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| April 2001 monthly assessment issued
1/5/2001 |
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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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| Changeable and very wet overall.
A wet start with some thundery rain at times, followed by
a short dry sunny spell. A cold third week with northerly
winds and wintry showers. Frequent outbreaks of rain, thundery
showers and hail featured for the remainder of the month.
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Diary of highlights
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1st - 10th This was a wet unsettled
period as a series of depressions passed to the north of
Scotland or traversed eastwards across northern England.
Although warm or very warm and dry at first (London reached
21.5 °C on the 2nd), periods of rain and showers, some
thundery and heavy affected many places soon after. Capel
Curig/Gwynedd recorded a gust of 57 kn on the 5th.
Some places in North Wales received from two to three inches
of rain during the 5th and 6th. It became chilly later with
some overnight frost in the north. There was some hill and
coastal fog in the west at first on the 9th.
11th - 13th It was mainly dry and sunny but rather cold
under transient high pressure, allowing some overnight frost.
Patchy rain and drizzle affected Wales and south-west England
during the 12th and 13th.
14th - 20th Cold northerly or north-westerly winds prevailed
as pressure rose to the west and depressions tracked southeast
from the Iceland area to Denmark. There were showers, some
thundery, from time to time, these showers became distinctly
wintry during the 18th to the 20th with hail, sleet, and
snow mixed in. North Wales and counties adjacent to the
North Sea were especially affected. There was widespread
overnight frost, Sennybridge in Powys fell to -4.4 °C
early on the 19th.
21st - 28th Rather cold, wet and unsettled as a complex
area of low pressure encroached upon and established itself
over the region from the North Atlantic. Bands of rain and
showers often heavy with thunder and hail mixed in, were
the prevailing feature of the weather, however most places
had some sunny periods. The 22nd was very cold and wet as
fronts became slow moving over western areas, Cynwyd in
Denbighshire only just rose above 4 °C. Bristol reported
a heavy thunderstorm on the 24th and there was some damaging
hail in Norfolk on the 25th. A funnel cloud was observed
off the Norfolk coast on the 26th. The remaining days to
the 28th saw more thundery showers in many areas.
29th - 30th A drier finish to the month as rain and
some scattered thundery showers over southern England slowly
petered out. There were good sunny spells in remaining areas
of England and Wales.
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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 7.3 °C, which
is equal to the 1961-1990 average, which is in the close
to average category. Coldest since 1989 when 6.1 °C
was recorded.
England & Wales Rainfall Series (series began
in 1961).
The final total for the month was 98.1 mm, which is
163 % of the 1961-1990 average, which is in the well
above average category.
England & Wales Sunshine Series (series began
in 1961).
The final total for the month was 134.6 hours, which is
94 % of the 1961-1990 average, which is in the close
to average category.
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| Scotland |
| Quiet month with few extremes. |
| Diary of Highlights |
April was a fairly quiet month, with a period of northerly
winds being sandwiched between unsettled spells with slack
low pressure systems. Most of the month was spent in polar
air, with the snow on the hills retreating only slowly
up the slopes. Despite the predominance of air of northerly
origin, temperatures for the month were close to average.
The warmest days were experienced at the beginning of
April as southerly winds advanced across the country.
It was fairly cloudy in the south, but sun in the north
enabled the temperature to reach 16.5 °C at Kinloss
on the 2nd.
The mild southerly was soon followed by a cool westerly
with sunny periods and showers for a couple of days. More
unsettled weather followed for a week as two depressions
passed close to the country, bringing a mixture of rain
and showers.
High pressure built across Scotland in the wake of the
lows, with many southern and western parts enjoying a
brilliant day on the 11th. The high pressure stayed for
a few days, but slow moving fronts gave rather cloudy
weather in the southwest. Cold air persisted in the north
and east, with temperatures falling to -4 °C at Lybster
and Altnaharra on the 12th and 13th respectively.
The anticyclone was pushed westwards by a strong surge
of northerly winds from the 15th to the 20th. There was
much sunshine in the south-west but more in the way of
cloud and wintry showers in the north and east. The temperature
rose to only 1.9 °C at Corgarff on the 18th and fell
to -5.7 °C at Loch Glascarnoch on the 20th.
More unsettled weather returned from the 21st to the
26th as slack low pressure areas and slow moving fronts
brought areas of cloud and slight rain, mostly to the
south. Shallow low pressure continued to dominate the
weather until the end of the month, but the fronts cleared
away to give most places bright and showery weather.
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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 5.4 °C, which
is equal to 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 75.2 mm, which is
93 % of the 1961-1990 average, which is in the close
to average category.
Scotland Sunshine Series (series began in 1961).
The final total for the month was 137.8 hours, which is
100 % of the 1961-1990 average, which is in the close
to average category. Sunniest since 1991, when 148.9
hours was recorded.
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| Northern
Ireland |
| This was another very disappointing April
month. Four of the five previous April months have been very
wet across Northern Ireland. April 1997 was actually quite
dry but it was also very dull. April 2001 has been quite wet
across most areas, with only some central lowland areas recording
slightly below average rainfall. The south-west was wettest,
where rainfall totals locally exceeded 100 mm, or almost
175 % of average. It was a persistently cool month, with
the month's highest temperature of only 15 °C recorded
on the 2nd, otherwise temperatures struggled to reach 13 °C. |
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Diary of Highlights
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1st - 4th Largely dry and sunny, but
rather cloudy on 1st, and with scattered showers on 3rd/4th.
5th - 9th Cloudy and quite wet, particularly on 5th
and 6th. Mostly dry on 7th, but rain or showers on 8th and
9th.
10th - 11th Largely dry and bright or sunny.
12th - 20th Largely dry, although some heavy rain
in far west on 14th. Some quite sunny days, especially on
15th, 16th, 19th and 20th, but also quite cold with wintry
showers during Easter week and with widespread overnight
frosts.
21st - 24th Generally dull and wet, particularly
on 21st, but dry and very sunny on 23rd.
25th - 30th Cloudy but largely dry on 25th and 26th.
Heavy showers on 27th and 28th, but showers becoming more
scattered to allow more prolonged sunshine on 29th and 30th.
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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 6.9 °C, which
is 0.2 °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 74.6 mm, which is 112
% of the 1961-1990 average, which is in the close to average
category.
Northern Ireland Sunshine Series (series began in
1961).
The final total for the month was 129.3 hours, which is
89 % of the 1961-1990 average, which is in the below
average category.
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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 7.7 °C which is 0.2 °C
below the 1961-90 normal of 7.9 °C and is in the close
to average category.
Others:- 2000/7.8, 1999/9.4, 1998/7.7, 1997/9.0, 1989/6.6 °C.
England and Wales Rainfall (series begins in 1766).
The total for the month was 100.0 mm, which is 161 %
of the 1961-90 average and is in the well above average
category.
Others:- 2000/142.6, 1999/75.8, 1998/130.9, 1997/23.7 mm.
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| Note: Diary values are provisional based
on data available at the time. |
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