December 2020 General Discussions & Observations Thread

[qg_omega]

Niño is very strong, I don’t believe the weakening forecasts

[MJO812]

27 minutes ago, JoshSnow said:

This means it’s going to be cold and snowy. I go with the opposite of models.

What lol

 

[the_other_guy]

12 minutes ago, MJO812 said:

What lol

 

Might as well. A few days ago the models said something else. Sounds ridiculous...but

[Allsnow]

@michsnowfreak

 

https://www.ecmwf.int/en/forecasts/charts/catalogue/

[donsutherland1]

Through today, New York City has received no snowfall. Winter 2020-21 is the 18th case on record during which New York City had seen no snowfall through December 6. For the prior 17 cases, mean winter snowfall was 19.9". The most snowfall occurred during winter 1870-71 when 33.1" was measured. The least snowfall occurred during winter 2001-02 when just 3.5" snow fell. Records go back to 1869.

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 -1.0°C and the Region 3.4 anomaly was -1.0°C for the week centered around November 18. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.87°C and the ENSO Region 3.4 anomaly has averaged -1.40°C. La Niña conditions will likely prevail at least through the winter.

The SOI was +11.78.

Today, the preliminary Arctic Oscillation (AO) figure was -1.324.

On December 5 the MJO was in Phase 4 at an amplitude of 1.023 (RMM). The December 4-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.

 

[MJO812]

 The vortex  has been getting attacked and it looks like it will continue.  Hopefully that means great news for us soon.

[Allsnow]

15 minutes ago, MJO812 said:

 The vortex  has been getting attacked and it looks like it will continue.  Hopefully that means great news for us soon.

Not if we continue with a bad mjo and -AAM 

[snowman19]

4 hours ago, bluewave said:

It looks like the eastern IO warm pool and La Niña are stalling the MJO in 4-5. Normally, the MJO has been progressing over to 6-7 flowing these frequent phase  4-5 transits. So we may get a rare 4-5 stall lasting most of December. The coldest Niño 4 SSTs in a while probably aren’t helping. Since that could also prevent the MJO from crossing the WPAC back to the DL and phase 6-7-8.

 

Region 4 hasn’t been this cold in over 16 years

[leo2000]

10 minutes ago, snowman19 said:

Region 4 hasn’t been this cold in over 16 years

Enjoy it Met DT has posted just awhile ago on another sub forum. He showed a model directly from ecmwf which shows a dramatic weakening of the Moderate La Nina. 

 

 IN MAJOR   DEVELOPMENT    the  ecmwf    enso model shwos   DRAMATIC  WEAKENING  of the Moderate  La Nina.

It is hard to understate   how  BIG  this is...or   COULD be... 

 a   rapidly  weakening   La Nina...   in essence a   WEAK  La nina combined with  SSW   EVENT

 t 

 

[qg_omega]

10 minutes ago, leo2000 said:

Enjoy it Met DT has posted just awhile ago on another sub forum. He showed a model directly from ecmwf which shows a dramatic weakening of the Moderate La Nina. 

 

 IN MAJOR   DEVELOPMENT    the  ecmwf    enso model shwos   DRAMATIC  WEAKENING  of the Moderate  La Nina.

It is hard to understate   how  BIG  this is...or   COULD be... 

 a   rapidly  weakening   La Nina...   in essence a   WEAK  La nina combined with  SSW   EVENT

 t 

 

It’s just a model, wouldn’t put much stock in it.  It’s very strong and there are no imminent signs of weakening

[donsutherland1]

28 minutes ago, qg_omega said:

It’s just a model, wouldn’t put much stock in it.  It’s very strong and there are no imminent signs of weakening

The new weekly numbers will be in tomorrow. They will provide further insight into the evolution of the ongoing La Niña event.

[snowman19]

56 minutes ago, leo2000 said:

Enjoy it Met DT has posted just awhile ago on another sub forum. He showed a model directly from ecmwf which shows a dramatic weakening of the Moderate La Nina. 

 

 IN MAJOR   DEVELOPMENT    the  ecmwf    enso model shwos   DRAMATIC  WEAKENING  of the Moderate  La Nina.

