.....

[Juliancolton]

KPOU ended February at -13.0F from normal. That's just incredible.

[chietanen]

KPOU ended February at -13.0F from normal. That's just incredible.

You and I would call that lucky 13.

[snywx]

KPOU ended February at -13.0F from normal. That's just incredible.

 

Stupid cold!

[Juliancolton]

You and I would call that lucky 13.

I mean, -13 is a formidable daily departure. A -13 week is downright cold. -13 for an entire month? Just unfathomable...

 

To put it in perspective, the big "polar vortex" month of Feb 14 was -5.6 at Poughkeepsie. I remember being very impressed by the cold last winter, but now it looks like child's play.

[RU848789]

 

An amazing 23.9 finish for NYC at -11.4 for third coldest February on record.

This was also the greatest negative monthly temperature departure recorded at Central Park.

 

19.9...1934

22.7...1885

23.9....2015...-11.4

24.1...1895

24.8...1905

 

Greatest negative monthly temperature departures in NYC

 

Feb 34.....19.9....est..-10.9

Jan 77......22.1..........-10.1

Dec 89.....25.9..........-10.3

 

http://www1.ncdc.noa...8D6223307C0.pdf

 

http://www1.ncdc.noa...737D3EB45CA.pdf

 

 

 

Considering how the climate base norms (1901-30 vs. 1981-10) have warmed, the -11.4° anomaly suggests that February 2015 is at least comparable to all of NYC's other cold months during its period of record.

 

When it comes to baseline departures, I didn't realize they used the most recent 30-year averages as the baseline for comparison for departures from the mean.  I had no idea the 30-year means had moved from 30.8F (if 1934's 19.9F was a -10.9F departure in the 1900-1930 timeframe) to 35.3F (if 2015's 23.9 was an 11.4F departure in the 1980-2010 timeframe).  Since the last I've read said that the Earth's global temp has increased 1.5F in the last ~100 years, due to global warming, I assume most of the 4.5F increase in the mean over the last 80 years in NYC is from the urban heat island effect.  

 

I understand the desire to use the more recent baseline, given such a large shift in that baseline since the early 1900s, but something bugs me about it vs. using the 145 year full record as the baseline and I can't quite put my finger on it.  1934 still holds the record for coldest month, which is a bigger deal to me than departure from 30-year baseline, so I guess I can live with the way the departures are calculated (as long as regular folks don't all start saying 2015 was the coldest month ever because of the largest ever departure, which I could see some doing).  

[Isotherm]

New Jersey statewide average will yield the second coldest February on record, only behind the benchmark coldest month, Feb 1934.

 

In terms of Januaries, 1918 and 1977 were colder (19.9 and 20.2 respectively).

 

Rank

Year

Feb Temp Avg

1

1934

17.9°

2

2015

21.8°

3

1979

21.9°

4

1905

22.7°

5

1895

22.9°

6

1907

23.0°

7

1978

23.2°

8

1936

24.0°

9

1904

24.2°

10

1901

24.7°

[jconsor]

Research by Judah Cohen backs up what you and FreeRain mentioned about a Feb cooling trend past 25 yrs or so @ Central Park, and demonstrates that winter cooling has taken place in the late 1980s-early 2010s over a wide area of eastern and central N. America, as well as northern Europe and northern and central Asia.  As is well known, Cohen suggests that a trend toward increasing high-latitude Eurasian snow cover is influencing the cooling in mid-latitudes.  A lesser known reason Cohen proposes is a trend toward increased high-latitude moisture.

