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Author Topic: Northern Hemisphere snow cover  (Read 41160 times)

bbr2314

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Re: Northern Hemisphere snow cover
« Reply #150 on: April 10, 2018, 08:55:06 AM »
I was browsing surface patterns and 2002 and 2003 are actually decent matches to this year (2002 especially). I wonder if that hints at a moderate Nino come fall and a repeat of our snow gains (or worse) into 2019?

In any case, perhaps the differentiating factor between 2018 and 2002 is the abundance of H2O and CO2, with CO2 having risen 10% since then. And the ensuing accumulation of oceanic heat / enlargement of the Hadley Cells.

The 00z EURO maintains and worsens its position from 12z, BTW. The zone of ice now fully ensconces Detroit and Pennsylvania's Upcountry has been added to the mix. If the trend continues expect to see Chicago and NYC next in line.

The below is only snow but is nevertheless impressive in its own right. While there will certainly be melting over the next 10 days, the gains are likely to counter or exceed (IMO).



« Last Edit: April 10, 2018, 09:07:40 AM by bbr2314 »

bbr2314

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Re: Northern Hemisphere snow cover
« Reply #151 on: April 10, 2018, 09:00:06 PM »
Today was a hold. In mid-April, a hold is remarkable in itself. It is spectacular when you are at the highest estimated continental SWE in satellite history.



I think we may see a slight drop through D2-3 and then a substantial push D4-D6 as the mega-apocalyptic moisture event sprawls across the toes of our largest-ever annual accumulation of snowpack (i.e. a nascent ice sheet).

Perhaps the problem we have now encountered is that IF atmospheric moisture is sufficient, AND sea ice is low enough, the onset of Hadley Cell formation occurs BEFORE snowmelt can manage to begin with vigor, enabling the advection of massive amounts of oceanic heat over areas of the continents covered by snow, where it precipitates out as more snow. This is because the Hadley Cells are driven partially by geography, which is a constant, and the RRR/etc are features of this.

This will likely collapse by mid-May at latest as the atmospheric heat will be sufficient to overwhelm the accumulated snow. But I think moving forward this dynamic will get worse and worse until it is very quickly INSUFFICIENT and we end up snowballing into a rapid-onset ice age in the span of 365 days or less. This is what is happening right now but thank goodness for our massive ongoing atmospheric farts of GHGs which will inevitably still overwhelm the increase, at least this year.

These kinds of anecdotes are illustrative how just how impactful the weather this year has been.

https://twitter.com/wxmvpete/status/983643221266923520/photo/1

Minneapolis has seen its coldest start to April. EVER. And these anomalies are going to widen into the end of the month and possibly into May, until the snow melts out. Until that occurs, and it might not be for several more weeks if the EURO is right, the anomaly is only going to get worse.

gerontocrat

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Re: Northern Hemisphere snow cover
« Reply #152 on: April 13, 2018, 12:11:18 PM »
Hard on the heels of a snowy mega-apocalyptica comes the rain and the warmth.
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bbr2314

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Re: Northern Hemisphere snow cover
« Reply #153 on: April 13, 2018, 05:56:18 PM »
Hard on the heels of a snowy mega-apocalyptica comes the rain and the warmth.
I would not use the GFS for Canada in the spring. CMC then EURO. GFS is terrible at integrating changing snowcover/sea ice (i.e. it doesn't do it at all over the course of its run, it only internalizes the GAINS projected in the models, none of the losses that would result from sensible wx).

Of course, it may be correct, but I would not use it.

bbr2314

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Re: Northern Hemisphere snow cover
« Reply #154 on: April 13, 2018, 06:12:33 PM »
e.g.





The GFS is good-for-SH*T

bbr2314

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Re: Northern Hemisphere snow cover
« Reply #155 on: April 13, 2018, 06:16:39 PM »
I think this may be plausible... it would be NYC's latest measurable on record (or close to it).



12z is a bit south



But I think the imminent situation over SE Canada is likely to yield a 50/50 low that is sufficient to suppress whatever comes behind it into the Mid Atlantic, with the abundance of snowcover over both Quebec and the Midwest/Northeast/New England the other necessary ingredient for late-season snow. Possibly record-breaking. We shall see....!

In other news: North American SWE anomalies are finally dropping. I suspect this may stall D2-3 or even reverse for the last time as we deal with the impending event.

bbr2314

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Re: Northern Hemisphere snow cover
« Reply #156 on: April 14, 2018, 10:39:30 PM »
https://twitter.com/NWSCaribou/status/984911627010084865/photo/1

It is not coincidental that this is happening at the same time the same records for snow/etc are being set across the entire Canadian Shield...

It is also not coincidental that the Younger Dryas came with the same pattern and with no change/warming over the far SE US. This is exactly what we are now seeing.

I think the CAUSE of the Younger Dryas is what is misunderstood... it was not a shutdown in AMOC, it was an abundance of oceanic heat content and a lack of sea ice that resulted in a temporary period of prolific snows, which THEREAFTER depleted the ocean of its heat content, started sea ice expansion, and pushed the Gulf Stream way S. This did not occur until continental ice sheets began building year-round, which started abruptly (it only takes one year).

