Cold and dry start, then milder for a while

There are many occasions when Decembers have seen anticyclonic tendencies dominating during the first week. Some have seen these tendencies continue into the middle of the second week, a few have been characterized by high pressure ruling the roost into the beginning of the third week, although the number where high pressure has dominated throughout have been limited.

When high pressure takes hold early to the east, it is usual to see these characteristics continue into the middle of the second week of the month, then the tendency is for high pressure to decline, albeit slowly, to allow a more mobile westerly to southerwesterly flow to establish by the end of the third and into the beginning of the fourth week; but certainly a milder regime is established by Christmas itself.

The trick is not to get caught-out by the few that have followed this trend then turn-tail just prior to the Christmas period allowing a colder plunge of air either from the north or northwest. Any change to milder weather is the interesting part, just prior to or over Christmas, or even delayed bringing a cold holiday period.

On balance the pattern is indicating something traditional as high pressure declines, allowing low pressure to control by mid-month.

There does then appear to be a situation developing when a clash of airmasses will take place. Initially mild conditions will be replaced by a colder regime over the Christmas period, remaining unsettled and a wintry mix is possible.

The remainder of 2004 is expected to be changeable before a drier and more settled interlude develops in the New Year. There is then more settled conditions for the start of 2005, although the prospects for mid-January at this stage looks unsettled and cool

Updated Monday 14th December 2004. Valid Tuesday 15th December 2004 to Wednesday 13th January 2005.

Issued by Weather Consultancy Services Ltd in cooperation with WeatherOnline Ltd.

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