Wednesday, September 03, 2008

Snow in August

Thought I had blogged this ages ago, but it seems to be still at the draft stage...

Snow fell on Mt Fuji Aug 9 at earliest time ever

However, it seems that this new record is due to an arbitrary decision to redefine some hail as snow. It has still been unseasonally wet and cold for the latter part of the summer - which I would have been quite happy about but for the fact that we were hoping to have another trip into the mountains. I'm certainly glad we made the effort earlier.

1 comment:

Kooiti MASUDA said...

This is not a formal meteorological observation, but still a piece of official business of Kofu Local Meteorological Observatory (http://www.tokyo-jma.go.jp/home/kofu/ ). They want to have a consistent long-term record, so they have a bureaucratic definition of "the earliest snow of the year".

It is the earliest date when snow cover on Mt. Fuji was viewed from Kofu observatory _after_ the date when the surface air temperature at Mt. Fuji took its annual maximum.

"Snow" here actually means solid precipitation, so hail is included. (In the case of this year, a Japanese newspaper confirms that it was hail according to the staff of a lodge:
http://www.yomiuri.co.jp/eco/news/20080827OYT1T00663.htm .)

The "news" needed to be delayed until the observatory staff was confident that there would be no more warmer days this year. The date of the annual maximum temperature this year was 21 July. Though I have not yet found an authoritative value, the normal date of the maximum temperature should be in the first week of August.

Snowfall is not rare in summer at the top of Mt. Fuji (3776 m above sea level). But it has been rare in a short time slot around the date of the annual maximum temperature.

(The annual cycle of temperature is curious. A decade ago, I made an analysis. Though I have not made it into official publication, I put the report in Japanese at http://web.sfc.keio.ac.jp/~masudako/memo/annual/glextr/index.html . The normal date of the annual maximum temperature is around the first week of August at most places in in Japan, and Mt. Fuji (though not included in that report of mine) is not an exception. On the other hand, the timing on the European Alps is similar to Japanese places, but it is much earlier in the plain areas of the European continent. See http://web.sfc.keio.ac.jp/~masudako/memo/annual/glextr/discuss.html" . Note: my analysis was about the 1-year harmonic component, contrary to the above info about Mt. Fuji which refers to the actual time series.)