January 2018 Discussions & Observations Thread

[Rtd208]

January 2018 could potentially start out stormy, discuss here.

[donsutherland1]

This morning’s preliminary teleconnection index values were -0.562 for the Arctic Oscillation (AO) and +0.291 for the PNA. This tendency is likely to predominate through the first week of January.  Overall, the AO has averaged -0.005 through the first 29 days of December and 59% of days have had negative values. In contrast, during December 2016, the AO had averaged +1.723 through the first 29 days of the month and 83% of the days had positive AO values. The end result is that December has had a predominant AO neutral /AO- and PNA+ pattern with the month extremely likely to finish colder than normal in much of the Middle Atlantic and New England areas.

January is likely to open with severe cold. Further, despite the major change on the 0z ECMWF concerning a possible storm for the middle of the first week of January from the preceding 12z run, the pattern is one that favors more frequent measurable snow events than the climatological probability.

The latest run of the EPS shows the recent EPO- ridge rebuilding into the polar region toward the end of its range. As a result, the AO, should it go positive (and the EPS is less aggressive on a positive AO than it had been a few days ago), should return to negative values. The GEFS are in good agreement, with most members showing a generally negative AO through January 10.

As a result, the stage has been set for the first colder than normal December and January pair since winter 2010-11. Running sensitivity analysis against the most recent model output, January has approximately a 60% probability of winding up colder than normal. Both the Euro monthly and CFSv2 are in agreement about cold anomalies for the NYC metro area and larger northern Mid-Atlantic and southern New England areas for January.

Further, the frequent AO-/PNA+ combination suggests that January snowfall will likely be above to possibly much above normal.  Snowfall amounts from January 1994, 2004, 2014, and 2015 are likely within the realm of possibility. January snowfall amounts for those cases were:

1994: 12.0”
2004: 17.3”
2014: 19.7”
2015: 16.9”

So, very broadly speaking, monthly snowfall in the 10”-15” range seems likely. There would be upward potential, as some January cases with frequent AO-/PNA+ combinations have experienced major storms that brought a foot or more of snow to the region.

In any case, December started off what appears likely to be a very nice winter. January is looking to be filled with potential, especially as the month appears likely to be colder than normal.

[MJO812]

Nam has a high of 13 for NYC on Jan 1

[frd]

2 hours ago, donsutherland1 said:

 

 

This morning’s preliminary teleconnection index values were -0.562 for the Arctic Oscillation (AO) and +0.291 for the PNA. This tendency is likely to predominate through the first week of January.  Overall, the AO has averaged -0.005 through the first 29 days of December and 59% of days have had negative values. In contrast, during December 2016, the AO had averaged +1.723 through the first 29 days of the month and 83% of the days had positive AO values. The end result is that December has had a predominant AO neutral /AO- and PNA+ pattern with the month extremely likely to finish colder than normal in much of the Middle Atlantic and New England areas.

January is likely to open with severe cold. Further, despite the major change on the 0z ECMWF concerning a possible storm for the middle of the first week of January from the preceding 12z run, the pattern is one that favors more frequent measurable snow events than the climatological probability.

The latest run of the EPS shows the recent EPO- ridge rebuilding into the polar region toward the end of its range. As a result, the AO, should it go positive (and the EPS is less aggressive on a positive AO than it had been a few days ago), should return to negative values. The GEFS are in good agreement, with most members showing a generally negative AO through January 10.

As a result, the stage has been set for the first colder than normal December and January pair since winter 2010-11. Running sensitivity analysis against the most recent model output, January has approximately a 60% probability of winding up colder than normal. Both the Euro monthly and CFSv2 are in agreement about cold anomalies for the NYC metro area and larger northern Mid-Atlantic and southern New England areas for January.

Further, the frequent AO-/PNA+ combination suggests that January snowfall will likely be above to possibly much above normal.  Snowfall amounts from January 1994, 2004, 2014, and 2015 are likely within the realm of possibility. January snowfall amounts for those cases were:

1994: 12.0”
2004: 17.3”
2014: 19.7”
2015: 16.9”

So, very broadly speaking, monthly snowfall in the 10”-15” range seems likely. There would be upward potential, as some January cases with frequent AO-/PNA+ combinations have experienced major storms that brought a foot or more of snow to the region.

In any case, December started off what appears likely to be a very nice winter. January is looking to be filled with potential, especially as the month appears likely to be colder than normal.