It is hard to understate   how  BIG  this is...or   COULD be... 

 a   rapidly  weakening   La Nina...   in essence a   WEAK  La nina combined with  SSW   EVENT

 t 

 

Enjoy what? Not understanding your post

[leo2000]

7 minutes ago, snowman19 said:

Enjoy what? Not understanding your post

Enjoy the suppose record cold 3.4 Enso as the chart I sent you shows a dramatic weakening of the La Nina. 

[Snowstorms]

7 hours ago, bluewave said:

Without some kind of record -EPO or -NAO blocking, we can’t get cold winters anymore. 09-10, 10-11, 13-14, and 14-15 were our only 4 cold winters out of the last 11 years. 09-10 to 10-11 was the strongest -NAO of 187 years that I posted earlier. 13-14 and 14-15 featured the record -EPO patterns. The -EPO developed during the summer of 2013 and intensified during November and carried into the next spring. 14-15 saw a similar extreme -EPO combined with El Niño for the backloaded cold. But since the super El Niño in 15-16, all our winters have been warm with intervals when the unfavorable MJO phases ran the table. Some winters like the 18-19 and 19-20 featured the unfavorable MJO phases dominating for warmth and lack of snow. 15-16 to 17-18 had the unfavorable MJO for warmth but we got intervals of blocking for snowy outcomes. 
 

Papers on our only cold recent winters:

Winter 2009/2010 temperatures and a record‐breaking North Atlantic Oscillation index

https://rmets.onlinelibrary.wiley.com/doi/10.1002/wea.660

The North American winter ‘dipole’ and extremes activity: a CMIP5 assessment

https://rmets.onlinelibrary.wiley.com/doi/10.1002/asl2.565

 

 

 

I wonder if that record breaking -EPO in 2013-14 and 2014-15 is somehow connected towards what Anthony is alluding to in his tweet here. Because after 2014, SST's in the North Pacific skyrocketed and we haven't been able to shake it off since. Coincidentally, we haven't had a cold winter since then either.  I wonder if there is an underlying relationship tied back to that warm pool. The PDO also flipped to positive in early 2014 as a result. Although we maybe in a -PDO right now, it's far from the -PDO phase we had from 2007-2014. The strong El Nino in 2015-16 may have further enhanced that warm pool and the lack of any strong La Nina configuration since 2010-2011 has prevented SST's in the Pacific from properly cooling off. 

Just my 2 cents. 

 

[MJO812]

CMC tries to get a storm going along the front just like the Euro did. It also shows another storm at 240. Active run.

[Eduardo]

9 hours ago, bluewave said:

Without some kind of record -EPO or -NAO blocking, we can’t get cold winters anymore. 09-10, 10-11, 13-14, and 14-15 were our only 4 cold winters out of the last 11 years. 09-10 to 10-11 was the strongest -NAO of 187 years that I posted earlier. 13-14 and 14-15 featured the record -EPO patterns. The -EPO developed during the summer of 2013 and intensified during November and carried into the next spring. 14-15 saw a similar extreme -EPO combined with El Niño for the backloaded cold. But since the super El Niño in 15-16, all our winters have been warm with intervals when the unfavorable MJO phases ran the table. Some winters like the 18-19 and 19-20 featured the unfavorable MJO phases dominating for warmth and lack of snow. 15-16 to 17-18 had the unfavorable MJO for warmth but we got intervals of blocking for snowy outcomes. 
 

Papers on our only cold recent winters:

Winter 2009/2010 temperatures and a record‐breaking North Atlantic Oscillation index

https://rmets.onlinelibrary.wiley.com/doi/10.1002/wea.660

The North American winter ‘dipole’ and extremes activity: a CMIP5 assessment

https://rmets.onlinelibrary.wiley.com/doi/10.1002/asl2.565

 

 

 

I took special care not to take those winters for granted.  I remember somebody posting a map at the time, which showed that the only below-normal anomalies were parked over us.  At some point, that had to give.

Over the next few decades, we'll get some great blocky winters.  But given the warming base state, you have to think that they'll be fewer and further between the mehh's and ratters.  Before anything else, we need to do something about that WPAC warm pool that's stalling the MJO in the unfavorable phases.  What's it going to take though?  Another extreme ENSO event?

[NorthShoreWx]

13 hours ago, MJO812 said:

We were on pace to break the 1996 record if the blocking didn't fall apart .

 

 

We were, but it was over after groundhog day.

