A-L-E-X Posted January 16, 2011 Share Posted January 16, 2011 The cold in central park in the 30s was because it was an extreme cold outbreak. While urban expansion does increase the heat island effect, it has been a very very long time since Manhattan experienced radiational cooling. February 9, 1934 had absolutely nothing to do with radiational cooling. Sorry Nate, but you are wrong about this. I agree that the airmass in Feb 1934 was much much colder than anything we've seen in our lifetimes-- as daytime highs arent influenced by UHI (the main reason why I advocate not using mins in evaluating averages in the summer or winter)-- and would most certainly have resulted in temps much below the -2 lows we've seen in our most recent frigid outbreaks, though Im not sure the low would have gotten down to -10. When was the last time NYC had a low of less than -2? Link to comment Share on other sites More sharing options...
uncle W Posted January 16, 2011 Share Posted January 16, 2011 from 1944 to 1960 NYC didn't get below zero...NYC has not gotten below zero since 1994...we are over due for a real arctic blast... Link to comment Share on other sites More sharing options...
NorthShoreWx Posted January 16, 2011 Share Posted January 16, 2011 Here's some January low temperatures: http://docs.lib.noaa.gov/rescue/mwr/062/mwr-062-02-0057.pdf Link to comment Share on other sites More sharing options...
bluewave Posted January 16, 2011 Author Share Posted January 16, 2011 I agree that the airmass in Feb 1934 was much much colder than anything we've seen in our lifetimes-- as daytime highs arent influenced by UHI (the main reason why I advocate not using mins in evaluating averages in the summer or winter)-- and would most certainly have resulted in temps much below the -2 lows we've seen in our most recent frigid outbreaks, though Im not sure the low would have gotten down to -10. When was the last time NYC had a low of less than -2? We have not seen an arctic outbreak here since then with nearby record breaking high pressure like that one had. Erie,PA recorded a record high pressure of 1051 mb when it got so cold here. Back on 1/10/04 NYC made it down to 1 degree above without such impressive 850 mb temperatures at the time of the morning low.That set up had a really strong arctic high just to our west and a northerly flow. I found an old map of the 34 record breaking high but part of it is cut off since I found it on a euro site. I also included the 1/10/04 map. Link to comment Share on other sites More sharing options...
nzucker Posted January 16, 2011 Share Posted January 16, 2011 The cold in central park in the 30s was because it was an extreme cold outbreak. While urban expansion does increase the heat island effect, it has been a very very long time since Manhattan experienced radiational cooling. February 9, 1934 had absolutely nothing to do with radiational cooling. Sorry Nate, but you are wrong about this. No, I'm not wrong, you are just so set in your viewpoint that you can't understand any alternative perspectives. When Central Park hit -15F on February 9, 1934, there was certainly radiational cooling involved. Radiational cooling just means losing heat at night, and it happens all the time. Whenever it is a calm, clear night, heat is released to the atmosphere from the surface, and cold air pools near ground level since it is heavier than warmer air. This is basic physics and cannot be refuted. In 1934, many buildings were made of brick and wood, materials that don't accumulate nearly as much heat during the day as steel and concrete. There were fewer cars, less development in the surrounding suburbs, and more open land around the city. This makes it much easier to radiate at night than it is today, when the city is almost 100% steel and concrete, surrounded by miles of highways, developments, shopping centers, etc. There's less penetration of cold air and less radiational cooling in 2011 than there was in 1934; it's as simple as that. I'm not saying that it wasn't an extreme cold outbreak; it certainly was, and 850s were probably around -30C. But Central Park wouldn't get as cold today with those 850s, they'd probably bottom out just slightly below 0F. You can clearly tell that radiational cooling has changed due to the increase in UHI over the years. The problem is not just that we're seeing mild airmasses in winter; Danbury, CT got down to -5F last night with 850s around -13C. Central Park had very similar 850s, being only 50 miles away, and yet only hit 23F. That's clearly an indication of the UHI problem since both stations are low elevation with heavy snowpack. You can tell just from memory that there's a disparity between the minima recorded by Central Park and what 850s would suggest for lows....-19C 850s in December this year only got the park down to 19F. -24C 850s in January 2009 only got the park down to 6F, even with snow cover. These are cold airmasses, but they just aren't doing the trick for Central Park because they radiate at an agonizingly slow rate. We have not seen an arctic outbreak here since then with nearby record breaking high pressure like that one had. Erie,PA recorded a record high pressure of 1051 mb when it got so cold here. Back on 1/10/04 NYC made it down to 1 degree above without such impressive 850 mb temperatures at the time of the morning low.That set up had a really strong arctic high just to our west and a northerly flow. I found an old map of the 34 record breaking high but part of it is cut off since I found it on a euro site. I also included the 1/10/04 map. You can see here that the wind direction is almost due north because of the high pressure's position; this creates cold air drainage from the Hudson Valley and allows Central Park to get colder. As I've said before, KNYC gets much colder with a light north wind than with no wind at all. I also assume the Hudson River was starting to freeze over with the cold snap in January 2004, and that may have have reduced the moderating influence on the water when winds are close to due north. Link to comment Share on other sites More sharing options...
