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December 2020 General Discussions & Observations Thread

bluewave

By bluewave,
in New York City Metro

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Rjay
Rjay

Took this at a red light on the way to work this morning    

forkyfork
forkyfork

wow i had no idea you wanted it to snow more

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bluewave

bluewave

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4 hours ago, Allsnow said:

This is definitely not last winter. Snow mean on the eps looks amazing. @bluewave look at this blocking!!!

 

We need the block to press hard enough so the low tracks out near the benchmark. That would put the coast in a great spot for some of the higher accumulation potential. But a track a little too close to the area would focus the higher accumulations near or north of I-80. So plenty for the models to work out over the next week. My guess is that the snowfall accumulation from this storm in NYC could determine  the snowfall outcome for the entire season. La Niña winter snowfall has been very sensitive in NYC to December snowfall. The 3 inch number has been pretty important. Over or under that amount in December has predicted how the snowfall would go for the rest of the season. It may be that a strong enough block in December for a significant 3.0”+ snowfall signals further winter or early spring blocking. 
 

La Niña years highlighted 

Monthly Total Snowfall for NY CITY CENTRAL PARK, NY
Click column heading to sort ascending, click again to sort descending.
Year
Oct
Nov
Dec
Jan
Feb
Mar
Apr
Season
2019-2020 0.0 0.0 2.5 2.3 T T T 4.8
2018-2019 0.0 6.4 T 1.1 2.6 10.4 0.0 20.5
2017-2018 0.0 T 7.7 11.2 4.9 11.6 5.5 40.9
2016-2017 0.0 T 3.2 7.9 9.4 9.7 0.0 30.2
2015-2016 0.0 0.0 T 27.9 4.0 0.9 T 32.8
2014-2015 0.0 0.2 1.0 16.9 13.6 18.6 0.0 50.3
2013-2014 0.0 T 8.6 19.7 29.0 0.1 T 57.4
2012-2013 0.0 4.7 0.4 1.5 12.2 7.3 0.0 26.1
2011-2012 2.9 0.0 0.0 4.3 0.2 0.0 0.0 7.4
2010-2011 0.0 T 20.1 36.0 4.8 1.0 T 61.9
2009-2010 0.0 0.0 12.4 2.1 36.9 T 0.0 51.4
2008-2009 0.0 T 6.0 9.0 4.3 8.3 T 27.6
2007-2008 0.0 T 2.9 T 9.0 T 0.0 11.9
2006-2007 0.0 0.0 0.0 2.6 3.8 6.0 T 12.4
2005-2006 0.0 T 9.7 2.0 26.9 1.3 0.1 40.0
2004-2005 0.0 T 3.0 15.3 15.8 6.9 0.0 41.0
2003-2004 0.0 0.0 19.8 17.3 0.7 4.8 0.0 42.6
2002-2003 T T 11.0 4.7 26.1 3.5 4.0 49.3
2001-2002 0.0 0.0 T 3.5 T T T 3.5
2000-2001 T 0.0 13.4 8.3 9.5 3.8 0.0 35.0
1999-2000 0.0 0.0 T 9.5 5.2 0.4 1.2 16.3
1998-1999 0.0 0.0 2.0 4.5 1.7 4.5 0.0 12.7
1997-1998 0.0 T T 0.5 0.0 5.0 0.0 5.5
1996-1997 0.0 0.1 T 4.4 3.8 1.7 T 10.0
1995-1996 0.0 2.9 11.5 26.1 21.2 13.2 0.7 75.6
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Allsnow

Allsnow

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Posted
5 minutes ago, bluewave said:

We need the block to press hard enough so the low tracks out near the benchmark. That would put the coast in a great spot for some of the higher accumulation potential. But a track a little too close to the area would focus the higher accumulations near or north of I-80. So plenty for the models to work out over the next week. My guess is that the snowfall accumulation from this storm in NYC could determine  the snowfall outcome for the entire season. La Niña winter snowfall has been very sensitive in NYC to December snowfall. The 3 inch number has been pretty important. Over or under that amount in December has predicted how the snowfall would go for the rest of the season. It may be that a strong enough block in December for a significant 3.0”+ snowfall signals further winter or early spring blocking. 
 

