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bluewave

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Plain and simple folks - January is the coldest month of the year in most areas of the Northern Hemisphere because the sun angle is at its lowest during the month as a whole. In addition, there is no sun at all above the Arctic Circle and does not allow for any warmth from the sun at all. Hence, it gets colder and colder there. Now, these airmasses regularly come down into our regions of the U.S. and bring with them colder and colder temperatures.

 

The sun angle is at its lowest from about December 6th to January 5th...i.e. the 30 day period with the lowest angular elevation.  However, just as June is not the hottest month despite the maximum angular elevation of the sun on 21 June (or thereabouts), December is not the coldest month...all based on the fundamental concept of heat capacity. 

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from 1959-60 to 2013-14 the coldest month was...

Dec Jan Feb Mar

...5...32...17...1.....

 

1869-70 to 1909-10...

...3...22...13...2...

during the 1910's February was coldest seven times while January was three times...

March was the coldest twice in the 40 years...December three times...The last 55 years December was the coldest five times and January 32...February had 17 while March just once...1960...

 

Yes...we can certainly look at it from a variety of angles...but I'll go with the 70 year mean temperature as sufficient evidence that February was colder than January for an extended spell in NYC.

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Definitely heat island, there's so much more concrete and asphalt sprawl over the area since the 1800's. Also, I wouldn't be surprised to see if NYC's snowfall is relatively unchanged since then either due to UHI having little effect during storms. Generally NYC's temps remain the same outside the UHI when it's snowing, although during marginal temp events and spring time April events snow typically falls as white rain, even in the park where grassy accumulations may occur but usually less than areas outside of the UHI. I'm sure Uncle has these stats readily available. Hope he can comment soon.

 

Nope...the records out of Newark show a major drop in snowfall averages when comparing the modern era & the 19th century.  The current annual average at Newark Field is about 29 inches, give or take.  However, a man named William Whitehead had an extended snowfall record not far from the location of the current airport from 1843 - 1870...and he observed a mean annual snowfall of 43.8 inches.  The fact that the Northern Hemisphere was still in the midst of the closing act of the LIA would seem to be as good a reason as any for the discrepancy.

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Nope...the records out of Newark show a major drop in snowfall averages when comparing the modern era & the 19th century.  The current annual average at Newark Field is about 29 inches, give or take.  However, a man named William Whitehead had an extended snowfall record not far from the location of the current airport from 1843 - 1870...and he observed a mean annual snowfall of 43.8 inches.  The fact that the Northern Hemisphere was still in the midst of the closing act of the LIA would seem to be as good a reason as any for the discrepancy.

 

Though, no doubt, urbanization  has also played some role in reducing snowfall in the city...

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Though, no doubt, urbanization  has also played some role in reducing snowfall in the city...

 

Also, I wouldn't be surprised to see if NYC's snowfall is relatively unchanged since then either due to UHI having little effect during storms. Generally NYC's temps remain the same outside the UHI when it's snowing, although during marginal temp events and spring time April events snow typically falls as white rain, even in the park where grassy accumulations may occur but usually less than areas outside of the UHI.

 

Board member NorthShoreWx wrote on this and gave me carte blanche to post his commentary (with attribution)...he has yet to rescind it... 

 

Proximity to the New York City urban heat island

Another factor that periodically influences snowfall accumulations across Long Island is the proximity to the urban heat island of NYC, and to a lesser extent localized heat islands in some of the more densely developed areas, particularly in Nassau County.

Buildings and paved surfaces tend to store and then release heat. In certain situations, the effect can be significant enough to cause snow to melt faster as it settles on the ground, or even to cause areas of rain embedded in a more general area of snow.

March19-2004s.gif This seems to occur most often during springtime snowfalls when the temperature is very close to or just above freezing. The heat added to the lowest levels of the atmosphere in urban areas may be just enough to cause most of the snow to melt as it falls. At times the impact can be quite dramatic, especially in areas close to New York City. This may have been the case on March 19, 2004 when 2 to 6 inches of snow fell in areas surrounding New York City, while only trace amounts were reported in 199604092300s2.gif Manhattan and urban New Jersey. The map to the right shows some reported snowfall totals for this storm.

