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powderfreak

NNE Winter Thread

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BTV4 is pretty nice looking...even taking the customary 33% reduction on the QPF levels.  Its got near constant upslope flow for its entire run cycle starting tonight.

This is through midday Saturday.  I've noticed the models are showing a more unblocked flow with precipitation spreading quite a bit downwind of the Spine.  It really smokes the RT 100 corridor, which should be interesting to see if we can get anything decent out of this.

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19 minutes ago, powderfreak said:

BTV4 is pretty nice looking...even taking the customary 33% reduction on the QPF levels.  Its got near constant upslope flow for its entire run cycle starting tonight.

This is through midday Saturday.  I've noticed the models are showing a more unblocked flow with precipitation spreading quite a bit downwind of the Spine.  It really smokes the RT 100 corridor, which should be interesting to see if we can get anything decent out of this.

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I'm trying to learn and understand more about how upslope snows work. So with that in mind, does your last statement mean that unblocked flow can amount to less snow in the higher elevations and spill more into the valley? Oh and how and where can you determine blocked vs. unblocked flow on a model? Thanks for any help. 

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Event totals: 0.2” Snow/0.01” L.E.

 

Checking the models and BTV NWS forecast discussion, I’m putting last night’s snow accumulations into this upcoming event, which appears to be best described as a broad upper/mid-level trough with embedded shortwaves.  A look at the latest run of the GFS doesn’t show any obvious breaks in the snowfall until about Monday night, but we’ll see what happens going forward and I’ll split things out if needed.

 

Details from the 9:00 P.M. Waterbury observations:

 

New Snow: 0.1 inches

New Liquid: 0.01 inches

Snow/Water Ratio: 10.0

Snow Density: 10.0% H2O

Temperature: 30.0 F

Sky: Light Snow/Flurries (1-3 mm flakes)

Snow at the stake: 5.0 inches

 

Details from the 6:00 A.M. Waterbury observations:

 

New Snow: 0.1 inches

New Liquid: Trace

Temperature: 32.9 F

Sky: Cloudy

Snow at the stake: 5.0 inches

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35 minutes ago, zeepowderhunter said:

I'm trying to learn and understand more about how upslope snows work. So with that in mind, does your last statement mean that unblocked flow can amount to less snow in the higher elevations and spill more into the valley? Oh and how and where can you determine blocked vs. unblocked flow on a model? Thanks for any help. 

Some light Froude reading:) BTV NWS I know also has Froude number outputs on their website somewhere that show values, RH, QPF to see if flow is blocked vs unblocked.

http://www.weather.gov/btv/froude

 

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55 minutes ago, zeepowderhunter said:

I'm trying to learn and understand more about how upslope snows work. So with that in mind, does your last statement mean that unblocked flow can amount to less snow in the higher elevations and spill more into the valley? Oh and how and where can you determine blocked vs. unblocked flow on a model? Thanks for any help. 

 

PF will sometimes put up those wind profile plots showing the wind direction at various elevations, and you can get a sense for the blocked/unblocked nature of the flow there.  The blocked/unblocked nature of the flow can be depicted by the Froude number (you’ll hear us using it in the NNE thread to discuss the nature of the flow over the local mountains), where smaller numbers below 1 are blocked, and larger numbers above 1 are more unblocked.  It’s a nice parameter to have here in the mountains, so the BTV NWS actually has a very detailed page describing it:

 

http://www.weather.gov/btv/froude

 

They also have a real time Froude number mountain profile reporting page, but perhaps that link has changed because my link below isn’t working:

 

http://www.erh.noaa.gov/btv/mountain/profile/definitions/froude.html

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3 hours ago, adk said:

This is a classic northern green pattern. Upper level trough entrenched behind a wet mild storm. Low levels are moist and warm right now. As successive shortwaves move through with cooler and cooler weather these low levels just get wrung out a little more each time along the spine....throw in some synoptic lift and a clear connection to the great lakes and you get 4 days with snow. 

Right now, I'd say the most moisture falls tonight into Friday but the most snow may be sat-sun due to better snow growth temps. Which is ideal because we could use 4" of dense snow topped with 4" of fluff.....

