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December 2020 General Discussions & Observations Thread


bluewave
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1 hour ago, bluewave said:

The 2nd week of December has featured the best snow chances since the Boxing Day Blizzard. But I would keep expectations low since the models aren’t even showing any virtual snow in that time frame. Looks like the models have a dueling northern and southern stream split flow. With competing El Niño +AAM and the more Niña-like MJO 4-5. So it may be tough to get anything more than a light event in this continuing cutter, hugger, and occasional suppressed southern stream storm track pattern.

I would need a new shovel by now if we received all the virtual snow the models had the last two years. IMO that means nothing 

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1 hour ago, bluewave said:

The 2nd week of December has featured the best snow chances since the Boxing Day Blizzard. But I would keep expectations low since the models aren’t even showing any virtual snow in that time frame. Looks like the models have a dueling northern and southern stream split flow. With competing El Niño +AAM and the more Niña-like MJO 4-5. So it may be tough to get anything more than a light event in this continuing cutter, hugger, and occasional suppressed southern stream storm track pattern.

Perhaps a trailing wave following a cutter like January 2012

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17 hours ago, CIK62 said:

Some BN T's YES----but accumulating snow NO.

All the Ensembles are basically barren.        GEFS leads the trio with a 20% chance of at least 2" in the next 15 days, or a 60% chance of seeing anything that can be measured.        The EURO and CMC Ensembles are just 20% to 30% of seeing anything.           I will keep checking to detect an improvement.

Dec. 10-12 could have our first sub-32 degree High T.

what is the accuracy of the snow total forecasts 3 weeks out? 

Just entertainment

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18 minutes ago, bluewave said:

You have to remember that the beginning of last December was colder than this year. So the cutters and huggers corrected north at the last minute pushing the heavily snow further up into the interior Northeast. The lack of virtual snow so far in the models reflects the warmer start to this December. It doesn’t look like Hartford will see another top 5 snowiest early December like last year.

Time Series Summary for Hartford Area, CT (ThreadEx)
Click column heading to sort ascending, click again to sort descending.
Rank
Ending Date
Total Snowfall Dec 1 to Dec 15
Missing Count
1 2003-12-15 23.4 0
2 2019-12-15 19.5 0
3 1915-12-15 15.0 0
4 1969-12-15 14.8 0
5 1926-12-15 13.7 0

We missed one storm last December because surface temps were between 33-34. 

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18 minutes ago, bluewave said:

You have to remember that the beginning of last December was colder than this year. So the cutters and huggers corrected north at the last minute pushing the heavily snow further up into the interior Northeast. The lack of virtual snow so far in the models reflects the warmer start to this December. It doesn’t look like Hartford will see another top 5 snowiest early December like last year.

Time Series Summary for Hartford Area, CT (ThreadEx)
Click column heading to sort ascending, click again to sort descending.
Rank
Ending Date
Total Snowfall Dec 1 to Dec 15
Missing Count
1 2003-12-15 23.4 0
2 2019-12-15 19.5 0
3 1915-12-15 15.0 0
4 1969-12-15 14.8 0
5 1926-12-15 13.7 0

I forgot how close last December was to delivering.  It's comforting to see a lid on the SE ridge mid-month, although you'd think the Niña would snap it back into place at some point (OTOH, I am still waiting for last year's anticipated Niño atmospheric response...).  But a ridge pressing inland from the NATL won't do us much better in the snow department since it'll just push the storm track inland too.

Man, the glory years really spoiled us.  I still don't think we'll see another shutout year like last year, but these past few years have been a cruel reality check: It's difficult to get solid snows down to the coast!

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6 minutes ago, bluewave said:

That’s a hybrid lingering +AAM ,+PNA ,and La Niña pattern. While the timing could be off by a few days, the ridge near and east of New England with a trough in the SW is classic La Niña MJO 5 influence. Any shortwave ejecting from the SW in such a pattern will pump the SE Ridge ahead of it. But that may not show up in a smoothed ensemble mean.