My question for everyone here:

We are normally at 1,000 or so KM^3 as of 4/1, in terms of accumulated SWE across North America, according to the Canucks. This takes three months to melt down to zero.

IF we are at 1,250KM^3 as of 5/1 this year (i.e., 250 KM^3+ of ice ABOVE what is normally seen at April, also still more than the seasonal max most years), will it take 3.5 months to melt that ice? Will it take three months? Or will it be unchanged vs normal and all melt out at same time anyways, taking only two months?

I do not think it will be unchanged. An additional month would put melt-out at 8/1 instead of 7/1. Another month and a half would put it at 8/15.

IF we begin to see melt-out extend later in the year, that is when the runaway impact of albedo feedbacks begin to take hold. We are one week away from the same insolation as 8/21, with over 1,500KM^3 of snowpack still accumulated across the continent.

If we can hold onto 1,250KM^3 come 5/1, I think it shows that in the absence of significant Arctic sea ice relative to the 20th Century and in the presence of warmer oceans than ever, weather becomes increasingly stagnant. This is because when sea ice retreats, the "jet stream" falls apart. When this happens in the absence of snowcover, the Hadley Cells deliver heat everywhere. But *if snowcover is still substantial* when the Hadley Cells rear their heads in February and March, the "heads" of the Hadley Cell are much more prone to MAINTAINING cover as massive amounts of heat are advected thanks to the albedo surplus, while the oceanic warmth allows sufficient moisture for near-year-round snows.

This is interesting because as we see more oceanic warming, the Hadley Cells will continue becoming increasingly potent earlier and earlier in the year. This means stagnant weather becomes the norm instead of our old seasons. And this is the natural mechanism that resolves excess oceanic heat content onto the continents in the form of SNOW (i.e. ice sheet expansion). It is not due to the cold that the ice sheets form, it is due to the WARMTH (i.e., MOISTURE).

This year, we are likely to still see full melt-out. It will be late, but it will happen.

But, if next year or in five years, we have 2,000 KM ^3 of SWE across North America on 5/1 -- what happens then? That is a number that would ordinarily take six months to melt under pre-crazy conditions. Will it simply melt faster? Or will enough stay around until August that there is no "summer or fall," with the residual feedbacks of extant snowpack in areas where it normally does not exist during summertime allowing gains to begin again by late August, instead of late October? The act of persistence itself allows the snowpack to build much earlier in the year IF it survives peak insolation....

bbr2314

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Re: Northern Hemisphere snow cover
« Reply #157 on: April 15, 2018, 08:33:27 AM »
00z EURO through D5 is...



It has accumulating snow possible in NYC on 4/20...

And today's Canuck graph... the impending event should produce another rise if we have already stalled...!



If we hold above 1,400 KM^3 through 5/1 we approach 3X normal SWE for the date... moving forward I suspect this will translate into fortitude for Hudson Bay ice in particular, which is going to be shielded by its blanket of peripheral cover unlike any year previously...

The freshwater release from the melt in May and June is also going to be orders of magnitude above any other years... perhaps come autumn we see a NATL cold spot like never before?
« Last Edit: April 15, 2018, 09:55:37 AM by bbr2314 »

oren

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Re: Northern Hemisphere snow cover
« Reply #158 on: April 15, 2018, 10:42:23 AM »
think the CAUSE of the Younger Dryas is what is misunderstood... it was not a shutdown in AMOC, it was an abundance of oceanic heat content and a lack of sea ice that resulted in a temporary period of prolific snows, which THEREAFTER depleted the ocean of its heat content, started sea ice expansion, and pushed the Gulf Stream way S. This did not occur until continental ice sheets began building year-round, which started abruptly (it only takes one year).
The actual science about the Younger Dryas onset, from Wikipedia:
The prevailing theory is that the Younger Dryas was caused by significant reduction or shutdown of the North Atlantic "Conveyor", which circulates warm tropical waters northward, in response to a sudden influx of fresh water from Lake Agassiz and deglaciation in North America. Geological evidence for such an event is so far lacking. The global climate would then have become locked into the new state until freezing removed the fresh water "lid" from the North Atlantic. An alternative theory suggests instead that the jet stream shifted northward in response to the changing topographic forcing of the melting North American ice sheet, which brought more rain to the North Atlantic, which freshened the ocean surface enough to slow the thermohaline circulation.

Quote
My question for everyone here:

We are normally at 1,000 or so KM^3 as of 4/1, in terms of accumulated SWE across North America, according to the Canucks. This takes three months to melt down to zero.

IF we are at 1,250KM^3 as of 5/1 this year (i.e., 250 KM^3+ of ice ABOVE what is normally seen at April, also still more than the seasonal max most years), will it take 3.5 months to melt that ice? Will it take three months? Or will it be unchanged vs normal and all melt out at same time anyways, taking only two months?
Unchanged vs. normal, maybe up to 2 weeks more.

