View Single Post
  #1   Report Post  
Old January 2nd 06, 02:35 PM posted to uk.sci.weather
Philip Eden Philip Eden is offline
external usenet poster
 
First recorded activity by Weather-Banter: Jul 2003
Posts: 6,134
Default December 2005: Synoptic Overview

Cyclonic episodes from 1st-8th and 29th-31st contributed most
of December's rain ... otherwise the month was predominantly
anticyclonic although the centre of high pressure was not often
located over the British Isles. Locally on the south coast there
were 21 consecutive days with no significant rain (from the
6th-26th). The anticyclone of the 11th-12th was intense, pressure
reaching 1046.9 mbar in NW Ireland which is probably the
highest in Dec in the UK since 1980.

More available:
Charts: http://www.climate-uk.com/monpre/0512.htm
The Monthly Review will appear later today or tomorrow
at: http://www.climate-uk.com/monthly/0512.htm
Graphs: http://www.climate-uk.com/graphs/0512.htm and
http://www.climate-uk.com/graphs/200512.htm
Not The Long Range Forecast will be uploaded on Jan 3 to
http://www.climate-uk.com/page4.html

The mean sea-level chart shows a markedly diffluent W-ly
flow over the British Isles. The Icelandic Low (999 mbar) is
displaced to the west of Greenland, although a significant
weakness extends eastwards towards Iceland, thence north-
eastwards towards Svalbard. There are further weak lows,
indicative of favoured locations for depressions for part of
the month, near Stockholm (1012) and Naples (1015).
The Azores high (1023) is located somewhat to the
northeast of its usual position.

The sea-level pressure anomaly field is quite unusual in
having above-normal pressure over such a large area -
practically the whole of the Atlantic north of 35 degN
together with all of western and northern Europe. The main
anomaly centres a
+12mbar near Novaya Zemlya
+7mbar in the Norwegian Sea
+7mbar west of Ireland at 51N 23W
-6mbar over Quebec
-2mar in the northern Adriatic.
Over the British Isles pressure anomaly ranges from +2mbar in
Kent to +5.5mbar in Shetland and the W.Isles. The anomalous
flow over the UK is NE-ly.

CET (after Manley) 4.6°C (-0.5 degC wrt 1971-2000)
CET (after Hadley) 4.7°C (-0.4 degC)
making it the coldest December since 2001, and the
coldest Nov/Dec since 1996
E&W Rain: 73.9mm ( 73% of 1971-2000 mean)
not quite as dry as Dec 2004
E&W Sunshine: 64.5 hr (135% of 1971-2000 mean)
in fourth place behind 1886, 1962 and 2001, while
Nov/Dec was the sunniest on record.

CScotT: 4.9°C (+0.4 degC)
ScotRain: 71.3mm ( 67%)
ScotSun: 33.7 hr ( 98%)

NIT: 6.3°C (+0.1 degC)
NI Rain: 89.8mm ( 96%)
NI Sun: 36.4 hr ( 97%)

Rainfall totals ranged from 195mm at Cardinham (Cornwall)
to 23mm at Scampton and Holbeach (both Lincs). Percentages
ranged from 125 at Cardinham to 33 at Shap (Cumbria).

Sunshine totals ranged from 103.4hr at Eastbourne (Sussex)
to 12.5 hr (KZ sensor), 14.9 hr (CS recorder) at Lerwick
(Shetland). Percentages ranged from 188 at Church Fenton
(N.Yorks) and Odiham (Hants) to 65 at Kirkwall (Orkney).
One wonders just how sunny this December would have been
had it occurred during, say, the 1920s or 30s when
particulate pollution was so much higher.

(c) Philip Eden