 

See http://onlinelibrary.wiley.com/doi/10.1029/2011GL050582/epdf("Asymmetric seasonal temperature trends", Cohen et. al 2012)

 

and http://iopscience.iop.org/1748-9326/7/1/014007/pdf/1748-9326_7_1_014007.pdf

("Arctic warming, increasing snow cover and widespread boreal winter cooling", Cohen et. al 2011)

 

Also nice review article: http://epic.awi.de/36132/1/Cohenetal_NGeo14.pdf

 

During the period from 1986 - 2000 the mean February temperature was 35.64 F (the height of the warm spell).  However, during the ensuing 15 years (2001 - 2015) the mean February temperature at Central Park plummeted to 34.27 F...a decrease of 1.37 F...clearly indicating a long term cooling trend.  This assumes that February 2015 ends up at 24.1 F with one day to go (per Uncle W's prediction). 

[Guest Pamela]

Thank you JConsor; thank you very much...

[doncat]

One more stat from my station...The mean min temp for the month of 12.9 degrees is the coldest on my record beating Jan 1977.

[donsutherland1]

When it comes to baseline departures, I didn't realize they used the most recent 30-year averages as the baseline for comparison for departures from the mean.  I had no idea the 30-year means had moved from 30.8F (if 1934's 19.9F was a -10.9F departure in the 1900-1930 timeframe) to 35.3F (if 2015's 23.9 was an 11.4F departure in the 1980-2010 timeframe).  Since the last I've read said that the Earth's global temp has increased 1.5F in the last ~100 years, due to global warming, I assume most of the 4.5F increase in the mean over the last 80 years in NYC is from the urban heat island effect.  

 

I understand the desire to use the more recent baseline, given such a large shift in that baseline since the early 1900s, but something bugs me about it vs. using the 145 year full record as the baseline and I can't quite put my finger on it.  1934 still holds the record for coldest month, which is a bigger deal to me than departure from 30-year baseline, so I guess I can live with the way the departures are calculated (as long as regular folks don't all start saying 2015 was the coldest month ever because of the largest ever departure, which I could see some doing).  

I fully agree that one should not argue that February 2015 was colder than February 1934. It was not. The departures relative to the recent base normals are a different measure and should be used in the proper context.

 

 

[Isotherm]

One more stat from my station...The mean min temp for the month of 12.9 degrees is the coldest on my record beating Jan 1977.

 

 

Truly awesome month.

 

 

Some stats from my station.

 

 

Temp departure of -11.5

 

Mean max: 32.6F

 

Mean min: 12.1F

 

Mean: 22.3F

 

12 days with a low temperature < 10 degrees

 

Of those 12, 7 of the days were low temperatures < 5 degrees

 

Two sub zero readings: -0.7F on the 18th and -4.9F on the 21st.

 

-5F is the lowest I've recorded since installing my station in 2007.

[USCG RS]

It looks like the UHI increase since 1900 was responsible for about 1/3 of the total warming in NYC.

http://pubs.giss.nas...ffin_etal_1.pdf

We analyse historical (1900 – present) and recent (year 2002) data on New York city’s urban heat island (UHI) effect, to characterize changes over time and spatially within the city. The historical annual data show that UHI intensification is responsible for ∼1/3 of the total warming the city has experienced since 1900. The intensification correlates with a significant drop in windspeed over the century, likely due to an increase in the urban boundary layer as Manhattan’s extensive skyline development unfolded. For the current-day, using 2002 data, we calculate the hourly and seasonal strength of the city’s UHI for five different case study areas, including sites in Manhattan, Bronx, Queens and Brooklyn. We find substantial intra-city variation (∼2 °C) in the strength of the hourly UHI, with some locations showing daytime cool islands – i.e., temperatures lower than the average of the distant non-urban stations, while others, at the same time, show daytime heat islands. The variations are not easily explained in terms of land surface characteristics such as building stock, population, vegetation fraction or radiometric surface temperatures from remote sensing. Although it has been suggested that stations within urban parks will underestimate UHI, the Central Park station does not show a significant underestimate, except marginally during summer nights. The intra-city heat island variations in the residential areas broadly correlate with summertime electricity demand and sensitivity to temperature increases. This relationship will have practical value for energy demand management policy, as it will help prioritize areas for UHI mitigation.

