October 12th, 2012 – Waterbury Winter Weather Event Updates

A short summary of this winter storm is also available in the J&E Productions web log.



Friday, October 12th, 2012



powderfreak, on 11 Oct 2012 - 1:09 PM, said:https://www.amwx.us/public/style_images/American_Weather/snapback.png

Another 1-3" tonight, maybe more if upslope can crank for a bit following the front.


It wasn’t quite a carbon copy of yesterday morning, but the this morning’s weather at the house was certainly reminiscent – 0.18” of liquid in the gauge and a temperature a degree warmer at 42 F.  The rain was only light/moderate at 6:00 A.M. observation time, but I heard some much heavier precipitation come through around 4:30 A.M.  I figured that the snow line could be a little higher with the slightly warmer temperature, but the Mt. Mansfield ridgeline thermometer is reading the same 30 F as yesterday at this time, so we’ll see how it goes.  Roger Hill looked around at some of the regional weather stations this morning during his broadcast, and said that Saranac Lake at 1,800’ reporting unknown precipitation at 35 F was probably a sign of some mixing there.  Relative to yesterday, the precipitation seems a lot more widespread this morning based on the radar:





I grabbed a picture of yesterday morning’s snow for my web page report, but I figured I’d add it here in the NNE thread for reference.  The snow line yesterday morning seemed like it was higher than it was on Monday morning based on Powderfreak’s images but it was difficult to tell from my pictures later in the day after some melting had already occurred.  There’s lots of color here in the Champlain Valley, but still plenty of green trees as well, so that provides some nice contrast to the snow in the peaks.





mreaves, on 12 Oct 2012 - 12:06 PM, said:https://www.amwx.us/public/style_images/American_Weather/snapback.png

A colleague just told me his wife emailed him to say it was snowing at their house in Barre Town.  Yay!, unsubstantiated third-hand eyewitness reports for FTW!


Yeah, from here on the hill at UVM I can see snow crashing out all along the spine – first time I’ve seen that this season.  It’s 26 F on Mansfield, so it’s definitely snow; it’s getting all the way down into the town of Stowe based on what Powderfreak reported.  I snapped some pictures and I’ll see if any of them work out to show the snowfall.



When I saw the amount of snow crashing out along the western slopes of the Greens earlier today, I figured that some flakes would be making it to the mountain valleys, but I was definitely surprised when Powderfreak revealed that there was even some graupel accumulating down low.  That meant that the same thing was probably going on at our place, especially with the way the radar showed the flow of moisture coming in from the northwest.  I had to head home to Waterbury in the mid afternoon timeframe, and it became my first trip of the season heading from the Champlain Valley into the snow in the mountains.  There was no precipitation falling in Burlington, but by Richmond there were a few spits of rain, and some flakes in the air.  There was no snow falling at the Waterbury Park and Ride when I arrived, but everything was wet from previous precipitation.  I headed toward the house, and about a mile before I got there I was hit with what seemed like moderate rainfall, but I quickly saw that it was actually snowfall comprised of very wet flakes.  Flakes were in the air on and off at the house after I arrived, but at around 2:30 P.M. a strong pulse of moisture hit the area and we had a heavy downpour of snow and graupel.  The temperature was 40 F, and while the flakes couldn’t accumulate, the intense graupel accumulated quite readily, and easily passed the tenth of an inch threshold to mark our first accumulation of the season.  The presence of the accumulation was quite transient of course, so it was fortuitous that I was home at that time or I wouldn’t have been able to record it.  I suspect there were probably a couple of similar occurrences earlier in the day based on the radar, but that mid afternoon one was the only one I witnessed.  After that episode I didn’t see anything more in the way of graupel through the afternoon, just fluffy flakes.  They never accumulated, but there were some large ones up to about an inch in diameter.  Although not the earliest frozen precipitation I’ve noted since being at our current location, today does mark the earliest accumulating snowfall in my records, beating out the previous earliest of October 15th, 2010 by three days.  This event also drops the mean for the first accumulating snowfall in my data set by three days to Oct 26th ± 12 days.  Below I’ve added a midday radar shot and a couple of pictures from that time period in Burlington as the mountains got swallowed up in snowfall:









White tendrils of snow began to appear along the western slopes of the Green Mountains late this morning as the cold air moved into the area, and people started seeing snow all the way down into the valleys.  Although the snow from Monday and Thursday only affected the mountains, we picked up our first accumulating snow at the house today as a heavy graupel storm came through in the afternoon.  Tonight is supposed to be the coldest of the season so far, and there’s still the chance for a bit more snow before the weather warms up going into next week.  For more information about today’s snowfall, be sure to check out my post in the American Weather Forum.



'powderfreak', on 13 Oct 2012 - 08:05 AM, said:https://www.amwx.us/public/style_images/American_Weather/snapback.png

Ahh yes that's what I was missing.  Even though it was enough to turn car tops and hoods white at times, we still had small empty spaces between grauple and flakes.  I don't think I saw any surface COMPLETELY covered solid so I'll stick with a trace.


J.Spin's post got me thinking about it and Although you could probably have measured a tenth or two at times, there was also parts of the underlying surface showing.  That's a tough call...but if you are extremely diligent about it like JSpin and measure every last bit of frozen, yesterday's showers/squalls were right on the fence.


Yeah, these types of precipitation events are sort of a judgment call in my opinion.  Short of wind issues, which thankfully aren’t generally a concern at our location, I find that the most challenging measurement situations arise from minimal storms of graupel and large upslope-style or wet aggregate flakes.  I think that Dendrite’s approach of looking for complete surface coverage is a fairly logical one, and while I find that that can work well in the case of smaller flakes below a few tenths of an inch in diameter, it’s tough with other events that feature more “atypical” shapes and sizes of frozen precipitation.  Large flakes often accumulate irregularly, such that there can be areas where the snow has stacked up to a ½ inch or even an inch in depth, while there are still parts of the underlying surface that are visible.  When 5% of the snowboard remains uncovered, but the remaining 95% of the board is full of huge mounds of upslope flakes approaching an inch in depth, deciding what to report can be a challenge.  With the rolling nature of graupel, the accumulation can often be in the form of clumps depending on the texture of the collection surface or whether or not there is any wind – this may result in depths of a few tenths of an inch, without complete coverage of the snowboard.  Especially in the case of graupel, determining “complete” coverage of the surface is somewhat arbitrary (i.e. like you asked PF, “how small does the space between graupel pellets need to be before one considers it full coverage”).  Trying to avoid that arbitrary stuff, I’ve always taken the approach of setting the standard as whether or not the accumulation breaks the 0.1” depth plane on the defined 2’ x 2’ surface of the snowboard.  This is one place where an elevated board provides an advantage, since one can easily set their eye level with the plane of the board and scan across with a tenth of an inch ruler to see if anything breaks the 0.1” barrier.  There’s no question that this is a more liberal approach than waiting for full board coverage when it comes to these marginal accumulation events.  I try to err on the side of catching every “accumulating” event that I can as you mentioned PF, especially since I know I miss many of these marginal events because I’m not at home (Friday was a great example, since I would typically have been at work at that hour and never would have been able to document the accumulation).  Since people have mentioned the appearance of sleet this morning, I should mention that I’ve found sleet a lot easier to deal with in terms of these “atypical” frozen precipitation types.  The sleet pellets themselves are generally well under 0.1” in diameter, so by the time the 0.1” barrier is broken, the snowboard is typically well covered with a nice even coating.


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