December 2020 General Discussions & Observations Thread

[Allsnow]

3 hours ago, Allsnow said:

This isn’t going to be last winter where the PV gained strength and the mjo went wild at the end of December. The vortex is going to stay in Canada which will keep them cold. All we would need is something to buckle the flow to get the cold here. 
 

This December is acting more like a niño then Niña. Perhaps we get a niño January/February instead then. Who knows 

 

[Nibor]

32 minutes ago, JoshSnow said:

Verga 

Do you mean virga? Or were you cursing in Spanish?

[Will - Rutgers]

1 hour ago, Allsnow said:

Light snow for nyc Wednesday morning. 

i weenie'd your post, but only to be ironic 

[Will - Rutgers]

to paraphrase an old forky post, you pretty much need a perfect synoptic setup just to get to below average anymore.

[Dark Star]

1 hour ago, North and West said:

I feel like our running theme the past few years is who can call out Winter's Over the quickest. I feel like someone just said we're running out of days in December... it's December 7th. Enjoy the journey. 

 When we are at January 15th, and there is no tangible signs of colder weather progged, you can pretty much kiss winter goodbye. Otherwise, by the time a cool down would start, you have very little time left, unless a complete long term pattern change occurs.

[Allsnow]

1 hour ago, JoshSnow said:

Verga 

No 

[Rtd208]

23 minutes ago, Dark Star said:

 When we are at January 15th, and there is no tangible signs of colder weather progged, you can pretty much kiss winter goodbye. Otherwise, by the time a cool down would start, you have very little time left, unless a complete long term pattern change occurs.

That has always been my cutoff date. You may get a rogue snowstorm or two but overall the winter is usually cooked.

[Brian5671]

59 minutes ago, Dark Star said:

 When we are at January 15th, and there is no tangible signs of colder weather progged, you can pretty much kiss winter goodbye. Otherwise, by the time a cool down would start, you have very little time left, unless a complete long term pattern change occurs.

I agree-last year was a prime example.  

[rclab]

33 minutes ago, wizard021 said:

Keep laughing when I school all of you like I did during the summer with hurricanes. 

I and others are not laughing. The general hope is that you are correct and even conservative in your prediction. The science tools we presently have say such a prediction is a dream. A wonderful, inspiring, magnificent dream but one that is still likely to be impossible. As always.....

[NEG NAO]

1 hour ago, wizard021 said:

This will be a great great winter for our area. A lot of the downcasting is too funny. I have our area getting 70 to 80 inches of snow.

1995 -96 is one of the top analogs for this upcoming winter.............75 inches of snow at Central Park............according to LC

There are suspicions of a pattern change across North America as we head into late December. But I can assure you that any alteration in the 500MB longwave configuration will be slow, and be dependent on two factors. One is the active southern branch jet stream, which all of the numerical models are having trouble handling. The other is the potential for a sudden stratospheric warming event, which could have a "cascade/domino" effect on lower layers of teh atmosphere as we head into January.

 

The subtropical jet stream has been a force in apparent weather in the U.S., with a surface temperature response quite unlike the "typical La Nina" calls that have dominated traditional and online media since November. Quite simply, we have seen a warm Canada and northern U.S. response, with colder than average readings common along and below 40 N Latitude. The various guidance formats use climatology in the equations, and the numerical model expectation of a very warm pattern continues to be at odds with readings that often fall lower than what can be expected for the season. This is why when you look at the monthly outlooks, they appear to be almost ablaze with record warmth across most, if not the entire, continent. Check the analog predictions as a balance. We are now down to ten usable comparison seasons, with 1995-96 and 2007-08 being the most similar. This set-up gives credence to teh idea that a shift to a colder outcome will occur in January, and keep going through February and March.

 

The 10MB temperature and height forecasts are interesting because the reveal a sudden stratospheric warming over Siberia, with a re-alignment of the circumpolar vortex in a linear manner from eastern North America through much of Europe and western Russia. Keep in mind that the predictions and boundary layer response for this level fall often into uncertainty. And, that the eventual outcome from 500MB on down usually happens after about a two week delay. But if the December 21 panel verifies, then we will see a shift to a -AO/+PNA configuration by the second or third week of January. That would mean a more traditional, colder winter across the eastern two-thirds of North America.

 

If the energy from the southern branch can interact with more profound digging troughs from Canada, it might make us forget some of those longer term predictions by the world agencies. There is hope, at least!

[Brian5671]

This month at least is nothing like 1995.    1995 got cold the last week of November and kicked off with a 2-4 inch even to end the month-  December continued that theme with 3 to 4 more snowfalls including a bigger one around 12/20.   I see zero similiarity with that winter so far at least.