 

 

best part is no overwhelming deep Arctic cold, these are the situations where the Greens can get lit up quickly

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16 minutes ago, J.Spin said:

 

PF will sometimes put up those wind profile plots showing the wind direction at various elevations, and you can get a sense for the blocked/unblocked nature of the flow there.  The blocked/unblocked nature of the flow can be depicted by the Froude number (you’ll hear us using it in the NNE thread to discuss the nature of the flow over the local mountains), where smaller numbers below 1 are blocked, and larger numbers above 1 are more unblocked.  It’s a nice parameter to have here in the mountains, so the BTV NWS actually has a very detailed page describing it:

 

http://www.weather.gov/btv/froude

 

They also have a real time Froude number mountain profile reporting page, but perhaps that link has changed because my link below isn’t working:

 

http://www.erh.noaa.gov/btv/mountain/profile/definitions/froude.html

http://www.weather.gov/btv/froudeNAM

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1 hour ago, backedgeapproaching said:

Some light Froude reading:) BTV NWS I know also has Froude number outputs on their website somewhere that show values, RH, QPF to see if flow is blocked vs unblocked.

http://www.weather.gov/btv/Froude

 

Sorry about doubling up on that link backedge – missed your post before mine went out.

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Late in posting on the "kitchen sink" storm - long work day yesterday, including a short drive thru the rain with no wiper on the driver's side.  Thanks to sleetcake sliding forward from the roof, the blade flipped onto the passing lane of I-95 about 25 miles south of BGR.  1st safe place to stop was 15 miles away at a rest area, where I switched the other blade.

Storm total of 2.09" LE is only 0.01" less than from the 21" dump on Dec. 29-30, but in much less pleasing form.  Started with 1" of rime-encrusted sort-of-flakes then went over to mainly IP for most of Tuesday.  Then a bit of ZR (trees still lightly iced above 750' on Mile Hill) then to 33F RA.  Got 4.5" of "stuff" that was so dense I had to push the snowblower to avoid its climbing atop the mess.  That 4.5" had an estimated 1.62" LE, the other 0.47" falling in liquid form.  The 20" at the stake probably holds close to 7" SWE, fairly high for late January.

Temps have pulled a real switcheroo this month.  1st 10 days ran 4.3F BN; since then it's been +10.8, and +16.7 for 19-25, which ironically are my coldest 7 days of the year on average.   The minima for that period were 23F above my 1.5F average; have not seen sub-20 since the 18th.  2008 was the only other year featuring a 7-day 20+ run in January; would love to repeat that year's snowfall.  :weenie:

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39F bright sun, no wind.  Will be a great afternoon.  Let's see how much 3" of sleet can melt in an increasing sun angle.

I keep thinking about a PF comment awhile back about how the other guys  (like me) don't post that much in the NNE forum.  Great example how I will have basically no weather of importance over the next several days while people like PF in the Greens or Alex in the Whites get blasted with upslope.  Like a wall 25 miles to my NW nothing happens here but a few flurries or perhaps a quick dusting. 

 

 

 

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46 minutes ago, tamarack said:

Late in posting on the "kitchen sink" storm - long work day yesterday, including a short drive thru the rain with no wiper on the driver's side.  Thanks to sleetcake sliding forward from the roof, the blade flipped onto the passing lane of I-95 about 25 miles south of BGR.  1st safe place to stop was 15 miles away at a rest area, where I switched the other blade.

Storm total of 2.09" LE is only 0.01" less than from the 21" dump on Dec. 29-30, but in much less pleasing form.  Started with 1" of rime-encrusted sort-of-flakes then went over to mainly IP for most of Tuesday.  Then a bit of ZR (trees still lightly iced above 750' on Mile Hill) then to 33F RA.  Got 4.5" of "stuff" that was so dense I had to push the snowblower to avoid its climbing atop the mess.  That 4.5" had an estimated 1.62" LE, the other 0.47" falling in liquid form.  The 20" at the stake probably holds close to 7" SWE, fairly high for late January.

Temps have pulled a real switcheroo this month.  1st 10 days ran 4.3F BN; since then it's been +10.8, and +16.7 for 19-25, which ironically are my coldest 7 days of the year on average.   The minima for that period were 23F above my 1.5F average; have not seen sub-20 since the 18th.  2008 was the only other year featuring a 7-day 20+ run in January; would love to repeat that year's snowfall.  :weenie:

20" with 7" LE, your definitely the pack master of the forum. Amazing variance in climates just within the NNE subforum as gene was just pointing out with his last post.

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48F and bright sunshine.  It's another stellar March day here in the southern Champlain Valley.  Snow is melting, driveway is rutting, and lake ice is thinning and receding from the shoreline.  Looking forward to April starting in 5 days.

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39 minutes ago, backedgeapproaching said:

20" with 7" LE, your definitely the pack master of the forum. Amazing variance in climates just within the NNE subforum as gene was just pointing out with his last post.

Since continuous cover began on 12/5, I've recorded 7.79" total precip.  There's been settling and sublimation, but any melting has been pretty much absorbed by the white sponge; nothing's been running out from under the pack.