La Niña years highlighted 

Monthly Total Snowfall for NY CITY CENTRAL PARK, NY
Click column heading to sort ascending, click again to sort descending.
Year
Oct
Nov
Dec
Jan
Feb
Mar
Apr
Season
2019-2020 0.0 0.0 2.5 2.3 T T T 4.8
2018-2019 0.0 6.4 T 1.1 2.6 10.4 0.0 20.5
2017-2018 0.0 T 7.7 11.2 4.9 11.6 5.5 40.9
2016-2017 0.0 T 3.2 7.9 9.4 9.7 0.0 30.2
2015-2016 0.0 0.0 T 27.9 4.0 0.9 T 32.8
2014-2015 0.0 0.2 1.0 16.9 13.6 18.6 0.0 50.3
2013-2014 0.0 T 8.6 19.7 29.0 0.1 T 57.4
2012-2013 0.0 4.7 0.4 1.5 12.2 7.3 0.0 26.1
2011-2012 2.9 0.0 0.0 4.3 0.2 0.0 0.0 7.4
2010-2011 0.0 T 20.1 36.0 4.8 1.0 T 61.9
2009-2010 0.0 0.0 12.4 2.1 36.9 T 0.0 51.4
2008-2009 0.0 T 6.0 9.0 4.3 8.3 T 27.6
2007-2008 0.0 T 2.9 T 9.0 T 0.0 11.9
2006-2007 0.0 0.0 0.0 2.6 3.8 6.0 T 12.4
2005-2006 0.0 T 9.7 2.0 26.9 1.3 0.1 40.0
2004-2005 0.0 T 3.0 15.3 15.8 6.9 0.0 41.0
2003-2004 0.0 0.0 19.8 17.3 0.7 4.8 0.0 42.6
2002-2003 T T 11.0 4.7 26.1 3.5 4.0 49.3
2001-2002 0.0 0.0 T 3.5 T T T 3.5
2000-2001 T 0.0 13.4 8.3 9.5 3.8 0.0 35.0
1999-2000 0.0 0.0 T 9.5 5.2 0.4 1.2 16.3
1998-1999 0.0 0.0 2.0 4.5 1.7 4.5 0.0 12.7
1997-1998 0.0 T T 0.5 0.0 5.0 0.0 5.5
1996-1997 0.0 0.1 T 4.4 3.8 1.7 T 10.0
1995-1996 0.0 2.9 11.5 26.1 21.2 13.2 0.7 75.6

Awesome post! Thanks. 3 is definitely the magic number

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bluewave

bluewave

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22 minutes ago, Allsnow said:

It’s like something out of 10/11 playbook with how quickly the blocking came 

This almost reminds me of how quickly the Kara Barents block built back across the North Pole to Greenland at the end of December 2015. We had an intense PV that December with the historic warmth and near record +AO. It suddenly reversed at the end of the month. We saw a near record +AO and PV this November with the record warmth. There have been some recent studies linking that KB block to the low sea ice. At the beginning of the month, it was one of the strongest +PNA rises that we ever saw during a moderate La Niña December. So we are  getting several overlapping influences all at the same time.

 


 

 
A stratospheric pathway linking a colder Siberia to Barents-Kara Sea sea ice loss
  1. View ORCID ProfilePengfei Zhang1,2,*, 
  2. View ORCID ProfileYutian Wu2, 
  3. Isla R. Simpson3, 
  4. Karen L. Smith4, 
  5. Xiangdong Zhang5, 
  6. View ORCID ProfileBithi De1 and 
  7. Patrick Callaghan3

 See all authors and affiliations

Science Advances  25 Jul 2018:
Vol. 4, no. 7, eaat6025
DOI: 10.1126/sciadv.aat6025 