60" of snow in a month had a nice look to it:

[CIK62]

The next 8 days are averaging 42degs.(36/47).         Making it 37degs., or about -1.0.

EURO has a Trace of snow on the 10th.     Other models are zippo all the way.

32*(64%RH) here at 6am.       36* by 10am.    38* by Noon..       42* by 3pm.       37* by 8pm.

[the_other_guy]

28F here. A snow lover in Virginia is happy this morning

[STORMANLI]

Frosty 25°

South Commack

[donsutherland1]

Morning thoughts...

At 7:45 AM, Richmond reported a temperature of 32 degrees with light snow. South and east of Richmond, moderate snow was falling. This system will pass too far offshore to affect the New York City and Philadelphia areas.

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

New York City (Central Park): 39°

Newark: 42°

Philadelphia: 42°

Cool temperatures should persist through the middle of the week.

[bluewave]

Following several says of slightly cooler than average temperatures, we will rebound back to 50s. Notice how the day 10 guidance was biased too cold again. So a continuation of the ridge over the area verifying stronger than forecast. 

KNYC   GFSX MOS GUIDANCE  12/07/2020  0000 UTC                       
 FHR  24| 36  48| 60  72| 84  96|108 120|132 144|156 168|180 192      
 MON  07| TUE 08| WED 09| THU 10| FRI 11| SAT 12| SUN 13| MON 14 CLIMO
 X/N  41| 30  41| 33  45| 38  49| 39  49| 44  56| 49  54| 38  42 31 44

 

New run

Old run

 

[Cfa]

Low of 27 here. Currently 30.

[North and West]

7 hours ago, NorthShoreWx said:

We were, but it was over after groundhog day.

60" of snow in a month had a nice look to it:

Pretty, but I'm thinking of the flood potential and wet basement looking at that. 

[SnoSki14]

I think if late Dec through late Jan can't give us anything then we'll probably challenge the record low snowfall years. 

However a crazy squall (possible given the high winter lapse rates we've seen lately) could easily drop a quick inch. 

[Brian5671]

28 minutes ago, SnoSki14 said:

I think if late Dec through late Jan can't give us anything then we'll probably challenge the record low snowfall years. 

However a crazy squall (possible given the high winter lapse rates we've seen lately) could easily drop a quick inch. 

yeah it's tough to get completely shut out.  A squall, a well timed snow shower etc.  Even in the worst winters we tend to get one plowable event.  

[Brian5671]

1 hour ago, North and West said:

Pretty, but I'm thinking of the flood potential and wet basement looking at that. 

lots of ice dam damage and collapsed roof damage that winter...

[wdrag]

Warmer than normal DEC here... i understand...  Still, something not fitting all the negatives on snow.  I could be wrong but this not last winter.  Seems to me modeling is hanging on to weak blocking in the N Atlantic for many days, and I see a ridge in AK for awhile (7 more days) and an undercutting Pac Jet.  This may provide for more opportunities beyond the 16th?  I see the MJO indicies are trending weaker with time which may be a climo bias?   I know the modeled MJO phase is not favorable for us, but I am interested in this pattern...  I just dont see cold air ripping off to the east in southern Canada as easily in the GEFS dailies through D16 (laying in wait for something in the southern stream?).  Again a GEFS blocking bias?  And yes, it's nice to have cold air in place PRIOR to a precip event. 

Critical science is needed here to void my snow interest beyond the 16th.  Have at it. 

fwiw...i checked CP first measurable snow date in xmacis... looks like Dec 7 (today) over the entire CP climate history.  Monitoring Wednesday's 12z/7 3K  NAM forenoon snow shower risk (probably melt on contact?, but of minor interest). Lapse rates don't look all that interesting... sort of surprised by the modeling of snow showers down to NYC at ~54 hrs. 

[MJO812]

47 minutes ago, SnoSki14 said:

I think if late Dec through late Jan can't give us anything then we'll probably challenge the record low snowfall years. 

However a crazy squall (possible given the high winter lapse rates we've seen lately) could easily drop a quick inch. 

Remember the squall we had last year in mid December? That was crazy.

[wdrag]

8 minutes ago, MJO812 said:

Remember the squall we had last year in mid December? That was crazy.

Yes but lapse rates were MUCH MUCH steeper and as i recall there was a decent surface trough.