WInter Minimum Temperatures

[nzucker]

As blue wave pointed out, there have been a lot of intense arctic outbreaks that gave NYC a glancing blow. The core of the cold air in both the 1985 and 1977 outbreaks was to the west and southwest of NYC. In 2004 it was to the NE of NYC. Both BOS and NYC were in a sub zero drought going back to 1994. Boston broke it's drought in 2004 with a -7, NYC did not. The 850 maps showed core 850s around -30c passing just north of NYC and moving towards the northeast. The glancing blow of the coldest core bypassed NYC around midnight or a little thereafter. It was directly over Boston around sunrise...perfect timing.

I'm not arguing with you that the heat island isn't real or that the NYC climate isn't 'effed. I just believe that if the synoptic conditions of one of the historical outbreaks that produced very low temperatures in NYC were reproduced, the modern day result would be similar. I can't say it wouldn't be off by a degree or two, but it would be very similar and would for a short time blow the UHI effect out to sea..

Which brings me back to the reason I made the original post...NYC has not had good hit from the core of an anomalously cold artic airmas in a very long time. The reason I made the post in the first place was because I have been reading a lot of hyperbole about "arctic" the temps have been. I know thats not you because I know you understand that 18 as the low temp for the winter is pretty cheesy for "arctic" conditions, even with the Manhattan heat island. The January 2004 and 2009 arctic pushes didn't deliver the goods because they just plain missed the mark.

OK, I think we are coming closer to agreement now...sorry this argument got so heated as you're a very knowledgeable poster and I enjoy reading what you write. I agree this winter has been more remarkable for persistent cold and chilly high temperatures rather than brutally cold nights. 850s have consistently been in the -10C range, which is well below average but certainly not arctic conditions. I did think the mid-December cold snap was pretty close to an arctic outbreak, given that 850s fell to -19C at a time when the average is probably around -3C. We only had a high of 22F here in the suburbs, which is about 20F below the average temperature for December 14th. But yes, real arctic cold has been missing this winter, although I think next weekend is going to be a good opportunity to see some colder readings.

If NYC was close to -30C in January 2004, you'd definitely expect a reading below 0F. When I was at Middlebury, VT in January 2009 for college, we had -30C 850s and the low temperature was -20F. That just shows how the airmasses reaching NYC are still cold, but they're not achieving the minima you'd expect with such brutal airmasses. I know many of the suburban towns did achieve a low of 0F in January 2009, so NYC was surprisingly mild with a low of 6F.

And yes, I do think that we could still see the UHI effect muted if the synoptic set-up were perfect. The problem is that you need strong CAA from the north, which is uncommon. A 300 wind isn't going to cut it because then NYC downslopes and can never achieve true cold. It's rare to have CAA on due N winds, and NYC doesn't have consistent snow cover during the winter either. So many conditions have to be met to see a 0F reading at Central Park compared to other places, and that's why it's going to be difficult. Even with a February 1934 synoptic set-up, I doubt the Park could get below -5F these days. There are just so many more steel buildings, concrete roadways, and cars....not easy to radiate when your surroundings are like that.

[sferic]

Cold air advection....the idea of having a cold night not because of radiational cooling but because of strong north/northwest winds bringing in arctic air.

Well in that case, the most brutal cold I've witnessed ala 1977, chritmas 1980, Feb 1994 and others were with STRONG NNW Winds hence CAA.

Even the end of August record tying lows in 1976 and 1982 were with STRONG strong NNW winds not with that non existant NYC radiational cooling.

Thanks for the definition NZucker. (we're in the same profession too) worked with a Zucker too once

[nzucker]

Well in that case, the most brutal cold I've witnessed ala 1977, chritmas 1980, Feb 1994 and others were with STRONG NNW Winds hence CAA.

The key to these extreme outbreaks are that winds are NNW, not NW or WNW...this allows for cold air drainage from the Hudson Valley, which is particularly effective if the Hudson River is frozen as it was in January 1977. If the wind takes on too much of a westerly component, NYC downslopes and doesn't hit the really low numbers.

It seems in recent years, most of the arctic air has been in Siberia and sometimes leaking into Europe...Europe had historic cold in Winter 09-10 and December 2010 this time around. For example, most of Poland was close to 15F below average this past December, an incredible departure. England saw its coldest December in 100 years of records. The last time the cold really lined up over North America was January 2004, although this winter looks promising in that the polar vortex is moving into Canada with -40C 850s.

