Snowpack

[MarkO]

Living in different parts of New England, I've noticed some areas develop and retain a snowpack. If I were to define that area it would look something like this. Thoughts?

[ORH_wxman]

What's your definition of retention? 

The line you drew seems to bound roughly the "75 days per year" of snow cover which is defined as 1" or more on the ground. 

It's not a bad definition...2.5+ months is a lot. But some might argue 2 months is a lot too.

The max depth might be another way to define it. Those same areas typically seem to approach an 18 inch (or more) depth most winters. Partly because these same areas highlighted are traditionally the last places to turn to liquid rain in a lot of our storms with CAD/freezing rain. So they don't melt as much in those types of storms which are somewhat frequent. 

[dendrite]

As bad as that downslope zone is in Littleton NH, I don't think I'd put MHT/ASH ahead of them on retention.

Some kind of ratio between total snowfall and snow depth days may work as well. That would tell you who does the best at keeping what they get.

[tamarack]

19 hours ago, dendrite said:

As bad as that downslope zone is in Littleton NH, I don't think I'd put MHT/ASH ahead of them on retention.

Some kind of ratio between total snowfall and snow depth days may work as well. That would tell you who does the best at keeping what they get.

I've been tracking that and call it "retention metric."  At my place it's varied from 10.55 (05-06) to 31.53 last winter.  This calculation shows well the snowpack difference between my CAD-king/synoptic snow area and J.Spin's fluff/low-CAD site, as my average 07-08 on (start of his full records afaik) thru last winter is 21.80 while his is 9.21.

[Great Snow 1717]

On 1/6/2020 at 5:16 PM, MarkO said:

Living in different parts of New England, I've noticed some areas develop and retain a snowpack. If I were to define that area it would look something like this. Thoughts?

 Parts of Pelham and Methuen border each other but Pelham area retains snow better than what Methuen does.  I was in Pelham on Saturday and the yards were all snow covered. In Methuen many of the yards were snow free or just had patchy snow. The west side of Methuen is a bit better for retention compared to the east side. 

[ORH_wxman]

1 hour ago, tamarack said:

I've been tracking that and call it "retention metric."  At my place it's varied from 10.55 (05-06) to 31.53 last winter.  This calculation shows well the snowpack difference between my CAD-king/synoptic snow area and J.Spin's fluff/low-CAD site, as my average 07-08 on (start of his full records afaik) thru last winter is 21.80 while his is 9.21.

Yeah, if you measuring solely retention, your way is better than overall snow cover days....someone on the west side of the green mountain spine could have snow cover most of the winter but that is largely due to the extreme frequency of snowfalls there but not their retention ability. They'll melt down quite a bit of what falls during cutters but it's always being replenished so bare ground is very rare....unlike to the east of the spine (or nestled down in it) and especially your area which could get much less frequent snowfalls but rarely torches any snow fully down to bare ground once you get a few inches established.

[HIPPYVALLEY]

On 1/6/2020 at 5:16 PM, MarkO said:

Living in different parts of New England, I've noticed some areas develop and retain a snowpack. If I were to define that area it would look something like this. Thoughts?

Drop your Ct River Valley ridge about 20mi S.

Brattleboro to Greenfield (especially Greenfield) has some great snow retention due to CAD and elevated valley topography.   Just ask all the posters who get sick of pictures of my yard. 

 

[tamarack]

1 hour ago, ORH_wxman said:

Yeah, if you measuring solely retention, your way is better than overall snow cover days....someone on the west side of the green mountain spine could have snow cover most of the winter but that is largely due to the extreme frequency of snowfalls there but not their retention ability. They'll melt down quite a bit of what falls during cutters but it's always being replenished so bare ground is very rare....unlike to the east of the spine (or nestled down in it) and especially your area which could get much less frequent snowfalls but rarely torches any snow fully down to bare ground once you get a few inches established.

I've yet to have a 5"+ pack go to zero in met winter; closest was the 4" on 12/8/06 disappearing by the 13th.  We did have 9" go to bare ground Nov. 23-28, 2011.  When we lived  in Gardiner (not particularly CAD-rich) a 12" pack on Jan. 3, 1995 was gone after the 16th - 2 days of rainy 50s with overnight mid 40s will do that.

[MarkO]

With a defined metric it would obviously easier to mathematically model. I've just noticed over the years there are places that just build a pack and are able to hold onto it. In Lowell we can retain a pack on abnormally high, say >60", but most average winters, it tends to disappear. My friend who lives in NW Nashua retains snow much more significantly. It's probably midway between what I experience in Lowell vs Thornton. For example currently in Lowell, it's essentially down to snow banks. But's he's got 4-6" dense pack. I'm probably at 6-8" dense in Thornton.