Quote
This is interesting because as we see more oceanic warming, the Hadley Cells will continue becoming increasingly potent earlier and earlier in the year. This means stagnant weather becomes the norm instead of our old seasons. And this is the natural mechanism that resolves excess oceanic heat content onto the continents in the form of SNOW (i.e. ice sheet expansion). It is not due to the cold that the ice sheets form, it is due to the WARMTH (i.e., MOISTURE).
No. Ice sheets form because summers are cool enough that snow doesn't melt out.

Quote
But, if next year or in five years, we have 2,000 KM ^3 of SWE across North America on 5/1 -- what happens then? That is a number that would ordinarily take six months to melt under pre-crazy conditions. Will it simply melt faster? Or will enough stay around until August that there is no "summer or fall," with the residual feedbacks of extant snowpack in areas where it normally does not exist during summertime allowing gains to begin again by late August, instead of late October? The act of persistence itself allows the snowpack to build much earlier in the year IF it survives peak insolation....
Recent statistics on this thread showed that higher snows do not result in a later melt-out.

johnm33

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Re: Northern Hemisphere snow cover
« Reply #159 on: April 15, 2018, 12:19:14 PM »
" It is not due to the cold that the ice sheets form, it is due to the WARMTH (i.e., MOISTURE). "
It takes a phenomenal amount of heat to pick up all that water and drop it as snow somewhere far enough from the ocean, and high enough to allow it to survive summer.
I can't remember where I read it, it was years ago [40+?], but the ancients were worried about the spread of ice sheets before the great flood. But they were all catastrophists anyway, at least the ones who tried to communicate with us were, so irrelevent in a uniformitarian world.

gerontocrat

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Re: Northern Hemisphere snow cover
« Reply #160 on: April 15, 2018, 12:42:41 PM »
Meanwhile, Eurasia melts.
Despite the massive additional snow fall in EURASIA (especially Tibet and the Himalaya), extent reduction is less than a week behind average.

I also note that the very very high snow depth anomaly in N America is mainly confined the the NE.
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Daniel B.

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Re: Northern Hemisphere snow cover
« Reply #161 on: April 15, 2018, 03:59:20 PM »
I think that NA anomaly will change with the recent blizzard that just hit the center of the country.  With record lows and two more storms forecast next week, the snows may linger awhile longer.

Tealight

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Re: Northern Hemisphere snow cover
« Reply #162 on: April 15, 2018, 06:08:51 PM »
...........
It is not due to the cold that the ice sheets form, it is due to the WARMTH (i.e., MOISTURE).

bbr2314 as much as I like your covering of snow cover I advise you to focus on more immediate consequences like river discharge, flooding or plant growing season and not on the forming of ice sheets. While it is true that dry conditions prevent ice sheets from forming (e.g. in north Greenland)  North America and Eurasia are still far far away from forming an ice sheet due to increased snow fall.

With a simplistic calculation I would say that we can discuss ice-sheets when the snow water equivalent increased by 500% over today's high numbers. That's 8000 km3 for North America.

I get this number by using melt numbers from Greenland (already a high albedo area)

A = Average Greenland summer melt: 220 km3
B = Average melt area: 342,000 km2 (20% of ice sheet)
=============
A / B =  0.64 m

A = North America snow water equivalent: 1600 km3
B = Snow Cover Extent: 12.000.000 km2
===========
A / B = 0.1333 m

So the already high albedo ice sheet could melt 4.8 times the amount of snow that's currently in North America if it were equal in area. This still ignores vegetation which reduces albedo and that most of the continent consists of low flatland. The low ice sheet regions in Greenland loose mass every year and only survive because they gain ice from the cold central interior.

With this in mind we should probably wait until 10.000-12.000 km3 for North America before ice sheets become a meaningful discussion due to increased snowfall.

data from:
http://www.dmi.dk/en/groenland/maalinger/greenland-ice-sheet-surface-mass-budget/#
https://www.ccin.ca/ccw/snow/current
« Last Edit: April 15, 2018, 06:20:53 PM by Tealight »

Tealight

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Re: Northern Hemisphere snow cover
« Reply #163 on: April 15, 2018, 06:32:05 PM »
If you wonder how to deal with immense amount of snow just visit Japan  ;)






Even these 20m high walls melt out every year in July.

https://www.atlasobscura.com/articles/snow-canyon-japan
https://www.japan-guide.com/e/e7553.html
« Last Edit: April 15, 2018, 06:43:19 PM by Tealight »

TerryM

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Re: Northern Hemisphere snow cover
« Reply #164 on: April 15, 2018, 08:38:53 PM »
Wow Tealight
That's worse than Buffalo!  ::)


In the earlier post you had mentioned river discharge. Anecdotal evidence, but locally we had the worst spring floods in decades - a month or more ago. Almost all of the accumulated snow, ice, and such has already melted and been flushed out to the lakes.
Whatever runoff we have from here on in will be very late in the season, but there won't be much of it.


Terry - in SW Ontario Canada

bbr2314

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Re: Northern Hemisphere snow cover
« Reply #165 on: April 15, 2018, 09:14:51 PM »
If you wonder how to deal with immense amount of snow just visit Japan  ;)






Even these 20m high walls melt out every year in July.

https://www.atlasobscura.com/articles/snow-canyon-japan
https://www.japan-guide.com/e/e7553.html

I would argue the situation in Japan is different from the Canadian Shield.

