December 2021 Obs/Disco...Dreaming of a White-Weenie Xmas

[40/70 Benchmark]

Here are my thoughts on December. I still feel okay about this, through it may end up being a bit warmer then I thought.

December 2021 Outlook

December Analogs: 2007, 2000 (x2), 1974, 1970, 1995, 2005 (x2), 2017 (x2), 2008, 1983, 2020

The polar vortex should take some assaults throughout the latter portion of November and much of December, however, it should remain intact and ultimately intensify and consolidate beyond the New Year and later in January. This is consistent with basin-wide, mixed-type la nina events. The month should be active with a multitude of moderate snowfalls for the northeast, with the most significant event likely to occur the week of Christmas between the 19th and 26th. A white Christmas is highly likely for the majority of the region and a storm on the holiday itself is a distinct plausibility. Plan accordingly. Although the focus will be on the northeast via a mix of Miller B systems and southwest flow events whenever blocking relaxes, the mid atlantic should receive some snowfall due to a subtle subtropical influx coupled with a variable PNA.

 

 

 

The month should not be exceedingly frigid, as the very mild fall has ensured a late developing cold reservoir. Anywhere from near normal close to the coast to as much -2 departures well inland should cover the monthly departures

 

 

The thing to watch this month is whether we can get the lower heights flushed out of AK this month. If we can, I think we are right on track for  a decent season....if we do not, then that spells trouble IMO.

Hopefully someone can post the latest guidance...

[40/70 Benchmark]

6 hours ago, snowman19 said:

Not sure if you follow Griteater on twitter but what he tweeted yesterday is the most disturbing thing I’ve seen all fall. A severely positive EPO is the kiss of death for winter, even if you pop a -NAO/-AO all that would do is bring down and trap PAC junk air with the EPO floodgates wide open: 

 

 

10 minutes ago, 40/70 Benchmark said:

Yea, I'm sure that broke your heart.

It seems worse for la nina than it is for el nino.

I did see that and actually quoted and commented on it. What I said was that it is the most disturbing piece of data yet fans of winter on the east coast, and is a viable concern. 2005-2006 is one of my main analogs, and I have 2011-2011 as a strong extratropical Pacific analog. That said, I am not yet imminently concerned. If December is awful even in New England, then sound the alarms.

 

[40/70 Benchmark]

 

[MJO812]

32 minutes ago, 40/70 Benchmark said:

 

[mahk_webstah]

44 minutes ago, 40/70 Benchmark said:

 

my 1st reaction to this is that it is horrible, but I can't see the date stamp.  Is the big ridge building nw of Alaska a good thing?   And if it continues to build what happens to the trough south of Alaska?  This is starting to remind me of parts of last year where all the good looks just kept getting worse as we got closer

[40/70 Benchmark]

8 minutes ago, mahk_webstah said:

my 1st reaction to this is that it is horrible, but I can't see the date stamp.  Is the big ridge building nw of Alaska a good thing?   And if it continues to build what happens to the trough south of Alaska?  This is starting to remind me of parts of last year where all the good looks just kept getting worse as we got closer

Its pretty bad.

[CoastalWx]

The GEFs and EPS I thought looked decent. They try for a little ridge bridging and keep the PV on our side. That’s a good thing. If anything the dateline ridge signal has gotten stronger. 
Again look beyond first week of December. That week is gone.

 

[ORH_wxman]

Yeah model gudiance has punted very early December for a few days now....we're gonna get a full torch for a few days there.

But they are pretty adamant about rebuilding the Aleutian ridging into the WPO region by about Dec 7-9 or so. That should set the stage for some cold air bleeding down into northern CONUS and get some winter wx threats. 

[40/70 Benchmark]

16 minutes ago, CoastalWx said:

The GEFs and EPS I thought looked decent. They try for a little ridge bridging and keep the PV on our side. That’s a good thing. If anything the dateline ridge signal has gotten stronger. 
Again look beyond first week of December. That week is gone.

 

Yea, that looks good. I think we will see some NAO later in the month, too.

