention that at this time of year as long as daytime temperatures are above zero, snowmelt will occur and snow cover extent reduce, even though night temperatures are well below zero.

So I reckon Canada below 60 degrees North is going to lose a lot of snow in the next few days.
Also Eastern Europe and lower latitudes in Siberia?

Surely it depends on ground temperatures and just how long temperatures are above zero for? If the temperatures are only above zero for only a limited amount of time, then any snow melt will be limited?
Obviously the longer the time temperatures are above zero the greater the snowmelt. But as far as North America is concerned the last 2 days suggest it's warm enough for long enough for a real reduction in SCE and SWE.

Mind you, Eurasia is not cooperating very well.
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gerontocrat

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #172 on: March 23, 2021, 09:58:31 AM »
https://ccin.ca/ccw/snow/current

North America snow melted (SCE & SWE) fast in the last week or so.

Eurasia SWE increased while SCE dithered.

Forecasts suggest that in the next few days snowmelt may pause in North America and accelerate in Eurasia - especially SWE.

click images to enlarge and start gif
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blu_ice

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #173 on: March 23, 2021, 12:27:07 PM »
Based on personal experience snow melt is slow as long as night time temps are below zero and snow cover is fairly thick.

White snow reflects the sun and thick snow keeps itself cold.

Comradez

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #174 on: March 23, 2021, 09:22:41 PM »
Keep in mind too that, as long as the ground and lower layers of snow are still frozen, any snow that thaws on top just filters down and re-freezes at night in place as ice, just compacting the frozen layer (but leaving the amount of energy needed to thaw it again virtually unchanged) unless there is a steep gradient in the terrain to carry it away as river water (assuming the nearby streams and rivers are not completely frozen too).  And we know that much of Canada and Siberia is fairly flat, with a lot of lakes that don't drain, which means that temporarily-thawed snow just stays in place and re-freezes as ice in the night. 

Some ice/snow will also sublimate, and when it briefly thaws during the day, some of it may evaporate a little faster into the air because evaporation is faster than sublimation.  But yeah, in areas of deep snow, it really takes average day/night temperatures significantly above 0C to make melting progress.  A few hours of above-0C temperatures during the day isn't going to noticeably cut it. 

Here in Missouri, 6 inches of snow can melt with just a few days of 5C (~40F) highs in the afternoon, even if it dips below freezing again during the nights, but that's because the ground beneath isn't frozen, so as soon as the thawed snow seeps down as water into the ground, it won't refreeze, and it is home free to percolate down into the water table.  It's not the same in the continuous permafrost zone. 

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #175 on: March 23, 2021, 11:42:07 PM »
a nitpick really
When the snow melts on permafrost then refreezes. The energy is absorbed by the snow and melts it. Then the energy is dispersed to the permafrost allowing the water to refreeze as ice. The energy required to melt something is of course unchanged. The energy in the permafrost snow gets redistributed to raise the temperature of permafrost where the energy in snow closer to the equator remains in the phase transformation to liquid. The overall result is as you described comradez.

gerontocrat

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #176 on: March 25, 2021, 12:29:24 PM »
https://ccin.ca/ccw/snow/current

North America SWE continues to decline almost vertically, while SCE has stalled.
My guess is after looking at GFS forecasts is that SCE will decline, even if slowly, especially as there is rain at the southern edge of some of the snowfall events in the coming days.

SWE may also continue its decline but see the quote from Comradez below.

Eurasia
SCE is in rapid decline again, and maybe SWE has peaked.
Once again, after looking at GFS forecasts I reckon both SWE and SCE will decline rapidly for at least for the next few days, melt spreading from West to East and South to North into Siberia.

But SWE decline - see quote from Comradez below

Keep in mind too that, as long as the ground and lower layers of snow are still frozen, any snow that thaws on top just filters down and re-freezes at night in place as ice, just compacting the frozen layer (but leaving the amount of energy needed to thaw it again virtually unchanged)

Decline in SWE may be partly a mirage, instead recording snow compaction and the formation of a layer of ice at ground level.

This is the environment that causes starvation in the caribou and reindeer herds, as the grass is trapped under the ice layer instead of snow that the herds can shift away with their hooves to reach the fodder.

i.e. AGW causes snowfall to increase and later in the season rapid melt which creates the ice layer on the ground that means starvation for the herds.