Abstract

Previous studies have extensively investigated the impact of Arctic sea ice anomalies on the midlatitude circulation and associated surface climate in winter. However, there is an ongoing scientific debate regarding whether and how sea ice retreat results in the observed cold anomaly over the adjacent continents. We present a robust “cold Siberia” pattern in the winter following sea ice loss over the Barents-Kara seas in late autumn in an advanced atmospheric general circulation model, with a well-resolved stratosphere. Additional targeted experiments reveal that the stratospheric response to sea ice forcing is crucial in the development of cold conditions over Siberia, indicating the dominant role of the stratospheric pathway compared with the direct response within the troposphere. In particular, the downward influence of the stratospheric circulation anomaly significantly intensifies the ridge near the Ural Mountains and the trough over East Asia. The persistently intensified ridge and trough favor more frequent cold air outbreaks and colder winters over Siberia. This finding has important implications for improving seasonal climate prediction of midlatitude cold events. The results also suggest that the model performance in representing the stratosphere-troposphere coupling could be an important source of the discrepancy between recent studies.

 

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bluewave

bluewave

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1 hour ago, qg_omega said:

The lack of sea ice and associated -AO had a ton of momentum a few years ago, but then the sea ice remained low and the blocking went away.  It doesn't mean the research is bad, could be other influences overwhelmed the pattern.

It could mean climate model studies that show a more -NAO and others a +NAO could both be correct. A corals study that came out in 2009 indicated that the NAO has exhibited wider swings as the climate has warmed. The last 10 years since this study came out featured record -NAO/-AO and +NAO/+AO intervals. We have never seen a decade with such wild swings from record highs to record lows. 

https://www.sciencedaily.com/releases/2009/01/090113101200.htm

Swings In North Atlantic Oscillation Variability Linked To Climate Warming

Date:
January 14, 2009
Source:
Woods Hole Oceanographic Institution
Summary:
Using a 218-year-long temperature record from a Bermuda brain coral, researchers have created the first marine-based reconstruction showing the long-term behavior of one of the most important drivers of climate fluctuations in the North Atlantic.
 

Using a 218-year-long temperature record from a Bermuda brain coral, researchers at the Woods Hole Oceanographic Institution (WHOI) have created the first marine-based reconstruction showing the long-term behavior of one of the most important drivers of climate fluctuations in the North Atlantic.

The North Atlantic Oscillation (NAO) is a wide-ranging pressure seesaw that drives winter climate over much of North America, Europe and North Africa. Past reconstructions of the NAO have relied mainly on terrestrial, or land-based records, such as tree ring chronologies combined with ice cores and historical climate data. Those records do not fully capture oceanic processes linked to NAO variability, and short instrumental records from relatively few locations limit the understanding of ocean–atmosphere dynamics with regard to NAO behavior.

“By analyzing the coral, we were able to look at changes in the ocean relative to changes on land,” said Nathalie Goodkin, lead author of the study published in the December issue of the journal Nature Geoscience. “Because they are slow growing and have long life-spans, corals can provide high resolution records that are well dated and centuries long.”

As they grow, corals accrete seasonal and annual growth layers, similar to tree rings.  The proportions of trace elements versus the major element (calcium) found in the layers of the skeleton largely depend on the temperature of the seawater in which it was formed.  By analyzing the strontium to calcium ratio in the Bermuda brain coral, Goodkin and colleagues — WHOI scientists Konrad Hughen, Scott Doney and William Curry — were able to reconstruct monthly changes in ocean temperatures and evaluate variability of the NAO during both cold and warm periods from the Little Ice Age (1800–1850) to modern day. 

The research team found the variability of the NAO decade-to-decade (multi-decadal scale) has been larger, swinging more wildly, during the late twentieth century than in the early 1800s, suggesting that variability is linked to the mean temperature of the Northern Hemisphere. This confirms variability previously reported in past terrestrial reconstructions.

“When the Industrial Revolution begins and atmospheric temperature becomes warmer, the NAO takes on a much stronger pattern in longer-term behavior,” said Goodkin. “That was suspected before in the instrumental records, but this is the first time it has been documented in records from both the ocean and the atmosphere.”

The North Atlantic Oscillation is described by the NAO index, calculated as a weighted difference between the polar low and the subtropical high during the winter season. (For more information about the NAO index, see animation.) In a positive phase, both the low-pressure zone over Iceland and high pressure over the Azores are intensified, resulting in changes in the strength, incidence, and pathway of winter storms crossing the Atlantic. In a negative phase, a weak subtropical high and a weak Icelandic low results in fewer and weaker winter storms crossing on a more west-east pathway.