1) Japan is mid-latitude
2) Japan is not proximate to a large fresh-ish body of water that can potentially retain ice through summertime (Hudson Bay). Okhotsk can certainly freeze, but the duration of Okhotsk is no match for HB (even if HB, to date, also melts out every summer).
3) When ice in the Greenland Sea is lacking, easterlies prevail, putting the Canadian Shield down-wind of the coldest airmass in the Hemisphere. Japan lacks an air conditioning unit anywhere near as potent.

bbr2314

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Re: Northern Hemisphere snow cover
« Reply #166 on: April 15, 2018, 09:22:41 PM »
" It is not due to the cold that the ice sheets form, it is due to the WARMTH (i.e., MOISTURE). "
It takes a phenomenal amount of heat to pick up all that water and drop it as snow somewhere far enough from the ocean, and high enough to allow it to survive summer.
I can't remember where I read it, it was years ago [40+?], but the ancients were worried about the spread of ice sheets before the great flood. But they were all catastrophists anyway, at least the ones who tried to communicate with us were, so irrelevent in a uniformitarian world.

That heat is already manifesting IMO!

I think the below image illustrates my point re: Hawaii as well. Beyond the albedo, I think that this year, we have continued the trend of snowy Himalayas (though they have been WARM, this allows for the snow).

As airmasses move east, the downsloping dries/cools them out over SE Asia/the ocean, which is one of the reasons we have that streak of blues extending east of the continent. On the S side of the blues, the track picks up enormous amounts of heat/moisture.

Once Hawaii is reached, the volcanoes act as a lift cannon, pushing the "suppressed" track NE into North America instead of allowing it to continue straight E. This re-inforces the RRR while delivering another major heat source for NA snows besides the warmth in the NW NATL.

https://physicsworld.com/a/atmosphere-agitated-by-breaking-waves/

Hopefully the below image makes ^ make sense... and if someone can refine my language to be more technical, I would appreciate!

Also: one more amendment -- Wake Island is also apparently important, if you look at the below map, you can see a moderate area of + anomalies above Wake, and then a much larger one above Hawaii. They are both directly correlated to the only land areas between Japan & the West Coast.
« Last Edit: April 15, 2018, 09:56:28 PM by bbr2314 »

bbr2314

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Re: Northern Hemisphere snow cover
« Reply #167 on: April 15, 2018, 09:31:11 PM »
And SSTs... blazing!

The current event is dumping Caribbean moisture onto Canada btw

https://www.star.nesdis.noaa.gov/GOES/GOES16_CONUS_Band.php?band=GEOCOLOR&length=24
« Last Edit: April 15, 2018, 09:49:06 PM by bbr2314 »

johnm33

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Re: Northern Hemisphere snow cover
« Reply #168 on: April 16, 2018, 12:09:40 AM »
"That heat is already manifesting IMO!"
Not enough to start ice sheets yet by a long way, but recasting the weather systems of N.America very likely imho. My expectations won't begin to manifest until Beaufort is ice free and above 10c year round but we should see signs when it's ice free and a deep low establishes west of Hudson.

bbr2314

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Re: Northern Hemisphere snow cover
« Reply #169 on: April 16, 2018, 12:25:31 AM »
"That heat is already manifesting IMO!"
Not enough to start ice sheets yet by a long way, but recasting the weather systems of N.America very likely imho. My expectations won't begin to manifest until Beaufort is ice free and above 10c year round but we should see signs when it's ice free and a deep low establishes west of Hudson.
I don't know about that. I think once Bering is ice-free year-round (or nearly so, as it now is), the amount of heat transported into Chukchi/Beaufort is going to increase even more drastically.

You are probably more correct than not, but I suspect the threshold is not +10C year-round, more like the current state of the Bering (re: Beaufort).

Then again, others have said we need 8,000KM^3 of annual SWE to make it through summer. I think this is high. I would think it is on the order of 2,000-2,500KM^3, given the sensible impact an extra 500-1,000KM^3 is having on this April's weather.

Something to consider is that, whenever snow does make it through summer, SWE volume is going to begin increasing in late August instead of mid-October (if it can increase in mid-April, it can do the same in late August, when insolation is similar). Adding another 1.5-2 months to the snow season across the Canadian shield will naturally allow more snow to accumulate by the time spring melt begins to get going. This could mean that if/when we do start to snowball, it happens exceptionally quickly.

It is absolutely nuts that we are just about two months from declining sun angle yet we are still seeing continental gains...

PS: Minneapolis was 28/22 today. They may drop lower overnight. In any case that is an average of 25F on 4/15 (a 22-23F departure). The next five days should sustain similar/slightly warmer averages, all below freezing.

There are many reports that locations in WI/MI/MN are now nearing their all-time snow depths as well.

Truly incredible!

Also: the pattern is actually quite similar to 2013 (maybe another sign that lopsided reformation after massive high latitude losses results/contributes to this crazy)?