The upper curve in Fig. 1a is the Central Park record, while the lower curve is the average of the 23 non-urban stations. Figure 1b explicitly shows the temperature offset, Turban–rural (year) between these two historical records. It reveals a growth of the Central Park UHI strength from 2.0 C in 1900 to 2.5 C today.

The relative strength of New York’s UHI in 1900, and subsequent modest growth of 0.5 C, is interesting given the intensive increase in urban infrastructure since that time and continu- ing today. Historical photographs show that the building heights around Central Park were quite low in 1900, compared to the tall structures today, with a much greater skyview then (Black 1973). The resulting reduction in skyview over time should lead to UHI enhancement through reduced net longwave cooling (Oke 1986). Given the vast scale of New York’s skyline de- velopment since 1900, one might a priori expect a larger increase than 0.5 C. It is possible though that the Central Park station, located 300 m from the nearest streets, was less impacted by skyview loss over time. Additionally, although New York’s urban landscape and building heights were different, the Manhattan island population in 1900 was even larger (1.85 million persons in 1900) than today (1.54 million in 2000), due to turn-of-century immigration. So to the extent that population is an indicator of UHI strength, the relative 1900 UHI magnitude may be partial- ly understandable.

The data in Fig. 1 thus suggest that of the total 1.5 C warming Central Park has experienced over the century, roughly 33% of it was due to an increase in the UHI strength

Awesome research. Thank you.

[bluewave]

Awesome research. Thank you.

 

Sure, the UHI topic comes up quite a bit in the forum.

[donsutherland1]

 

It looks like the UHI increase since 1900 was responsible for about 1/3 of the total warming in NYC.

 

http://pubs.giss.nas...ffin_etal_1.pdf

 

We analyse historical (1900 – present) and recent (year 2002) data on New York city’s urban heat island (UHI) effect, to characterize changes over time and spatially within the city. The historical annual data show that UHI intensification is responsible for ∼1/3 of the total warming the city has experienced since 1900. The intensification correlates with a significant drop in windspeed over the century, likely due to an increase in the urban boundary layer as Manhattan’s extensive skyline development unfolded. For the current-day, using 2002 data, we calculate the hourly and seasonal strength of the city’s UHI for five different case study areas, including sites in Manhattan, Bronx, Queens and Brooklyn. We find substantial intra-city variation (∼2 °C) in the strength of the hourly UHI, with some locations showing daytime cool islands – i.e., temperatures lower than the average of the distant non-urban stations, while others, at the same time, show daytime heat islands. The variations are not easily explained in terms of land surface characteristics such as building stock, population, vegetation fraction or radiometric surface temperatures from remote sensing. Although it has been suggested that stations within urban parks will underestimate UHI, the Central Park station does not show a significant underestimate, except marginally during summer nights. The intra-city heat island variations in the residential areas broadly correlate with summertime electricity demand and sensitivity to temperature increases. This relationship will have practical value for energy demand management policy, as it will help prioritize areas for UHI mitigation.

 

 

The upper curve in Fig. 1a is the Central Park record, while the lower curve is the average of the 23 non-urban stations. Figure 1b explicitly shows the temperature offset, Turban–rural (year) between these two historical records. It reveals a growth of the Central Park UHI strength from 2.0 C in 1900 to 2.5 C today.

The relative strength of New York’s UHI in 1900, and subsequent modest growth of 0.5 C, is interesting given the intensive increase in urban infrastructure since that time and continu- ing today. Historical photographs show that the building heights around Central Park were quite low in 1900, compared to the tall structures today, with a much greater skyview then (Black 1973). The resulting reduction in skyview over time should lead to UHI enhancement through reduced net longwave cooling (Oke 1986). Given the vast scale of New York’s skyline de- velopment since 1900, one might a priori expect a larger increase than 0.5 C. It is possible though that the Central Park station, located 300 m from the nearest streets, was less impacted by skyview loss over time. Additionally, although New York’s urban landscape and building heights were different, the Manhattan island population in 1900 was even larger (1.85 million persons in 1900) than today (1.54 million in 2000), due to turn-of-century immigration. So to the extent that population is an indicator of UHI strength, the relative 1900 UHI magnitude may be partial- ly understandable.