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Comradez

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #177 on: March 27, 2021, 03:55:45 PM »
According to Cryosphere Computing, NH snow cover extent now (3/26) has an anomaly of -1.144 million km^2.

Looks like it would be lower without a sizable swath of new snow in the Kuban steppe region of Southern Russia which likely won't last long with 24-hr average temperatures above 5C there over the coming days. 

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #178 on: April 02, 2021, 11:37:54 AM »
https://ccin.ca/ccw/snow/current

North America snow cover extent (SCE) continuing its normal erratic descent mostly at or below average. Snow water equivalent (SWE) still high but declining again.

It looks to me that in the next 5 to 10 days most snow below 60 North will disappear, and after 5 days melt will push even farther north. Time will tell if high SWE in the farther north will slow down declines in SCE.

click images to enlarge
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Shared Humanity

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #179 on: April 02, 2021, 02:16:33 PM »
Torngat Mountains are buried in snow. Dare I say...

gerontocrat

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #180 on: April 02, 2021, 03:50:36 PM »
Torngat Mountains are buried in snow. Dare I say...
You should've added that famous bit of soundtrack from jaws

https://youtu.be/E-sX2Y0W8l0?t=22
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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #181 on: April 05, 2021, 12:24:28 PM »
https://ccin.ca/ccw/snow/current

North America
- So far very high and even gains in SWE  has not stopped rapid loss in SCE. It must still be snowing somewhere.

Will high SWE, i.e.very deep snow at around 60 North and above, slow the loss of snow cover?

Eurasia Average SCE extent and rate of loss while SWE declining from a very high level. It still looks to me that there will be rapid melt from the West to East and South to North as temperatures and +ve temperature anomalies increase over the next week or so (apart from far Eastern Siberia and Alaska).
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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #182 on: April 06, 2021, 05:09:02 PM »
GFS forecast is quite aggressive in Eurasia.

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #183 on: April 06, 2021, 06:21:38 PM »
The ice thickness on the Tanana River was 45.2" yesterday.  The highest measurement since 2013.  That year, the ice moved the tripod on May 20, the latest ever, and only one of two years in which the ice lasted past May 16.  The ice is also covered by over three feet of snow, and forecasted temperatures are well below freezing over the next week.

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #184 on: April 06, 2021, 06:55:55 PM »
I remember looking at that product last year and noticing that it tends to over-estimate snow loss.  Still, I do expect the NH snow extent anomaly to plunge deeper into negative territory in the coming days.  Currently (as of 4/5/2021) at -1.265 million km^2 according to Cryosphere Computing. 

Last year, snow extent was further retreated in eastern Europe, but much more extensive in North America at this time.  Probably higher snow extent overall, if I had to eyeball it. 

I wish I could compare directly, but Cryosphere Computing pulls its snow extent data from https://nsidc.org/data/g02156, and that website does not have a simple user interface for looking at old historical data. 

gerontocrat

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #185 on: April 08, 2021, 12:03:07 PM »
https://ccin.ca/ccw/snow/current

EURASIA
Snow Water Equivalent (SWE) is still very much above average and Snow Cover Extent (SCE). This implies average snow depth is well above average,

Can above average snow depth delay the snow melt and warming of the ground (and thus sea ice?) ?

SWE is declining fast but reduction in SCE has stalled. So at the moment the answer is yes. But perhaps if this warmth increases and spreads North (see gif for illustration) SCE will suddenly crash in a few days.

PS: The gif is of 3 / 5 /10 day forecast max temps as this shows the gathering warmth very nicely.

PPS: My bet is that Global Heating trumps higher snowfall.

click images to enlarge
"Para a Causa do Povo a Luta Continua!"
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gerontocrat

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #186 on: April 10, 2021, 04:17:41 PM »
For a change here are Tealight's images @ https://cryospherecomputing.tk/

Mostly all about Ameriky - 1.6 million km2 less snow cover extent than average (that is nearly 20%?)

I sure wish Tealight could do the same about Snow Water Equivalent. But like Oliver Twist, I always ask for more than the Beadle is willing or able to give.
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

Comradez

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #187 on: April 11, 2021, 07:48:55 PM »
According to Cryosphere Computing, NH snow extent anomaly is now (4/10/21) at -2.104 million km^2.