Excellent write up Don. I agree with your vision on how things will play out. If I may ask, what weather mechanism do you think will possibly lead to higher than normal climo snowfall in Jan ? 

Would it be from clippers, Miller A, B, over-running / more active STJ, or a combination. I know you stated yesterday in Ninas where precip was low during Dec and prior , the following Feb. more than likely returned to normal .     

[EastonSN+]

GFS just showed the dreaded cold dry followed by warm and wet with a big cutter. Hopefully just a blip. 

[donsutherland1]

57 minutes ago, frd said:

Excellent write up Don. I agree with your vision on how things will play out. If I may ask, what weather mechanism do you think will possibly lead to higher than normal climo snowfall in Jan ? 

Would it be from clippers, Miller A, B, over-running / more active STJ, or a combination. I know you stated yesterday in Ninas where precip was low during Dec and prior , the following Feb. more than likely returned to normal .     

Since we're looking a month out, I can't identify specific types of storms or candidates for possible storms.

My premise is that an AO-/PNA+ pattern will be more common than is typically the case. Days with measurable snow are 12% more frequent than climatology and days with 4" or more snowfall are 16% more frequent than climatology in such a pattern (in La Niña January cases during the 1981-2010 base period). So, if I had to venture a guess, more frequent small events coupled with the higher than climatological probability of a significant or major event would lead to such an outcome. Having a larger number of cold days to work with should, in theory, allow for more precipitation events to bring snow than would otherwise be the case.

Back on November 29, I liked the pattern that appeared likely for December. I noted:

...These figures do not necessary suggest KU-type storms, but they reflect higher snowfall that results from increased opportunities for snow due to sufficient cold.

Despite the CFSv2's forecast of a warmer than normal December as of right now, my guess is that December will probably have a mean temperature around 35.0° +/- 0.5° (2°-3° below the monthly normal) with a fairly high probability of 6" or more monthly snowfall (vs. the monthly average of 4.8"). The potential for 8" or more exists, but that would assume that the strong blocking would last through most of December once it takes hold.

https://www.americanwx.com/bb/topic/50504-december-2017-discussions-observations-thread/?do=findComment&comment=4672960

Projected December Mean Temperature (assuming the MOS is reasonably accurate): 35.0°-35.3°.
Snowfall through 12/29: 7.0"

I like January's potential even more than I did December's. That the EPS has abandoned its earlier idea of a strongly positive AO after the first week of January and is now rebuilding an EPO- and AO- leads me to believe that things are on course for a good January. It suggests that a relaxation of the current pattern would likely be temporary (1-2 weeks in duration), not a fundamental shift toward a prolonged warm regime.

Obviously, if my assumption about the predominant pattern is incorrect, than my thinking for January would be incorrect. Right now, I'm thinking that the month will have a mean temperature: 30.5° +/- 0.5° right now) and above normal snowfall, probably 10"-15" (possibly more if a KU-type storm occurs at some point).

[MJO812]

Euro shows the very cold temps to continue through hour 240

Very cold and dry

[frd]

1 hour ago, donsutherland1 said:

Since we're looking a month out, I can't identify specific types of storms or candidates for possible storms.

My premise is that an AO-/PNA+ pattern will be more common than is typically the case. Days with measurable snow are 12% more frequent than climatology and days with 4" or more snowfall are 16% more frequent than climatology in such a pattern (in La Niña January cases during the 1981-2010 base period). So, if I had to venture a guess, more frequent small events coupled with the higher than climatological probability of a significant or major event would lead to such an outcome. Having a larger number of cold days to work with should, in theory, allow for more precipitation events to bring snow than would otherwise be the case.

Back on November 29, I liked the pattern that appeared likely for December. I noted:

...These figures do not necessary suggest KU-type storms, but they reflect higher snowfall that results from increased opportunities for snow due to sufficient cold.

Despite the CFSv2's forecast of a warmer than normal December as of right now, my guess is that December will probably have a mean temperature around 35.0° +/- 0.5° (2°-3° below the monthly normal) with a fairly high probability of 6" or more monthly snowfall (vs. the monthly average of 4.8"). The potential for 8" or more exists, but that would assume that the strong blocking would last through most of December once it takes hold.

https://www.americanwx.com/bb/topic/50504-december-2017-discussions-observations-thread/?do=findComment&comment=4672960

Projected December Mean Temperature (assuming the MOS is reasonably accurate): 35.0°-35.3°.
Snowfall through 12/29: 7.0"

I like January's potential even more than I did December's. That the EPS has abandoned its earlier idea of a strongly positive AO after the first week of January and is now rebuilding an EPO- and AO- leads me to believe that things are on course for a good January. It suggests that a relaxation of the current pattern would likely be temporary (1-2 weeks in duration), not a fundamental shift toward a prolonged warm regime.