The NAO index varies from year to year, but also exhibits a tendency to remain in one phase for intervals lasting more than a decade. An unusually long period of positive phase between 1970-2000 led to the suggestion that global warming was affecting the behavior of the NAO.

“Anthropogenic (human-related) warming does not appear to be altering whether the NAO is in a positive or negative phase at multi-decadal time scales,” said WHOI paleoclimatologist Konrad Hughen. “It does seem to be increasing variability. Clearly, this has implications for the future.”

“As temperatures get warmer, there’s potential for more violent swings of the NAO — the phases becoming even more positive and even more negative,” Hughen added. “If the NAO locks more into these patterns, intense storms will become more intense and droughts will become more severe.”

The climatic influence of the NAO extends from the eastern United States to Western Europe, impacting human activities such as shipping, oil drilling, fisheries, hydroelectric power generation and coastal management. Improving the ability to predict shifts in the phase and intensity of the NAO is a prerequisite to mitigating the economic impacts of future climate change.

While additional modeling and palaeoclimatic studies are needed, a broad distribution of marine records could advance our knowledge of NAO variability and serve to improve future projections, said Goodkin, now an assistant professor in the Department of Earth Sciences at the University of Hong Kong.

A WHOI Ocean and Climate Change Institute Fellowship, and grants from the National Science Foundation and Woods Hole Oceanographic Institution supported this work.

 

 

 

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weathermedic

weathermedic

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Posted

Freezing fog a possibility in rural areas tonight. From OKX AFD: 

Of particular concern is the potential for freezing fog tonight.
As the high shifts offshore, low level moisture will increase,
especially for western areas. With temperature dipping below
freezing, freezing fog is possible (more likely for the outlying
areas of non-metro northeast New Jersey and the Lower Hudson
Valley). However, there is still a fair amount of uncertainty
with the development of the fog, therefore, only went with
patchy freezing fog.
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donsutherland1

donsutherland1

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With milder air moving into the region overnight, temperatures rose into the upper 40s and lower 50s today. Tomorrow will be even milder. The remainder of the week will feature above normal to perhaps some much above normal temperatures.

Colder air could return to the region after next weekend. The recent guidance has suggested a more impressive cold shot than had previously been modeled. The return of the colder air could coincide with some storminess. The potential exists for at least part of the region to experience one or two snow events.

A sustained warmer pattern could 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 latest CFSv2 weekly guidance favors much warmer than normal readings.

Historic experience following exceptionally warm November cases suggests that a warmer than normal December remains the base case. 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 +10.79.

Today, the preliminary Arctic Oscillation (AO) figure was -1.126.

On December 9 the MJO was in Phase 5 at an amplitude of 1.079 (RMM). The December 8-adjusted amplitude was 0.906.

Based on the latest guidance, no significant stratospheric warming event is likely through the third week of December.

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 69% probability that New York City will have a warmer than normal December. December will likely finish with a mean temperature near 39.8°.

 

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CIK62

CIK62

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Posted

The next 8 days are averaging 39degs.(34/44).        Making it 34degs , or -3.0.

Month to date is 40.3[-0.5].          Should be 37.5[-1.6] by the 19th.

Snowstorm outlook on the 17th:     EURO 9", GFS 8", CMC 5".       Storm looks like it is running to catch the bus.    Fast mover.

42*(70%RH) here at 6am, hazy blue.      50* by Noon.       51* at 1pm.        55* at 3pm.        Held at 54* till 53* at 7pm.

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donsutherland1

donsutherland1

Posted
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Morning thoughts...

Today will be mostly sunny and noticeably warmer than yesterday. Temperatures will likely top out in the lower and middle 50s in most of the region. Likely high temperatures around the region include:

New York City (Central Park): 55°

Newark: 55°

Philadelphia: 56°

Milder air will prevail through the remainder of the week. Next week could see the return of colder air. There is also strong ensemble support for at least one accumulating snow event.

