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dryslot

NNE Winter Thread II

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You are counting this snowfall in with the front end snow yesterday right...to get the 3.6"?

Yes, that's right PF; the 3.6" event total through 1:00 P.M. includes the 2.2” of front end snow from this storm. There is another 1.3" down on the snowboard now, so it’s 4.9” total as of 5:00 P.M. I’ll do another assessment later this evening.

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Fairly unblocked flow helping out the spine and east today. Heaviest snow falling downwind of the mountains so far today as the wind pushes it up and over. May back up a little this evening if the inversion can strengthen. Pretty much light-moderate snow here along the western slopes, but only 1.5" as of 4:45pm.

Really no difference here in Stowe Village 5 miles down the road from the ski resort. I had 1.5" as reported to BTV at 3:30pm when I got home, but I don't think we've added anything more than an additional dusting since then.

My feeling from looking at the webcam in Underhill was that they were getting the same on the west slope as the ski area on the east slope. Although there was almost 4" at 2pm on the upper mountain, 1,500ft was only 2.5".

It just looks a lot more impressive in the photos because of the high winds. It was snowing heavily but the wind just wasn't allowing it to stack up like usual. It had that feel of a day where if the winds were calm, we would've gotten 6-8" instead of 2-4" of wind hammered snow. There's just no QPF in that stuff so the wind just crushes it.

I'm surprised this is a relatively unblocked flow based on the radar... I know composite radar can be misleading (except its the only one that seems to give me the best idea of what's happening at the mountain), but when the radar echos "peak" in the Williston/Richmond area, that to me seems to translate to the ground on the western slope. Usually the strong winds aloft seem to cause that snow to propagate downwind (in my experience) from where the composite radar shows them... so that stuff is probably ending up in the Bolton-Underhill corridor. I just know that when composite radar shows the heaviest echos in central Chittenden County, its too far east for here in town. When they are over western Chittenden County or the county line, that's usually good for here. For whatever reason, heavier echos overhead don't seem to matter, haha, its the echos to the west that seem to relate more to my home precipitation rates.

For comparison, here's a composite from last February's big upslope storm when we got 17" even in Stowe Village to the east of the Spine. The echos seem to "peak" right over the ridgeline (county line) and that snow ends up falling downwind in town. For me in Stowe Village, I like to see the composite radar echos reach their max dbz over the Spine.

This was producing 1-2"/hr rates down in Stowe village where echos are much less overhead. My assumption is the strong winds were blowing the snow shown by those 30dbz+ echos over the Spine, downwind into town.

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interesting PF. was there for that historic upslope in Feb. last year. It never really 'shut off' in town, as you'd think it would be confined to the higher terrain- it wasn't for that event. the higher terrain just got slammed, and the village got relatively slammed as well.

along the spine, directly, it's really a coin toss it seems. you never quite know whether the west or east slopes are gonna prevail until it's just about happening (Jan 2010 being the most obvious example). still trying to wrap my head around this localized phenomena. overall, both sides seem to make out pretty well when you average things out.

you'd think, back in the day, that some ski area would have popped up on the underhill side of mansfield and been sustainable... as the snow over there is pretty solid. alas, it didn't happen. the ski industry is a fickle beast.

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For comparison, here's a composite from last February's big upslope storm when we got 17" even in Stowe Village to the east of the Spine. The echos seem to "peak" right over the ridgeline (county line) and that snow ends up falling downwind in town. For me in Stowe Village, I like to see the composite radar echos reach their max dbz over the Spine.

This was producing 1-2"/hr rates down in Stowe village where echos are much less overhead. My assumption is the strong winds were blowing the snow shown by those 30dbz+ echos over the Spine, downwind into town.

I think you've pretty much got it there. The big difference between base and composite being that you don't know what height that highest dBZ echo is coming from. It's probably at least 1-2 kft AGL, and that would translate a good distance downwind by the time it reaches the ground.

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PF I imagine the height of the inversion and presence of instability plays a large role in where that heaviest sets up. The super BTV snow was when you had a really low inversion at the flow was blocked past Underhill so you wound up getting incredible snowfall farther west.

You really want a conditionally unstable layer above the summits (say 4kft-8kft) that allows the air parcels forced up over the spine to continue to rise.