[jm1220]

Urban heat island and coastal affects already showing up this evening. Down to about 28 in my area but on the LI Sound/South shore and in NYC still in the mid to upper 30s. 

[donsutherland1]

Earlier today, a system brought snow to parts of Virginia. Richmond picked up 1.0" snow. Another weak system could bring some snow flurries and snow showers to the region late tomorrow night or early Wednesday morning. Parts of the area could pick up a coating. Before then, tomorrow will be partly sunny and cool.

Through mid-week, temperatures will run somewhat below normal. Milder weather will return for a time afterward, before the next push of cooler air arrives. Through mid-December, no exceptional cold is likely.

Meanwhile, another round of near record and record warmth is likely in parts of western Canada through mid-week.

A warmer pattern could begin to develop toward the winter solstice. The closing 10 days of December could wind up generally warmer than normal. The EPS weeklies and new subseasonal guidance are in strong agreement that the last week of December will likely be warmer than normal. The duration of the current AO-/PNA+ pattern will be key to how long the developing colder pattern persists.

Statistical guidance based on the ENSO state and teleconnections would typically favor a colder regime for the first half of December in the Middle Atlantic and southern New England regions. Both historic experience following exceptionally warm November cases suggest that a warmer than normal December remains the base case even if the first half of the month winds up colder than normal. Almost 90% of cases with a November mean temperature of 51.5° or above in Central Park (2020 saw the temperature average a record 52.9° in November) went on to record a warmer than normal December and just over three-quarters of such cases saw December register a monthly mean temperature of 40.0° or above.

The ENSO Region 1+2 anomaly was -0.5°C and the Region 3.4 anomaly was -1.1°C for the week centered around December 2. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.77°C and the ENSO Region 3.4 anomaly has averaged -1.35°C. La Niña conditions will likely prevail at least through the winter.

The SOI was +15.15.

Today, the preliminary Arctic Oscillation (AO) figure was -1.528.

On December 6 the MJO was in Phase 4 at an amplitude of 0.741 (RMM). The December 5-adjusted amplitude was 1.020.

Based on the latest guidance, no significant stratospheric warming event is likely through the first two weeks of December. The warming above 3 mb in response to recent strong Wave 1 activity could abate toward or just after mid-month.

Since 1950, there have been five cases where a La Niña developed during June-July-August or afterward following an El Niño winter. 4/5 (80%) of those cases saw a predominant EPO+/AO+ winter pattern. The most recent such case was 2016-17. 10/11 (91%) of the La Niña winters that followed an El Niño winter featured a predominantly positive EPO. A predominant EPO+/AO+ pattern is very likely for winter 2020-21. It is likely that the Middle Atlantic and southern New England areas will see a warmer than normal winter with below normal snowfall.

Based on sensitivity analysis applied to the latest guidance, there is an implied 67% probability that New York City will have a warmer than normal December. December will likely finish with a mean temperature near 40.0°.

 

[Eduardo]

3 hours ago, Dark Star said:

 When we are at January 15th, and there is no tangible signs of colder weather progged, you can pretty much kiss winter goodbye. Otherwise, by the time a cool down would start, you have very little time left, unless a complete long term pattern change occurs.

Some winters got cranking late.  In 2014-2015, I remember we were all doom and gloom until mid January.  Different (exceptional) animal, for sure but for the more hopeful among us....

[CIK62]

For amusement purposes only:

Using the GEFS Extended------- the most extreme members for the Low T's show a first stab at the teen's on Dec. 15,   the single digits on Dec. 23,  and a sub-zero attempt on New Years Eve.

These are not predictions, just the most extreme possibilities.

 Unfortunately you have to add 40-60 degrees to these to obtain the most extreme High T possible on the same dates.   LOL

[psv88]

1 hour ago, jm1220 said:

Urban heat island and coastal affects already showing up this evening. Down to about 28 in my area but on the LI Sound/South shore and in NYC still in the mid to upper 30s. 

27 here

[MJO812]

1 hour ago, jm1220 said:

Urban heat island and coastal affects already showing up this evening. Down to about 28 in my area but on the LI Sound/South shore and in NYC still in the mid to upper 30s. 

37 here 

[qg_omega]

1 hour ago, jm1220 said:

Urban heat island and coastal affects already showing up this evening. Down to about 28 in my area but on the LI Sound/South shore and in NYC still in the mid to upper 30s. 

Odd 31 here

[sferic]

Can I reserve a spot atop Mt Washington to ride the winter out at  LOL ?

Poll:

Would you if you could?

