December 2021

[EastonSN+]

10 minutes ago, Allsnow said:

Weeklies!

That good?

[HeadInTheClouds]

13 minutes ago, Allsnow said:

Weeklies!

 

[Allsnow]

5 minutes ago, EastonSN+ said:

That good?

Looks good for most of January. Even though blocking breaks down the pv lobe sits near Hudson Bay. By February (way out in time) we go back to the Niña look we have now 

[BxEngine]

1 hour ago, snowman19 said:

The very cold and snowy end of November and December forecasts for the east are about to go down in flames….might be one of the biggest busts of all time…..

thats amazing. 

[donsutherland1]

Despite ample sunshine, readings were held much below normal today. But following another cold night, winter will lose its grip on the region, yet again. Temperatures will begin to moderate tomorrow. There will be one additional brief push of modestly colder air on Thursday. Overall, temperatures will generally be near or above normal throughout much of the remainder of December. The final week of December could still see temperatures begin to turn colder as month ends. No severe cold is likely.

Afterward, if the small sample of cases where the MJO moved into Phase 7 at a high amplitude (1.75 or above) during the December 10-20 period, as occurred this month, is representative, the first 10 days of January could see below to perhaps much below normal temperatures. However, the coldest air will likely remain confined to the Pacific Northwest, Northern Plains, and western and central Canada for much of this period.

January will likely commence with an AO-/PNA- pattern. That typically favors somewhat cooler than normal readings in the East. For NYC, the January 1-10, 1991-2020 mean temperature for such cases was 33.5° (normal: 34.8°). There are some hints that a milder pattern could begin to develop around mid-January.    

In the Midwest, Chicago has yet to receive its first measurable snowfall through 4 pm CST on December 20, 2021 has now tied the record for Chicago's latest first measurable snowfall. The existing record was set on December 20, 2012. That record is all but certain to be broken tomorrow.

Following very wet July-September periods, winter (December-February) precipitation has typically been near or below normal. The most recent exception was winter 2018-19.

The ENSO Region 1+2 anomaly was -1.4°C and the Region 3.4 anomaly was -1.1°C for the week centered around December 8. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -1.00°C and the ENSO Region 3.4 anomaly has averaged -0.92°C. La Niña conditions will likely persist into at least late winter.

The SOI was -9.81 today.

The preliminary Arctic Oscillation (AO) figure was -1.950 today.

On December 18 the MJO was in Phase 6 at an amplitude of 1.681 (RMM). The December 17-adjusted amplitude was 1.867 (RMM).

Based on sensitivity analysis applied to the latest guidance, there is an implied 98% probability that New York City will have a warmer than normal December (1991-2020 normal). December will likely finish with a mean temperature near 42.6° (3.5° above normal).

 

[snowman19]

1 hour ago, bluewave said:

The -PNA is the one constant on the latest extended EPS. Tries to press the gradient SE in early January for colder temperatures and maybe some overrunning snow potential. It loses the -AO during the 2nd half of January and temperatures rebound. 
 

Dec 20-27

 

Dec 27 to Jan 3

 

Jan 3 to 10

 

 

[EasternLI]

High AAM and phase 7. What happens to the strat in the period ahead? I think that's the answer for what the 2nd half of winter does. If nothing happens, it's probably spring starting in February this year. 

 

[Roger Smith]

Don or somebody else probably posted some of this back in the thread, but according to my search of the NYC data, the latest first measurable snowfall in any winter season was Jan 29 of 1973. Second place goes to Jan 21 of 1871 but I am not sure how reliable the zero snowfall of Dec 1870 and Jan 1-20 1871 are considered; the data set I have does not indicate any missing  snow data there and the mean temps were 34.2 for Dec and 30.7 for Jan 1-20. 

Other late starts I noted were Jan 20, 1966 and 2000, Jan 19, 2007, Jan 18, 1998, Jan 17, 2016 and Jan 11, 1995.  

The only other winter seasons to reach Jan 4th with no measurable snow were 1895-96 and 2001-02 (both Jan 7 first snow), 1891-92 (Jan 6 first snow) and 1971-72 (Jan 5 first snow). 

That is a total of 12 winters out of 153 making it to Jan 4 before the first measurable snow.

The total winter snowfalls in the same order were 2.8" (1972-73), 30.1" (1870-71), 21.4" (1965-66), 16.3" (1999-2000), 12.4" (2006-07), 5.5" (1997-98), 32.8" (2015-16, most of that on Jan 23rd), 11.8" (1994-95), 46.0" (1895-96), 3.5" (2001-02), 25.3" (1891-92), and 22.9" (1971-72). 

