CLIMATE-UK.COM'S REVIEW OF THE BRITISH METEOROLOGICAL SCENE

MONTHLY SUMMARY

No. 613

For JANUARY 2007

WARMEST SINCE 1921. DULL AND WET IN MOST WESTERN DISTRICTS BUT SUNNY IN THE EAST

Text Box: The very unsettled south-westerly type which set in just before the New Year lasted without interruption until the 20th. This was followed by a brief northerly outbreak, but rising pressure led to the establishment of a large anticyclone close to southwestern Britain from the 26th onwards. The mean monthly pressure chart shows a steep westerly gradient (somewhat veered from normal) over the British Isles. The anomalous flow over the region was therefore north-westerly, and sea-level pressure ranged from 8mbar below normal at Lerwick to 4mbar above at Scilly and Valentia. The main anomaly centres were -19mbar over Finland and +9mbar between Ireland and the Azores.

A vigorous west to south-westerly airflow covered the UK during the first week, Atlantic fronts crossed all parts at frequent intervals, and following the passage of a warm front on the 8th tropical maritime air swept the entire country for a period of 24-36h. The New Year’s Eve gale subsided quickly early on the 1st, but not before Sheerness (Kent) logged a gust of 64kn, and the first two days of the month brought sunshine and blustery showers. All areas where mild and wet on the 3rd and a high of 14.3°C was recorded at Hawarden (Flintshire), but showery weather returned for the next two days. Heavy orographic rain affected western and northern districts between the 6th and 10th - 245mm in 120h at Capel Curig (Snowdonia) - and it became exceptionally mild with 15°C reported from Prestatyn and Colwyn Bay (both in north Wales) on the 8th, while the minimum the following night at Sutton Bonington (Notts) was 12.5°C. On the 10th a gust of 82kn was logged at Benbecula (Western Isles).

The rapid succession of frontal systems resumed on the 10th maintaining the very unsettled and often very windy weather, but pressure became relatively high over southern Britain between the 10th and 15th resulting in relatively small amounts of rain here. A gust of 77kn was recorded at Lerwick (Shetland) on the 12th, while 60mm of rain fell at Loch Shin (Sutherland) on the 14th. An


	$Text Box: intense depression crossed central Scotland on the 18th and a severe gale swept England and Wales with gusts to 65-75kn over a wide area; 19 people died. Parts of central Scotland had 5-10cm of snow, but it was again exceptionally mild south of the border with highs close to 15°C at several sites in southern England, the southwest Midlands and along the north Welsh coast. Strong rises of pressure in mid-Atlantic on the 21st/22nd were associated with a short-lived northerly outbreak over the UK which brought light to moderate snowfalls to Scotland and northern England between the 21st and 24th, and to the Midlands and southeast England between the 22nd and 25th, although at low levels the snow did not last long on the ground. The temperature fell to -7.1°C at Dalwhinnie (Inverness-shire) overnight 24th/25th and to -6.8°C at Benson (Oxon) the next night. Falmouth (Cornwall) reported 8.4h of bright sunshine on the 25th. The Atlantic anticyclone drifted to a position off SW Ireland by the 26th and the flow over the British Isles backed northwesterly, bringing milder but cloudier weather with local drizzle and hill fog. The 31st was sunny in southern Britain and temperatures reached 13-14°C in some eastern districts. This January ranked fifth warmest in the entire CET record, after 1796, 1834, 1916 and 1921, but in Scotland and Northern Ireland that of 2005 was fractionally warmer. Rarely for January there was not a single instance of a sub-zero maximum at a low level (below 300m amsl) site in the UK. Rainfall ranged from about 60 per cent of the long-term average along the Channel coast from Dorset to Cornwall, in Lincolnshire and the East Riding, and locally in northeast Scotland, to 200-250 per cent locally in the southwest highlands, the Lake District and north Wales. Sunshine was in short supply until mid-month but was plentiful thereafter; sunshine percentages ranged from below 60 locally in western Scotland to 160 in northeast England where Boulmer (Northumberland), with 91h, reported its sunniest January since 1991.$

TEMPERATURE

SUNSHINE

RAINFALL

Highest and lowest totals

on record for month

on record for month

PLACE