The first half of the month was mainly northwesterly, although
two deep depressions tracked SE-wards across the UK on the
4th/5th and 13th/14th. A southwest to westerly type lasted
from mid-month to just before Christmas, and then an east to
southeasterly flow took over during the final week.

It was in the top 25% of anticyclonic Decembers, but mean
pressure over the British Isles area was well short of that in
the Decembers of 2001 and 1991.

Mean pressure charts have already been uploaded to:
Charts: http://www.climate-uk.com/monpre/0812.htm
The Monthly Review will be uploaded later today to:
http://www.climate-uk.com/monthly/0812.htm
Graphs: http://www.climate-uk.com/graphs/0812.htm and
http://www.climate-uk.com/graphs/200812.htm
Not The Long Range Forecast should be available by Jan 4 on:
http://www.climate-uk.com/page4.html

The sea-level pressure chart shows the Icelandic low in its normal
position but considerably deeper than usual at 994mbar. The
Azores high has two centres: 1022mbar at 46N 52W and 1023
mbar at 47N 21W, and a belt of relatively high pressure extends
across Biscay, France and central Europe to Russia. A shallow
low pressure area is centred in the Tyrrhenian Sea at 1014mbar.
The mean flow over most of the British Isles is rather weakly
WSWly, but over southern England very weakly WNWly.


At the 500 mbar level there is a marked trough at 40-50degW,
and the flow becomes diffluent east of 10degW.

The sea-level pressure anomaly field is dominated by a broad
belt of above normal pressure extending across the Atlantic from
Bermuda to Ireland and thence to Scandinavia and northern
Russia. Pressure is below normal over Greenland and the Canadian
Arctic, and also slightly below normal in the western Mediterranean.

The main anomaly centres we
+10mbar over northern Russia
+ 6mbar off NW Ireland
+ 7mbar NE of Bermuda
- 8mbar over east Greenland
- 3mbar over the Balearic Is

Over the British Isles pressure anomaly ranges from +3mbar
in Kent and Sussex to +6mbar off counties Galway and Mayo.
A NE-ly anomalous flow covers southern England and East
Anglia, but the flow is flat/anticyclonic over Ireland and Scotland.

CET (after Manley) 3.60°C (- 1.5 degC wrt 1971-2000)
CET (after Hadley) prob 3.7°C
E&W Rain (provisional): 63.5mm ( 63% of 1971-2000 mean)
E&W Sunshine (prov): 74.9hr (157% of 1971-2000 mean)

It was the coldest December since 2001, averaged nationally,
and since 1996 locally in southern England

CScotT: 3.8°C (- 0.7degC)
ScotRain: 94mm ( 85 %)
ScotSun: 43hr ( 127 %)

NIT: 5.2°C (- 1.0degC)
NI Rain: 58mm ( 57 %)
NI Sun: 56hr ( 151 %)

Rainfall totals ranged from 255mm at Inveruglas (Dunbartonshire)
and 213mm at Tyndrum (Perthshire) to 12mm at Shoeburyness
(Essex) where it was the driest December since 1991. Averaged
over England and Wales it was the driest since 2001.

Percentages ranged from 161 at Carter Bar (Roxburghshire)
to 22 at Shoeburyness.

Sunshine totals ranged from 106.2h at Jersey airport (Ch Is)
and 105.0h at Weymouth (Dorset) to 17.4h at Lerwick
(Shetland).

Percentages ranged from 201 at Jersey airport to 74 at
Stornoway (Isle of Lewis) and 75 at Boulmer (Northumberland)

(c) Philip Eden

On 1 Jan, 19:31, "Philip Eden" philipATweatherHYPHENukDOTcom wrote:
The first half of the month was mainly northwesterly, although
two deep depressions tracked SE-wards across the UK on the
4th/5th and 13th/14th. A southwest to westerly type lasted
from mid-month to just before Christmas, and then an east to
southeasterly flow took over during the final week.

It was in the top 25% of anticyclonic Decembers, but mean
pressure over the British Isles area was well short of that in
the Decembers of 2001 and 1991.

Mean pressure charts have already been uploaded to:
Charts: *http://www.climate-uk.com/monpre/0812.htm
The Monthly Review will be uploaded later today to:http://www.climate-uk.com/monthly/0812.htm
Graphs: *http://www.climate-uk.com/graphs/0812.htm*and
* * * * * * *http://www.climate-uk.com/graphs/200812.htm
Not The Long Range Forecast should be available by Jan 4 on:
* * * * * * *http://www.climate-uk.com/page4.html

The sea-level pressure chart shows the Icelandic low in its normal
position but *considerably deeper than usual at 994mbar. The
Azores high has two centres: 1022mbar at 46N 52W and 1023
mbar at 47N 21W, and a belt of relatively high pressure extends
across Biscay, France and central Europe to Russia. A shallow
low pressure area is centred in the Tyrrhenian Sea at 1014mbar.
The mean flow over most of the British Isles is rather weakly
WSWly, but over southern England very weakly WNWly.