The average of those twelve was 19.2" which indicates roughly normal snowfall for the average of about 70% of the winter season still available at the zero start. However 1896 and 2016 excluded, the average was only about 15" per season and among these we find three of the seven lowest seasonal totals including 1st, 2nd and 7th lowest. The other four in the seven least snowy winters had as little as 0.1" by Jan 1st in 1900-1901 (fifth lowest snowfall total of 5.1"), that winter's first inch of snow came on Jan. 30th with the total only 0.3" before that. For third least snowy 1918-19 (3.8") most of the snow fell in March, the total being a mere 1.1" before that. 1931-32 and 2019-20 also in the bottom seven had larger portions before New Years than the rest of this group, with 2.5" in Dec 2019 of the 4.8" seasonal finish, and 2.1" Nov-Dec 1931 of the 5.3" seasonal total. 

The 1895-96 winter certainly reversed form more notably than any of the rest of this list, some record cold (Jan 6, Feb 17 record low maxima) and heavy snowfall events in Mar gave a generally wintry period of weather throughout January to March, then the spring set numerous high temperature records (some still extant) in April and May. Rather than being a one-shot wonder like 2016, 1896 had four record snowfalls in March. There wasn't a lot of snow with the cold weather earlier though (a total of 3" in January and 9.5" in Feb, then 30.5" in March and 3" more in early April.

I suspect this winter might go a bit like these better outcomes of the late starters, it is not setting up like a torch winter with plenty of cold massing for later delivery. I would compare it perhaps to 1981-82 which had some wintry episodes after Jan 8th and not much before then.

Winter 2011-12 had the freak late October snow (2.9") then nothing measurable until Jan 21, 2012 when 4.3" fell. So it probably seemed like another very late start. 

[lee59]

27 degrees already. Don't expect the quick drop in temperature to continue as the wind is already South Southwest

[bluewave]

2021 was probably the first year that the NYC coldest daily temperature departure occurred on the Memorial Day weekend. The July 4th weekend was the last time this year that there was a -10 or lower departure. The one bright spot with the few -10 departure days is that we got some great snowstorms with them in early February.

2021 -10 departure days in NYC

1-21….-13.9

1-31…..-10.6

2-08…..-11.6

2-12…..-10.3

3-12……-12.0

3-15…..-10.8

4-22….-14.2

5-29….-17.7

5-30….-18.0

7-3…….-14.1

[EasternLI]

Another QBO link 

 

[hudsonvalley21]

18z GFS is still teasing us for Christmas Eve/ Christmas morning.

 

[donsutherland1]

1 hour ago, Roger Smith said:

Don or somebody else probably posted some of this back in the thread, but according to my search of the NYC data, the latest first measurable snowfall in any winter season was Jan 29 of 1973. Second place goes to Jan 21 of 1871 but I am not sure how reliable the zero snowfall of Dec 1870 and Jan 1-20 1871 are considered; the data set I have does not indicate any missing  snow data there and the mean temps were 34.2 for Dec and 30.7 for Jan 1-20. 

Other late starts I noted were Jan 20, 1966 and 2000, Jan 19, 2007, Jan 18, 1998, Jan 17, 2016 and Jan 11, 1995.  

The only other winter seasons to reach Jan 4th with no measurable snow were 1895-96 and 2001-02 (both Jan 7 first snow), 1891-92 (Jan 6 first snow) and 1971-72 (Jan 5 first snow). 

That is a total of 12 winters out of 153 making it to Jan 4 before the first measurable snow.

The total winter snowfalls in the same order were 2.8" (1972-73), 30.1" (1870-71), 21.4" (1965-66), 16.3" (1999-2000), 12.4" (2006-07), 5.5" (1997-98), 32.8" (2015-16, most of that on Jan 23rd), 11.8" (1994-95), 46.0" (1895-96), 3.5" (2001-02), 25.3" (1891-92), and 22.9" (1971-72). 

The average of those twelve was 19.2" which indicates roughly normal snowfall for the average of about 70% of the winter season still available at the zero start. However 1896 and 2016 excluded, the average was only about 15" per season and among these we find three of the seven lowest seasonal totals including 1st, 2nd and 7th lowest. The other four in the seven least snowy winters had as little as 0.1" by Jan 1st in 1900-1901 (fifth lowest snowfall total of 5.1"), that winter's first inch of snow came on Jan. 30th with the total only 0.3" before that. For third least snowy 1918-19 (3.8") most of the snow fell in March, the total being a mere 1.1" before that. 1931-32 and 2019-20 also in the bottom seven had larger portions before New Years than the rest of this group, with 2.5" in Dec 2019 of the 4.8" seasonal finish, and 2.1" Nov-Dec 1931 of the 5.3" seasonal total. 

The 1895-96 winter certainly reversed form more notably than any of the rest of this list, some record cold (Jan 6, Feb 17 record low maxima) and heavy snowfall events in Mar gave a generally wintry period of weather throughout January to March, then the spring set numerous high temperature records (some still extant) in April and May. Rather than being a one-shot wonder like 2016, 1896 had four record snowfalls in March. There wasn't a lot of snow with the cold weather earlier though (a total of 3" in January and 9.5" in Feb, then 30.5" in March and 3" more in early April.