Except, as of our current date, the scale for 2018 is... a *tad* lower!




gerontocrat

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Re: Northern Hemisphere snow cover
« Reply #170 on: April 16, 2018, 12:48:32 AM »
I think once Bering is ice-free year-round (or nearly so, as it now is), the amount of heat transported into Chukchi/Beaufort is going to increase even more drastically.


I think once Bering is ice-free year-round.....

Define ice-free ?

The number of days when Bering Sea ice area is less than 5% of recent years' maxima has increased by about 50 days ( from about 150 days to 200 days) in the period 1979 to 2017. So the Bering Sea on that measure can be considered ice-free for about half the year.

The 2018 low area is an outlier until proved otherwise. One year's data is not a trend.

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bbr2314

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Re: Northern Hemisphere snow cover
« Reply #171 on: April 16, 2018, 03:19:38 AM »
I think once Bering is ice-free year-round (or nearly so, as it now is), the amount of heat transported into Chukchi/Beaufort is going to increase even more drastically.


I think once Bering is ice-free year-round.....

Define ice-free ?

The number of days when Bering Sea ice area is less than 5% of recent years' maxima has increased by about 50 days ( from about 150 days to 200 days) in the period 1979 to 2017. So the Bering Sea on that measure can be considered ice-free for about half the year.

The 2018 low area is an outlier until proved otherwise. One year's data is not a trend.

I do not think 2018 is an outlier. It is a new beginning. Just like 2007.

Atmospheric CO2 is now 6% or so above 2007 btw. The forcing for oceanic warmth is mounting which is why the slow decline in the Bering is suddenly... not so slow. There is no way the accumulated heat that has resulted in this year's anomalies can be resolved in a way that results in a recovery (IMO), when more of the same is en route.

Could 2019 be a bit above 2018? Yes. Will it recover beyond 2016-17 levels? I do not think so. Could it be even less than 2018? I think that is probably the most likely option.
« Last Edit: April 16, 2018, 04:07:42 AM by bbr2314 »

bbr2314

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Re: Northern Hemisphere snow cover
« Reply #172 on: April 16, 2018, 09:44:21 AM »


The blues are spreading.


bbr2314

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Re: Northern Hemisphere snow cover
« Reply #173 on: April 18, 2018, 08:51:38 AM »
!!!



If the recent trends are any indicator, the airmass over Quebec will be 10-15C colder by the time of the event. This may be a record-breaking late season tropical-blizzard hybrid IMO.

And look at the PV plunging south again!!! Substantial NA SWE melt may be delayed to post 5/1.

PS: Canuck SWE shows another day of NA SWE gains! I think we see another 1-2 before we see a few days (or months) of sustained drops.
« Last Edit: April 18, 2018, 09:32:22 AM by bbr2314 »

gerontocrat

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Re: Northern Hemisphere snow cover
« Reply #174 on: April 18, 2018, 12:46:12 PM »
There can be no doubt that the winter of 2107-18 has been a record for snowfall in the Northern hemisphere. There is also no doubt that the procession of snow-storms across North America (into the NE quadrant especially) since the late February amazing Arctic melt is also one for the record books.

This also surely adds to the evidence that a weakened polar vortex is leading to big Rossby waves in turn leading to very unusual, extreme and long-lasting weather events ? However, a single event, by definition cannot be defined as a trend until it is repeated and more than once. We all look for patterns. One pattern could be that there is no longer a pattern - the pace of climate change may have reached the stage that weather is no longer predictable from year to year?

Meanwhile, Eurasia and N. America are showing totally different trends in snow cover.

Eurasia extent loss is just a couple of days behind average, even though SWE is still around 750gt above average (though declining quickly).
In contrast N. America extent loss is about one month behind schedule and going nowhere and SWE is still hovering around the maximum.

However, cci-reanalyzer and weather-forecast.com do both reckon that from the weekend on there will be some very cold days but also days of warmth, sunshine and rain  moving north even into the Canadian Barrens on occasion.

But we will see the reality by May 1st?
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bbr2314

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Re: Northern Hemisphere snow cover
« Reply #175 on: April 20, 2018, 06:26:47 AM »
Last North American mini-maximum now either underway or likely within a day IMO... we are officially +100% or 2X normal SWE for the date (1,550 KM^3 vs. approx 775 KM^3).

April SWE has so far increased by about 50 KM^3... this has widened the discrepancy from about 500 KM^3 vs. avg as of 3/31. I.E. the departure vs. normal has increased by 55% over the past three-ish weeks.

Rolling forward, if the same departure "schedule" is maintained, it will still result in impending losses. But it would indicate we are probably going to be at or over 1,250KM^3 as of 5/1 (150% of normal). And if gains vs. normal remain steady through May, we will still have approximately 750-800KM^3 of SWE remaining as of 6/1 (vs. 225KM^3 or so normally).

If we are not at or near 1,250KM^3 by 5/1, these estimates will need upward revisions (IMO).

In any case, the dynamic of snow melt this year is going to be far more important far deeper into the season than is normally the case. I do not think May will resolve the anomaly, it is IMO going to take at least the addition of June, and possibly even the entirety of July. It will still be resolved, but the implications for sea ice melt and sensible weather over North America are likely to result in summer extremes that have not been seen in Industrialized History.

