ern's: Lookback: February Lookback - A month of two halves, Mar 07

Thursday, March 22, 2012

Lookback: February Lookback - A month of two halves, Mar 07 - 16:15

High pressure dominated to such an extent during February that it ended up the eighth most anticyclonic February in 140 years of records. Mean sea-level pressure ranged from 7mbar above normal in Shetland to 17mbar above in southwest Ireland and the Isles of Scilly. During the first 12 days of February a strong ridge of high pressure extended towards the UK from a Russian anticyclone, and as a result the weather during this period was very cold indeed. Subsequently, highest pressure was often found close to southern Britain, so consequently from mid-month the weather became unusually mild.

Mean maximum temperature for February ranged from 9.8°C at Murlough (Co Down) to 5.0°C at Thorncliffe (Staffs), while mean minimum temperature varied between 6.8°C at St Mary's (Isles of Scilly) and minus 1.2°C at Chesham (Bucks). Mean monthly temperature was 1.5-2.0degC above the 1981-2010 normal over much of Scotland and Northern Ireland, but around 1degC below in parts of Southeast England and East Anglia. The Central England Temperature (CET) of 4.1°C was 0.4 degC below the long-term mean, colder than last February but warmer than that of 2010; in the last 100 years, 60 Februarys were warmer and 40 colder.

The highest maximum at a standard site (i.e excluding rooftop and mountain sites) in the UK was 18.7°C at Coleshill (Warwicks) on the 23rd, while the lowest minimum was minus 18.3°C at Chesham (Bucks) early on the 11th. The lowest daytime maximum was minus 5.4°C at Coningsby (Lincs) on the 11th, and the warmest night was that of 27th/28th with a minimum of 13.2°C at Aboyne (Aberdeenshire).

Rainfall averaged over England and Wales during February was 31mm which is 47 per cent of the average for the standard reference period 1981-2010, the lowest for this month since 1998; in the last 100 years, 13 Februarys were drier while 87 were wetter. The equivalent figures for Scotland were 60mm and 88 per cent of the normal amount, and for Northern Ireland 46mm and 78 per cent. Monthly totals at routinely-available sites varied between 310mm at Cluanie Inn (Wester Ross) and 6mm at Shoeburyness (Essex).

Sunshine averaged over England and Wales during February was 79 hours which is 94 per cent of the 1981-2010 mean; nevertheless this has been the sunniest February since that of 2008. In the last 100 years 36 Februarys were sunnier while 64 were duller. (This may appear at odds with a below-average sunshine total; the reason is a sharp rise in the long-period mean in recent decades). The equivalent figures for Scotland were 62 hours and 78 per cent, and for Northern Ireland 44 hours and 54 per cent. Largest total in the UK was 106 hours at Southampton and the smallest was 34 hours at Tiree (Inner Hebrides).