[ORH_wxman]

What is good is that all the ensemble guidance (EPS/GEFS/GEPS) all show the Aleutian ridge rebuilding into the Bering Strait....so this isn't just one model ensemble showing it.

We just need to keep an eye on the timing....if it keeps getting pushed back, then that would be trouble. If not, then we're probably going to have a nice period IMHO in mid-December.

[40/70 Benchmark]

Lets bump this. I still say white xmas for most of New England.

[40/70 Benchmark]

37 minutes ago, ORH_wxman said:

What is good is that all the ensemble guidance (EPS/GEFS/GEPS) all show the Aleutian ridge rebuilding into the Bering Strait....so this isn't just one model ensemble showing it.

We just need to keep an eye on the timing....if it keeps getting pushed back, then that would be trouble. If not, then we're probably going to have a nice period IMHO in mid-December.

Strongly doubt a grincher this year.

[40/70 Benchmark]

Ha, take a look at the first 10 days of 12/95:

Climatological Data for BOSTON, MA - December 1995
Click column heading to sort ascending, click again to sort descending.

Date	Max Temperature	Min Temperature	Avg Temperature	Avg Temperature Departure	HDD	CDD	Precipitation	Snowfall	Snow Depth
1995-12-01	47	28	37.5	-2.3	27	0	0.10	0.3	3
1995-12-02	46	27	36.5	-3.0	28	0	0.00	0.0	0
1995-12-03	47	25	36.0	-3.2	29	0	0.07	0.0	0
1995-12-04	50	37	43.5	4.6	21	0	0.00	0.0	0
1995-12-05	40	30	35.0	-3.7	30	0	0.00	0.0	0
1995-12-06	46	34	40.0	1.6	25	0	0.10	0.0	0
1995-12-07	39	29	34.0	-4.1	31	0	0.00	0.0	0
1995-12-08	33	22	27.5	-10.3	37	0	0.00	0.0	0
1995-12-09	48	21	34.5	-3.0	30	0	0.69	2.2	0
1995-12-10	37	20	28.5	-8.7	36	0	T	0.0	0

[Torch Tiger]

Grass still nice and lush green, wonder if we have a green Christmas instead of brown?

[codfishsnowman]

5 minutes ago, 40/70 Benchmark said:

Strongly doubt a grincher this year.

Partly Cloudy and 30-35 would be great compared with all the grinches of recent years, ideal would be a regionwide 2 to 4 inch currier and ives a day or two before.

[40/70 Benchmark]

1 minute ago, codfishsnowman said:

Partly Cloudy and 30-35 would be great compared with all the grinches of recent years, ideal would be a regionwide 2 to 4 inch currier and ives a day or two before.

I honestly think the odds for a decent event on the actual holiday are well above climo this season...same way I felt in 2017.

[NorEastermass128]

This all sounds good to me. For those of us on the coast, let’s push the good look further into Dec, as climo gets less hostile. 

[tamarack]

34 minutes ago, 40/70 Benchmark said:

I honestly think the odds for a decent event on the actual holiday are well above climo this season...same way I felt in 2017.

Best 12/25 event I've seen.  1978 in Ft. Kent had the same 8" (and another 8.5" thru sunrise on 12/27) but much of that earlier 12/25 accum came after dark.  2017 was all in daylight.

[WxWatcher007]

57 minutes ago, 40/70 Benchmark said:

Strongly doubt a grincher this year.

That alone would be a big win in my book. 

[Eduardo]

1 hour ago, 40/70 Benchmark said:

Ha, take a look at the first 10 days of 12/95:

Climatological Data for BOSTON, MA - December 1995
Click column heading to sort ascending, click again to sort descending.

