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November 2012 forecast


Thundery wintry showers

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The forecast ran as follows:
[quote]Changeable, near-average temperatures


November 2012 will be a changeable month with low pressure set to control the weather for most of the time. The long-range signals point to near-average temperatures and no significant cold spells during the first two-thirds of the month at least.

Low pressure centred over northern Scotland will bring a rather cool and showery theme during the first five days of the month, with the majority of the showers in western areas, but some will penetrate into eastern areas too, particularly over north-east England. On the 4th and 5th a secondary low will track over southern England and will give a spell of cloudy weather and prolonged rain from the Midlands southwards with snow on high ground. Further north, a mix of sun and showers will continue but as the wind switches around to a northerly or north-easterly direction, showers on the 5th will mostly be concentrated in eastern areas bordering the North Sea.

Between the 6th and 8th the weather is expected to turn milder and cloudier with a moist west to north-westerly airflow in occupation, and there will be some persistent rain over Scotland, Ireland, Wales and northern and western England on the 6th and 7th although south-eastern England will probably stay dry. Temperatures will generally reach highs of 10 to 13C. The 8th/9th will see low pressure become established again to the north and north-west of the country, so a band of rain will sweep south-eastwards across the country, followed by brighter, showery weather.

Towards mid-November we can expect a generally showery regime with low pressure sat to the north and north-west of the British Isles. Most of the showers will be concentrated in western areas, while there is also the possibility of some more organised belts of rain at times, particularly over southern and central parts of England. Temperatures will mostly be close to the seasonal average. After midmonth a milder, unsettled regime will take over with more frequent frontal systems and some inputs of warm tropical air, and it will become generally cloudy and wet, particularly in north-western Britain.

The last third of November is likely to feature a colder, quieter interlude, most likely during the last week of the month, which may feature some snow showers for northern and eastern counties for a time although confidence on this is low. Broadly speaking mild and unsettled weather around the 20th will give way to high pressure heading in from the west. I am not expecting any exceptional cold snowy weather like most of us saw at the end of November 2010- just an ordinary late-November cold snap.

Overview
Temperatures during November 2012 will generally be within a degree of the 1981-2010 average, with southern England up to a degree warmer than average and northern Scotland up to a degree colder. A Central England Temperature of around 7.1C is expected.

Due to the changeable nature of the weather it will generally be another wet month with rainfall excesses of 30-70% in most regions, and western and southern England plus much of Wales will generally be wettest relative to normal. Eastern Scotland will be the main exception, where rainfall will be near or slightly below average.

Sunshine totals will be well above average over much of eastern Scotland and north-east England with excesses of 20-50%, but sunshine will be near or below average elsewhere, with south Wales and south-west England probably dullest relative to the long-term average (shortages of 20-30% are possible).

[/quote]

After a couple of forecasts which were rather wide of the mark, I thought this one went quite well, particularly during the first and last weeks of the month. The showery north-westerly regime that I had predicted leading up to midmonth lasted just a couple of days though, and instead high pressure was the dominant theme around midmonth, though a rather cloudy high for most of us. I managed to pick out the colder interlude towards the end of the month with high pressure advancing from the west, though not the exceptional rainfall events which led to widespread flooding.

Statistically sunshine, temperature and rainfall anomalies were generally similar to what I predicted, although I won't lie- I got a bit lucky with the rainfall stats as the unsettled periods of the 1st-20th were generally less wet than I had envisaged, while the last third of the month was wetter, and the two cancelled each other out resulting in my monthly rainfall projections being near the mark.

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