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2/13 Significant/Major Winter Storm Discussion & Observations


Northof78
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1 minute ago, SBUWX23 said:

The liquid equivalent out here was impressive in the 12-18z timeframe. Even here where it was 32-33, the temps and compaction were real. Probably would have had closer to 10 if not more but I'll settle with the half foot. Still a nice event.

The biggest issue I noticed was when rates slipped below 1.5/hr then compaction starting eating away at totals. In the period from 8am-10am and then again 1115-1pm totals rapidly increased but between 6-8am and 10-11;15 despite decent rates it barely kept up with compaction 

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1 minute ago, Kaner587 said:

The biggest issue I noticed was when rates slipped below 1.5/hr then compaction starting eating away at totals. In the period from 8am-10am and then again 1115-1pm totals rapidly increased but between 6-8am and 10-11;15 despite decent rates it barely kept up with compaction 

If we had been in the 20s that would not have happened. It's impressive enough that we had the cooling we did without the nice high to our north.

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4 minutes ago, SBUWX23 said:

If we had been in the 20s that would not have happened. It's impressive enough that we had the cooling we did without the nice high to our north.

Woke up at 3am and already had a coating. Knew we were in for 6+ after that. Seriously doubted it when I went to bed 

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31 minutes ago, Kaner587 said:

Woke up at 3am and already had a coating. Knew we were in for 6+ after that. Seriously doubted it when I went to bed 

1am sleet was falling on my roof while heading to bed & at 4am saw on camera wife’s car was white. Knew things were on track for 4-8”. Happy we finally got a storm to produce, it has been over 2 years I think. 

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5 minutes ago, uofmiami said:

1am sleet was falling on my roof while heading to bed & at 4am saw on camera wife’s car was white. Knew things were on track for 4-8”. Happy we finally got a storm to produce, it has been over 2 years I think. 

I think we had that 5” slop fest last year? 
 

up to 13” on the season here, almost halfway to average. A few event this seek could get us to 15”. Not terrible 

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12 minutes ago, psv88 said:

I think we had that 5” slop fest last year? 
 

up to 13” on the season here, almost halfway to average. A few event this seek could get us to 15”. Not terrible 

You may be correct. Such a slop event I didn’t even put it to memory.

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3 hours ago, bluewave said:

I am not sure exactly how the low measurements are occurring in each given situation. But it has been an ongoing issue over the years. Notice how LGA got 3.3 with less precipitation and warmer temperatures. We know that many spots had issues with low ratios due to the warmth. Plus we lost some accumulation to the higher temperatures. The NYC ratio looks a little low to me. So maybe the snowfall there was actually in the 3.5 to 4.0 range. But this isn’t enough of a difference to materially change the flavor of the seasonal snowfall rankings since and extra 0.5 to 0.8 isn’t going to make a big difference. 

Past issues with low measurements 

https://www.nymetroweather.com/2015/12/21/central-park-conservancy-will-take-over-snowfall-measurements/


https://www.nytimes.com/2003/02/11/science/flawed-snowfall-data-jeopardize-climate-change-research.html

 

snowfall vs precipitation today

EWR…4.9…..0.58

NYC….3.2…..0.77

LGA…..3.3…..0.64

JFK……4.2…..0.65

ISP…….4.3…..0.72

 

 

My snow ratio today was 8.3" snow per inch of liquid, which is pretty close to Newark's 8.4 from above.  Sad that CPK's was 4.2, half of Newark's.  I know the UHI is more significant in Manhattan but I would think being in the Park would reduce that difference somewhat.  Still makes me wonder if they have measuring issues in CPK, although hard to imagine it being off by more than 10-20% vs. the 100%+ difference between EWR and CPK.  But at least maybe it would've been more like LGA's 5.2, which would've given CPK 4.0".  

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Melted core sample was 0.93" from 6.4" of snow (just under 7:1).  It was pretty much all frozen; maybe a drop or two of rain mixed initially, but maybe not. It looked like all sleet.  There could have been a hundredth or two that escaped, but I have no way of determining that.