NH sea ice extent anomaly is now (4/10/21) at -0.511 million km^2. 

Combined NH extent anomaly (let's call it the NH albedo extent anomaly) is now -2.615 million km^2. 

As we head into the melting season, the latter is a number I will be starting to watch. 

Tealight

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #188 on: April 12, 2021, 09:15:05 PM »
I wish I could compare directly, but Cryosphere Computing pulls its snow extent data from https://nsidc.org/data/g02156, and that website does not have a simple user interface for looking at old historical data.

Somewhat fixed. I simply copied my past SIC page and made a few adjustments for snow cover.
https://cryospherecomputing.tk/PastSnow

I sure wish Tealight could do the same about Snow Water Equivalent. But like Oliver Twist, I always ask for more than the Beadle is willing or able to give.
Do what exactly? Simply copying the Canadian Cryosphere Watch doesn't add anything new. Is the data even available for download?

btw what is "Environment and Climate Change Canada Canada"?
see https://www.ccin.ca/index.php/ccw/snow/current

Jim Hunt

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #189 on: April 12, 2021, 10:35:37 PM »
What is "Environment and Climate Change Canada Canada"?

An unfortunate global search/replace malfunction?
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

gerontocrat

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #190 on: April 12, 2021, 11:24:41 PM »

I sure wish Tealight could do the same about Snow Water Equivalent. But like Oliver Twist, I always ask for more than the Beadle is willing or able to give.
Do what exactly? Simply copying the Canadian Cryosphere Watch doesn't add anything new. Is the data even available for download?

I drew a blank several times when I searched for a download of Snow Water Equivalent. I was hoping you knew of somewhere to get it.

You separate Eurasia into Europe and Asia - Environment Canada do not.

Your graphics are far classier.

ps: Are you going to do the AWP stuff again this year? That was ace++ and gives such an insight into overall and individual seas.

pps: Are you going to have a go at the SIPN prediction this year?

ppps: methinks you are a victim of your success
"Para a Causa do Povo a Luta Continua!"
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Tealight

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #191 on: April 13, 2021, 12:58:37 AM »
ps: Are you going to do the AWP stuff again this year? That was ace++ and gives such an insight into overall and individual seas.

pps: Are you going to have a go at the SIPN prediction this year?

ppps: methinks you are a victim of your success

Triple yes

AWP is already running
https://cryospherecomputing.tk/NRTawp

I also started calculating regional sea ice area/extent, however I'm still working on a neat way to show all 26 images (13 for area and 13 for extent)

bbr2315

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #192 on: April 13, 2021, 01:30:59 PM »
To my eyes, there is a clear "inversion" of the see-saw we have seen in recent years (snowy Quebec, warm-ish west). This year, Quebec is, again -- to my eyes -- the least snowy of any year since I have began tracking SWE (2016?). Meanwhile, there is a LOT of snow in Alaska and the Yukon.

In Eurasia, the situation looks bad in the landmass leading up to the Kara / Barentz. Okhotsk's periphery is also full of red.

I think altogether these portend a strong continental component to Arctic melt this year, in North America, it could be the strongest melt year in quite some time (early melt out of Hudson Bay possible, also CAA melt possible).

I wonder how resilient the snow in AK / Yukon will be, though, and whether this will really help the ice in Bering / Beaufort survive. I think there is some possibility that AK's snowcover is more resilient than Quebec's due to its higher latitude and higher elevations in general, so these purples could have more staying power than those we have seen in Quebec in recent years. The ice in Bering is also pretty high vs recent years, however, Pacific heat blasts have been formidable in recent times, and the snow / ice will probably not hold out against it. I could, however, see a delay in snow melt across AK / Yukon given the current situation, at least vs normal, which would probably yield a cold pocket over the Rockies and NW North America into at least June, possibly July. This would likely be joined by a warm area and +500MB anomalies over Northeast North America.


Comradez

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Re: Northern Hemisphere Winter 2020-2021 Snowcover / Misc Obs
« Reply #193 on: April 13, 2021, 05:09:26 PM »
According to Cryosphere Computing, NH snow extent anomaly is now (4/12/21) at -1.318 million km^2.

NH sea ice extent anomaly is now (4/12/21) at -0.694 million km^2.

Combined NH extent anomaly (let's call it the NH albedo extent anomaly) is now -2.012 million km^2.