[Ottawa Blizzard]

The key to these extreme outbreaks are that winds are NNW, not NW or WNW...this allows for cold air drainage from the Hudson Valley, which is particularly effective if the Hudson River is frozen as it was in January 1977. If the wind takes on too much of a westerly component, NYC downslopes and doesn't hit the really low numbers.

It seems in recent years, most of the arctic air has been in Siberia and sometimes leaking into Europe...Europe had historic cold in Winter 09-10 and December 2010 this time around. For example, most of Poland was close to 15F below average this past December, an incredible departure. England saw its coldest December in 100 years of records. The last time the cold really lined up over North America was January 2004, although this winter looks promising in that the polar vortex is moving into Canada with -40C 850s.

These are very good points. It really does seem that the cold has been aimed more at Europe these past few years. I was talking to some people today and they commented on how Januaries were much colder back in the 80s and 90s (although I pointed out that they were also very cold in January 2003,2004 and 2005). Cold air is still being formed, but it doesn't seem to be focussed much on our side of the pole anymore. Hopefully, as you pointed out, this will soon change.

[NorthShoreWx]

The key to these extreme outbreaks are that winds are NNW, not NW or WNW...this allows for cold air drainage from the Hudson Valley, which is particularly effective if the Hudson River is frozen as it was in January 1977. If the wind takes on too much of a westerly component, NYC downslopes and doesn't hit the really low numbers.

It seems in recent years, most of the arctic air has been in Siberia and sometimes leaking into Europe...Europe had historic cold in Winter 09-10 and December 2010 this time around. For example, most of Poland was close to 15F below average this past December, an incredible departure. England saw its coldest December in 100 years of records. The last time the cold really lined up over North America was January 2004, although this winter looks promising in that the polar vortex is moving into Canada with -40C 850s.

There is evidence in support of that from the January 2004 cold outbreaks.

The snowcover in central park on 1/16/2004 was 5" (please note that the wunderground snowdepth for that day is incorrect), and wind direction may have been a limiting factor for going below zero:

http://www.wundergro...eq_statename=NA

Yet a week earlier (1/10), the same low temperature (1F) was reached with a more favorable wind direction despite significantly warmer uppers and no snowcover :

http://www.wundergro...eq_statename=NA

[A-L-E-X]

Alex, my one and only point intended was that we have not had a decent arctic outbreak in this part of the country. You don't need that for below normal daytime temperatures. You don't need that to have a very cold night with clear skies, calm winds, and low dewpoints out side of urban areas. You do need that to get sub-zero cold into urban heat islands.

When was the last time KFOK went below zero with strong winds on CAA? Its been a while. Probably the same length of time that it has been for NYC. We have not had a true arctic airmass this winter or for quite a long time. One in 2004 was close but didn't set up quite right..

Thats what I've been talking about. I have no idea why some insist on treating my posts as some kind of global warming argument. I'm not going to get drawn into absurd arguments that NYC's climate isn't warmer than it was 100 years ago (I'm not talking about you here Alex).

I agree with this Ed-- I was just trying to illustrate that -15 is not likely to happen in NYC until the concrete gets torn up. The last really decent Arctic outbreak we had was back in Jan 2004.

[A-L-E-X]

These are very good points. It really does seem that the cold has been aimed more at Europe these past few years. I was talking to some people today and they commented on how Januaries were much colder back in the 80s and 90s (although I pointed out that they were also very cold in January 2003,2004 and 2005). Cold air is still being formed, but it doesn't seem to be focussed much on our side of the pole anymore. Hopefully, as you pointed out, this will soon change.

Is there a reason why the arctic air has been more focused on the other side of the globe? I've noticed this to be the case also. The last time we had cold air consistently focused on our side of the globe was back in the 80s-- and that coincided with positive NAO, so we really wouldnt want that lol. Arctic air on our side of the globe plus neutral NAO (not too negative, because that means suppression) is the ticket

[NorthShoreWx]

I agree with this Ed-- I was just trying to illustrate that -15 is not likely to happen in NYC until the concrete gets torn up pigs fly. The last really decent Arctic outbreak we had was back in Jan 2004.