This leads me to make one bold prediction: June will be the coldest on record across the upper Midwest and Northeast US. It will also mark the start of a substantial slowdown in the Gulf Stream, a la 2009, but worse. Perhaps I will be wrong, but this should be verifiable! :)
« Last Edit: April 20, 2018, 06:37:56 AM by bbr2314 »

gerontocrat

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Re: Northern Hemisphere snow cover
« Reply #176 on: April 20, 2018, 10:55:45 AM »
I think the melt is starting now in N. America and will continue in Eurasia.
I think the thing to watch will be extent reduction c.f. SWE reduction, i.e. how long will extent reduction be delayed by the SWE anomaly.

I also think that maximum daytime temperatures will be the driver of melt. But that is just my speculation.
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Re: Northern Hemisphere snow cover
« Reply #177 on: April 20, 2018, 10:38:35 PM »
Churchill currently +12C and sunny. Strong melt around Hudson at the moment. Next days,however, should see dropping temperatures and blizzard conditions. So snow cover should regenerate for a while.

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Re: Northern Hemisphere snow cover
« Reply #178 on: April 21, 2018, 07:27:20 AM »
Churchill currently +12C and sunny. Strong melt around Hudson at the moment. Next days,however, should see dropping temperatures and blizzard conditions. So snow cover should regenerate for a while.
It looks like 4/20 may have been the first very strong SWE melt day of the season. Let's see how long it takes to provoke a rebound.

& it was!

« Last Edit: April 21, 2018, 09:43:49 AM by bbr2314 »

gerontocrat

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Re: Northern Hemisphere snow cover
« Reply #179 on: April 21, 2018, 11:34:27 AM »
From Weather Underground:-

https://www.wunderground.com/news/2018-04-20-snow-cover-meltdown-midwest-satellite

Good Riddance, Winter! Satellite Imagery Reveals Mid-April Snow Cover Rapidly Retreating in the Midwest
Jon Erdman
Published: April 20, 2018

Quote
A fresh cover of snow began retreating almost as fast as it was laid down in parts of the Midwest on Thursday, providing for some spectacular satellite imagery.

A one-two punch from Winter Storm Xanto, then another swath of up to a foot of snow just days later, left an impressive, expansive snowpack by April standards from parts of the Dakotas and northern Nebraska into the Great Lakes by Thursday morning.

In the wake of the second system, sunshine quickly returned to the nation's heartland Thursday.

With the mid-April sun being higher in the sky and able to warm the ground and air above it more efficiently, the snowpack immediately began to melt at its edges, where snow depth was less.

And it was all visible thanks to the GOES-East satellite. Most eye-catching was the snow footprint's southern edge.

Early Thursday morning, snow cover blanketed a swath of northern Illinois, virtually the entire northern half of Iowa, all of Wisconsin, and Lower Michigan almost as far south as Grand Rapids.

See GOES Gif attached

Also looks as though for at least some of the time over the next 5 days real warmth in the high latitudes.
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Re: Northern Hemisphere snow cover
« Reply #180 on: April 22, 2018, 10:24:58 AM »
Snow extent and SWE as at 21 April from https://www.ccin.ca/ccw/snow/current

What a difference 4 days can make.

North America:- 4 days ago extent loss looked about 30 days behind average. Now it looks about 3 weeks. SWE has also dropped very fast.

Eurasia Extent is reducing pretty much in line with average. the decline in SWE seems to have slowed a bit.
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Re: Northern Hemisphere snow cover
« Reply #181 on: April 22, 2018, 03:57:25 PM »
NORTH AMERICA SNOW COVER- What happens next.

The cci-renalyzer forecast of temperature over the next 10 days tend to look like the 1st image below, i.e. warmth to the East and th West and cold in the middle reaching as far as the 49th parallel.

The only longer-term temperature forecast for (May, June July) Canada I can find is from Environment Canada (also attached). Normal temperatures in the middle, warmth in the far north, the East and the West. (Weather-forecast.com for the USA has similar but colder in the middle).

So "my prediction that belongs to me" is that the snow is going to go pretty quick - though perhaps in the far north and middle of Canada there will be a couple of weeks delay from normal.

We will see in the next few weeks.
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oren

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Re: Northern Hemisphere snow cover
« Reply #182 on: April 23, 2018, 12:12:09 PM »
This thread has recently become calmer - a good development.
Here are some more links with data about NA snow cover, with a reminder that albedo is dictated by extent rather than thickness/SWE:

A 30-day animation of snow extent and ice cover (as well as SSTs). The last few days show nicely that when the weather comes, snow can disappear very fast. (click play icon)
https://weather.gc.ca/saisons/animation_e.html?id=month&bc=sea

Another animation of NA snow and Hudson sea ice, with an easier selection of date range and a different map projection.
https://www.ncdc.noaa.gov/snow-and-ice/snow-cover/

An analysis of snow cover extent anomalies, unfortunately only goes to 2010 but still interesting IMO. Clearly shows how fall/winter have positive extent anomalies while spring/summer have negative ones. I expect this trend to have continued to the present.

gerontocrat

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Re: Northern Hemisphere snow cover
« Reply #183 on: April 24, 2018, 12:20:48 PM »
Snow extent and SWE as at 21 April from https://www.ccin.ca/ccw/snow/current

What a difference 6 days can make. I was expecting a rapid drop, but even so...

