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| December 2001 monthly assessment issued 2 January
2002 |
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Monthly summaries available for: England
and Wales | Scotland | Northern
Ireland
Homogenous time series based upon selected station data:
CET | England and Wales
rainfall
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| Dry and very sunny especially in the
south. Mild at first but colder later with widespread frost.
There was snow in a number of areas from the 22nd. A white
Christmas in some places. |
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Diary of highlights
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1st - 5th A mostly mild unsettled start to the
month as Atlantic fronts crossed the region. Wet weather
on the 3rd heralded more of the same during the 4th/5th
as a low-pressure system moved east over northern
England. The rain turned showery and heavy at times on
the 5th.
6th - 11th With high pressure firmly established
over the region, a dry, mostly sunny regime prevailed. It
was mild at first especially around western coastal areas,
however temperatures elsewhere later slid into the rather
cold category. There was some rain and drizzle around western
coasts at first, otherwise many places had patchy mist or
fog and some overnight frost. Where fog persisted in the
Midlands and north-east England it stayed cold. Some western
areas stayed mild, with Nantmor/Gwynedd reaching 16.1 °C
on the 11th.
12th - 18th The anticyclone
migrated northwards allowing a light easterly flow in
the south. It continued very dry and generally sunny at
first, but rather cold with fairly widespread frost at
night. Cloud increased later with patchy rain and
drizzle from the 15th to the 17th.
19th - 26th Changeable with some snow in places as
deep depressions moving south-south-east from the Norwegian
sea brought cold northerly outbreaks. The first of these
on the 21st /22nd brought snow showers to east coast counties
as far south as north Essex, giving 2 to 5 cm in places.
The second outbreak on Christmas Day brought snowfalls to
North Wales especially on high ground. More snow showers
fell in the north-west on the 26th.
27th - 31st A vigorous low near Iceland on the 27th
moved south-east to Denmark by the 28th deepening rapidly
as it passed Scotland. Strong to gale NW winds brought progressively
colder air from the Iceland/Greenland area, with many places
receiving significant accumulations of snow by the 29th/30th.
St Bees Head (Cumbria) had a gust of 68 kn on the 28th.
A weather band gave substantial snow over high ground in
extreme south and south-west England early on the 29th,
with some on low ground also, parts of Sussex receiving
2 to 3 cm. Widespread frost, severe at times, developed
later, with Sennybridge/Powys falling to -10.9 °C early
on the 31st.
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| Statistical details (using best available
data/estimates): updated 2003 |
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England & Wales Mean Temperature Series (series
began in 1961).
The final value for the month was 3.4 °C, which
is 0.9 °C below the 1961-1990 average, which is
in the below average category.
England & Wales Rainfall Series (series began
in 1961).
The final total for the month was 44.3 mm, which is
46 % of the 1961-1990 average, which is in the well
below average category. 3rd driest in series and driest
since 1971, driest being 1963 with 28.6 mm.
England & Wales Sunshine Series (series began
in 1961).
The final total for the month was 75.3 hours, which is 169 %
of the 1961-1990 average, which is in the exceptionally
above average category. Sunniest in series, previous
sunniest 1962 with 64.6 hours.
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| Scotland |
| Dry and sunny. |
| Diary of Highlights |
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A large and intense anticyclone dominated Scotland's
weather for the middle fortnight of December. It started
life over eastern Europe and moved slowly west to the
Atlantic, giving dry weather with variable amounts of
cloud. During the first week a changeable westerly
regime prevailed, while the last 10 days saw northerly
winds become established.
The weather during the
first week was varied, with rain and gales during the
night of 3rd/4th followed by rain in the south on the
5th. More rain reached the north-west on the 7th.
Between these rainfall events there was much bright
weather with broken cloud and some showers.
The large anticyclone first influenced Scotland's weather
on the 7th and 8th by directing a very mild southwesterly
airstream across the country, and the temperature at Lochcarron
reached 14.4 °C. As the anticyclone approached Scotland,
dry continental air spread north, bringing clear skies that
gave cold nights inland from the 9th to the 13th.