NorthShoreWx Posted January 16, 2011 Share Posted January 16, 2011 We have not seen an arctic outbreak here since then with nearby record breaking high pressure like that one had. Erie,PA recorded a record high pressure of 1051 mb when it got so cold here. Back on 1/10/04 NYC made it down to 1 degree above without such impressive 850 mb temperatures at the time of the morning low.That set up had a really strong arctic high just to our west and a northerly flow. I found an old map of the 34 record breaking high but part of it is cut off since I found it on a euro site. I also included the 1/10/04 map. Shows that 850 temps are not the last word on cold at the surface. If you check you'll see that NYC also made it down to +1 6 days later (1/16) and at that time if I recall the 850s were insanely cold...around -30C. They might have even been -33 over BOS where it got down to -7. Link to comment Share on other sites More sharing options...
NorthShoreWx Posted January 16, 2011 Share Posted January 16, 2011 No, I'm not wrong, you are just so set in your viewpoint that you can't understand any alternative perspectives. blah blah blah Seriously, with a lead-in like that do you think I read the rest? Talk about the pot calling the kettle black. Grow up! Link to comment Share on other sites More sharing options...
nzucker Posted January 16, 2011 Share Posted January 16, 2011 Seriously, with a lead-in like that do you think I read the rest? Talk about the pot calling the kettle black. Grow up! You just wrote "Sorry Nate, but you're wrong about this" How is my comment any different? That sounded quite derogatory to me. You also said radiational cooling did not exist in NYC in 1934. You said a -15F low has nothing to do with radiational cooling. This is illogical and nonsensical. Ask some of the meteorologists on here, and I bet 99% of them agree with me. Don't tell me to grow up...I don't appreciate such insults. I have contributed many great insights and information to this forum, and I'm tired of the small contingent of members who consistently display a lack of respect towards others. It is one reason I have thought about shutting my account, just too many ignorant and rude members here... BTW, we are arguing about radiational cooling in Central Park, not exactly a life or death situation. Why do so many have to get bent out of shape over the weather? Link to comment Share on other sites More sharing options...
NorthShoreWx Posted January 16, 2011 Share Posted January 16, 2011 In the 1930 census, NYC had a population of 6.9 million (compared to 8.36 million for 2010). The vast majority of those 7 million people heated their homes and apartments with coal (or coal fired steam) in 1934. More on the history of the use of coal: http://sunhomedesign.wordpress.com/2007/10/26/a-brief-history-of-heating-and-cooling-americas-homes/ Link to comment Share on other sites More sharing options...