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8 minutes ago, backedgeapproaching said:

Looks like a pretty impressive statewide event for favored areas. I would gladly take 4-6" even if it just the dreaded "fluff" eveyone hates..lol

It won't be fluff until the weekend probably.  The snow growth temps don't necessarily line up for the first half of it.  The best omega on the Coolwx plots looks to be under the snow growth zone.  Tonight should be dense QPF snow at least here.

 

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2 hours ago, wxeyeNH said:

39F bright sun, no wind.  Will be a great afternoon.  Let's see how much 3" of sleet can melt in an increasing sun angle.

I keep thinking about a PF comment awhile back about how the other guys  (like me) don't post that much in the NNE forum.  Great example how I will have basically no weather of importance over the next several days while people like PF in the Greens or Alex in the Whites get blasted with upslope.  Like a wall 25 miles to my NW nothing happens here but a few flurries or perhaps a quick dusting. 

 

 

 

I'll be too busy skiing to post. :P

GYX seems to think some of the snow will make it past the Whites, at least on Friday. So there MAY be something for you as well! I like that BTV includes us in their map. No offense to GYX but... can they adopt us??? They seem to do a great job with mountain weather.

Actually, an interesting factoid I noticed when I moved to BW. On the other side of Crawford Notch, in the Bartlett/No Conway area everything revolves around Maine. In the BW/Littleton area, everything is aligned with VT. Not surprising, I guess, considering Littleton is a border town, but it's always been interesting to me of how much of a wall that notch creates between the 2 sides, even culturally. 

Back to the regularly scheduled programming.

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1 hour ago, powderfreak said:

We have the sun out but a cloud over the mountain just started spitting wet snow down to the base.  So looks like precipitation has started.

 

There’s been a notable change in the weather here in Burlington as well – it was just cloudy much of the day, but I was recently outside and it was a steady rain.  I don’t always know if the Champlain Valley is going to join in to any great degree with these types of events, but they’re at least getting some of it.

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After a beautiful afternoon in the mid 40's the clouds came back in.   Just had a light to moderate rain shower that briefly turned to snow during its height.  Temp 40.1F so cold air is just above.  Could easily see the virga snow/rain line as it passed over head.  Skies now breaking again.

Love to see a quick squall or two make it over the Greens.  An inch of powder would nicely cover this sad sleet.  Even though it got into the mid 40's with sun my SW slopes remained snow covered.  

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Dumpage this afternoon at the mountain.

Sierra style wet snow that accumulated to 2.5" by 4pm at 3,000ft with 1" of very water logged snow at 1,500ft.

Flakes the size of your fist at times, haha.

 

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8 hours ago, J.Spin said:

 

PF will sometimes put up those wind profile plots showing the wind direction at various elevations, and you can get a sense for the blocked/unblocked nature of the flow there.  The blocked/unblocked nature of the flow can be depicted by the Froude number (you’ll hear us using it in the NNE thread to discuss the nature of the flow over the local mountains), where smaller numbers below 1 are blocked, and larger numbers above 1 are more unblocked.  It’s a nice parameter to have here in the mountains, so the BTV NWS actually has a very detailed page describing it:

 

http://www.weather.gov/btv/froude

 

They also have a real time Froude number mountain profile reporting page, but perhaps that link has changed because my link below isn’t working:

 

http://www.erh.noaa.gov/btv/mountain/profile/definitions/froude.html

Honestly, there are three big groups for the Froude number in my mind. REALLY BLOCKED, normal and way unblocked. 

In really blocked blow - sub .5 the snow just gets caught on the west slopes and you'll see like 4x the amount of snow in underhill than you will on the ski mountains. .5-1.25 I consider normal. Elevation plays a greater role in these events and wind transport from east side of spine to west side makes it hard to really pin down exactly the difference at elevation.  The caveat is that in like .8, .75 events Smuggs and some north facing places do better than east facing. 

1.25 and above - don't believe the numbers. This is when the air starts moving too fast over the mountains. Squally type snow that can blow in streaks. 

For PF the difference is like between .75 and 1.1 - that's where you see zero flakes in stowe proper and 6" on the mtn. 

As good as the BTV science is on it, there are soooooooo many variable that go into how snow falls and stacks that it isn't the best single judge. 

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Definitely an east side event right now with the radar look.  I'm not a fan of the 1.5 degree scan because the higher peaks block it and create radar gaps, but you can better see where precipitation is reaching the ground.  Right now its pretty solidly been staying on the eastern slope.

Snowing nicely in Stowe but wet big flakes that are having trouble really accumulating.  Need another degree or two of cooling.

Jan_26_530pm_zps4zl3yp7p.gif

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