[Allsnow]

1 hour ago, donsutherland1 said:

Earlier today, a system brought snow to parts of Virginia. Richmond picked up 1.0" snow. Another weak system could bring some snow flurries and snow showers to the region late tomorrow night or early Wednesday morning. Parts of the area could pick up a coating. Before then, tomorrow will be partly sunny and cool.

Through mid-week, temperatures will run somewhat below normal. Milder weather will return for a time afterward, before the next push of cooler air arrives. Through mid-December, no exceptional cold is likely.

Meanwhile, another round of near record and record warmth is likely in parts of western Canada through mid-week.

A warmer pattern could begin to develop toward the winter solstice. The closing 10 days of December could wind up generally warmer than normal. The EPS weeklies and new subseasonal guidance are in strong agreement that the last week of December will likely be warmer than normal. The duration of the current AO-/PNA+ pattern will be key to how long the developing colder pattern persists.

Statistical guidance based on the ENSO state and teleconnections would typically favor a colder regime for the first half of December in the Middle Atlantic and southern New England regions. Both historic experience following exceptionally warm November cases suggest that a warmer than normal December remains the base case even if the first half of the month winds up colder than normal. Almost 90% of cases with a November mean temperature of 51.5° or above in Central Park (2020 saw the temperature average a record 52.9° in November) went on to record a warmer than normal December and just over three-quarters of such cases saw December register a monthly mean temperature of 40.0° or above.

The ENSO Region 1+2 anomaly was -0.5°C and the Region 3.4 anomaly was -1.1°C for the week centered around December 2. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.77°C and the ENSO Region 3.4 anomaly has averaged -1.35°C. La Niña conditions will likely prevail at least through the winter.

The SOI was +15.15.

Today, the preliminary Arctic Oscillation (AO) figure was -1.528.

On December 6 the MJO was in Phase 4 at an amplitude of 0.741 (RMM). The December 5-adjusted amplitude was 1.020.

Based on the latest guidance, no significant stratospheric warming event is likely through the first two weeks of December. The warming above 3 mb in response to recent strong Wave 1 activity could abate toward or just after mid-month.

Since 1950, there have been five cases where a La Niña developed during June-July-August or afterward following an El Niño winter. 4/5 (80%) of those cases saw a predominant EPO+/AO+ winter pattern. The most recent such case was 2016-17. 10/11 (91%) of the La Niña winters that followed an El Niño winter featured a predominantly positive EPO. A predominant EPO+/AO+ pattern is very likely for winter 2020-21. It is likely that the Middle Atlantic and southern New England areas will see a warmer than normal winter with below normal snowfall.

Based on sensitivity analysis applied to the latest guidance, there is an implied 67% probability that New York City will have a warmer than normal December. December will likely finish with a mean temperature near 40.0°.

 

What a waste of a -A0. We finally get it but no way to get the cold down here 

[White Gorilla]

19 minutes ago, sferic said:

Can I reserve a spot atop Mt Washington to ride the winter out at  LOL ?

Poll:

Would you if you could?

No.  Too extreme. 

[donsutherland1]

1 minute ago, Allsnow said:

What a waste of a -A0. We finally get it but no way to get the cold down here 

That happened in winter 2001-02, as well.

[psv88]

What’s snow?

[Allsnow]

7 minutes ago, donsutherland1 said:

That happened in winter 2001-02, as well.

Looks negative going forward into December. Just nothing to get it down here with a +epo -pna 

[uncle W]

we did get a noreaster and seasonably cold air with the neg ao thats going on now...there was some snow way north of here...later on in the season I can see a snowstorm that started as rain if we see a storm like Fridays a month or two later...

[MJO812]

[STORMANLI]

2 hours ago, psv88 said:

What’s snow?

Frozen precipitation that likes to reside anywhere but here.

[ForestHillWx]

28 currently; projected low of 22. 

[MJO812]

Active Euro run with 2 coastals.

Rain for both for the area lol

[LongBeachSurfFreak]

8 hours ago, sferic said:

Can I reserve a spot atop Mt Washington to ride the winter out at  LOL ?

Poll:

Would you if you could?

For a week yes. But after a week it would get old real fast. The weather is too extreme to enjoy. On many days it’s just not humanly possible to be outside for more then a few minutes at a time. I have been out in -20 with 40mph winds in the Vermont mountains and it’s not at all appealing. 
The major thing I’m liking about this winter so far (cold season) are the differences from the last two. The last two winters were as bad as it can get for the immediate coast so to see a different storm track and pattern is at least somewhat encouraging. We almost had a real shutout last winter with 3” near the bay.