7 replies to this topic

[Stormchaser]

Short answer: Very little correlation compared to October. Note the following statistics.

First for all Novembers since 1950:

For NYC -- November:

A) Of the 31 warmer than normal winters, 16 featured a warm November prior to it. So 16/31: 52%

B) Of the 28 colder than normal winters, 12 featured a cold November prior to it. So 12/28: 43%


NYC's snowiest winters since 1950 -- 9/11 of them had warm Novembers preceding the winter. Below is the composite:





Now here's the data for Novembers following a cold October:

For NYC - 25 cold Octobers since 1950.

IF October is cold...

And November is cold, 5 of 7 ensuing winters colder than normal, 1967(weak), 1972(strong), 1980(weak), 1981(weak), 1992(strong), 2002(moderate).

And November is normal, 1 of 6 ensuing winters colder than normal (2 warm, 3 normal), 1952(weak), 1974(weak), 1978(weak), 1987(strong), 1988(strong), 2008(weak).

And November is warm, 8 of 12 ensuing winters colder than normal (3 warm, 1 normal), 1957(moderate), 1958(weak), 1964(moderate), 1965(strong), 1966(weak), 1977(weak), 1979(weak), 1993(weak), 1994(moderate), 1999(moderate), 2003(weak), 2006(weak).

So for cold Novembers, 71% of ensuing winters were cold, and for warm Novembers, 67% of ensuing winters were cold. Essentially it's consistent w/ my earlier NYC results that November doesn't matter much.


Average snowfall for cold Nov winters: 20.0"
Average snowfall for normal Nov winters: 18.6"
Average snowfall for warm Nov winters: 29.7"

Of those 25 cold Octobers in NYC, 9 of them were El Ninos.

Of those 9:

5 had warm Novembers, 3 of 5 years had cold ensuing winters
3 had cold Novembers, 2 of 3 had cold ensuing winters
1 had a normal November, the ensuing winter was also normal.

Again not much of a signal there. 60% versus 66% for warm vs cold. The big thing was getting the colder than normal October which we have in the books now.


Bottom line: the temp profile in November doesn't mean much, especially following a cold October. And a warm Nov is much better statistically speaking for higher snowfall in the NYC area.

[snowfreak188]

im starting to get a little excited for this winter!thanks for posting this here.

[Virgaman]

Thanks storm

great writeup, i enjoyed reading this and yes i also heard november is a poor signal to what can happen for the winter. ONe winter that stands out was the winter of 1975-76, i remember November being very warm throughout the month, then by mid december into january it became very cold and snowy, but in february and march that year it turned very warm again, not saying the same thing can happen, but november being warm or cold does not matter, the main thing is to watch for a pattern flip which is not being seen anytime soon unfortunately.

[lab94]

nice work Storm. A quick question. What do they concider above or brlow temp wise.? Is it +1 or higher above and -1 or lower below and inbetwwen normal?

[roughsurf]

lab94, on Nov 17 2009, 06:50 AM, said:

nice work Storm. A quick question. What do they concider above or brlow temp wise.? Is it +1 or higher above and -1 or lower below and inbetwwen normal?

Thanks for putting in the time to write this up Storm. All is appreciated. To piggy back on Labs question and it may be a stupid one, but when you talk about above/below normal for October, how is the average temp figured out, country wide or specific regions and would it matter if we were below normal and the rest of the country was above normal, could the same thought process be used for the ensuing winter?

Thanks again,
mark

[shark253]

I believe that mother-nature brings what she wants to bring. Cold November..warm November, and etc can equal to any kind of Winter. Bottom-line is, will Mother Nature cooperate this winter and give us a few nice healthy snowstorms. Folks....I have a gut feeling this may be a really good winter coming up in terms of snow and cold.

[snowfreak188]

all i cared about was the cold October like what got dont care about November one bit.

[Stormchaser]

Thanks guys.

lab94, on Nov 17 2009, 06:50 AM, said:

nice work Storm. A quick question. What do they concider above or brlow temp wise.? Is it +1 or higher above and -1 or lower below and inbetwwen normal?

Lab,

Thanks, It's all pretty subjective when it comes to exact demarcation lines for above/below/normal, but for the departures of each particular month, the ranges are usually as follows: +1.3 or greater; warmer than norma, -1.3 or lower; colder than normal, and normal in between that.

roughsurf, on Nov 17 2009, 09:00 AM, said:

Thanks for putting in the time to write this up Storm. All is appreciated. To piggy back on Labs question and it may be a stupid one, but when you talk about above/below normal for October, how is the average temp figured out, country wide or specific regions and would it matter if we were below normal and the rest of the country was above normal, could the same thought process be used for the ensuing winter?

Thanks again,
mark

Mark,

Thanks and your question is definitely a good one -- usually it's beneficial to include a larger geographical area as this will enhance the overall correlation. The entire Northeast region experienced a colder than normal October, which is a favorable signal for the winter (temp profile of October is positively correlated with the winter DJF). If we look at the nation as a whole, it was the 3rd coldest October on record; winters that followed Octobers w/ top 10 cold also featured below normal temp winters as well. So in general the connection between cold Eastern US Octobers and ensuing winters is a pretty strong one (as shown by the data above; about 70%). Obviously one statistically correlation is only going to get you so far which is why I researched many other factors for my winter outlook.