A similar situation occurred during a strong nor'easter on April 9-10, 1996. The storm caused heavy precipitation through much of New Jersey, New York City, Long Island and southern New England. The precipitation was in the form of heavy snow throughout this area, except for in New York City and urban northeast New Jersey where slightly warmer temperatures caused the snow to mix with and at times change to rain. This kept accumulations there under one inch, even as areas just to the south received up to 8 inches of snow and parts of Long Island received over a foot of heavy wet snow. This snowfall map and chart shows snowfall and liquid equivalent totals for this storm.

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Board member NorthShoreWx wrote on this and gave me carte blanche to post his commentary (with attribution)...he has yet to rescind it... 

 

 

A similar situation occurred during a strong nor'easter on April 9-10, 1996. The storm caused heavy precipitation through much of New Jersey, New York City, Long Island and southern New England. The precipitation was in the form of heavy snow throughout this area, except for in New York City and urban northeast New Jersey where slightly warmer temperatures caused the snow to mix with and at times change to rain. This kept accumulations there under one inch, even as areas just to the south received up to 8 inches of snow and parts of Long Island received over a foot of heavy wet snow. This snowfall map and chart shows snowfall and liquid equivalent totals for this storm.

 

and the other map as the link does not seem to work...

 

1996April10Snowstorm.gif

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Yeah had 4 " here from that storm

i used your observation... :snowing: I visited my wife's family who lived in Sunnyside at the time and estimated they got at least a few inches...The April fools storm gave us a few inches while Central Park got a trace...31 degrees or 33 degrees makes a big difference...

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I would have to say that the NYC temperature difference between January and February

since 1980 is mainly a result of changing teleconnection indices.

The 10 coldest NYC Januaries since 1980 had a stronger -EPO/-AO pattern than the 10 coldest Februaries.

The 10 warmest NYC Februaries featured a stronger +EPO/+AO pattern than the 10 warmest Januaries.

The end result is more impressive January cold and February warmth in NYC since 1980

resulting in faster rising February temperatures relative to January.

10 warmest Januaries since 1980 in NYC

JANW.png

10 warmest Februaries

FEBW.png

10 coldest Januaries

JANC.png

10 coldest Februaries

FEBC.png

That's what I suspect as well.
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Statistically January is a wetter month than December and it also has less sunlight than the month of December. So therefore it's safe to say that January would stay a bit colder and especially colder than February. Since February is even wetter than January but with a lot more sunlight causing it to warm even more. The point is global warming is taking it effect but it's having a hard time to warm it as much on January because of the phenomena stated above.

Edit: Technically I was wrong about the precipitation average for NYC. December is wetter than January by 0.20 inches but I would have to guess (maybe someone could research it) but I would guess that January has less daylight than December and especially February. And I checked the January average sunny days are less than Decembers resulting a slower global warming effects.

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Statistically January is a wetter month than December and it also has less sunlight than the month of December. So therefore it's safe to say that January would stay a bit colder and especially colder than February. Since February is even wetter than January but with a lot more sunlight causing it to warm even more. The point is global warming is taking it effect but it's having a hard time to warm it as much on January because of the phenomena stated above.

 

Your argument may need a little more specificity...do you mean globally or in NYC...December is generally a wetter month than January in NYC...and January is wetter than February...so both comparisons you made are wrong.

As I noted previously, the angular elevation of the sun is higher for a higher percentage of January than it is for December; so your argument than "January has less sunlight than the month of December" would also be incorrect. 

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Your argument may need a little more specificity...do you mean globally or in NYC...December is generally a wetter month than January in NYC...and January is wetter than February...so both comparisons you made are wrong.

As I noted previously, the angular elevation of the sun is higher for a higher percentage of January than it is for December; so your argument than "January has less sunlight than the month of December" would also be incorrect.

I have always measured meteorological winter as Decembrer 6 to March 6. I am wondering how the calculations would change if we started each statistical month on the sixth.
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Statistically January is a wetter month than December and it also has less sunlight than the month of December. So therefore it's safe to say that January would stay a bit colder and especially colder than February. Since February is even wetter than January but with a lot more sunlight causing it to warm even more. The point is global warming is taking it effect but it's having a hard time to warm it as much on January because of the phenomena stated above.

Edit: Technically I was wrong about the precipitation average for NYC. December is wetter than January by 0.20 inches but I would have to guess (maybe someone could research it) but I would guess that January has less daylight than December and especially February. And I checked the January average sunny days are less than Decembers resulting a slower global warming effects.

