December 2020 General Discussions & Observations Thread

[MJO812]

6 minutes ago, snowman19 said:

What is it showing?  Just saw a tweet saying it was showing a miss, nothing. Not around my computer right now

It forms a low but misses to the south and east. It is warm right now because the low is disjointed. 

[binbisso]

5 hours ago, donsutherland1 said:

I suspect that the frozen precipitation threat is well north of the big cities on January 3. Somewhere between Poughkeepsie and Albany might have a good chance of seeing ice and/or at least some snow.

As for the transition, it’s still there on the overnight guidance. Sometimes, the guidance rushes things. At that time, the stratosphere will likely be cooling from what was a significant, but not major warming event. The zonal winds are forecast to reverse at 1 mb and 10 mb, but not 30 mb. The polar vortex will be weakening dramatically. 

Don is it then more likely that the vortex will just weaken and not split and if so would that be a more favorable outcome for us here since a split usually favors Eurasia

[donsutherland1]

1 hour ago, hooralph said:

Thanks, Don! 

That's odd... I'll have to look at the raw data. This is an ingestion of the raw daily data from NOAA Climate Data Online. The only transformation i did was to decode the years to be a snowfall season and it appears to have worked overall. (i.e. so Jan '96 is part of the 1995-1996 season).

It’s possible that the climate data might be missing some of the events. That might be leading to the low figure for 1898-99. 

[bluewave]

39 minutes ago, MJO812 said:

It forms a low but misses to the south and east. It is warm right now because the low is disjointed. 

I think our best shot would be the upper low closing off like the Euro and GFS v16. Then we would need just the right amount of spacing between the New Years storm so the low doesn’t get suppressed. A perfect thread the needle would start warm and then transition colder. It would have to go off without a hitch due to the warmth after the New Years storm.

[donsutherland1]

20 minutes ago, binbisso said:

Don is it then more likely that the vortex will just weaken and not split and if so would that be a more favorable outcome for us here since a split usually favors Eurasia

If it weakens or is displaced, that would be better for us.

[NEG NAO]

Threat early next week is real now since EURO shows it'

[snowman19]

55 minutes ago, bluewave said:

I think our best shot would be the upper low closing off like the Euro and GFS v16. Then we would need just the right amount of spacing between the New Years storm so the low doesn’t get suppressed. A perfect thread the needle would start warm and then transition colder. It would have to go off without a hitch due to the warmth after the New Years storm.

Looks like the EPS wants no part of it at all so far

[MJO812]

NAO plummets on the Euro in January

 

Wow

 

If we get the epo and pna to cooperate , very fun times ahead .

[MJO812]

[Heisy]

8 minutes ago, snowman19 said:

Looks like the EPS wants no part of it at all so far

Yeah but last few runs starting to increase that wave strength. I think temps will end up being the issue 

[MJO812]

2 people gave me weenie icons but Eric is absolutely right here. The ensembles are showing a very favorable pattern as we move into January 

When was the last time the NAO was severely negative as the Euro shows?

[bluewave]

31 minutes ago, snowman19 said:

Looks like the EPS wants no part of it at all so far

Every single model has a different storm evolution and solution for the 3-4th. Probably because it’s coming so soon behind the New Year’s Day storm. In general, models don’t handle storm details very well beyond 3-5 days out. Unless we are dealing with the Euro and Hurricane Sandy.

[MJO812]

Weeklies show the pacific getting better by 2nd week of January with a strenghting negative NAO through the whole month into February.

[Eduardo]

6 minutes ago, MJO812 said:

Weeklies show the pacific getting better by 2nd week of January with a strenghting negative NAO through the whole month into February.

I'm cautiously optimistic.  The December snowstorm showed us that, with slight PAC improvements, our unfamiliarly less-than-craptastic ATL setup can get snow down to the coast.  As we approach peak climo in mid and late January, we won't need true arctic air to get the job done (although it'd be great to get some high-ratio stuff here).  All we would need to be back in business is to pinch off the flow of pure PAC puke into Canada a bit.  Back that GOA vortex westward some and we can have some fun!

The potential SSW-induced PV split is the wildcard and, as we've seen before, they don't always reshuffle things in our favor.  Personally, given how the overall pattern already contains more potential than we've seen in a few years, I don't think it's worth rolling the dice.

[donsutherland1]

Following a frontal passage, the sun returned and readings rose into the upper 40s and lower 50s. Tomorrow will be fair but colder with highs mainly in the upper 30s and lower 40s.

