Why Have Major Arctic Outbreaks Been Focused West Of NYC since 1950?

[bluewave]

It's interesting that the brunt of Arctic outbreaks since 1950 have been centered west of NYC.

It can't really be explained by UHI or a generally warming climate since other urban stations

further west don't seem to be effected. For example, the coldest temperature on record at

Chicago was -27 on 1/20/1985. The coldest modern temperature in NYC was -15 on 2/9/1934.

Philly dropped to -11 on 2/9/1934 for their coldest temperature. Philly approached their record

within 4 degrees during the 1980's. NYC has only been able to manage a -2 degree low since

1950 which was off the record by 13 degrees. I put together a list of the coldest days in the

three cities to illustrate the point.

NYC...............................Chicago.................... Philly

1/16/2004...+1..............12/22/1872....-21.......1/17/1982...-7

1/19/1994...-2...............12/23/1983...-21........1/19/1994...-5

1/21/1985..-2................12/24/1983..-25...... ...1/21/1985..-6

1/17/1977...-2................1/9/1875....-20...........1/22/1984...-7

2/8/1963...-2..................1/10/1982...-26..........1/29/1963...-5

2/2/1961...-2..................1/16/1982...-25..........2/2/1961...-4

1/15/57....0.....................1/17/1982...-23.........2/2/1961...-4

2/15/1943...-8.................1/18/1994...-21.........2/9/1934...-11

1/20/1942...-4.................1/19/1985...-23

1/23/1936...-3.................1.20/1985...-27

2/9/1934...-15.................1/21/1984...-22

12/30/1933..-6.................1/25/1897...-20

2/15/1918...-6..................2/9/1899....-21

12/30/1917...-13

1/14/1914...-5

1/13/1912...-3

1/15/1904...-4

[Stormlover74]

I do think the UHI still plays a major role. We'd have to look at surrounding stations in the recent outbreaks and compare to the 1934 outbreak.

It's interesting that the brunt of Arctic outbreaks since 1950 have been centered west of NYC.

It can't really be explained by UHI or a generally warming climate since other urban stations

further west don't seem to be effected. For example, the coldest temperature on record at

Chicago was -27 on 1/20/1985. The coldest modern temperature in NYC was -15 on 2/9/1934.

Philly dropped to -11 on 2/9/1934 for their coldest temperature. Philly approached their record

within 4 degrees during the 1980's. NYC has only been able to manage a -2 degree low since

1950 which was off the record by 13 degrees. I put together a list of the coldest days in the

three cities to illustrate the point.

NYC...............................Chicago.................... Philly

1/16/2004...+1..............12/22/1872....-21.......1/17/1982...-7

1/19/1994...-2...............12/23/1983...-21........1/19/1994...-5

1/21/1985..-2................12/24/1983..-25...... ...1/21/1985..-6

1/17/1977...-2................1/9/1875....-20...........1/22/1984...-7

2/8/1963...-2..................1/10/1982...-26..........1/29/1963...-5

2/2/1961...-2..................1/16/1982...-25..........2/2/1961...-4

1/15/57....0.....................1/17/1982...-23.........2/2/1961...-4

2/15/1943...-8.................1/18/1994...-21.........2/9/1934...-11

1/20/1942...-4.................1/19/1985...-23

1/23/1936...-3.................1.20/1985...-27

2/9/1934...-15.................1/21/1984...-22

12/30/1933..-6.................1/25/1897...-20

2/15/1918...-6..................2/9/1899....-21

12/30/1917...-13

1/14/1914...-5

1/13/1912...-3

1/15/1904...-4

[bluewave]

I do think the UHI still plays a major role. We'd have to look at surrounding stations in the recent outbreaks and compare to the 1934 outbreak.

It's too small a factor to explain such a big difference . UHI is about 1/3 of the total warming in NYC since those times.

There has been a steady .45 degree F per decade rise in DJF temperatures in NYC. You can also see that the core of the

cold was further west in a year like 1985 when Chicago set its record.It's also worth noting that Erie, PA set it's all time

high pressure record during the 1934 outbreak. The highs in the more recent outbreaks have been back toward the plains

with the lowest temperatures located to our west.