North America:- 6 days ago extent loss looked about 30 days behind average. Now it looks about 2 weeks. SWE has also dropped very fast. (Images below).

CC-reanalyzer seems to say that for the remainder of the month in N. America temperatures plus a mixture of rain and clear days at high latitudes should maintain this rapid pace of snow melt.

Watch out for above average river flows and associated ice jams?

PS:- Eurasia Extent and SWE are reducing pretty much in line with average (No images added this time).
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Re: Northern Hemisphere snow cover
« Reply #184 on: April 24, 2018, 04:50:47 PM »
Snow extent and SWE as at 21 April from https://www.ccin.ca/ccw/snow/current

What a difference 6 days can make. I was expecting a rapid drop, but even so...

North America:- 6 days ago extent loss looked about 30 days behind average. Now it looks about 2 weeks. SWE has also dropped very fast. (Images below).

CC-reanalyzer seems to say that for the remainder of the month in N. America temperatures plus a mixture of rain and clear days at high latitudes should maintain this rapid pace of snow melt.

Watch out for above average river flows and associated ice jams?

PS:- Eurasia Extent and SWE are reducing pretty much in line with average (No images added this time).

The drop has been ridiculous. But this spring I have noticed when Eurasia or North America tanks, the other steadies. I wonder if we see another pause in NA in the next few days and then Eurasia tanks again?

In either case, the amount of melt this (late) month has been... substantial... and I am re-assured that we must see much more snow accumulate vs currently to sustain snow through July.

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Re: Northern Hemisphere snow cover
« Reply #185 on: April 25, 2018, 10:52:35 AM »
NH snow cover is taking a dive:



And I'm also seeing something I hadn't noticed before. This map doesn't show the extreme snow height (which I would think is correlated to SWE) in Eastern Canada, corresponding with the purple on the Environment Canada SWE anomaly map:

edit: the map background is too dark, here's a http://link.

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Re: Northern Hemisphere snow cover
« Reply #186 on: April 25, 2018, 12:19:07 PM »
I believe the thick snow is still there. Here is the (very hard to read) Environment Canada snow depth map, showing 160-210 cm snow depth across parts of Quebec.

I've also taken the opportunity to update the three snow depth charts I've made in mid-March of specific SYNOP stations (Goose Bay and Cartwright in Canada, Sredne-Kolymsk in Russia). The updated charts show, again, that winter snow depth during winter is not very predictive of spring snow depth, in opposition to certain predictions posted in this thread.

Deep land snow seems to be a consequence of AGW. For people living with all that snow I am sure it's a severe consequence, but it does not create a significant climate feedback.

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Re: Northern Hemisphere snow cover
« Reply #187 on: April 25, 2018, 02:13:11 PM »
NH snow cover is taking a dive:





And looking at the chart, we see that NH snow extent was actually tracking with the lowest years until late February and March when extent grew dramatically. I believe heavier snowfall in the winter is a new feature of AGW (more moisture load in the atmosphere etc.) but the phenomenon  this April is simply weather IMHO.

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Re: Northern Hemisphere snow cover
« Reply #188 on: April 25, 2018, 03:01:34 PM »
Whether the heavy snowfall is a consequence or not is rather contentious.  More moisture will generate greater snowfall in those areas where sufficient cold exists.  However, many areas will see more snow transition to rain, as temperatures rise.  The premise is that the rain/snow edge should move further poleward, with areas in higher latitudes receiving greater snowfall, and those in lower receiving less.  The thought is that more snow would fall in the depths of winter, as moisture invades the drier air, while spring and fall receive less, due to temperatures rising above freezing.  This past year shows the opposite.  Hence, I agree that it was probably just weather.

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Re: Northern Hemisphere snow cover
« Reply #189 on: April 26, 2018, 10:23:33 AM »
Snow extent and SWE as at 25 April from https://www.ccin.ca/ccw/snow/current

I was expecting the rapid drop to continue, but even so...

North America:- 8 days ago extent loss looked about 30 days behind average. Now it looks about 10 days. SWE has also dropped very, very fast. (Images below).

CC-reanalyzer still seems to say that for the remainder of the month and the first few days in May  N. America temperatures will be above zero for most of the time except the for centre of Northern Canada.  And a mixture of rain and clear days at high latitudes should maintain this rapid pace of snow melt.

Above average river flows and associated ice jams?

PS:- Eurasia Extent following the 1 SD above average line while SWE well above average but reducing pretty much in line with average (No images added this time).
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Re: Northern Hemisphere snow cover
« Reply #190 on: April 26, 2018, 11:56:01 PM »
The high anomalous snow cover in eastern Canada is getting torched today. Not only is it above freezing, it is also very humid and raining. The best mix to melt snow effectively.