 

The data in Fig. 1 thus suggest that of the total 1.5 C warming Central Park has experienced over the century, roughly 33% of it was due to an increase in the UHI strength

 

 

 

Great find, Bluewave.

[Isotherm]

Truly awesome month.

 

 

Some stats from my station.

 

 

Temp departure of -11.5

 

Mean max: 32.6F

 

Mean min: 12.1F

 

Mean: 22.3F

 

12 days with a low temperature < 10 degrees

 

Of those 12, 7 of the days were low temperatures < 5 degrees

 

Two sub zero readings: -0.7F on the 18th and -4.9F on the 21st.

 

-5F is the lowest I've recorded since installing my station in 2007.

 

 

DJF departure from normal here of -2.9, very impressive for a 3 month period. Mean temp of 30.5F.

[Isotherm]

KNYC:

 

DJF Temp departure for 2013-14:  -2.13

 

DJF Temp departure for 2014-15:  -3.63

 

 

Very impressive. If we include the Nov-March period, we're going to have 2 consecutive very cold 5 month periods.

[doncat]

DJF departure from normal here of -2.9, very impressive for a 3 month period. Mean temp of 30.5F.

And Dec was +3 lol.....Also have not had an above normal max temp here since Jan 25th when it hit 43.

[Isotherm]

And Dec was +3 lol.....Also have not had an above normal max temp here since Jan 25th when it hit 43.

 

 

Even warmer here -- my December 2014 temp departure was +4.7! So the fact that I ended up -3.0 on the season is incredible. A -1.9 Jan and -11.5 Feb. Going into mid January I was telling myself I'd be happy with a -1 DJF finish for my backyard. Just an incredible reversal, and probably the best comeback winter I can recall. 2004-05 featured a great snowfall comeback, but December 2004 wasn't a torch like this past Dec, so not as impressive.

[Juliancolton]

Even warmer here -- my December 2014 temp departure was +4.7! So the fact that I ended up -3.0 on the season is incredible. A -1.9 Jan and -11.5 Feb. Going into mid January I was telling myself I'd be happy with a -1 DJF finish for my backyard. Just an incredible reversal, and probably the best comeback winter I can recall. 2004-05 featured a great snowfall comeback, but December 2004 wasn't a torch like this past Dec, so not as impressive.

It's almost easy to forget the abominations that were December and early January.

[Kaner587]

The 45 day period from jan 20 trough March 5th could be among the best we've had pending results of the weds thurs storm. Snow, cold, snow cover, lack of any warm days, no rain all worked together to make this pretty classic

[SnoSki14]

This month could end up below normal because we'll be starting the month off with some very low departures.

Of course mid month could turn much warmer but the net result will likely yield negative unless we see record breaking warmth, which is unlikely at this point.

[nzucker]

The 45 day period from jan 20 trough March 5th could be among the best we've had pending results of the weds thurs storm. Snow, cold, snow cover, lack of any warm days, no rain all worked together to make this pretty classic

We still need a major snowstorm to make this winter historic, especially for places like western New Jersey and Westchester/Rockland, which missed the blizzard by being west and the SW flow event by being too far south. For those of us in these in between zones, snowfall is just slightly above average despite the brutal cold. Much of southern Westchester has seen 35-40" which is equivalent to seasonal average.

[Guest Pamela]

There is a difference between a long term trend and short term variation. This thread dealt with

with the rarity of the record cold this February against the long term warming trend at Central Park

since the late 1800's. How would an argument about a long term cooling trend developing in the

60's and 70's after the mild 50's worked out when we saw the milder 80's and 90's?