As of December 28, the preliminary monthly Arctic Oscillation (AO) average has been -1.560. 75% of days have seen the AO at or below -1.000. This is a dramatic change from Winter 2019-20 when Arctic blocking was virtually non-existent. The last comparable December was December 2012 when the December 1-28 average AO was -1.786 and 79% of days saw the AO at or below -1.000. However, that December was even warmer, on account of a mainly positive EPO and negative PNA.

The likely continuation of Arctic blocking through at least the first 10 days of January would typically provide a higher than climatological probability for above normal snowfall. Ideally, an expansive block would be anchored across the Baffin Bay or Greenland, not south of the Davis Strait.

Blocks that are anchored near Newfoundland and Labrador can inhibit opportunities for snowfall and result in warmer to much warmer than normal conditions in the Middle Atlantic and southern New England regions. This is now the most likely scenario for much of the first half of January. Under this scenario, the first 10-15 days of January will likely be much warmer than normal across the northeastern United States, Quebec, and much of eastern Canada. After January 10, there is some indication on the EPS that a transition that could lead to a trough's moving into the East could get underway.

The ENSO Region 1+2 anomaly was -1.1°C and the Region 3.4 anomaly was -0.9°C for the week centered around December 23. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.70°C and the ENSO Region 3.4 anomaly has averaged -1.15°C. La Niña conditions will likely prevail at least through the winter.

The SOI was +19.15 today.

Today, the preliminary Arctic Oscillation (AO) figure was -3.452. That is the lowest figure since November 26, 2018 when the AO was -3.629.

On December 27 the MJO was in Phase 6 at an amplitude of 0.061 (RMM). The December 26-adjusted amplitude was 0.165.

Based on the latest guidance, a significant stratospheric warming event near or just after the start of January is likely. The highest levels of the stratosphere will warm during the closing days of December. The warming will begin to descend during the opening week of January. In addition, the mean zonal winds at 1 mb and 10 mb will likely reverse while the mean zonal wind at 30 mb will likely slacken considerably. Toward the end of the first week in January, the top layers of the stratosphere could begin to cool.

The significant December 16-17 snowstorm during what has been a blocky December suggests that seasonal snowfall prospects have increased especially from north of Philadelphia into southern New England. At New York City, there is a high probability based on historic cases that an additional 20" or more snow will accumulate after December. Were blocking to disappear, snowfall prospects would diminish. For now, blocking appears likely to continue through the first half of January.

Based on sensitivity analysis applied to the latest guidance, there is an implied near 100% probability that New York City will have a warmer than normal December. December will likely finish with a mean temperature near 39.0°.

 

[NEG NAO]

While we are waiting for the next snowstorm in the NYC Metro here is a review of snowstorms from 1953 up till the the one just a couple weeks ago:

https://thestarryeye.typepad.com/weather/2014/11/each-winters-snowstorms-1970-2014.html

 

[Stormlover74]

34 minutes ago, NEG NAO said:

While we are waiting for the next snowstorm in the NYC Metro here is a review of snowstorms from 1953 up till the the one just a couple weeks ago:

https://thestarryeye.typepad.com/weather/2014/11/each-winters-snowstorms-1970-2014.html

 

This is quite shocking. We've had at least 6 such December snowfalls in the 30 years since.

Dec. 28, 1990 - Today's 7.2" snowfall (which began late last night) was the largest accumulation in nearly four years (since January 1987) - and the biggest December snowfall since 1960.  Snow ended shortly before 11:00 AM.   

[weatherpruf]

52 minutes ago, Stormlover74 said:

This is quite shocking. We've had at least 6 such December snowfalls in the 30 years since.

Dec. 28, 1990 - Today's 7.2" snowfall (which began late last night) was the largest accumulation in nearly four years (since January 1987) - and the biggest December snowfall since 1960.  Snow ended shortly before 11:00 AM.   

I surely would have remembered that so it must have been well east of us;; there was no significant snow in these parts until march 92.

[Stormlover74]

7 minutes ago, weatherpruf said:

I surely would have remembered that so it must have been well east of us;; there was no significant snow in these parts until march 92.

Nope I was in Linden and we had 8". It melted in 3 days however

[weatherpruf]

On 12/28/2020 at 1:03 AM, LibertyBell said:

I was looking up NYC historical snowfall climatology and I found this ridiculous page lol

https://en.wikipedia.org/wiki/Climate_of_New_York_City#:~:text=Snowfall is now a rare,is exposed to the Atlantic.

The city can be prone to extremes. Snowfall is now a rare occurrence in the city, on average occurring on only 12 days per year, and it is infrequently heavy.   I can get behind the "infrequently heavy part" but not the "is now a rare occurrence in the city" part.  That statement may be true 20 years from now but not yet.

It actually was true 30 years ago. we had a long stretch of next to nothing.

