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Autumn/Winter FI Charts 2012/13
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Few interesting posts from a few others over on net weather including MT, also the ECM 12Z run hinting at a scandi ridge in its later frames, If this developed could lead to an easterly down the line.
This was posted by GP, Head forecaster for Netweather.
I suggest that with a strong collaboration of MJO wave, poleward +AAMr signal and succession of Wave 2 activity in the next 2 weeks, the stratospheric vortex may be on the bring of collapse 1st week December and ripe for a higher latitide block to take root in December. Whilst not totally against any Scandinavian ridge, I think the wavelengths here more favor a ridge to our W / NW.
Then this was posted by MT
I am continuing to call for cold and possibly severe cold in February with onset in late January. So out of interest, I took the daily CET values in a research file and calculated daily averages for the winters with the 14 coldest Februaries to see what sort of early signals were on display. On the average, the Novembers of these winters averaged 6.3 and the Decembers 4.3, so that there was no strong signal of cold before January. Some days were considerably above normal in this period, for example 24 Nov was 6.9, and 14 Dec was 5.9 on average.
The data set show a decline around New Years and the average January associated with these 14 coldest Februaries averaged 1.4 with sub-freezing averages setting in on 24 Jan. The average of the 14 cold February cases was -0.3 C. The coldest day in the series was 14 Feb at -1.7 C.
Now although my model-based prediction shows a mild January followed by a cold February, this is an unusual combination and given the strength of the cold signal, I should hedge that by saying that any early mild spells could be cancelled out by later cold spells on the way towards a cold February. We would be in almost uncharted waters to see a combination like (6,0) for the first two monthly CET values. The years that came closest to this sort of reversal since the Maunder provided a couple of good examples were 1902, 1956, 1969 and 1986. January could be described as near normal rather than mild in most of these cases, but in 1969 (where Jan was 5.5) there was an extreme reversal, from 9.1 C in the week of 21-27 Jan to -1.8 in the week of 13-19 Feb.
Anyone pondering these stats should of course keep in mind that all years mentioned refer to Jan and Feb, the year we are now in corresponds to the year before all the years cited.
The general conclusion is that if my research model is picking up an accurate "read" on the winter, we should expect some big ups and downs and not get too discouraged about any blocking mild patterns between now and mid to late January as these are almost implied by the cold February signal. We could break into the cold early as in 1894-95, or late as in the above examples. Last winter demonstrated that a strong signal has to be blended into the "modern climate" and that even when Europe is generally in an extreme winter pattern this can have difficulty extending all the way west to some parts of the UK and certainly Ireland which almost escaped the whole episode. I have the impression from looking at analogues that this winter's severe cold in Europe might be sourced a bit further north which will help the chances of getting it further west into Britain and Ireland.
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