I guess another way to look at it is where snowmobile trails are, or if only there were three seasons, fall, winter and spring, where would glaciers exist?

[ORH_wxman]

14 minutes ago, MarkO said:

With a defined metric it would obviously easier to mathematically model. I've just noticed over the years there are places that just build a pack and are able to hold onto it. In Lowell we can retain a pack on abnormally high, say >60", but most average winters, it tends to disappear. My friend who lives in NW Nashua retains snow much more significantly. It's probably midway between what I experience in Lowell vs Thornton. For example currently in Lowell, it's essentially down to snow banks. But's he's got 4-6" dense pack. I'm probably at 6-8" dense in Thornton.

I guess another way to look at it is where snowmobile trails are, or if only there were three seasons, fall, winter and spring, where would glaciers exist?

Well if you want to get technical, probably down past our latitude considering eliminating summer would be subtracting like 4C from our temperatures....which would in turn cause a re-advance of the Laurentide ice sheet from the north (the remnants only now exist on Baffin island and a few nearby higher elevation glaciers) which would in turn probably cause global temps to fall even further with feedbacks, yadda, yadda, yadda........but yeah, I get what you're saying. We'd still probably only have glaciers on the peaks because even MWN doesn't support glaciers and their current average annual temp is 27F or so. You'd probably need it a few degrees below MWN's current temps (which would happen in your scenario at least on the peaks of NNE)

[tamarack]

I think that a site with MWN's average annual temp but on level ground where the 250"+ snowfall didn't blow away would have glacier-starting potential if it had a several-year run of AN winters.  For the 9 winters 68-69 thru 76-77, MWN averaged 420" - might be enough in a cold valley that makes a 150"+ pack out of that much snowfall.

[ORH_wxman]

14 minutes ago, tamarack said:

I think that a site with MWN's average annual temp but on level ground where the 250"+ snowfall didn't blow away would have glacier-starting potential if it had a several-year run of AN winters.  For the 9 winters 68-69 thru 76-77, MWN averaged 420" - might be enough in a cold valley that makes a 150"+ pack out of that much snowfall.

MWN did have a few rogue winters where tuckermans had a glacier survive the entire ablation season. I have posted a paper on this in the past and it happened several times in the late 1800s when records began....the final time being 1926. But the paper was published in 1960 so I'm not sure if they had a glacier survive the ablation season in the 1960s/1970s which had some exceptionally cold years that would have rivaled those previous ablation seasons. 

[MarkO]

13 minutes ago, ORH_wxman said:

MWN did have a few rogue winters where tuckermans had a glacier survive the entire ablation season. I have posted a paper on this in the past and it happened several times in the late 1800s when records began....the final time being 1926. But the paper was published in 1960 so I'm not sure if they had a glacier survive the ablation season in the 1960s/1970s which had some exceptionally cold years that would have rivaled those previous ablation seasons. 

I relish those studies, but I did not know Tuck's made it through summers, as in witnessed. I remember reading one about possibility of Great Gulf being glaciated since retreat of the Laurentide ice sheet. I've wondered if parts of presidential peaks were glaciated during the Little Ice age, if not, it must have been pretty close.

 

Edit, would be interesting to find out about summer of '69. Maybe Brian Adams knows.

[ORH_wxman]

1 hour ago, MarkO said:

I relish those studies, but I did not know Tuck's made it through summers, as in witnessed. I remember reading one about possibility of Great Gulf being glaciated since retreat of the Laurentide ice sheet. I've wondered if parts of presidential peaks were glaciated during the Little Ice age, if not, it must have been pretty close.

 

Edit, would be interesting to find out about summer of '69. Maybe Brian Adams knows.

I was going to check MWN's records but strangely I cannot get anything prior to 2005 now. Really weird. 

Maybe someone here has a link for monthly data going back to the beginning. I was going to compare ablation season temps to find the most likely years after 1960 they may have been able to support a glacier surviving. 

[tamarack]

15 hours ago, MarkO said:

I relish those studies, but I did not know Tuck's made it through summers, as in witnessed. I remember reading one about possibility of Great Gulf being glaciated since retreat of the Laurentide ice sheet. I've wondered if parts of presidential peaks were glaciated during the Little Ice age, if not, it must have been pretty close.

 

Edit, would be interesting to find out about summer of '69. Maybe Brian Adams knows.

Many years ago I read in Appalachia (AMC's magazine) that folks discussed the "MWN Glacier" after 68-69 but that the Tucks snow didn't quite survive the warm seasons.  The Pinkham Notch co-op had recorded something like 320" (MWN over 500) that winter and the co-op's pack reached 164" at the end of the 77" dump in late Feb '69.