2/9/1934 Erie...31.04

[uncle W]

the February 1934 arctic outbreak moved south over us from Canada...The core of the cold was funneled down the Hudson Valley...February 1943 was probably the same...

[bluewave]

the February 1934 arctic outbreak moved south over us from Canada...The core of the cold was funneled down the Hudson Valley...February 1943 was probably the same...

Right, the more recent record outbreaks in the Eastern US came in further to the west with strong CAA on west to NW

winds in our area.

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

[QVectorman]

The air is modified by the ocean near NYC. In addition, cold air masses (Continental Polar air masses) are typically generated near the center of land masses where the air is the driest, the furthest away from maritime air. So cP airmasses originate around the Northwest Territories for the most part, thus it is a shorter distance to Chicago than to NYC and less opportunities for air mass modification. I will also mention that the times NYC dropped to -15 in 1934 and -11 1917 as you mentioned, the air masses were brutally cold, and set records in the GL's and South, in '34 Michigan set it's all time state record low of -51 and in '17 Tennessee set its state record of -32. Also if you look at lowest state records set since 1950, the NE and EC are pretty well represented. I guess my point is you need EXTREME Arctic air to over ride the ocean's influence to produce those kinds of numbers for NYC. Those two air masses didn't produce extreme low temps b/c the outbreak was centered over the NE but rather because the air mass was EXTREMELY cold.

Oklahoma -31 Feb. 9, 2011

Illinois -36 Jan. 5, 1999

Iowa -47 Feb. 3, 1996

Minnesota -60 Feb. 2, 1996

Wisconsin -55 Feb.4, 1996

Rhode Island -25 Feb. 5, 1996

Kentucky -37 Jan. 19, 1994

Indiana -36 Jan. 19, 1994

Utah -69 Feb. 1, 1985

Colorado -61 Feb. 1, 1985

Virginia -30 Jan. 22, 1985

South Carolin a -19 Jan. 21, 1985

North Carolin a -34 Jan. 21, 1985

Massachusetts -35 Jan. 12, 1981

New York -52 Feb. 18, 1979

Hawaii 12 May 17, 1979

Alaska -80 Jan. 23, 1971

Arizona -40 Jan. 7, 1971

Washington -48 Dec. 30, 1968

Alabama -27 Jan. 30, 1966

Mississippi -19 Jan. 30, 1966

Montana -70 Jan. 20, 1954

New Mexico -50 Feb. 1, 1951

[bluewave]

The air is modified by the ocean near NYC. In addition, cold air masses (Continental Polar air masses) are typically generated near the center of land masses where the air is the driest, the furthest away from maritime air. So cP airmasses originate around the Northwest Territories for the most part, thus it is a shorter distance to Chicago than to NYC and less opportunities for air mass modification. I will also mention that the times NYC dropped to -15 in 1934 and -11 1917 as you mentioned, the air masses were brutally cold, and set records in the GL's and South, in '34 Michigan set it's all time state record low of -51 and in '17 Tennessee set its state record of -32. Also if you look at lowest state records set since 1950, the NE and EC are pretty well represented. I guess my point is you need EXTREME Arctic air to over ride the ocean's influence to produce those kinds of numbers for NYC. Those two air masses didn't produce extreme low temps b/c the outbreak was centered over the NE but rather because the air mass was EXTREMELY cold.

Oklahoma -31 Feb. 9, 2011

Illinois -36 Jan. 5, 1999

Iowa -47 Feb. 3, 1996

Minnesota -60 Feb. 2, 1996

Wisconsin -55 Feb.4, 1996

Rhode Island -25 Feb. 5, 1996

Kentucky -37 Jan. 19, 1994

Indiana -36 Jan. 19, 1994

Utah -69 Feb. 1, 1985

Colorado -61 Feb. 1, 1985

Virginia -30 Jan. 22, 1985

South Carolin a -19 Jan. 21, 1985

North Carolin a -34 Jan. 21, 1985

Massachusetts -35 Jan. 12, 1981

New York -52 Feb. 18, 1979

Hawaii 12 May 17, 1979

Alaska -80 Jan. 23, 1971

Arizona -40 Jan. 7, 1971

Washington -48 Dec. 30, 1968

Alabama -27 Jan. 30, 1966

Mississippi -19 Jan. 30, 1966

Montana -70 Jan. 20, 1954

New Mexico -50 Feb. 1, 1951

Nice post,but I have to disagree with your conclusion. The reason 1934 and 1917 were colder here is mainly

due to the upper pattern at the time not because they were colder than the more modern Arctic outbreaks.