NorthShoreWx Posted January 16, 2011 Share Posted January 16, 2011 Some bedtime reading: One Hundred Years of New York City's "Urban Heat Island": Temperature Trends and Public Health Impacts Rosenthal, J. E.; Knowlton, K. M.; Rosenzweig, C.; Goldberg, R.; Kinney, P. L. American Geophysical Union, Fall Meeting 2003, abstract #U32A-0030 In this paper, we examine the relationship between the historical development of New York City and its effect on the urban climate. Urban "heat islands" (UHI) are created principally by man-made surfaces, including concrete, dark roofs, asphalt lots and roads, which absorb most of the sunlight falling on them and reradiate that energy as heat. Many urban streets have fewer trees and other vegetation to shade buildings, block solar radiation and cool the air by evapotranspiration. The historical development of the NYC heat island effect was assessed in terms of average temperature differences of the city center relative to its surrounding 31-county metropolitan region, comprised of parts of New York State, New Jersey, and Connecticut. Monthly maximum and minimum temperatures for 1900-1997 were obtained from NOAA's National Climatic Data Center, the NASA-Goddard Institute for Space Studies, and the Lamont-Doherty Earth Observatory of Columbia University for 24 weather stations within the region that are part of the U.S. Historical Climatology Network. Analysis of annual mean temperatures shows an increasing difference between NYC (Central Park weather station) and its surrounding region over the twentieth century. Analysis of the temperature differences over time between NY Central Park (NYCP) station and 23 regional weather stations classified according to distance and level of urbanization show a heat island effect existing in NYC, with mean temperatures in the NYCP Station generally higher than the surrounding stations, ranging from 1.20\deg C to 3.02\deg C. A difference of at least 1\deg C already existed at the beginning of the 20th century between the mean temperature in NYC and its surrounding rural areas, and this difference increased over the twentieth century. There was a significant decrease in the monthly and seasonal variability of the UHI effect over the century. Temperature extremes and summertime heat can create heat stress and other health consequences for urban residents. Public health impacts are assessed as the proportion of heat-related regional mortality estimated to be attributable to New York City's heat island effect during an average 1990's summer. Concentration-response functions describing the temperature-mortality relationship in NYC derived from the epidemiological literature are used to estimate numbers of deaths in a typical 1990s summer and those attributable to the city's heat island effect. The techniques and potential public health benefits of a pilot project to mitigate the heat island effect in NYC will be discussed. http://adsabs.harvard.edu/abs/2003AGUFM.U32A0030R The magnitude of the UHI, in terms of the temperature differential between a city and its surrounding countryside, is greatest during dry, clear, low‐wind nights. This occurs because the surfaces that comprise the urban built environment retain and re‐radiate more heat into the air at night than vegetation and non‐urbanized land cover. Also, the surface geometry and thermal properties of urban built environment’s non‐vegetative surfaces greatly impact the magnitude of the urban heat island (Voogt, 2002).1 The heat island effect has existed in New York City since at least the end of the 19th century. Urban Planning student Monica Pena Sastre (Columbia University) demonstrated that a difference of at least 1.8ºF (1ºC) already existed at the beginning of the 20th century between the mean temperature in NYC and its surrounding rural areas, and this difference increased over the 20th century (Sastre, 2003). Analysis of annual mean temperatures between 1900 – 1997 shows that mean temperatures in New York City (Central Park weather station) were generally higher than that of the surrounding region, ranging from 2.2F (1.2C) to 5.4F (3.0C) (Rosenthal et al., 2003), and demonstrate a significant decrease in the monthly and seasonal variability of the UHI effect over the century. Gedzelman et al. conclude that from 1997 to 1998, the mean of New York City’s heat island was 7.2ºF (4C) in the summer and fall and 5.4ºF (3C) in the winter and spring (2003). http://csud.ei.columbia.edu/sitefiles/file/SSBx_UHI_Mit_Can_Improve_NYC_Enviro%5B1%5D.pdf Link to comment Share on other sites More sharing options...