At the 500 mbar level there is a marked trough at 40-50degW,
and the flow becomes diffluent east of 10degW.

The sea-level pressure anomaly field is dominated by a broad
belt of above normal pressure extending across the Atlantic from
Bermuda to Ireland and thence to Scandinavia and northern
Russia. Pressure is below normal over Greenland and the Canadian
Arctic, and also slightly below normal in the western Mediterranean.

The main anomaly centres we
* *+10mbar over northern Russia
* *+ *6mbar off NW Ireland
* *+ *7mbar NE of Bermuda
* *- *8mbar over east Greenland
* *- *3mbar over the Balearic Is

Over the British Isles pressure anomaly ranges from +3mbar
in Kent and Sussex to +6mbar off counties Galway and Mayo.
A NE-ly anomalous flow covers southern England and East
Anglia, but the flow is flat/anticyclonic over Ireland and Scotland.

CET (after Manley) * 3.60°C *(- 1.5 degC wrt 1971-2000)
CET (after Hadley) * *prob 3.7°C
E&W Rain (provisional): * *63.5mm *( 63% of 1971-2000 mean)
E&W Sunshine (prov): * * * 74.9hr * (157% of 1971-2000 mean)

It was the coldest December since 2001, averaged nationally,
and since 1996 locally in southern England

CScotT: * * * * 3.8°C *(- 0.7degC)
ScotRain: * * * 94mm *( * 85 %)
ScotSun: * * * *43hr * *( 127 %)

NIT: * * * * * *5.2°C *(- 1.0degC)
NI Rain: * * * 58mm ( * 57 %)
NI Sun: * * * *56hr * ( 151 %)

Rainfall totals ranged from 255mm at Inveruglas (Dunbartonshire)
and 213mm at Tyndrum (Perthshire) to 12mm at Shoeburyness
(Essex) where it was the driest December since 1991. Averaged
over England and Wales it was the driest since 2001.

Percentages ranged from 161 at Carter Bar (Roxburghshire)
*to 22 at Shoeburyness.

Sunshine totals ranged from 106.2h at Jersey airport (Ch Is)
and 105.0h at Weymouth (Dorset) to 17.4h at Lerwick
(Shetland).

Percentages ranged from 201 at Jersey airport to 74 at
Stornoway (Isle of Lewis) and 75 at Boulmer (Northumberland)

(c) Philip Eden

Just looking at England and Wales - colder than normal but drier and
sunnier (which is not surprising) can you look in your records to find
similar rain and sun figures and see how the mean temperature
compares? In itself, coldest since 2001 isn't that meaningful in the
sense that given the synopic setup we've had it would be remarkable if
it wasn't. What is interesting is, if given this setup, it wasn't as
cold as one would expect, say, 20 years ago.

"Pete L" wrote:
On 1 Jan, 19:31, "Philip Eden" philipATweatherHYPHENukDOTcom wrote:

CET (after Manley) 3.60°C (- 1.5 degC wrt 1971-2000)
CET (after Hadley) prob 3.7°C
E&W Rain (provisional): 63.5mm ( 63% of 1971-2000 mean)
E&W Sunshine (prov): 74.9hr (157% of 1971-2000 mean)

It was the coldest December since 2001, averaged nationally,
and since 1996 locally in southern England

: Just looking at England and Wales - colder than normal but drier and
: sunnier (which is not surprising) can you look in your records to find
: similar rain and sun figures and see how the mean temperature
: compares? In itself, coldest since 2001 isn't that meaningful in the
: sense that given the synopic setup we've had it would be remarkable if
: it wasn't. What is interesting is, if given this setup, it wasn't as
: cold as one would expect, say, 20 years ago.

Pete ... I do try to do something similar from time to time, but
relating the temperature anomaly to a component of the mean
monthly airflow. It works best when a given month has a single
dominant character rather than the dog's breakfast we had last
month.

For instance, I showed that August 2006 (the most
'northerly' August in 130 years, but with a CET fractionally
above the long-term mean) should have been about a degree
colder than it actually was, and that the probability that that had
happened by chance was exceedingly small (sorry, can't
remember the exact figures ... it's probably googlable).

It is necessary, of course, that the parameters being tested
are actually correlated, preferably reasonably strongly, and
a northerly component to the flow in August is strongly
correlated to mean temperature.

November 2008 was similar (strong northerly component,
CET marginally above the long-term mean).

Philip