Fixed.

I don't think tearing up the concrete would help.

[A-L-E-X]

Fixed.

I don't think tearing up the concrete would help.

Ed, have you heard that Chicago is trying to reduce UHI by increasing the foliage in the city? One of the things theyre doing is putting vegetation on the rooftops of buildings and surrounding areas of concrete. Do you think this would work in NYC too?

They basically look at UHI as another form of pollution and are saying that theyre greening up Chicago to try and curtail the effects of another 1995 style heat wave.

[Fantom X]

this is an arctic outbreak... when do we ever get dews that low?

http://www.wunderground.com/history/airport/KISP/1982/1/17/DailyHistory.html?req_city=NA&req_state=NA&req_statename=NA

[Alpha5]

this is an arctic outbreak... when do we ever get dews that low?

http://www.wundergro...eq_statename=NA

HPN was colder somehow

http://www.wunderground.com/history/airport/Khpn/1982/1/17/DailyHistory.html?req_city=NA&req_state=NA&req_statename=NA

[NorthShoreWx]

HPN was colder somehow

http://www.wundergro...eq_statename=NA

That is a forgotten "cold day" because of the midnight high temps and because Central Park didn't go below zero. But the low in the park was zero 2 days in a row and the afternoon high on the 17th seems to have been around 6F (-14.4C). It looks like HPN might have stayed below 0 during the daylight hours.

http://www.wundergro...ilyHistory.html

[NorthShoreWx]

HPN was colder somehow

http://www.wundergro...eq_statename=NA

I just checked my notes. I recorded minimum temps of -5 on the 17th and -6 on the 18th in northeastern Nassau County (January 1982). I didn't make any notes about the high temps.

I have some decent photos from that month that I'll try and dig up tonight. Ice on Cold Spring Harbor, the Hudson River, etc.

[A-L-E-X]

I just checked my notes. I recorded minimum temps of -5 on the 17th and -6 on the 18th in northeastern Nassau County (January 1982). I didn't make any notes about the high temps.

I have some decent photos from that month that I'll try and dig up tonight. Ice on Cold Spring Harbor, the Hudson River, etc.

It's funny how cold the 80s were and yet we didnt see a single year of above average snowfall between 1979 and 1994 (and no 10 inch or above snowfalls between 1983 and 1994.) Basically, the arctic air and the moisture were not usually present at the same time.

One of your favorite winters of all time, 1977-78 would not be considered a very cold winter by these standards, as I dont believe NYC reached a single digit low at all that winter. Given a choice between a snowy winter and a cold one-- most of us would choose snowy. Outside of Apr 82 and Feb 83, the 80s were pretty boring!

[NorthShoreWx]

It's funny how cold the 80s were and yet we didnt see a single year of above average snowfall between 1979 and 1994 (and no 10 inch or above snowfalls between 1983 and 1994.) Basically, the arctic air and the moisture were not usually present at the same time.

One of your favorite winters of all time, 1977-78 would not be considered a very cold winter by these standards, as I dont believe NYC reached a single digit low at all that winter. Given a choice between a snowy winter and a cold one-- most of us would choose snowy. Outside of Apr 82 and Feb 83, the 80s were pretty boring!

2/4/78 and 2/5/78 had mins of 10 in Central Park. That was the low for the winter but there were lots of low teens and the max for the entire month of February was only 41. It was a consistently cold winter (significantly colder than this one has been) and ranks among NYC's coldest for a 3 month winter period.

There was planty of decent weather in the 80s and not all of the winters were as bad on LI as in NYC. A couple even had above average snowfall. It was still a lame decade, but the winters of 1981, 1982, 1984 and 1987 all weren't too bad. Plus there were some noteworthy spells of winter in 1985 and 1988. Even 1983, that firehose of an el nino winter had a couple of interesting events in addition to the February Blizzard. I wouldn't say that we were spoiled by the 80s by a long stretch, but the really bad stuff didn't hit until 1989 - 1992. That was the bottom of the bottom. Oh yeah, 79 - 80 sucked too.

But I digress, NYC is overdue for some serious chill

[uncle W]

speaking of 1982...

http://bus.nycsubway.../perl/show?3287

no winter had an April Blizzard until 1982...