Patrick-02540 Posted January 16, 2011 Share Posted January 16, 2011 No, I'm not wrong, you are just so set in your viewpoint that you can't understand any alternative perspectives. When Central Park hit -15F on February 9, 1934, there was certainly radiational cooling involved. Radiational cooling just means losing heat at night, and it happens all the time. Whenever it is a calm, clear night, heat is released to the atmosphere from the surface, and cold air pools near ground level since it is heavier than warmer air. This is basic physics and cannot be refuted. In 1934, many buildings were made of brick and wood, materials that don't accumulate nearly as much heat during the day as steel and concrete. There were fewer cars, less development in the surrounding suburbs, and more open land around the city. This makes it much easier to radiate at night than it is today, when the city is almost 100% steel and concrete, surrounded by miles of highways, developments, shopping centers, etc. There's less penetration of cold air and less radiational cooling in 2011 than there was in 1934; it's as simple as that. I'm not saying that it wasn't an extreme cold outbreak; it certainly was, and 850s were probably around -30C. But Central Park wouldn't get as cold today with those 850s, they'd probably bottom out just slightly below 0F. You can clearly tell that radiational cooling has changed due to the increase in UHI over the years. The problem is not just that we're seeing mild airmasses in winter; Danbury, CT got down to -5F last night with 850s around -13C. Central Park had very similar 850s, being only 50 miles away, and yet only hit 23F. That's clearly an indication of the UHI problem since both stations are low elevation with heavy snowpack. You can tell just from memory that there's a disparity between the minima recorded by Central Park and what 850s would suggest for lows....-19C 850s in December this year only got the park down to 19F. -24C 850s in January 2009 only got the park down to 6F, even with snow cover. These are cold airmasses, but they just aren't doing the trick for Central Park because they radiate at an agonizingly slow rate. You can see here that the wind direction is almost due north because of the high pressure's position; this creates cold air drainage from the Hudson Valley and allows Central Park to get colder. As I've said before, KNYC gets much colder with a light north wind than with no wind at all. I also assume the Hudson River was starting to freeze over with the cold snap in January 2004, and that may have have reduced the moderating influence on the water when winds are close to due north. Amen. Finally someone who understands the physics of temperature. Link to comment Share on other sites More sharing options...
NorthShoreWx Posted January 16, 2011 Share Posted January 16, 2011 I agree that the airmass in Feb 1934 was much much colder than anything we've seen in our lifetimes-- as daytime highs arent influenced by UHI (the main reason why I advocate not using mins in evaluating averages in the summer or winter)-- and would most certainly have resulted in temps much below the -2 lows we've seen in our most recent frigid outbreaks, though Im not sure the low would have gotten down to -10. When was the last time NYC had a low of less than -2? We won't know unless we try but its very hard to know if we've ever duplicated soundings from 1934. Link to comment Share on other sites More sharing options...
Patrick-02540 Posted January 16, 2011 Share Posted January 16, 2011 You just wrote "Sorry Nate, but you're wrong about this" How is my comment any different? That sounded quite derogatory to me. You also said radiational cooling did not exist in NYC in 1934. You said a -15F low has nothing to do with radiational cooling. This is illogical and nonsensical. Ask some of the meteorologists on here, and I bet 99% of them agree with me. Don't tell me to grow up...I don't appreciate such insults. I have contributed many great insights and information to this forum, and I'm tired of the small contingent of members who consistently display a lack of respect towards others. It is one reason I have thought about shutting my account, just too many ignorant and rude members here... BTW, we are arguing about radiational cooling in Central Park, not exactly a life or death situation. Why do so many have to get bent out of shape over the weather? They get bent out of shape because it doesn't the Gorean GW line. Link to comment Share on other sites More sharing options...
Patrick-02540 Posted January 16, 2011 Share Posted January 16, 2011 Apparently a practice from some obscure series of science fiction novels... Yes ! Link to comment Share on other sites More sharing options...
bluewave Posted January 16, 2011 Author Share Posted January 16, 2011 I would attribute the lack of days lower than -2 at NYC since 1943 on the fact that since then the more extreme arctic outbreaks had the core of cold further to our west in places like PA in January 1994 and in Chicago in January 1982. January 1977 was very close in temperature at Central Park to January 1918 which was 59 years later. January 1977 averaged 22.1 degrees in Central Park and January 1918 averaged 21.7 degrees. The low temperature for the month of January 1918 was -4 which was very close to -2 for January 1977. Link to comment Share on other sites More sharing options...