NYC needs more of a northerly flow down the Hudson Valley which occurs when air masses drop down

further east in Canada. Notice how January 1977 had similar extreme departures for the month to February 1934.

You can see that there was more of a ridge out west in 1934 so the coldest air was directed further east. Some of the recent

examples that you provided for the East were examples of radiational cooling. NYC and the immediate coast

need strong CAA to set record lows. that's more of what I was getting at for us. But I do agree that it's more

common for the arctic air masses to invade the central and western areas more frequently due to some of the

factors that you discussed.

[Guest Pamela]

First of all Chicago is going to record *much* lower minima than NYC for two reasons: Most arctic airmasses originate over the NW Territories and Canadian Prarie Provinces and then head southeast....they generally reach Chicago after passing over nothing but snow covered flat farmland...but to reach NYC, they must pass over the Great Lakes, which possess a tremendous warming influence; as well as the Appalachian Mountains, which not only slow the advent of the cold...but modifies it also, as it compressionally warms sinking air down the eastern slopes... The roll of the Lakes tends to diminish a bit by late January, when Erie and Huron are usually frozen over, and Superior and Michigan are partially iced over. Lake Ontario, on the other hand, never freezes over. Later in the winter, arctic anticyclones have a tendency to form a bit further east; more towards the Ontario / Quebec area. It is only when this takes place, as the airmass sinks south-south eastward, that the modification by the Great Lakes can be avoided in part...and the coldest weather in the NYC area will be experienced...

[bluewave]

First of all Chicago is going to record *much* lower minima than NYC for two reasons: Most arctic airmasses originate over the NW Territories and Canadian Prarie Provinces and then head southeast....they generally reach Chicago after passing over nothing but snow covered flat farmland...but to reach NYC, they must pass over the Great Lakes, which possess a tremendous warming influence; as well as the Appalachian Mountains, which not only slow the advent of the cold...but modifies it also, as it compressionally warms sinking air down the eastern slopes...

Later in the winter, arctic anticyclones have a tendency to form a bit further east; more towards the Ontario / Quebec area. It is only when this takes place, as the airmass sinks south-south eastward, that the modification by the Great Lakes can be avoided in part...and the coldest weather in the NYC area will be experienced...

The point about Chicago is that the later half of the 20th century saw the record lows there while NYC occurred

during the early half. The early century cold was directed further east than during the second half. The 1980's

cold in Chicago surpassed the records of 100 years earlier.

[Guest Pamela]

The point about Chicago is that the later half of the 20th century saw the record lows there while NYC occurred

during the early half. The early century cold was directed further east than during the second half. Also the cold

was centered far enough east early on to freeze Lake Ontario at times.

I believe it is related to where the readings were taken; the 1980's numbers in Chicago are from O'Hare Airport which radiates extremely well and is far removed from the urban Chicago area....earlier readings were taken at Midway Airport...which is in the midst of the Chicago heat island...even earlier readings were likely taken at lakefront or downtown....

[bluewave]

I believe it is related to where the readings were taken; the 1980's numbers in Chicago are from O'Hare Airport which radiates extremely well and is far removed from the urban Chicago area....earlier readings were taken at Midway Airport...which is in the midst of the Chicago heat island...even earlier readings were likely taken at lakefront or downtown....

