The second half of January was pretty unremarkable,
temperature-wise, but the intensity of cold during the first
half of the month was such that overall this turned out to
be the coldest January since 1987 and the 9th coldest
in the last 100 years.

Mean pressure charts will soon be uploaded to:
Charts: http://www.climate-uk.com/monpre/1001.htm
The Monthly Review will shortly be made available at:
http://www.climate-uk.com/monthly/1001.htm
Graphs: http://www.climate-uk.com/graphs/1001.htm and
http://www.climate-uk.com/graphs/201001.htm
Not The Long Range Forecast should be available by Feb 4 on:
http://www.climate-uk.com/page4.html

The mean sea-level pressure distribution over the Atlantic/Europe
sector during January 2010 was unusual, with the Icelandic Low
well SW of its normal position at 54N 48W (between the southern
tip of Greenland and Newfoundland) at 998mbar, an Azores
high of 1020mbar near Madeira, a deeper-than-usual Mediterranean
low of 101mbar, and a strong ridge of high pressure extending
westward from the Siberian High across the Baltic and southern
Scandinavia towards NE Scotland. Over the British Isles
pressure was almost uniform (probably the weakest gradients
since Jan 1985).

Aloft, there was a trough at 50-60degE, and and the jet
bifurcated over the eastern Atlantic with one arm heading past
Iceland to the Barents Sea and the other arm diving into the
southern part of the Mediterranean Basin.

The sea-level pressure anomaly field showed below average
pressure across the Atlantic/Europe sector south of approx
latitude 50-55degN, and above average further north.

The main anomaly centres we
-9mbar between the Azores and Newfoundland
-7mbar in the western Mediterranean
+14mbar over NW Russia
+12mbar north of the Faeroes

Over the British Isles pressure anomaly ranged from +9 mbar
over Shetland to -1.5 mbar over the Channel Is. The anomalous
flow over the British Isles was E to NE-ly.

CET (after Manley) 1.2°C (3.0degC below the 1971-2000 mean)
CET (after Hadley) 1.4 or 1.5°C (1.7 or 1.8degC below)
E&W Rain (provisional): 67.6mm ( 72% of 1971-2000 mean)
E&W Sunshine (prov): 70.1hr (127% of 1971-2000 mean)

The Manley CET was the lowest for January since 1987 and
the ninth lowest in the last 100 years (after 87, 85, 79, 63, 45,
42, 41, and 40)

CScotT: 1.6°C (-2.2degC)
ScotRain: 65mm ( 68 %)
ScotSun: 57hr (133 %)

NIT: 2.9°C (-2.2degC)
NI Rain: 57mm ( 64 %)
NI Sun: 73hr (148 %)

Rainfall totals ranged from 147mm at Capel Curig (Snowdonia)
and 160mm at Valentia (Irish Rep) to 31mm at Tain (Cromarty)
.... however, the large number of unattended sites means
that few stations in Scotland actually have a correct rainfall
for this month as snowfalls have not been melted manually.

Percentages ranged from 156 at Aboyne (Aberdeenshire)
to 29 at Loch Glascarnoch (Wester Ross) - flagged as
questionable.

Sunshine totals ranged from 107.0h at Culdrose (Cornwall)
[believed to be CS recorder] and 117.5h at Cork (Irish
Republic) to 27.8h at Aviemore (Inverness-shire) [KZ sensor].

Percentages ranged from 215 at Valentia, and 184 at
Camborne (Cornwall) to 68 at Aviemore. [The usual caveat
about the change in sunshine recorders applies]

(c) Philip Eden