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bluewave

bluewave

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Starting the day with a heavy frost here in SW Suffolk. But there was a very wide temperature spread across Long Island this morning. The breeze off the ocean kept the South Shore beaches 10° to 20° warmer than areas of the island that were able to radiate.

  

Long Island New York

CITY           SKY/WX    TMP DP  RH WIND       PRES   REMARKS
Jones Beach      N/A     45 N/A N/A SW7G13      N/A
Wantagh          N/A     32  30  93 NW3         N/A
Hempstead      NOT AVBL
Matinecock Pt    N/A     39 N/A N/A SW2         N/A
Farmingdale    PTCLDY    30  27  88 CALM      30.22R
MacArthur/ISP  PTCLDY    27  26  96 CALM      30.22R
Shirley        PTCLDY    28  23  81 CALM      30.23R
Mt Sinai Harb    N/A     36 N/A N/A S3          N/A
Westhampton    PTCLDY    20  17  88 NW3       30.24R
East Hampton   FAIR      24  23  94 CALM      30.22F
Southold         N/A     28  28 100 SW1         N/A
Montauk          N/A     36  34  92 CALM      30.24S
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Eduardo

Eduardo

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Posted
22 minutes ago, bluewave said:

The EPS and GEPS are milder than the GEFS. They match our warm up around the solstice pattern. It will be interesting to see if NYC can make it 10 years in a row reaching 55° or warmer.

 

Time Series Summary for NY CITY CENTRAL PARK, NY
Click column heading to sort ascending, click again to sort descending.
Ending Date
Highest Max Temperature Dec 18 to Dec 25
Missing Count
2019-12-25 57 0
2018-12-25 61 0
2017-12-25 55 0
2016-12-25 58 0
2015-12-25 72 0
2014-12-25 62 0
2013-12-25 71 0
2012-12-25 56 0
2011-12-25 62 0

Great stuff, as always Chris.  IIRC, some of those years managed to sneak in a colder Xmas.  2013 comes to mind, for example.  Was my first Xmas back up here after three years of law school in DC and it felt nice to experience actual cold again.

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LibertyBell

LibertyBell

Posted
Posted
1 hour ago, bluewave said:

Starting the day with a heavy frost here in SW Suffolk. But there was a very wide temperature spread across Long Island this morning. The breeze off the ocean kept the South Shore beaches 10° to 20° warmer than areas of the island that were able to radiate.

  


Long Island New York

CITY           SKY/WX    TMP DP  RH WIND       PRES   REMARKS
Jones Beach      N/A     45 N/A N/A SW7G13      N/A
Wantagh          N/A     32  30  93 NW3         N/A
Hempstead      NOT AVBL
Matinecock Pt    N/A     39 N/A N/A SW2         N/A
Farmingdale    PTCLDY    30  27  88 CALM      30.22R
MacArthur/ISP  PTCLDY    27  26  96 CALM      30.22R
Shirley        PTCLDY    28  23  81 CALM      30.23R
Mt Sinai Harb    N/A     36 N/A N/A S3          N/A
Westhampton    PTCLDY    20  17  88 NW3       30.24R
East Hampton   FAIR      24  23  94 CALM      30.22F
Southold         N/A     28  28 100 SW1         N/A
Montauk          N/A     36  34  92 CALM      30.24S

what was the low at JFK compared to FOK, Chris?

 

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CPcantmeasuresnow

CPcantmeasuresnow

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Posted
1 hour ago, bluewave said:

The EPS and GEPS are milder than the GEFS. They match our warm up around the solstice pattern. It will be interesting to see if NYC can make it 10 years in a row reaching 55° or warmer.

 

Time Series Summary for NY CITY CENTRAL PARK, NY
Click column heading to sort ascending, click again to sort descending.
Ending Date
Highest Max Temperature Dec 18 to Dec 25
Missing Count
2019-12-25 57 0
2018-12-25 61 0
2017-12-25 55 0
2016-12-25 58 0
2015-12-25 72 0
2014-12-25 62 0
2013-12-25 71 0
2012-12-25 56 0
2011-12-25 62 0

Oh God I hope not

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