The site did move around through time but other record lows across the Midwest occurred in the late 1970's and

early 1980's which were all time lows. The coldest winter in the USA was 1979 surpassing 1936 and 1899. Chicago

is a good proxy for the location of the core of the cold during those years.You can see it in the Illinois vs NY State

winter comparison with the pattern repeated at Rockford, IL.

http://www.crh.noaa....t/?n=janrec-rfd

http://www.crh.noaa.gov/lot/?n=janrec-ord

Illinois DJF

NY State DJF

[uncle W]

can someone pull maps for 12/30/1917, 2/9/1934 and 2/15/1943...these are the coldest NYC temperatures...Most of the other arctic outbreaks were in the minus 2 range...

[bluewave]

can someone pull maps for 12/30/1917, 2/9/1934 and 2/15/1943...these are the coldest NYC temperatures...Most of the other arctic outbreaks were in the minus 2 range...

I found these off a European weather site so it only caught part of our area. You can see the great northerly flow down the

Hudson Valley during 1917 and 1934 and maybe a bit more of a NW/NNW flow in 1943 when it was not quite as cold.

http://www.wetterzen...n/fsslpeur.html

12/30/1917

2/9/1934

2/15/1943

[QVectorman]

It looks like answer, then from the maps above, the data you provided and based on the temperature and dates data I provided, arctic air masses have been in place over NY state since the 1950's (radiational cooling alone isn't going to allow state records to be set w/o some type of cold arctic air in place). There isn't any real proof that high pressure tracks are necessarily trended farther west. The caveat then, I believe, as you illustrated with the 2 maps above and stated is that NYC needs the combo of the brutally cold arctic air and strong northerly/NW'ly winds. You need the "brutally cold" arctic air so that even though you are not directly under the high, (which is typically the coldest reading, especially with radiational cooling in play...I'm sure you know this, just laying out for others) the "extremely" cold air can be advected on the NE side of the high down into NYC.(Brutally cold air under the center of the high and "extremely" cold...relative to the center of the high, alone the periphery of the high) So even though you have had events with strong CAA from the N/NW, the air mass hasn't been "brutally cold" and even though at other times "brutally cold" air masses have been in place they haven't had strong CAA or a decent pressure gradient or gradient orientation in place to advect the cold air. Therefore, the combination of both these ingredients being in place at the same time are extremely rare. Like being struck by lightning. The main issue as you pointed out appears to be achieving the strong enough CAA on a N/NW wind. I guess the only other way to test this out is if we were able to do an analog of all the events that have the sfc features of '17 and '34 and view the resulting composite temps, just to see that if at other times even with the same temps in place over Canada and sfc pressure features in place do not produce the same results for NYC every time. If so then we know something else is in play.

[bluewave]

It looks like answer, then from the maps above, the data you provided and based on the temperature and dates data I provided, arctic air masses have been in place over NY state since the 1950's (radiational cooling alone isn't going to allow state records to be set w/o some type of cold arctic air in place). There isn't any real proof that high pressure tracks are necessarily trended farther west. The caveat then, I believe, as you illustrated with the 2 maps above and stated is that NYC needs the combo of the brutally cold arctic air and strong northerly/NW'ly winds. You need the "brutally cold" arctic air so that even though you are not directly under the high, (which is typically the coldest reading, especially with radiational cooling in play...I'm sure you know this, just laying out for others) the "extremely" cold air can be advected on the NE side of the high down into NYC.(Brutally cold air under the center of the high and "extremely" cold...relative to the center of the high, alone the periphery of the high) So even though you have had events with strong CAA from the N/NW, the air mass hasn't been "brutally cold" and even though at other times "brutally cold" air masses have been in place they haven't had strong CAA or a decent pressure gradient or gradient orientation in place to advect the cold air. Therefore, the combination of both these ingredients being in place at the same time are extremely rare. Like being struck by lightning. The main issue as you pointed out appears to be achieving the strong enough CAA on a N/NW wind. I guess the only other way to test this out is if we were able to do an analog of all the events that have the sfc features of '17 and '34 and view the resulting composite temps, just to see that if at other times even with the same temps in place over Canada and sfc pressure features in place do not produce the same results for NYC every time. If so then we know something else is in play.