Date	Max Temperature	Min Temperature	Avg Temperature	Avg Temperature Departure	HDD	CDD	Precipitation	Snowfall	Snow Depth
1995-12-01	47	28	37.5	-2.3	27	0	0.10	0.3	3
1995-12-02	46	27	36.5	-3.0	28	0	0.00	0.0	0
1995-12-03	47	25	36.0	-3.2	29	0	0.07	0.0	0
1995-12-04	50	37	43.5	4.6	21	0	0.00	0.0	0
1995-12-05	40	30	35.0	-3.7	30	0	0.00	0.0	0
1995-12-06	46	34	40.0	1.6	25	0	0.10	0.0	0
1995-12-07	39	29	34.0	-4.1	31	0	0.00	0.0	0
1995-12-08	33	22	27.5	-10.3	37	0	0.00	0.0	0
1995-12-09	48	21	34.5	-3.0	30	0	0.69	2.2	0
1995-12-10	37	20	28.5	-8.7	36	0	T	0.0	0

Funny you posted this.  I actually just took a look at this data the other day (for my location, of course) and was pleasantly surprised by it.  I'd gladly sacrifice the first half of December for a wintry Xmas period.

[ORH_wxman]

Most of those early Dec 1995 days in BOS were below average. I think we only cracked 40F maybe twice in ORH during that stretch.....but the real snow started on 12/9 when we got about 5 inches and then some ZR (BOS changed to rain in that one).

 

We did have some leftover snow from 11/29/95 still in spots though before 12/9.

[DavisStraight]

6 hours ago, ORH_wxman said:

What is good is that all the ensemble guidance (EPS/GEFS/GEPS) all show the Aleutian ridge rebuilding into the Bering Strait....so this isn't just one model ensemble showing it.

We just need to keep an eye on the timing....if it keeps getting pushed back, then that would be trouble. If not, then we're probably going to have a nice period IMHO in mid-December.

I can wait until mid Dec going into Christmas, I don't need snow first week of Dec. Seems when I was a kid our first snow was usually first week of Dec, even end of Nov but my memory might not be accurate.

[40/70 Benchmark]

23 minutes ago, ORH_wxman said:

Most of those early Dec 1995 days in BOS were below average. I think we only cracked 40F maybe twice in ORH during that stretch.....but the real snow started on 12/9 when we got about 5 inches and then some ZR (BOS changed to rain in that one).

 

We did have some leftover snow from 11/29/95 still in spots though before 12/9.

I'm not sure the highs will be much warmer than that...haven't looked. But I'm guessing it may be the lows that make this period warmer.

[ORH_wxman]

Just now, 40/70 Benchmark said:

I'm not sure the highs will be much warmer than that...haven't looked. But I'm guessing it may be the lows that make this period warmer.

Maybe...there's a lot of uncertainty in our area actually for the first several days of December....several pieces of guidance are trying to drill a localized cold shot via a PV lobe into NE while the upper plains torch away....that could shorten the amount of time we have any real true torchy weather.

 

Here's an example from the 12z GFS below....yes, its clown range so obviousl this can/will change, but we don;t know which direction it will change. Maybe we end up torchier, but we could also end up colder/snowier like the 12z GGEM shows

 

[weathafella]

EPS is delaying the loss of the nao truncating the torch.

[CoastalWx]

Weeklies look warm. Maybe not week 3, but week 4 looks warm.

[SJonesWX]

25 minutes ago, CoastalWx said:

Weeklies look warm. Maybe not week 3, but week 4 looks warm.

screw off, Grinch! 

[CoastalWx]

6 minutes ago, SJonesWX said:

screw off, Grinch! 

I think as long as that ridge doesn't retro west past the dateline, we would be ok. If it did move west, it would be ugly. No real blocking, so at the mercy of the PAC. Of course they could be totally wrong too. It's not my forecast, just stating what they show.

[powderfreak]

29 minutes ago, CoastalWx said:

I think as long as that ridge doesn't retro west past the dateline, we would be ok. If it did move west, it would be ugly. No real blocking, so at the mercy of the PAC. Of course they could be totally wrong too. It's not my forecast, just stating what they show.

Cue up a comment in a day or two that “Scooter already canceled December…”

[TauntonBlizzard2013]

I’m about ready to lock in a grinch period centered on Christmas of course