Cloud spread from the east on
the 13th and the period when the anticyclone was closest
to Scotland was associated with generally cloudy skies.
As the high continued its westward movement away from
Scotland, breaks in the cloud appeared on the 17th and
18th.
The remainder of December was characterised by outbreaks
of cold northerly winds alternating with milder air associated
with depressions moving south-east from Iceland. The first
snow showers arrived on 21st December, and on Christmas
Day there was snow lying in the north-east, with light snow
flurries further south. The most intense of the depressions
brought gales during the early hours of the 28th, with a
gust of 74 kn at Barra, while blizzards affected northern
districts. By the 31st over 20 cm of snow lay over
much of northern Scotland and the temperature at Tulloch
Bridge fell to -11.6 °C.
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Statistical details (using
best available data/estimates): updated 2003
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Scotland Mean Temperature Series (series
began in 1961).
The final value for the month was 2.5 °C, which
is 0.4 °C below the 1961-1990 average, which is
in the close to average category.
Scotland Rainfall Series (series began in 1961).
The final total for the month was 117.2 mm, which is
75 % of the 1961-1990 average, which is in the below
average category.
Scotland Sunshine Series (series began in 1961).
The final total for the month was 43.7 hours, which is 147 %
of the 1961-1990 average, which is in the exceptionally
above average category. Sunniest in series, previous
sunniest 1995 with 38.6 hours.
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| Northern
Ireland |
| Dry and very sunny. |
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Diary of Highlights
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1st to 6th A rather cold but sunny
start to December on the 1st, otherwise quite mild. Widespread
persistent heavy rain fell on the 3rd and 4th giving combined
daily totals of between 21 and 50 mm for the two days
which equated to between 50 % and 80 % of the
total monthly rainfall recorded.
7th to 18th Widespread ground frosts occurred throughout
much of this period, locally severe on the 12th and 15th.
Little or no rainfall was recorded anywhere during this
period. It was very sunny from the 9th and 13th inclusive
and again on the 17th. Around half of the total sunshine
duration for the month were recorded on these days alone.
The 7th was the warmest day of the month everywhere with
the highest maximum temperature of 14.5 °C being recorded
in the Lagan Basin area.
19th
to 28th Air temperatures frequently fell below
freezing and widespread ground frost, some locally
severe, were recorded throughout this period. Only small
amounts of rainfall were recorded between the 19th and
23rd. Moderate to heavy rain and showers, some wintry in
nature, fell on 24th, 25th and 26th. It was very sunny
in most places on the 22nd.
29th to 31st
Predominantly cold with heavy snowfalls on the 29th
followed by air temperatures below freezing and
widespread ground frost, some locally quite severe. This
meant that by 31st snow was still lying in many areas
causing hazardous conditions to pedestrians and
motorists.
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Statistical details (using
best available data/estimates): updated 2003
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Northern Ireland Mean Temperature Series (series
began in 1961).
The final value for the month was 4.1 °C, which
is 0.4 °C below the 1961-1990 average, which is
in the close to average category.
Northern Ireland Rainfall Series (series began in
1961).
The final total for the month was 82.8 mm, which is
76 % of the 1961-1990 average, which is in the below
average category.
Northern Ireland Sunshine Series (series began in
1961).
The final total for the month was 59.8 hours, which is 170 %
of the 1961-1990 average, which is in the exceptionally
above average category. Sunniest in series, previous
sunniest 1963 with 46.3 hours.
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Homogeneous series based upon selected station data: updated
2003 |
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Central England Temperature (series begins in 1659).
The mean value for the month was 3.6 °C which is 1.1 °C
below the 1961-90 normal of 4.7 °C and is in the above
average category.
Others:- 2000/5.8, 1999/5.0, 1998/5.5, 1996/2.9 °C.
England and Wales Rainfall (series begins in 1766).
The total for the month was 43.5 mm, which is 45 %
of the 1961-90 average and is in the well below average
category.
Others:- 2000/142.2, 1999/142.4, 1998/97.4, 1991/49.3 mm.
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| Note: Diary values are provisional based
on data available at the time. |
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