Obviously, if my assumption about the predominant pattern is incorrect, than my thinking for January would be incorrect. Right now, I'm thinking that the month will have a mean temperature: 30.5° +/- 0.5° right now) and above normal snowfall, probably 10"-15" (possibly more if a KU-type storm occurs at some point).

Thanks Don, your track record brings a smile to my face. I wish you the best with your forecast.  

[MJO812]

Below freezing everyday on the Euro through hour 240.

[bluewave]

NYC is on track for a top 10 coldest Dec 26th to Jan 7th. The ice build up on local water ways by next weekend will be very impressive.

 

 

 

[Hailstorm]

10 hours ago, donsutherland1 said:

Since we're looking a month out, I can't identify specific types of storms or candidates for possible storms.

My premise is that an AO-/PNA+ pattern will be more common than is typically the case. Days with measurable snow are 12% more frequent than climatology and days with 4" or more snowfall are 16% more frequent than climatology in such a pattern (in La Niña January cases during the 1981-2010 base period). So, if I had to venture a guess, more frequent small events coupled with the higher than climatological probability of a significant or major event would lead to such an outcome. Having a larger number of cold days to work with should, in theory, allow for more precipitation events to bring snow than would otherwise be the case.

Back on November 29, I liked the pattern that appeared likely for December. I noted:

...These figures do not necessary suggest KU-type storms, but they reflect higher snowfall that results from increased opportunities for snow due to sufficient cold.

Despite the CFSv2's forecast of a warmer than normal December as of right now, my guess is that December will probably have a mean temperature around 35.0° +/- 0.5° (2°-3° below the monthly normal) with a fairly high probability of 6" or more monthly snowfall (vs. the monthly average of 4.8"). The potential for 8" or more exists, but that would assume that the strong blocking would last through most of December once it takes hold.

https://www.americanwx.com/bb/topic/50504-december-2017-discussions-observations-thread/?do=findComment&comment=4672960

Projected December Mean Temperature (assuming the MOS is reasonably accurate): 35.0°-35.3°.
Snowfall through 12/29: 7.0"

I like January's potential even more than I did December's. That the EPS has abandoned its earlier idea of a strongly positive AO after the first week of January and is now rebuilding an EPO- and AO- leads me to believe that things are on course for a good January. It suggests that a relaxation of the current pattern would likely be temporary (1-2 weeks in duration), not a fundamental shift toward a prolonged warm regime.

Obviously, if my assumption about the predominant pattern is incorrect, than my thinking for January would be incorrect. Right now, I'm thinking that the month will have a mean temperature: 30.5° +/- 0.5° right now) and above normal snowfall, probably 10"-15" (possibly more if a KU-type storm occurs at some point).

Very insightful post as usual, Don.

Just one question: After the brief relaxation, do you think that NYC has another chance of getting another 7+ day arctic shot as severe as the one we are currently in?

Also, I assume that you expect our current dry spell to end soon. Can you give us your rationale for your outlook in regards to the precipitation anomalies?

[Paragon]

16 hours ago, donsutherland1 said:

 

 

This morning’s preliminary teleconnection index values were -0.562 for the Arctic Oscillation (AO) and +0.291 for the PNA. This tendency is likely to predominate through the first week of January.  Overall, the AO has averaged -0.005 through the first 29 days of December and 59% of days have had negative values. In contrast, during December 2016, the AO had averaged +1.723 through the first 29 days of the month and 83% of the days had positive AO values. The end result is that December has had a predominant AO neutral /AO- and PNA+ pattern with the month extremely likely to finish colder than normal in much of the Middle Atlantic and New England areas.

January is likely to open with severe cold. Further, despite the major change on the 0z ECMWF concerning a possible storm for the middle of the first week of January from the preceding 12z run, the pattern is one that favors more frequent measurable snow events than the climatological probability.

The latest run of the EPS shows the recent EPO- ridge rebuilding into the polar region toward the end of its range. As a result, the AO, should it go positive (and the EPS is less aggressive on a positive AO than it had been a few days ago), should return to negative values. The GEFS are in good agreement, with most members showing a generally negative AO through January 10.