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you'd think, back in the day, that some ski area would have popped up on the underhill side of mansfield and been sustainable... as the snow over there is pretty solid. alas, it didn't happen. the ski industry is a fickle beast.

The east side preserves the snow better... but the west can get more total snowfall. I'm talking about the immediate slope of the mountain. In springtime, the natural snow on the Teardrop trail and Underhill State Park will melt out well before the east side in Stowe...that west side basks in sunlight all afternoon in the springtime when temps are the warmest of the day, while the east side has been in the shadow since like 1pm. Aside from SW flow warm air advection events where the Champlain Valley and west slopes can warm up quickly with cold air locked in east of the Spine, I really notice the snowmelt difference in the springtime (March/April). If you skin and ski the Teardrop, then drop into a similar natural snow run on the east side after a sunny week in March, the snowpack will be like twice as much.

There's a reason why the Mansfield "stake" was originally put in the shadow on the east side... someone knew that was like the last spot the snow melts in the springtime in the state of Vermont, lol.

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PF I imagine the height of the inversion and presence of instability plays a large role in where that heaviest sets up. The super BTV snow was when you had a really low inversion at the flow was blocked past Underhill so you wound up getting incredible snowfall farther west.

You really want a conditionally unstable layer above the summits (say 4kft-8kft) that allows the air parcels forced up over the spine to continue to rise.

I love how BTV usually identifies this and bases the forecast from that climo for inversions. I wish we had a more robust understanding of that up in the Whites.

But you can see on a day like today, how far southeast the snow can survive.

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I love how BTV usually identifies this and bases the forecast from that climo for inversions. I wish we had a more robust understanding of that up in the Whites.

But you can see on a day like today, how far southeast the snow can survive.

Yeah it's pretty cool. It's a lot easier in VT when you have a lot of populated areas right around there.

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PF I imagine the height of the inversion and presence of instability plays a large role in where that heaviest sets up. The super BTV snow was when you had a really low inversion at the flow was blocked past Underhill so you wound up getting incredible snowfall farther west.

You really want a conditionally unstable layer above the summits (say 4kft-8kft) that allows the air parcels forced up over the spine to continue to rise.

Yeah that's definitely the reason... and that inversion being lower can help "squeeze" out the low level moisture better.

I really want to read the paper on Froude numbers that BTV has been citing a lot lately.

And it makes sense if the inversion is at 4K ridgetop level that moisture won't be making it to the east side...but if its up at 7-8,000ft we'll see the better snow on the east side as the lift is more over the Spine, rather than upwind of it.

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Yeah it's pretty cool. It's a lot easier in VT when you have a lot of populated areas right around there.

It actually reminds of my semester in Hawai'i. It's really the same as forecasting downwind propagation of trade wind showers. The stronger the trade wind inversion, the more the windward side gets pounded. Right down the elevations too, most of the topography there is around the 2500 ft range.

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I love how BTV usually identifies this and bases the forecast from that climo for inversions. I wish we had a more robust understanding of that up in the Whites.

But you can see on a day like today, how far southeast the snow can survive.

I'd say the presence of a decent population (by VT standards) makes ground truth a lot easier and also how close the radar site is to the upslope region its easier to analyze.

I know people in SNE think the upslope region is in the sticks, but in reality, Chittenden County is the most populated in VT and the stretch of I-89 that runs through there between Montpelier and Burlington is the heaviest traveled stretch of interstate in Vermont. There's a lot more of a desire to "get that forecast right" due to the impacts...which likely drives more research and such. In NH and ME I would imagine that is a little different. Someone will still notice if 12" falls when 2" was forecast, but in VT have a foot of snow fall on I-89 at rush-hour when only a couple inches was forecast, and BTV is answering calls from the local papers and news stations wondering what went wrong.

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Nice squall going through AUG right now. Dropped to 1/2SM. BTV WRF snow squall parameter had this pegged between 1 and 4 local time.

That burst dropped visibility at my place to 1/4 mile shortlky before 2 PM, and dumped 0.3" in about 15 minutes. After two hours of watching scattered parachutes immolating on impact, it was nice to get a bit of fresh white.

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20f and snowing moderately. Snowed all day for the most part. Heavy at times but the winds were ripping so no idea how much fell on the mtn. Guestimating 4" here at the house.