CEE78CE2-C51A-4B89-8CE5-56D086A892A0.png.04e0d1816f759531d49ad4c6d0739b7c.png

 


 

760B27B6-F389-4F60-83A9-F3E2D8D6F8FB.gif.423a46180a9a538b82342c1980254335.gif

That’s a overrunning pattern imo. A full blown Niña look would have a ridge in the Aleutians. We also have a hint of a -nao with a split flow. 
 

This is the Niña composite for December p5

72D4334D-3251-4644-865B-729ABBD513AC.png

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16 minutes ago, donsutherland1 said:

Both December 2000 and 2010 had a lot of blocking. 

there is some blocking in the forecast but nothing as extreme as those years...but then again the block doesn't need to be that strong...I'd like to see an ao at -4sd...

lowest daily AO in December...

1950...-4.353...12/27...max/min 22/9 ...2.9" of snow on the 26th...biggest snow/coldest temp of the winter...

1952...-3.766...12/27...max/min 38/17..12 degrees 12/28...coldest of the winter...3" of snow 12/31...

1958...-3.814..,.12/22...max/min 29/12..cold dry...coldest temp of the month on the 22nd..

1961...-3.959...12/26...max/min 39/30...6" of snow 12/23-24...

1962...-4.159...12/31...max/min 13/4.....coldet temp of the month...

1963...-4.470...12/20...max/min 26/11...coldest temp of the month...6.6" of snow 12/23-24...

1966...-4.147...12/13...max/min 37/31...rain and snow 12/13-14...7" of snow 12/24-25...

1968...-4.547...12/27...max/min 28/21...2" of light snow 12/27...

1969...-3.714...12/30...max/min 36/31...freezing rain 12/30-31...

1976...-5.287...12/29...max/min 32/20...2" of snow 12/28-29...

1978...-4.294...12/27...max/min 38/27...19 on 12/29...coldest for the month...

1995...-4.353...12/19...max/min 33/22...8" of snow 12/19-20...

2000...-4.688...12/29...max/min 30/17...12" of snow 12/30...

2009...-5.821...12/21...max/min 38/26...11" of snow 12/19-20...

2010...-5.265...12/18...max/min 36/28...cold dry till 20" of snow 12/26-27...

2012...-3.902...12/8.....max/min 50/44...rain and mild...

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23 minutes ago, bluewave said:

That’s why I mentioned a hybrid pattern. You see elements of El Niño ,La Niña, and MJO influences at the same time. There are multiple pattern drivers running together.

after reviewing the 12Z models so far - it looks like a toxic mix for us next week at least .............

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1 hour ago, uncle W said:

there is some blocking in the forecast but nothing as extreme as those years...but then again the block doesn't need to be that strong...I'd like to see an ao at -4sd...

lowest daily AO in December...

1950...-4.353...12/27...max/min 22/9 ...2.9" of snow on the 26th...biggest snow/coldest temp of the winter...

1952...-3.766...12/27...max/min 38/17..12 degrees 12/28...coldest of the winter...3" of snow 12/31...

1958...-3.814..,.12/22...max/min 29/12..cold dry...coldest temp of the month on the 22nd..

1961...-3.959...12/26...max/min 39/30...6" of snow 12/23-24...

1962...-4.159...12/31...max/min 13/4.....coldet temp of the month...

1963...-4.470...12/20...max/min 26/11...coldest temp of the month...6.6" of snow 12/23-24...

1966...-4.147...12/13...max/min 37/31...rain and snow 12/13-14...7" of snow 12/24-25...

1968...-4.547...12/27...max/min 28/21...2" of light snow 12/27...

1969...-3.714...12/30...max/min 36/31...freezing rain 12/30-31...

1976...-5.287...12/29...max/min 32/20...2" of snow 12/28-29...

1978...-4.294...12/27...max/min 38/27...19 on 12/29...coldest for the month...

1995...-4.353...12/19...max/min 33/22...8" of snow 12/19-20...

2000...-4.688...12/29...max/min 30/17...12" of snow 12/30...

2009...-5.821...12/21...max/min 38/26...11" of snow 12/19-20...

2010...-5.265...12/18...max/min 36/28...cold dry till 20" of snow 12/26-27...

2012...-3.902...12/8.....max/min 50/44...rain and mild...

Hopefully, we can get something before the pattern changes after mid-December.