As a result, the stage has been set for the first colder than normal December and January pair since winter 2010-11. Running sensitivity analysis against the most recent model output, January has approximately a 60% probability of winding up colder than normal. Both the Euro monthly and CFSv2 are in agreement about cold anomalies for the NYC metro area and larger northern Mid-Atlantic and southern New England areas for January.

Further, the frequent AO-/PNA+ combination suggests that January snowfall will likely be above to possibly much above normal.  Snowfall amounts from January 1994, 2004, 2014, and 2015 are likely within the realm of possibility. January snowfall amounts for those cases were:

1994: 12.0”
2004: 17.3”
2014: 19.7”
2015: 16.9”

So, very broadly speaking, monthly snowfall in the 10”-15” range seems likely. There would be upward potential, as some January cases with frequent AO-/PNA+ combinations have experienced major storms that brought a foot or more of snow to the region.

In any case, December started off what appears likely to be a very nice winter. January is looking to be filled with potential, especially as the month appears likely to be colder than normal.

I'll be happy if these mild January forecasts bust, even if we don't get a lot of snow, it would actually be quite ironic if the Dec-Jan pair ends up colder than it was in 2010-11.

[Paragon]

10 hours ago, bluewave said:

NYC is on track for a top 10 coldest Dec 26th to Jan 7th. The ice build up on local water ways by next weekend will be very impressive.

 

 

 

At this rate, people will be able to walk across the Hudson and set up shops there again ;-)

[Paragon]

10 hours ago, bluewave said:

NYC is on track for a top 10 coldest Dec 26th to Jan 7th. The ice build up on local water ways by next weekend will be very impressive.

 

 

 

Why was 1917-18 so much darn colder than every other year lol?

[bluewave]

5 hours ago, Paragon said:

At this rate, people will be able to walk across the Hudson and set up shops there again ;-)

The Great South Bay began to freeze up on Friday. With another week of this to go, the ice on the local waterways will only expand.

 

 

[SnoSki14]

The ice growth should be really good with even colder temps expected later this weekend into early next week and probably the coldest weather of the season next fri-sat (-5 to 5). 

Jan 8 +/- 1 day will be our transition into a warmer pattern, but it'll probably be temporary. Winter patterns don't like to change drastically once they're set. 

[donsutherland1]

8 hours ago, Hailstorm said:

Very insightful post as usual, Don.

Just one question: After the brief relaxation, do you think that NYC has another chance of getting another 7+ day arctic shot as severe as the one we are currently in?

Also, I assume that you expect our current dry spell to end soon. Can you give us your rationale for your outlook in regards to the precipitation anomalies?

If I had to venture a guess, the Arctic outbreaks that will send temperatures into the single digits in coming days (New Year's Day and perhaps the end of the week) could be the most severe of the winter. I do think we'll get some additional Arctic outbreaks.

I'm cautiously optimistic about precipitation returning to normal levels later this month and February based on historic La Niña cases for which the September-December precipitation was 1 standard deviation or more below normal.

[PB COLTS NECK NJ]

57 minutes ago, SnoSki14 said:

The ice growth should be really good with even colder temps expected later this weekend into early next week and probably the coldest weather of the season next fri-sat (-5 to 5). 

Jan 8 +/- 1 day will be our transition into a warmer pattern, but it'll probably be temporary. Winter patterns don't like to change drastically once they're set. 

Too much ridging through Alaska and the EPO will remain NEG.

We are still N to BN day 10 - 15 , the flip of it occurs has been delayed 

Certainly these anomalies will release by day 10 , but the idea of warmer will just be relative to these extremes 

[bwt3650]

1 hour ago, SnoSki14 said:

The ice growth should be really good with even colder temps expected later this weekend into early next week and probably the coldest weather of the season next fri-sat (-5 to 5). 

Jan 8 +/- 1 day will be our transition into a warmer pattern, but it'll probably be temporary. Winter patterns don't like to change drastically once they're set. 

With that EPO staying negative, and the possibility of some decent snow cover, I think the "warm up" is further out than Jan 8th...Keep in mind that when we do relax, which we will, it will be during the historical peak of winter cold so while we may go to normal or slightly above, plenty of snow could occur in those temps when warmer meets colder. 