NorthShoreWx Posted January 16, 2011 Share Posted January 16, 2011 I would attribute the lack of days lower than -2 at NYC since 1943 on the fact that since then the more extreme arctic outbreaks had the core of cold further to our west in places like PA in January 1994 and in Chicago in January 1982. January 1977 was very close in temperature at Central Park to January 1918 which was 59 years later. January 1977 averaged 22.1 degrees in Central Park and January 1918 averaged 21.7 degrees. The low temperature for the month of January 1918 was -4 which was very close to -2 for January 1977. Bingo! http://www.americanwx.com/bb/index.php?/topic/8865-winter-minimum-temperatures/page__view__findpost__p__296437 Link to comment Share on other sites More sharing options...
bluewave Posted January 16, 2011 Author Share Posted January 16, 2011 Bingo! http://www.americanw...post__p__296437 I can still remember all the ice on the bays around here during January 1977. Link to comment Share on other sites More sharing options...
Alpha5 Posted January 16, 2011 Share Posted January 16, 2011 forecasted to get down to 4 above tonight. Upton has been busting slightly high the past few nights so hopefully I can reach 0 Link to comment Share on other sites More sharing options...
doncat Posted January 17, 2011 Share Posted January 17, 2011 LaGuardia with a temp. departure from normal of +0.3 so far during January, lol... Wow thats crazy. My station is -2.8 for the month so far. Link to comment Share on other sites More sharing options...
nzucker Posted January 17, 2011 Share Posted January 17, 2011 I have a feeling Upton is going to bust tonight here with a forecasted low of 9F. It's currently 25.8/9, no way we get into single digits with the urban heat island and 850s only around -14C. Upton has been much too aggressive this week with the low temperatures in Southern Westchester; knowing the area's climatology intimately, I realize that we need 850s close to -20C to crack single digits regardless of how much snowpack there is or how clear the skies are. Radiational cooling just doesn't happen fast in the inner suburbs. Link to comment Share on other sites More sharing options...
Alpha5 Posted January 17, 2011 Share Posted January 17, 2011 I have a feeling Upton is going to bust tonight here with a forecasted low of 9F. It's currently 25.8/9, no way we get into single digits with the urban heat island and 850s only around -14C. Upton has been much too aggressive this week with the low temperatures in Southern Westchester; knowing the area's climatology intimately, I realize that we need 850s close to -20C to crack single digits regardless of how much snowpack there is or how clear the skies are. Radiational cooling just doesn't happen fast in the inner suburbs. They busted too high here for two nights in a row. Looks like this one may be too low as were still in the 20's. Not an easy job to do, either way...... Link to comment Share on other sites More sharing options...
nzucker Posted January 17, 2011 Share Posted January 17, 2011 Tonight is a total bust on temps...still 21.3F here and mostly cloudy. Expected low was 9F, not even going to get close. Link to comment Share on other sites More sharing options...
Alpha5 Posted January 17, 2011 Share Posted January 17, 2011 Only got to 19 here Cold air was bottled up in NNE Link to comment Share on other sites More sharing options...
NorthShoreWx Posted January 17, 2011 Share Posted January 17, 2011 Forecasted low here was 8, actual low was 22 (its still 22). I can't remember such a big miss in the short term. 20/13 (actual/forecasted lows) for NYC too. Link to comment Share on other sites More sharing options...
Stormlover74 Posted January 17, 2011 Share Posted January 17, 2011 Reminds me of MLK 2000 only the opposite. We had a cold shot coming through and were supposed to be in the low to mid 20s I believe and instead the afternoon temperature was in the 10 to 15 range and I believe our coldest day of the winter Forecasted low here was 8, actual low was 22 (its still 22). I can't remember such a big miss in the short term. 20/13 (actual/forecasted lows) for NYC too. Link to comment Share on other sites More sharing options...
Quincy Posted January 17, 2011 Share Posted January 17, 2011 temperatures this morning are barely moving, so it looks like cold overestimated at night, only to be underestimated during the day. I thought we'd get into the low/mid 20s in SW CT, but now even 20 might be hard to get. our high may very well have occurred at midnight! Link to comment Share on other sites More sharing options...
Fantom X Posted January 17, 2011 Share Posted January 17, 2011 sounds like a delayed CAA arrival Link to comment Share on other sites More sharing options...
NorEaster27 Posted January 17, 2011 Share Posted January 17, 2011 Was up in the southern dacks my low was -6 and when I left at noon the temp was 5 Link to comment Share on other sites More sharing options...
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