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11 hours ago, RU848789 said:

As of about 12:15 the snow ended and that last good 45 min band got us to 6.0" as per my lousy pic below, using the yardstick I grew up with, lol. 

Not quite the 7.2" I predicted, due to probably missing out on 1.5-2.0" from being in that heinous subsidence hell hole for 3 hours, lol. But Woo-hoo! since my expectations several days ago, when things were trending warm/wet for 95, was maybe an inch or two of slop...although there was certainly some hope for a 10-12" event in the past day or two if things worked out perfectly, but not a surprise that that didn't happen, which is why my prediction was for a more realistic 7.2".

This brings the season total up to a respectable 13.3", still well below where we should be (about 18" through this point in the winter), but way better than last winter's 5.2" here. And there are some more snow chances over the next few weeks.

And this storm is one more data point showing that snow will easily accumulate on all untreated surfaces at 33-34F, as long as there is moderate to high intensity, even after a warm/rainy day. Curious to see what my ratios were (in progress). Guessing pretty low early in the storm with some sleet and pretty wet snow, but probably >10:1 once the snow started falling heavily around sunrise and especially by mid-morning as the snow was fairly fluffy with nice dendrites, but I'll only be able to get one aggregate number.

AaNdH5q.png

Snow ratio time.  I like the cuboid method over the core method: I simply carve a 10" x 10" slice of snow and shove it into a big bowl, melt it and measure the volume vs. the snow height I measured (it's a much bigger volume than most cores, so it should have less error associated with the measurement.  I had 9832 cc volume in my 10"x10"x6" cuboid vs. 1180 cc of melted snow, so my ratio was 8.33:1, which was very close to Newark's 8.4:1.  I suspect it was much lower over the first hour or two, when we had 1/4" or so of sleet followed by fairly wet snow, but that was maybe the first inch of depth.  Once we started getting higher intensity snowfall it clearly was at least 10:1 ratio snow as the flakes were very nice dendrites (although a little wet until later in the storm). Also, I had estimated we'd have ratios around 8:1 for most of 95, before the storm and at least EWR and I got very close to that, while Kuchera estimates were in the 6-7:1 range, depending on the model.  I get why Kuchera is used - I'd just rather do my own estimate.  

So much for the concerns over the ratio of the snow that fell from the sky.  And while we're at it, this storm also reconfirmed that snow will easily accumulate on all surfaces, including roads (and even treated, heavily traveled roads) at above 32F temps after a warm previous day and after a bunch of rain had fallen, as long as there is enough intensity.  The equation governing this is so simple: accumulation rate = snowfall rate - melting rate. And accumulation is only a challenge initially, when there's bare/wet ground at 33-34F, which is why the snowfall rate needs to be greater to overcome that initial melting rate; once there's a layer of snow/slush on the ground, the new "ground" is 32F snow/slush meaning the melting rate is far less than for bare ground and subsequent snow will accumulate easily (as 33-34F air does minimal melting of snow given air has 1/20th the heat transfer coefficient of wet ground).  There are certainly times where the intensity isn't enough to overcome that initial melting rate and we get a white rainstorm.  This wasn't one of them.  

 

 

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5 minutes ago, RU848789 said:

Snow ratio time.  I like the cuboid method over the core method: I simply carve a 10" x 10" slice of snow and shove it into a big bowl, melt it and measure the volume vs. the snow height I measured (it's a much bigger volume than most cores, so it should have less error associated with the measurement.  I had 9832 cc volume in my 10"x10"x6" cuboid vs. 1180 cc of melted snow, so my ratio was 8.33:1.  I suspect it was much lower over the first hour or two, when we had 1/4" or so of sleet followed by fairly wet snow, but that was maybe the first inch of depth.  Once we started getting higher intensity snowfall it clearly was at least 10:1 ratio snow as the flakes were very nice dendrites (although a little wet until later in the storm). 