Yeah, the combination of the two has been very rare. The surface highs with the most brutal arctic air masses to enter the

US have been further to our W or SW with the big outbreaks since 1950 giving us a strong WNW flow here. At other times

the highs have been closer to us with more of a northerly flow. 1994 illustrates this example very well. The historic

outbreak on the 19th had the high swing across to our SW and a more W to WNW flow here. The Big Arctic high

on the 27th was in a great spot for N to NNE winds down from the north. We made it down to -2 on the 19th

and 0 on the 27th.

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

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

[uncle W]

February 1934 was an extremely cold month in NYC...

Feb...1934 at Battery Park in lower Manhattan...

day...high...low...precip..snow....sc.8pm Pk Gust/Dir

01.....35.....30.....0.98"....9.6".....6.5"...34/sw

02.....31.....11........0........0........9.0"...34/nw

03.....23......4.........0........0........8.4"...22/n

04.....27.....15.....0.01"....0.1".....7.1"...28/nw

05.....29.....17........0........0........6.0"...25/nw

06.....20......5.........0........0........5.5"...27/n

07.....31.....13........T........T........5.0"...29/w

08.....21.....-7.........0........0........4.8"...30/n

09.......8...-14.........0........0........4.7"...32/nw

10.....27.....-2.........0........0........4.3"...27/n

11.....33.....12........0........0........3.4"...22/sw..

12.....39.....25........T........T........2.5"...16/w

13.....34......8......0.10"....1.1".....2.6"...50/nw

14.....21......3.........0........0........2.4"...35/nw

15.....41.....21........0........0........1.9"...27/n

16.....26......9.........0........0........1.4"...23/n

17.....28......9.........0........0........1.0"...22/n

18.....41.....18........0........0........0.5"...19/s

19.....42.....26.....0.42"....5.8".....1.6"...23/n

20.....27......9......0.24"....3.4".....8.6"...41/nw

21.....35.....10........0........0........8.0"...26/nw

22.....43.....27.....0.12".....0........6.0"...15/n

23.....36.....10........T........T........5.3"...51/nw

24.....18......6.........0........0........4.7"...44/nw

25.....21......9.....0.32"....3.2"......6.4"...21/ne

26.....25.....13....0.61"....6.9".....13.8"...34/nw

27.....20......9.........0........0.......13.4"...35/nw

28.....27......7.........0........0.......12.4"...21/nw

tot..28.9..10.8....2.80"...30.1"...........

[QVectorman]

I don't understand your argument about arctic air masses being bias to the west of you. '79 and '94 are two examples of arctic highs passing over NY, it just didn't produce a N/NW flow over NYC. I don't see any proof of them traversing the NE any less now that prior to 1950.

[bluewave]

I don't understand your argument about arctic air masses being bias to the west of you. '79 and '94 are two examples of arctic highs passing over NY, it just didn't produce a N/NW flow over NYC. I don't see any proof of them traversing the NE any less now that prior to 1950.

Where did I say that there are less arctic highs crossing our area? We have not had a favorable combination of

a cold enough airmass on northerly winds since 1934 to drop us below -10 is what I am saying. The airmass was

focused west of us in 1979 over the Midwest compared to the Northeast in 1934.

[QVectorman]

Ok no worries, we're on the same page then

[bluewave]

Ok no worries, we're on the same page then

No problem. Getting NYC to drop below -2 since 1950 has been like trying to break the speed of light.

Heck, our last sub zero day was all the way back in 1994. The best that we have been able to do in the

recent warmer pattern has been +1 back in 2004.

[Hoosier]

Just found this thread.  Good stuff.

I believe it is related to where the readings were taken; the 1980's numbers in Chicago are from O'Hare Airport which radiates extremely well and is far removed from the urban Chicago area....earlier readings were taken at Midway Airport...which is in the midst of the Chicago heat island...even earlier readings were likely taken at lakefront or downtown....

While it's true that ORD is not in the city proper, it's still a pretty urbanized area and it's a bit of a stretch to say it radiates extremely well.  Winds generally stayed up in the 15-20 mph range on the morning that Chicago set its all-time record low so radiational cooling was not much of a factor then.  That airmass was ridiculously cold aloft.