I suspect this winter might go a bit like these better outcomes of the late starters, it is not setting up like a torch winter with plenty of cold massing for later delivery. I would compare it perhaps to 1981-82 which had some wintry episodes after Jan 8th and not much before then.

Winter 2011-12 had the freak late October snow (2.9") then nothing measurable until Jan 21, 2012 when 4.3" fell. So it probably seemed like another very late start. 

Almost certainly, the 1870-71 date is incorrect. On December 28, 1870, the high temperature was 32 and 0.10” precipitation fell. On December 30, the temperature range was 30-10 and 0.05” precipitation was recorded. The NWS .pdf shows 3.0” snow in December 1870.

https://www.weather.gov/media/okx/Climate/CentralPark/monthlyseasonalsnowfall.pdf

[wdrag]

fwiw: 18 EC has spotty zr now expanded west to extreme nw NJ early Wed, and then this attached graphic is a sampler for early Christmas Eve morning... ie colder solution than the 12z counterpart and more in line with the GFS/GGEM. Whether this holds or not???  Will monitor for flurries or a period of S- into NYC around daybreak Friday (melt on contact NYC, mood snow nw of I95). 

 

 

[EasternLI]

Actually, after looking a little closer at the MJO. It's more like this current wave is dissipating on the doorstep of phase 8. With a new one emerging in phase 6 moving back into phase 7. Eps and gefs both have that look. Almost like a new pulse of energy? Interesting stuff.

[CIK62]

Earliest inkling of a BN Week on the EURO is centered on Jan. 02.       Area north of us in Canada is about 30+ warmer than some earlier outputs for this time period:

The peak BN is at mid-month and fades into Feb.:

[Rjay]

26 degrees

[Roger Smith]

Thanks Don, I suspected that might be the case. So we can remove 1870-71 from the list. I seem to recall getting some snowfall adjustments from you when I first started working with the data base, but that one needs to be adjusted (in my data set). Will see what I can find out. Looking at the rest of the 1870s I don't think this problem extends much further than that one winter. 

[MJO812]

Flakes for Christmas eve

[Rjay]

Up to 31 now

[Stormlover74]

11 minutes ago, MJO812 said:

Flakes for Christmas eve

It would actually be an inch of snow if it's cold enough to stick

[MJO812]

Gfs has wave after wave after wave

Wave train 

[MJO812]

Very nice gfs run starting from Dec 26.

 

Yes the storms get shredded but there is plenty of cold air around. NAO doing work.

[wdrag]

No thread for tonight or Christmas eve early morning... but may eventually begin OBS thread if anything looks more certain for near NYC, otherwise suggest the freezing-frozen are tucked into the NW-NE suburbs thread.  

This is my take upon looking at multiple model output: Best chance tonight for ice is interior MA, if precip occurs there.  HRRR,  SPC HREF, HRRR X favor up there. However, some other modeling allows for spotty icing all the way down to near I95 in NJ.  RGEM being one of them. Because of this I add the NWS 10z ensemble for chance of spotty icing tonight---LOW chance but not zero.  

The period of light snow risk (less than 1") continues for Thursday night-early Friday but it too may be a non player in NYC.  That's not much winter, but something.

My last on this til after 5P. Have a day!

[LoboLeader1]

26 here this AM

[bluewave]

Models continue in push back mode. The forecast colder pattern near the end of December is now warmer than the old run. This is the same thing that happened for Christmas from a week ago. It’s one of the problems with such a strong -PNA pattern.

New run

Old run

 

 

[qg_omega]

We said it was unlikely the MJO would make it out of 7 with a risk of stalling and looping due to destructive interference from the strong Nina, this is happening

[CIK62]

The next 8 days are averaging  37degs.(33/42) or +3>>>Normal nowadays.

Month to date is  45.2[+4.7].       Should be near  42.9[+3.4] by the 29th.

Reached 39 here yesterday.

Today:   42-45, wind w. to n. to e., m. clear early, cloudier late.      

GFS is into the 60's early January, where last night I showed the EURO going BN.   Pattern revealing all model foibles.

33*(72%RH) here at 6am.    32* at 7am.     36* at 9am.     40* at 11am.      42* at Noon.        43*/44* during PM/Evening.

[Tatamy]

24 minutes ago, LoboLeader1 said:

26 here this AM

Two days in a row with temps in the teens.  18 yesterday and 19 this morning.

[EastonSN+]

18 minutes ago, qg_omega said:

We said it was unlikely the MJO would make it out of 7 with a risk of stalling and looping due to destructive interference from the strong Nina, this is happening

As long as it keeps hitting 7 we will score.