February is typically our region's driest month of the year.
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but I would guess that January has less daylight than December and especially February. And I checked the January average sunny days are less than Decembers resulting a slower global warming effects.

 

Follow up from earlier: The sun angle is at its lowest from about December 6th to January 5th...i.e. the 30 day period with the lowest angular elevation.  However, just as June is not the hottest month despite the maximum angular elevation of the sun on 21 June (or thereabouts), December is not the coldest month...all based on the fundamental concept of heat capacity. 

Also, as a general rule, December tends to have fewer sunny days than January in NYC...which would not seem surprising, since the month is wetter.  Moreover, January features more bright sunny days as arctic anticyclones born over the Prairie Provinces of Canada predominate with greater frequency than during December. 

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So I guess my only argument is here is that the cold air masses on January are frigid I figured that January is the coldest month right? So is it safe to say that January has a more bigger average snow cover, than other two months (December and February) resulting any sunny days, for the sun rays to get sent right back in our atmosphere. Ultimately those rays warm the stratosphere which results wilder storm systems during February and March. So snow cover could be the result and it's cold averages staying relatively cold and having a hard time warming up because of snow cover.

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So I guess my only argument is here is that January may have cloudier days and the cold air masses on January are that cold and they have a hard time warming up. I figured that January is the coldest month right? So is it safe to say that January has a more bigger snow overall cover than other two months (DEC, FEB) resulting any sunny days, for the sun rays to get sent right back in our atmosphere. Ultimately those rays warm the stratosphere which results wilder storm systems during February and March.

 

I wouldn't even worry about the stratosphere at this point...our atmosphere has 4 layers...troposphere (where all our weather occurs), stratosphere, mesosphere, & exosphere.  I do know that arguments have been made about the role of stratospheric warming and how it impacts sensible weather below...but at this point, I would just focus in on the happenings in the troposphere.

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I wouldn't even worry about the stratosphere at this point...our atmosphere has 4 layers...troposphere (where all our weather occurs), stratosphere, mesosphere, & exosphere. I do know that arguments have been made about the role of stratospheric warming and how it impacts sensible weather below...but at this point, I would just focus in on the happenings in the troposphere.

ok so January snow cover and it's cold averages? What do you think?
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So I guess my only argument is here is that January may have cloudier days and the cold air masses on January are that cold and they have a hard time warming up. I figured that January is the coldest month right? So is it safe to say that January has a more bigger snow overall cover than other two months (DEC, FEB) resulting any sunny days, for the sun rays to get sent right back in our atmosphere. Ultimately those rays warm the stratosphere which results wilder storm systems during February and March.

A couple points:

1. February is on average drier than January since the Atlantic sst's have cooled throughout the winter months. This inhibits moisture availability for nor'easters, our primary source for snow in the winter.

2. Storms can be more intense in the Spring but not because of the stratosphere. It's more a result of increasing temperature contrasts from invading warm air masses caused by seasonal transition.

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So I guess my only argument is here is that the cold air masses on January are frigid I figured that January is the coldest month right? So is it safe to say that January has a more bigger average snow cover, than other two months (December and February) resulting any sunny days, for the sun rays to get sent right back in our atmosphere. Ultimately those rays warm the stratosphere which results wilder storm systems during February and March. So snow cover could be the result and it's cold averages staying relatively cold and having a hard time warming up because of snow cover.

 

Worldwide and in NYC, January is the coldest month.  However, in both NYC and the United States in general, February is the snowiest month of the year,

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A couple points:

1. February is on average drier than January since the Atlantic sst's have cooled throughout the winter months. This inhibits moisture availability for nor'easters, our primary source for snow in the winter.

2. Storms can be more intense in the Spring but not because of the stratosphere. It's more a result of increasing temperature contrasts from invading warm air masses caused by seasonal transition.

 

February is drier than January...though a bit of that can be attributed to the fact that it is the shortest month of the year. 

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snowiest yes but overall snow cover, January has more days with snow on the ground.

 

In a location like NYC...where continuous snow cover is very unusual...this sort of thing is generally a highly variable matter...but in say interior southern and central New England...where snow cover is continuous from December through March or early April...the greatest snow depths on the ground are usually reached in February or even March.

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