The First Snow Fall of the Season

Manni

"Yes! The first snowfall of the year" - someone, somewhere at least once a day

Is this statement true?

Ryan_m_b

How could one possibly know?

Jack21222

Every time I see or hear the words "first snow," this song pops into my head, and usually remains there for a few hours:

Manni

Sorry, I should've clarified. What I specifically want to know is whether there're enough places on Earth that would allow there to be a "first snow" for every day of the year at least once.

Ryan_m_b

I'm not sure what you mean by "first snow", it's not a term I'm familiar with. There are certainly grounds for saying that everyday it snows somewhere.

Manni

"First snow" is usually used to describe the first time it actually snows for any given place for that year. Does that help?

Ryan_m_b

It helps define the term. I'm not sure if the case could be made for that.

Manni

Oh ok.

klimatos

Not very much. If it snows on New Year's Day, then it is automatically the first snow of the year!

SW VandeCarr

I think the OP means the first measurable snowfall (more than a trace as defined by the local weather service) at a location during the (climatological) winter season. It might be interesting to plot these over some geographical area, but to be scientific, you need an existing observational framework such as exists in many countries. These data could probably be collected by a researcher, but it's not a priority for funding. More important would be something like the first killing frost. Haphazard observations reported on PF are not very meaningful.

Ophiolite

Clearly, for this to apply, you need to break those portions of the world that routinely experience snowfall into at least 365 discrete geographical areas. Roughly half of these need to be in the Southern hemisphere. In practice, to ensure you get a hit on every day, the areas would have to be more numerous. (Much more numerous if you take 'ensure' literally.)

That said, I think it would be an unusual year in which you could actually say this somewhere on the planet for every single day. And, as VandeCarr implies, it wouldn't be a very meaningful datum.

SW VandeCarr

Why? All we are talking about is taking note of the first measurable snowfall of the climatological winter season at a particular location. For example South Lake Tahoe, California, USA had its first measurable snowfall of the 2011-12 season on October 3rd of this year (about 10 cm). That's fairly early even for this location and might be of interest to some people. That's all we are talking about.

Climate atlases of the USA have contour maps for the average date of the first killing frost and for first hard freeze. Such a map might be constructed for the average date of the first measurable snow based on date spreads. It's really a very simple concept. Some areas will be outside the snow zone entirely and some areas might have recorded measurable snow in every month of the year, and can be so indicated.

EDIT: I re-read the OP. Obviously that's not a provable statement, particularly in considering that in the Northern Hemisphere the first seasonal snow in the temperate regions will usually be in Oct-Nov-Dec and in the Southern Hemisphere in April-May-June. In places where it can snow in any month, there is no such thing as a "first snow" except as defined arbitrarily.

klimatos

Given that Antarctica, central Greenland, and many high mountain areas are snow-covered the year around, it seem probable that somewhere in those areas it snows on any given day of the year.

Of more practical value for U. S. "first snows" is the NCDC publication "Climatological Data". This serial is published for each state each month, and has been in publication for about a century. It gives snowfall data day by day for that state and that month for cooperative observer stations as well as NOAA locations. Thus, the average state has snowfall data for more than fifty locations. If your local library is a federal depository (many are), it will have a collection for your state.

A meaningful period of record would be thirty years. A competent scholar could compile the data for a sizable area with a moderate day's work. I've done it.

D H

My first thought was that the title of the thread (The First Snow Fall of the Season) is very different from the question posed in the original post.

My second thought was that the question was a math/logic riddle posed as a climatological question. Something about continuity and a branch cut at midnight on January first? Nah.

My third thought was that the question posed in the original post is a bit ill-formed. Assuming the key is "year" rather than "season", I see four distinct interpretations. My second thought suggests a mathy rather than riddle-like expression. My interpretations are:

1. For every year and for every day of the year, there exists some location on the Earth at which the first snowfall of that year fell on that day at that location.
2. There exists some year such for every day of the year, there exists some location on the Earth at which the first snowfall of that year fell on that day at that location.
3. For every day of the year, there exists some year such that there exists some location on the Earth at which the first snowfall of that year fell on that day at that location.
4. None of the above.

Interpretation #4 is a catch-all in case I'm way off the mark. I'll ignore that interpretation, but am willing to stand corrected. Interpretation #1 involves two universal quantifiers and is the hardest to answer in the affirmative. Interpretation #2 changes the universal quantifier on the year to an existential quantifier; one flukey year is all it takes to say the answer is true. Interpretation #3 is weaker still.

One key to the problem is the branch cut at midnight on January first. Suppose a winter storm in the southern hemisphere brings the first snow of the season on June 30th in some areas, July 1st in others. That first snow of the season was most likely the first snow of the year as well.

Now look at the northern hemisphere, where the corresponding winter storm would bring the first snow of the season on December 31st in some areas, January 1st in others. While the January 1st snowfall was obviously the first snowfall of the year, the December 31st snowfall was the last snowfall of the year. That last snowfall of the year was the first snowfall of the year only if the area had not received any snow whatsoever for the 364 preceding days (365 preceding days in the case of a leap year).

While the first snowfall of the year occurring on June 30th is not at all problematic, the first snowfall of the year occurring on December 31st is a bit problematic. The branch cut at midnight on January first means that the key to answering in the negative lies in the northern hemisphere. There's no support from the southern hemisphere to make December 31st the first snowfall of the year. December 31st is well into climatological summer in the southern hemisphere. December 31st is not the answer, however. A place where it snows rather infrequently may well see a snowless winter followed a year later by a fluke New Year's Eve snow storm.

The key to the problem is late October / early November. Early climatological autumn in the northern hemisphere is early climatological spring in the northern hemisphere. Some place in the southern hemisphere that receives snow infrequently may well be hit by an early spring snowstorm that brings the first snow of the year. Support for first snowfall of the year occurring in climatological spring somewhere in the southern hemisphere dwindles as spring starts turning to summer. Places in the southern hemisphere that do experience snowfall in late October / early November almost certainly receive snow in June, July, and August. In the northern hemisphere, places that experience snowfall in late October / early November almost certainly experience snowfall in January, February, and March.

I would say that the answer is almost certainly no to interpretation #1, possibly yes to interpretation #3.

Manni

Thanks a lot DH! Just a little story on this, this statement came to mind when I was watching television and checking my phone. On both screens, there were people proclaiming the first snow of the season. And a few days later a friend who lives in Montreal said that they had received their first snow fall of the season. So I questioned whether this 'first snowfall' was unique for every location for every day of the year. I was hoping for a "yes" for interoperation #1. But oh well. It cleared everything up for me. Thanks again!