You guys were getting crushed for a while this morning when we were just light snow north of I-89. Radar and MRG webcam looked real nice like 8-10:30am especially.

This is a good one for everyone on the Spine...even Killington reporting 5.5" so far from the upslope with 4" of that falling last night. I think having the wind flow go SW to W and now NW has helped spread out the snow up and down the spine, as opposed to all being NW or NNW which tends to favor Jay Peak and northern Greens more.

Even now still pretty good north-south band along the west slope and Spine. Light snow continues where I am in Stowe... but I think it varies in the "town" of Stowe from partly cloudy and flurries on the eastern border of town, to moderate to heavy snow on the western border, lol.

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Some of the meso-models are pretty nice over the next few days for us in NNE...

On Monday a bunch of models have some sort of vort moving through with likely high ratio snow showers and some lake Ontario connection...meso-scale models showing this well. Here's the 18z NAM:

Then on Christmas we all get a light snow event...

18z NAM has up to a half inch of QPF over the next 3-4 days in this area which is likely overdone, but with -10C H85 air and orographics, probably some high ratio snow. Maybe two separate 1-3" events?

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I'd say the presence of a decent population (by VT standards) makes ground truth a lot easier and also how close the radar site is to the upslope region its easier to analyze.

I know people in SNE think the upslope region is in the sticks, but in reality, Chittenden County is the most populated in VT and the stretch of I-89 that runs through there between Montpelier and Burlington is the heaviest traveled stretch of interstate in Vermont. There's a lot more of a desire to "get that forecast right" due to the impacts...which likely drives more research and such. In NH and ME I would imagine that is a little different. Someone will still notice if 12" falls when 2" was forecast, but in VT have a foot of snow fall on I-89 at rush-hour when only a couple inches was forecast, and BTV is answering calls from the local papers and news stations wondering what went wrong.

I wish more people in the industry cared what went wrong even when their forecast busts over unpopulated North County or deserted prairie out west. It makes it extremely difficult without the ground truth, but even if I never get a phone call or web report, I like to have the correct (or near it) snow amounts in the mountains.

If we're off on the forecast enough for say Pittsburgh, NH, eventually they stop listening to us. And that one day when we want them to listen it will fall on deaf ears.

Maybe I'm just super uptight about my forecasts. :arrowhead:

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Snowing nicely out there now... I was pleasantly surprised to find around 2.5" of fluff on the ground now on top of the rain crust from last night. I really should get in the habit of clearing a snow board and measuring in 6 hour increments...but for some reason maybe I'm lazy, but I'd rather just measure it as it falls and call the total what it is when it stops. Even up at the mountain so far this season, I've only been clearing at most 2 times in any one 24 hour period.

Anyway, down in town we've had an additional inch since 3:30pm, which averages to 1/4-1/3"/hr.

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Man, what good reading in this thread. pf great job with those radars comparing this event with the events of last february.

I think the best point is the wind effect on the snow. It is hammering it to shreds. It feels like its just dumping cats and dogs out there but it isn't skiing that deep. Well it might have been in some spots but I screwed up and ducked a rope, losing the chance to go find out more. Bad me. Guess its time to follow the rules.

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1.6" of light fluff when I cleared the board at 7pm

Did you clear anything this morning? No way there's an inch more here on the Mtn Road near Luce Hill Rd intersection.

In other news... the Mansfield Co-Op reported 2" of new snow and snow depth increased by 6". Not surprising because with the winds, I wouldn't expect any of those flakes to actually find their way into an 8-inch diameter rain gage. Given that I had near 4" at 2pm, a 6 inch increase in depth this evening makes sense. I actually think this season so far if you just tallied up the daily increases in snow depth, it might be higher than the Co-Op's recorded snowfall.

DAILY HYDROMETEOROLOGICAL DATA

NATIONAL WEATHER SERVICE BURLINGTON VT

800 PM EST SAT DEC 22 2012

STATION PRECIP TEMPERATURE PRESENT SNOW

24 HRS MAX MIN CUR WEATHER NEW TOTAL SWE

...VERMONT...

MOUNT MANSFIELD 0.35 31 7 7 2.0 28

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Did you clear anything this morning? No way there's an inch more here on the Mtn Road near Luce Hill Rd intersection.