Short Energy comparison
liquid water 1 degree change: 4.18 J/g
Enthalpy of fusion: 333 J/g
Enthalpy of vaporization: 2257 J/g
(energy wise 1 gram of water vapor can melt 6.7 gram of ice)

Just before the shoreline the air contains 30 kg/m2 of water vapor and a bit further inland it drops to 20 kg/m2. With a perfect energy transfer (unlikely) it could melt 6.7 cm of ice. I can't calculate how much energy gets really transferred because the wind speed and direction varies significantly in the lower parts of the atmosphere.

I didn't manage to line up the green dot in my gif but all shown values are for the same location.

gerontocrat

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Re: Northern Hemisphere snow cover
« Reply #191 on: April 27, 2018, 11:55:13 AM »
Can't resist the graphs on https://www.ccin.ca/ccw/snow/current.

Goodbye to the snow in N. America. In the next few days I still say it is periods of warmth that matter more than cold nights for snow melt. Last image is maximum temperatures over the next 5 days. t says melting to very high latitudes to me. We will see.
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bbr2314

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Re: Northern Hemisphere snow cover
« Reply #192 on: April 27, 2018, 05:08:22 PM »
Can't resist the graphs on https://www.ccin.ca/ccw/snow/current.

Goodbye to the snow in N. America. In the next few days I still say it is periods of warmth that matter more than cold nights for snow melt. Last image is maximum temperatures over the next 5 days. t says melting to very high latitudes to me. We will see.
I think the speed with which the anomalies are resolving is another indicator the graphs are indeed accurate. And the sudden surge in melt is almost as anomalous as the first half of April!

gerontocrat

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Re: Northern Hemisphere snow cover
« Reply #193 on: April 28, 2018, 12:02:25 PM »
Still can't resist the graphs on https://www.ccin.ca/ccw/snow/current.
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Re: Northern Hemisphere snow cover
« Reply #194 on: April 28, 2018, 12:48:45 PM »
cheers Gerontocrat .. it's not often you see a whole Ice Age disappear in a week ! :) .. along with the all-pervasive commentary .. b.c.
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gerontocrat

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Re: Northern Hemisphere snow cover
« Reply #195 on: April 28, 2018, 01:04:31 PM »
cheers Gerontocrat .. it's not often you see a whole Ice Age disappear in a week ! :) .. along with the all-pervasive commentary .. b.c.

The data in the end has the last word (until next winter and spring?)
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Re: Northern Hemisphere snow cover
« Reply #196 on: April 28, 2018, 04:38:40 PM »
cheers Gerontocrat .. it's not often you see a whole Ice Age disappear in a week ! :) .. along with the all-pervasive commentary .. b.c.

The data in the end has the last word (until next winter and spring?)

The data always has the last word. Snowfall in the late winter and early Spring in NA was huge. The current melt is rapid. We have generally been seeing positive snowfall anomalies in the Fall and early winter and negative anomalies in the Spring, more than just a single season. It would be great if scientists would begin to definitively link the changes that we are seeing in weather with AGW.

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Re: Northern Hemisphere snow cover
« Reply #197 on: April 28, 2018, 11:13:44 PM »
cheers Gerontocrat .. it's not often you see a whole Ice Age disappear in a week ! :) .. along with the all-pervasive commentary .. b.c.

The data in the end has the last word (until next winter and spring?)

The data always has the last word. Snowfall in the late winter and early Spring in NA was huge. The current melt is rapid. We have generally been seeing positive snowfall anomalies in the Fall and early winter and negative anomalies in the Spring, more than just a single season. It would be great if scientists would begin to definitively link the changes that we are seeing in weather with AGW.
Indeed. At the very least, I am glad the melt has begun -- but as always, it has happened in a way almost as surprising as the great lengthening of peak SWE this year.

We have lost the same SWE that it normally takes ~36 days to melt in only six days. I suspect that this will translate into extreme cold and snow anomalies persisting into May and June as we still do have positive residuals, but they are imminently going to be coupled with a fairly abrupt freshwater pulse.

My suspicion is that these freshwater pulses (like we saw in the ante-Nino months of 2009...) result in more of the AMOC's energy translating upstream into the waters near Svalbard / also result in heat discharge into Greenland, thus encouraging +500MB anomalies in both regions and causing "-NAO".

If the 12z EURO is correct, the extended forecast is looking... rather anomalous... once more. Let's hope it doesn't severely impact the start of spring now underway across the Heartland / Great Plains.





^ is also a very terrible look for the sea ice...

gerontocrat

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Re: Northern Hemisphere snow cover
« Reply #198 on: April 29, 2018, 01:00:27 PM »
Still can't resist the graphs on https://www.ccin.ca/ccw/snow/current.
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Tor Bejnar

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Re: Northern Hemisphere snow cover
« Reply #199 on: April 29, 2018, 02:59:24 PM »
Will SWE (snow water equivalent) get below +1 S.D. before May 1st?  I'm guessing 'no' by a hair. 

In other news:  Who would 'a thought that snow would melt in the spring?  ::)  Response:  Well, those who expect recent precedent is predictive.

[Edit on May 9th:  It was "no", but it was off by more than a hair!]
« Last Edit: May 09, 2018, 08:56:56 PM by Tor Bejnar »
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