 

http://www.skepticalscience.com/graphics.php?g=47

 

 

 

I recall you posting a similarly themed article about a year ago in response to some of my claims; I dissented then and I continue to dissent now...my views on this topic are well established.  However, I will not impugn your motives; it is a weather & climate board and you most assuredly are at liberty to espouse whatever views you want regarding the nature of the atmosphere...just like everyone else here. 

The article you cite shares their opinion on how much of a factor the UHI has been with regards to temperature patterns in these parts.  It is nothing more than an opinion...far from demonstrable fact...and one must treat it as such.

[Guest Pamela]

I remember reading a respected science periodical while waiting to go in for an appointment circa 1990...on how computer modeling was demonstrating that temperatures in the District of Columbia would have increased so dramatically that normal life would be practically an impossibility by the second decade of the 21st century.  Washington was likely to experience "at least" 90 days per year where the temperature would exceed 100 F...this left me quite literally terrified...the idea of a summer so hellish that was so close was horrific.  Needles to say, nothing even vaguely resembling the nonsense in the article came to pass; temperatures peaked in 1998, they have been declining ever since...and I anticipate that they shall continue to do so into the foreseeable future. 

[Guest Pamela]

Coldest month ever; Islip & Bridgeport:

 

031130-

PUBLIC INFORMATION STATEMENT...RESENT
NATIONAL WEATHER SERVICE NEW YORK NY
610 PM EST MON MAR 2 2015

...RECORD SETTING COLD TEMPERATURES ACROSS THE FORECAST AREA...

THE AVERAGE TEMPERATURE FOR FEBRUARY 2015 AT ISLIP NY WAS 21.6.
THIS BREAKS THE OLD RECORD FOR THE COLDEST AVERAGE MONTHLY
TEMPERATURE FOR THE MONTH OF FEBRUARY OF 27.1 IN 2007. THIS ALSO
BREAKS THE RECORD FOR THE ALL TIME COLDEST AVERAGE MONTHLY
TEMPERATURE OF 23.5 SET IN JANUARY 2004.

THE AVERAGE TEMPERATURE FOR FEBRUARY 2015 AT BRIDGEPORT CT WAS
19.9. THIS BREAKS THE OLD RECORD FOR THE COLDEST AVERAGE MONTHLY
TEMPERATURE FOR THE MONTH OF FEBRUARY OF 24.1 IN 1978. THIS ALSO
BREAKS THE RECORD FOR THE ALL TIME COLDEST AVERAGE MONTHLY
TEMPERATURE OF 21.9 SET IN JANUARY 2004.

[JBG]

We still need a major snowstorm to make this winter historic, especially for places like western New Jersey and Westchester/Rockland, which missed the blizzard by being west and the SW flow event by being too far south. For those of us in these in between zones, snowfall is just slightly above average despite the brutal cold. Much of southern Westchester has seen 35-40" which is equivalent to seasonal average.

Last nights SWFE event came pretty close. And not many winters are "historic" both for snow and for cold. This one had about average snowfall and much below average temperatures. In my book this winter was historic.

[JBG]

I remember reading a respected science periodical while waiting to go in for an appointment circa 1990...on how computer modeling was demonstrating that temperatures in the District of Columbia would have increased so dramatically that normal life would be practically an impossibility by the second decade of the 21st century.  Washington was likely to experience "at least" 90 days per year where the temperature would exceed 100 F...this left me quite literally terrified...the idea of a summer so hellish that was so close was horrific.  Needles to say, nothing even vaguely resembling the nonsense in the article came to pass; temperatures peaked in 1998, they have been declining ever since...and I anticipate that they shall continue to do so into the foreseeable future.

The fear-mongers pandered to the tendency to panic. Of course their predictions were not going to be met. Those are changes that take centuries, even if relatively rapid in their development.

[Morris]

When was the last day the daily minimum was above freezing?

[uncle W]

When was the last day the daily minimum was above freezing?

1/24...

[Morris]

1/24...

 

 

Thanks uncle!