[weatherpruf]

7 hours ago, Stormlover74 said:

Nope I was in Linden and we had 8". It melted in 3 days however

That was a very mild winter, my first year teaching in Elizabeth; are you sure we aren't talking about a different year; there was a storm near Thanksgiving in 88 or 89; can't believe I wouldn't remember something in 1990. 

[CIK62]

The last 3 days of December areavering 37degs.(33/40).          Making it 36degs., or +3.0.

Month to date is 39.3[+1.4].          December should end at 39.0[+1.5].      btw:    Historical note: Decembers were averaging 35.9 in my 1967 Almanac, so we have added 1.6 degrees even before the May 2021 updates.

The first 14 days of January are averaging 41degs.(37/45), or +8.0 uncorrected.      Tight range.       Only reaches down to at least 32 degrees once!      It is Snowless throughout of course, as is the CMC.        EURO with 2" on Jan.3-4, Yippie.

Finally, the GEFS Extended makes up for this during the last 11 days of the month with all sub-zero days on at least some members.     Down to a record smashing -17.    SSWE wins the day, I suppose.

39*(50%RH) here at 6am. (High was 43* at Midnite)      38* at 7am.     37* by 10am.     Was 38-39 during PM.       32* by 11pm.

[weatherpruf]

7 hours ago, Stormlover74 said:

Nope I was in Linden and we had 8". It melted in 3 days however

On NY weather archives the guy mentions it, and two more storms that winter that I can say confidently did not effect me in this area. Weather service archive for Mt Holly ( my area ) mentions nothing about this date. It must have been some very tight gradient because I don't remember any snowfall at all of significance that whole winter, indeed the Star Ledger ran a cover story on what ever happened to winter that year....

[bluewave]

We continue to set records for warmth and snow together. This was only the 6th year with a 10”+ snowstorm in NYC from December 1st to the 20th. But it was the first December with an average temperature this warm. The warm up after the 20th was also a first to reach 60°.

2020.....39.3°......61°

2009.....35.9°......55°

2003.....37.6°......54°

1960.....30.9°......49°

1948.....38.3°......57°

1916.....34.0°......42°
 

 

Record warmth to some type of snowfall record is becoming more frequent in recent years. 
 

November 2020 was the warmest on record in NYC at 53.0°...5th earliest seasonal 10.0”+ snowfall of 10.5” in December

January to March  2020 was the 2nd warmest on record in NYC at 42.4°...trace of snow on May 9th tied with 1977 for latest on record after 7th coldest winter at 28.3°

February 2018 was the warmest on record around the area with a first 80° at Newark .....NYC warmest February at 42.0°....ISP snowiest March at 31.9” of snow

February 2017 featured 62° on 2-8 at ISP and 14.3” of snow on the 9th...2nd warmest February in NYC at 41.6°

January 2017 produced 6.3” on the 7th in NYC and rose to 66° on the 12th..the month finished +5.4

December 2015 was warmest on record with a +13.3...50.3° in December....greatest snowstorm on record in NYC during January of 27.5”

January 2006 was the 4th warmest in NYC at 40.9° followed by the 2nd biggest snowstorm in February of 26.9”

 

 

 

[Animal]

Light snow in Princeton..car topper in progress..roads slight coating..colder areas

[donsutherland1]

Morning thoughts...

At 7:30 am, a narrow band of snow extended from Lake Ontario east-southeastward just past the Massachusetts border to North Egremont. A few snow showers were also moving southeastward across parts of central New Jersey. Most of the region will not be impacted by the snowfall.

Today will be partly cloudy and cool. Temperatures will likely top out in the upper 30s and lower 40s across most of the region. Likely high temperatures around the region include:

New York City (Central Park): 39°

Newark: 40°

Philadelphia: 39°

Tomorrow will become mainly cloudy with similar readings.

 

[Stormlover74]

3 hours ago, weatherpruf said:

That was a very mild winter, my first year teaching in Elizabeth; are you sure we aren't talking about a different year; there was a storm near Thanksgiving in 88 or 89; can't believe I wouldn't remember something in 1990. 

Nope definitely 90-91. There was another decent event on January 11th. About 6" before changing to sleet and heavy rain. I remember walking home from school in heavy snow. The late Feb Strom was definitely a nyc east special 

[NJwx85]

21 hours ago, MJO812 said:

Congrats DC and Philly.

[Rjay]

On 12/28/2020 at 3:15 PM, MJO812 said:

 

Ridiculously misleading tweet. 

[North and West]

I surely would have remembered that so it must have been well east of us;; there was no significant snow in these parts until march 92.

We had that storm out here... IIRC, it was snow followed by a glaze of ice, and then it melted quickly, as it is wont to do around these parts.


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