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1 hour ago, donsutherland1 said:

Hopefully, we can get something before the pattern changes after mid-December.

mid December is to far away to worry about a pattern change that has not happened yet...I still think the best week or weeks of winter will come in Feb...

edit...I mean the pattern change before the pattern change...

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35 minutes ago, bluewave said:

The winter pattern since 18-19 has been the meteorological version of too many cooks in the kitchen.

a screwy winter pattern can last six years like it did from 1949-50 to 1954-55...good thing they were the first six winters of my life...I barely remember 1954-55...

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13 minutes ago, uncle W said:

a screwy winter pattern can last six years like it did from 1949-50 to 1954-55...good thing they were the first six winters of my life...I barely remember 1954-55...

The duration of multiyear below normal snowfall regimes can be uncertain. But it usually takes a 10.0”+ event to get the ball rolling back in the right direction. Great pattern breaking snowstorms like 1-20-78, 3-13-93, and 12-30-00 come to mind.

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1 hour ago, bluewave said:

That’s a hybrid lingering +AAM ,+PNA ,and La Niña pattern. While the timing could be off by a few days, the ridge near and east of New England with a trough in the SW is classic La Niña MJO 5 influence. Any shortwave ejecting from the SW in such a pattern will pump the SE Ridge ahead of it. But that may not show up in a smoothed ensemble mean.

CEE78CE2-C51A-4B89-8CE5-56D086A892A0.png.04e0d1816f759531d49ad4c6d0739b7c.png

 


 

760B27B6-F389-4F60-83A9-F3E2D8D6F8FB.gif.423a46180a9a538b82342c1980254335.gif

From Ben Noll: 

 

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2 minutes ago, bluewave said:

The duration of multiyear below normal snowfall regimes can be uncertain. But it usually takes a 10.0”+ event to get the ball rolling back in the right direction. Great pattern breaking snowstorms like 1-20-78, 3-13-93, and 12-30-00 come to mind.

March 56 was the first for me...then Jan 1978...

years between a 10" storm in NYC...

March 1956...last time was Dec. 1948...

January 1978...last time was Feb. 1969

March 1993...last time was Feb. 1983...

December 2000...last time was Feb. 1996...

last time was January 2016...

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20 minutes ago, uncle W said:

March 56 was the first for me...then Jan 1978...

years between a 10" storm in NYC...

March 1956...last time was Dec. 1948...

January 1978...last time was Feb. 1969

March 1993...last time was Feb. 1983...

December 2000...last time was Feb. 1996...

last time was January 2016...

3-21-18 was my last 10” event. It was also my 2nd favorite late season snowstorm behind 4-6-82.

https://www.weather.gov/okx/storm03212018

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6 minutes ago, bluewave said:

3-21-18 was my last 10” event. It was also my 2nd favorite late season snowstorm behind 4-6-82.

https://www.weather.gov/okx/storm03212018

staten island got a foot on 3/21/18 and in early January...nothing beats 4/6/1982 for April storms...2018, 2003 and way back in 1956 NYC had a snowstorm 4" or more...

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fwiw... EC starting to sit on a similar Monday-Tuesday event for this next weekend in our area, including similar event snowfalls... which if the EC is correct will offer spotty 2 feet in a part of west or northwest OHIO.  One event at a time... I want to see how this works out here on Monday before starting something for next weekend.  

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1 hour ago, qg_omega said:

Last December

 

You usually have to be north of I-80 to cash in on gradient snowfall patterns. EWR to ISP finished last December in the  2-4” range. The one exception was the cold 93-94 gradient. But even that one hit diminishing returns the closer you got to Philly.

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2 hours ago, uncle W said:

mid December is to far away to worry about a pattern change that has not happened yet...I still think the best week or weeks of winter will come in Feb...

edit...I mean the pattern change before the pattern change...

While the pattern change after mid-December is not assured, there are enough hints on the guidance to suggest that it is plausible. We’ll see how things evolve. There can always be surprises along the way.

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1 hour ago, donsutherland1 said:

Boll expresses my own concern about the pattern evolution, namely the possible shift back to sustained warmer conditions in the extended range.

Really?? Ugh...so a pattern we've already been stuck in of warmer than average shifts to a new pattern of warmer than average again?

Let it end.

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