In other news... the Mansfield Co-Op reported 2" of new snow and snow depth increased by 6". Not surprising because with the winds, I wouldn't expect any of those flakes to actually find their way into an 8-inch diameter rain gage. Given that I had near 4" at 2pm, a 6 inch increase in depth this evening makes sense. I actually think this season so far if you just tallied up the daily increases in snow depth, it might be higher than the Co-Op's recorded snowfall.

DAILY HYDROMETEOROLOGICAL DATA

NATIONAL WEATHER SERVICE BURLINGTON VT

800 PM EST SAT DEC 22 2012

STATION PRECIP TEMPERATURE PRESENT SNOW

24 HRS MAX MIN CUR WEATHER NEW TOTAL SWE

...VERMONT...

MOUNT MANSFIELD 0.35 31 7 7 2.0 28

one foot from the magical 40" mark. an amazing week given all the potential loss. we're on our way.

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You know, I'm usually too far east for decent upslope. I usually get the tail end leftovers which aren't bad...certainly better than just 8 miles down the road in Barre. Anyway after the small heavy burst around 1:30 this afternoon, it continued to snow lightly all day, not amounting to more than an inch. But man, over the last 4 hours it's really been coming down.

This has been the best upslope event for my house this year.

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Event totals: 9.5” Snow/1.21” L.E.

We left the house around 5:30 P.M. this evening to head to a Christmas party, and we almost turned right around on our road due to the intensity of the snowfall. We could only see a couple of yards in front of the car and had to drive at a crawl due to snow that must have been falling at over 2 inches an hour. We decided to push on for a bit, since we were headed to Colchester in the Champlain Valley, and I knew it wouldn’t be snowing with that intensity everywhere. Heading west on Route 2, the intensity of the snowfall dropped off a lot by the time we got down to the eastern edge of Bolton Flats a couple miles later. From there, it just tapered to essentially nothing in Richmond. In fact, there was very little snow on the ground in Richmond. Flurries reappeared once we got to the top of French Hill in Williston, but once we reached the Burlington area, roads were dry, there was just an occasional flurry, and there was no snow on the ground. With the benign conditions in Colchester, it was interesting chatting with people about how we’d just come from a veritable blizzard in Waterbury, but other folks who live out in the mountains were reporting similar conditions.

Snow shower activity had definitely increased around the area by the time we left, because even on Mills Point way out in the lake it was spitting flurries/light snow. The snow waned as we passed through Burlington proper, but quickly resumed as we approached Williston, where accumulations appeared along the side of the road. I hadn’t noticed it before, but just before you’re about to descend French Hill, they have an electronic alert sign, and it read “WINTER WEATHER ADVISORY, REDUCE SPEED”, to alert drivers heading into the mountains. The intensity of the snowfall continued to increase, and unlike our earlier pass through the area, Richmond was experiencing a steady light snow and fresh accumulations were visible. Roads were just wet through to Richmond, and then soon after they started to become snow covered. By Bolton we were into a steady moderate to heavy snow. That increased just a bit by the time we reached the house, so it certainly wasn’t falling at the intensity of the amazing blitz we’d witnessed when we left, but it was still solid inch per hour stuff.

We guessed that there were about 4 to 5 inches of snow on the snowboard at around 9:30 P.M., and I waited until 10:00 P.M. to do a measurement and clearing, at which point I found 5.9 inches comprised of 0.18” of liquid. I stacked two cores to make sure I got a very robust sampling of the snow, and it came in at 3.1% H2O – that’s major Champlain Powder™ territory, and impressively airy for a half foot stack. Depending on how nasty the wind is, there should be some very happy skiers out in the Greens tomorrow. My initial estimate of an inch per hour snowfall that I made while driving in was definitely low, I could tell while I was out there making my observations. After the clearing, the snowboard had taken on a half inch of new snow in just five minutes. That of course wouldn’t hold up in a significant stack, but as of 10:30 P.M. there’s already another inch on there, so it’s coming down in the 2 inch per hour range.

Details from the 10:00 P.M. Waterbury observations:

New Snow: 5.9 inches

New Liquid: 0.18 inches

Snow/Water Ratio: 32.8

Snow Density: 3.1% H2O

Temperature: 21.9 F

Sky: Heavy Snow (1-20 mm flakes)

Snow at the stake: 7.0 inches

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