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R J Smith winter forecast

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R J Smith winter forecast

Post by KTtom » Fri Dec 23, 2011 12:48 pm

I hope Mr Smith doesn't mind, but its really worth posting his forecast which was compiled at the start of November, already it has been uncannily accurate, compared to some of the others, lets hope January comes to fruition :)


Winter Forecast for 2011-12

General Forecast Statement

The winter season appears likely to be cold again, at least on balance, but unlike last year, January may be the most wintry month of the three. The very basic overview is for a rather cold November, a variable December near average overall, a cold and potentially snowy January, and a mild February, followed by a "backward" March that has a return to rather wintry weather later in the month. For reference, CET monthly temperatures are predicted at 5.8 for November, 4.5 for December, 1.5 for January, 6.2 for February, and 6.5 for March. Precipitation is expected to be generally 25-50 per cent above normal except for pockets near normal in the south and east. Snowfall is expected to be above normal almost everywhere with several wintry periods expected.

The detailed outlook

From what will evidently be a cold period in late October, expect a recovery to mild weather for a while in early NOVEMBER, but progressively colder weather mid to late month with some early signs of winter in northerly and easterly outbreaks. Some frost days may occur in central and northern regions but unlike last year, this late November cold is not expected to dig in and produce a lengthy cold spell.

DECEMBER may be a roller coaster of mild and cold spells. The coldest part of the month is likely to come around the 15th to 20th. Before that, the first two weeks may include some strong winds from deep Atlantic lows, heavy rainfalls, brief intervals of hail or snow, but eventually, arctic air should develop and there could be snow on the ground at times just before Christmas. Then the Christmas holiday period is expected to turn milder with fog and rain especially around the 27th when it could once again become rather stormy. By New Years Eve it may be turning a lot colder.

JANUARY may be "the" month for this coming winter, and there may be several occasions with snow although the first week to ten days may start with more of a northwest flow that would restrict snow to western and northern regions. This could be a windy period in general before deeper cold arrives probably from a Scandinavian high. This should direct the winds more easterly and give the higher snowfall potential in central and eastern counties. Severe frost may develop and the CET estimate (1.5) is conservative depending on snow cover feedback, but frost days seem very likely around mid-January. There may be further snowfalls later in the month as the storm track tries to push back north.

FEBRUARY could start out cold and snowy but the model output shows a strong warming early in the month and a peak of very mild conditions in mid to late February. This suggests that southerly flow may predominate and reverse the cold pattern to mild or even very mild. It may be rather dry in this pattern for the south and east, trending to wet in western Scotland and Northern Ireland.

MARCH is expected to start out mild but become a "backward" sort of early spring month with returns to wintry patterns later on. The below normal trend may deepen into early April. The warmth of April 2011 may be in contrast to a cold April in 2012 with May the warm month this time.

I will of course update this forecast if different indications are given from more reliable time scales, but this is what the numerical output shows at present. You could think of this method as being similar in concept to the CFS system although using (presumably) different input. As always, we hope for the best and consider "success" to be fairly loosely defined in terms of being more often right than wrong, or on the right side of normal two-thirds of the time.

A Few Other Notes

This winter, the lunar perigee falls about halfway from full moon to new moon or during the descending phase of lunar declination. This has in past analogues been associated with temperature reversals from mild to cold as the southward pull of the Moon towards southern max (at winter new moon) is enhanced. This is one reason why a lot of the colder intervals in the forecast are essentially lined up around mid-month although this period is only 28 days. The energy levels this winter will vary from an active phase lasting 5-6 days to a low-energy phase lasting 8-10 days. This may show up in a modulation of stormy weeks followed by blocked or inactive weeks. It's one reason why I suspect the main theme of the winter before any severe cold in January may be "from one extreme to the other." We may be reading a lot of comments in discussions about how the season cannot "make up its mind" and settle into one pattern. For those who like their winters active, this should be a good thing. For those who like cold and/or snow, patience may be necessary but January should deliver this time.

I think that in such an active pattern, a major windstorm seems a fairly good bet. While not wishing to be too specific, periods around the December and January full moons are favoured for strong westerly winds.

My advice to people in weather-sensitive areas of the economy would be to plan for a severe winter or at least a more severe winter than average, but not to expect it to be non-stop, there will be relaxed spells between wintry blasts. Some of the more extreme conditions in January may be harsh in isolated higher regions of the country. Livestock may need to be indoors or provided with extra feed at times. Road travel may be disrupted about 5 to 10 per cent of the time outside the more temperate south. There is a good chance of seeing four or five significant snowfall events and one or two major events possibly blizzards in some cases.

So now we wait ... and watch.


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