[gravitylover]

24 minutes ago, PB COLTS NECK NJ said:

 

Certainly these anomalies will release by day 10 , but the idea of warmer will just be relative to these extremes 

If warmer gets us closer to near normal I'll be ok with it. We're going through too much oil to keep the house warm   Actually PB, after seeing a couple of composites showing North America being the only cold spot on the planet the last week or so what are your thoughts as to how we maintain that look for an extended period? It seems to me that without a neg NAO it will be pretty tough to hold the cold in and it ought to start escaping and I don't see much for reload opportunities once it's gone. Are we just generating our own cold based on cold and extensive snowcover?

[PB COLTS NECK NJ]

36 minutes ago, gravitylover said:

If warmer gets us closer to near normal I'll be ok with it. We're going through too much oil to keep the house warm   Actually PB, after seeing a couple of composites showing North America being the only cold spot on the planet the last week or so what are your thoughts as to how we maintain that look for an extended period? It seems to me that without a neg NAO it will be pretty tough to hold the cold in and it ought to start escaping and I don't see much for reload opportunities once it's gone. Are we just generating our own cold based on cold and extensive snowcover?

 

The GFS ensembles, the EPS day 10 thru 15 and even new week 3 and 4 weeklies flipped back to mean ridging in Alaska at 500 mb

All of the guidance continue to produce a push poleward in the EPAC so the mean flow of the Asia jet is still being bent over the top and the BN flow on the backside of the ridging all the way through the middle of the month and possibly beyond continues.

The ridging that is showing up on the EC at 18k will get muted by Arctic HP that still connects through W Canada 

 

If one went out to day 15 , you see a trough in Europe , one in Asia and a continuation of a -EPO , that teleconnects to one in the east so I am leary of the ridge 

Remember that's not a SE ridge , so there is no torch , quite the contrary

The slight difference this time is the coldest air will drain into the nations midsection and then have some resistance coming to the EC 

But that just means you go from a 10 day period of 15 below to a 10 day period of N

And when N at 38/29 N is still cold. That might be your warmup , we will have to see but that's definitely an option 

With the nation and Canada cold if you break the STJ through with HP to your north in mid January, you will be in good shape

 

[EastonSN+]

9 minutes ago, bluewave said:

I agree with the bolded. The lingering -EPO and the gradual trough shift west will focus the coldest departures after the first week of January from the Rockies to the Apps. The trough over the NE will begin to slowly pull west after the first week of January. Beyond the 2nd week of January, we'll have to see how far the MJO progresses. 

Wouldn't the trough shifting slightly west of where it is now create better opportunity for storms and less suppression

[BxEngine]

8 minutes ago, EastonSN+ said:

Wouldn't the trough shifting slightly west of where it is now create better opportunity for storms and less suppression

Sometimes. But you also run the risk of cutters. 

[gravitylover]

I have a feeling that the trough may not shift west as guidance is showing currently. Picture this - I don't think many of the models are taking into account water temps cooling as quickly as they are and moving the gulf stream further offshore so there may not be as sharp a turn in the CP jet allowing the cold air drain to continue rather than maintaining a trough that may migrate westward. This would continue a suppressive environment and keep chances high for clippers rather than significant coastal storm development. We used to have winters where we'd have extended cool periods and a series of clippers moving through that each deposited a few inches of snow at a time rather than transient warm and cold periods with blockbuster storms. I'm envisioning a season more similar to that than the regime we've been in for the better part of the last 17 years.

Whether my reasoning (water temps and gulf stream moving further offshore) as to how this scenario is achieved is right or not I don't know but it has more of an old time winter feel at this point.

[MJO812]

Noaa has a normal January for our area

 

[the_other_guy]

Flew into JFK tonight. Interior waterways (bays inside barrier islands) in Jersey and south shore of LI totally frozen. Really gleamed with the snow.

One exception was the Great South Bay closest to the Freeport area...but that will freeze shortly.

That hasnt happened in 3 years or so. I imagine Flushing Bay around LGA will start to freeze over the weekend but I havent been flying in there and can not verify.

 

[Morris]

High of 8 in the city on Friday on the GFS. When was our last single-digits max?

[donsutherland1]

5 minutes ago, Morris said:

High of 8 in the city on Friday on the GFS. When was our last single-digits max?

January 21, 1985 when the high temperature was 9.

[tmagan]

4 minutes ago, donsutherland1 said:

January 21, 1985 when the high temperature was 9.

When was the last time Central Park didn't get to five degrees?

[JerseyWx]

15 minutes ago, Morris said:

High of 8 in the city on Friday on the GFS. When was our last single-digits max?

Interesting.  I think for me it was the Winter of 13-14.  I only hit 7° if I remember correctly.