So much for the concerns over the ratio of the snow that fell from the sky.  And while we're at it, this storm also reconfirmed that snow will easily accumulate on all surfaces, including roads (and even treated, heavily traveled roads) at above 32F temps after a warm previous day and after a bunch of rain had fallen, as long as there is enough intensity.  The equation governing this is so simple: accumulation rate = snowfall rate - melting rate. And accumulation is only a challenge initially, when there's bare/wet ground at 33-34F, which is why the snowfall rate needs to be greater to overcome that initial melting rate; once there's a layer of snow/slush on the ground, the new "ground" is 32F snow/slush meaning the melting rate is far less than for bare ground and subsequent snow will accumulate easily (as 33-34F air does minimal melting of snow given air has 1/20th the heat transfer coefficient of wet ground).  There are certainly times where the intensity isn't enough to overcome that initial melting rate and we get a white rainstorm.  This wasn't one of them.  

 

 

Have you compared results between cuboid vs a simple core?

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1 hour ago, RU848789 said:

My snow ratio today was 8.3" snow per inch of liquid, which is pretty close to Newark's 8.4 from above.  Sad that CPK's was 4.2, half of Newark's.  I know the UHI is more significant in Manhattan but I would think being in the Park would reduce that difference somewhat.  Still makes me wonder if they have measuring issues in CPK, although hard to imagine it being off by more than 10-20% vs. the 100%+ difference between EWR and CPK.  But at least maybe it would've been more like LGA's 5.2, which would've given CPK 4.0".  

It was a little worse than I had expected. I thought Central Park would have about 4” when it reported its final figure.

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10 hours ago, LibertyBell said:

But there's concrete jungles in Queens and Brooklyn too.  I've seen them lol.  Places like Jamaica and Hillside in Queens are like that too and Bay Ridge in Brooklyn.

Maybe near Bayside and Whitestone it's much more "suburban" and much less concrete.  I love Alley Pond Park up in NE Queens.

 

Yes parts of Queens, Brooklyn, and even the southern Bronx are very concrete but nothing is like midtown or downtown Manhattan. 

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2 hours ago, donsutherland1 said:

It would take more than 5 more years to reach that mark: 2,572 days (March 1, 1949 through March 15, 1956).

With all the discussion that's gone on here about relatively snowless periods, the fact that there was a 7 year stretch in which no storm dropped 6" that we haven't talked much about is incredible.

Can't imagine pulling for a 6"+ snowstorm knowing it would be our first since January 2017.

Eyeballing some rough maps I just found, I see that the 30 year climate average for 1931-1960 was the warmest one since 1901 for around here until being surpassed ever since starting with the 1971-2000 numbers, so maybe that played a role.

Anyway, what a dreadful stretch.  I bet that the mood on the internet weather boards in February 1956 was pretty sour.

 

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Just now, RU848789 said:

Actually, I never really did snow ratios before the past few years and I didn't have one of those core devices, plus I simply knew that taking a much larger sample would reduce the chance of error.  

"Device" is a stretch.  I just turn a 4" cocorahs gage upside down and push it into the snow, slide a piece of aluminum flashing under it, and bring it inside to melt.  It's not perfect, but it's easy enough and at least seems to be in the ballpark.

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2 hours ago, donsutherland1 said:

It was a little worse than I had expected. I thought Central Park would have about 4” when it reported its final figure.

Lonnie Quinn got sick of the usual Central Park BS under measurements and went to measure himself today. He measured 3.9 inches and that was most likely after some compacting.

 

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5 hours ago, donsutherland1 said:

It would take more than 5 more years to reach that mark: 2,572 days (March 1, 1949 through March 15, 1956).

Don, weren't the 50s almost a perpetual el nino state until the 1955-56 la nina?  I think 1955-56 was another one of those la nina after el nino scenarios very hot summer followed by a snowy winter.

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6 hours ago, SBUWX23 said:

The liquid equivalent out here was impressive in the 12-18z timeframe. Even here where it was 32-33, the temps and compaction were real. Probably would have had closer to 10 if not more but I'll settle with the half foot. Still a nice event.

Was it compaction though or was it melting? Because I saw puddles of water when the snow lightened up around 11 am and the sky brightened up.

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