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| April 2004 monthly assessment
issued 5 May 2004 |
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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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| Rather warm and wet overall. Some
warm dry spells falling between thundery outbreaks at start,
middle and end of month. |
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Diary of highlights
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1st to 7th Low pressure to the west
slowly moved east and north, driving bands of rain and showers
across the region. The 4th onwards saw showers, often heavy
and thundery, with hail in many places. Warm at first, colder
later as winds veered from the S to the NW. The south-east saw
most sunshine.
8th to 14th The Azores high extended
a weak ridge across southern parts of the UK. It was chilly at
first with some overnight frost, -4.0 °C being registered at
Sennybridge/Wales on the 9th. After a few showers on the 8th,
and a little light rain on the 9th and 10th, mainly dry warm
weather with good sunny periods prevailed. Northern areas were
cloudy at times, and some light rain spread in later on the
14th to the north-west.
15th to 21st Active depressions resided close to or
over the UK bringing a second spell of unsettled weather,
however, it was dry and warm at first, particularly in the
south-east. Fronts made erratic progress eastwards during
the 17th and 18th bringing lower temperatures and copious
amounts of rain to many places. Some local flooding was reported
in the Midlands. Further bands of rain and showers affected
most areas from the 19th to the 21st, with hail and thunder
mixed in, however, the sun shone in between. Reigate in Surrey
experienced a violent thunderstorm later on the 19th, with
heavy hail sleet and wet snow, children were seen making snowmen!
22nd to 25th
After scattered light showers on the 22nd, very warm sunny
weather arrived with 23.4 °C reached in central London on
the 24th. There was patchy hill and coastal fog in places, and
thunder later in the north on the 25th.
26th to 30th Low pressure developing off southern England
caused bands of thundery rain to affect many areas with numerous
reports of local flooding and lightning strikes. On the 26th
one band stretched from north-east England to the Severn estuary.
There was 33 mm in one hour during a storm at Sheffield which
caused local flooding; a shop was also struck in Selby. Overnight
on 26/27th, Worcestershire was hit by storms with many homes
or businesses struck by lightning with some local flooding.
Near Worcester, 43 mm fell in two hours. The south-east and
East Anglia were also affected later on the 27th with outbreaks
in south-east London causing much disruption to rail services
during evening rush hour. Heavy hail and local flooding were
reported from a number of localities. The 28th saw more outbreaks
over the south-east and East Anglia, and a particularly violent
storm broke out around the South Downs/Sussex area during
the late afternoon. It was warm at first but became colder
on the 28th as NNE winds picked up. The 29th saw more rain
heavy at times and again early on the 30th in the south.
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| Statistical details (using best
available data/estimates): Updated September 2004 |
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England & Wales Mean Temperature Series (series
began in 1961).
The final value for the month was 9.1 °C, which
is 1.8 °C above the 1961-1990 average, which is in the well above
average category. 4th warmest in series, warmest 1987 with 9.6 °C.
England & Wales Rainfall Series (series began
in 1961).
The final total for the month was 78.5 mm, which is 131% of
the 1961-1990 average, which is in the above average category.
England & Wales Sunshine Series (series began
in 1929).
The final total for the month was 133.3 hours, which is 93%
of the 1961-1990 average, which is in the close to average
category.
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| Warm, dull and wet. |
| Diary of Highlights
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A strong south-easterly airstream on the 1st gave bright
and warm conditions in the north-west However, fronts crossed
Scotland on the 2nd and 3rd as low pressure in the Atlantic
moved north towards Iceland, bringing rain to most parts.
From the 4th to the 7th the low pressure transferred from
Iceland to the Norwegian Sea and winds over Scotland veered
into the north-west and then the north. The weather was rather
cold with sunny periods and showers that fell as snow over the
hills.
On the 8th high pressure developed in the mid Atlantic and
milder air spread south-east across Scotland, accompanied by
cloud and overnight rain. The next day was rather cloudy but
sunny spells to the lee of the hills enabled the temperature
at Leuchars to reach 17 °C.
From the 10th to the 12th an anticyclone near the Azores
extended a ridge to England with light westerly winds across
Scotland. The weather was mainly cloudy but mostly dry and
mild with some sunny intervals.
A marked deterioration in the weather set in on the 13th as
low pressure became established near Iceland and mild
south-westerly winds covered Scotland. There was much rain as
fronts moved north across Scotland on the 13th, returned from
the west on the 14th and did not clear eastward until the
15th. Clearer and colder conditions with light winds arrived
on the 16th, allowing the overnight temperature to fall to -4
°C at Aboyne.
More wet weather followed from the 17th to the 19th as
another major depression approached Scotland from the west and
became slow moving before retreating towards Iceland. On the
17th there was 32 mm of rain at Eskdalemuir and the wind
gusted to 62 m.p.h. at Barra.
A brief respite followed on the 20th with southerly winds
giving mainly fair weather in the north and the temperature
reached 16 °C at Altnaharra. Another depression moved north to
the west of Scotland over the next two days, bringing a return
to unsettled weather. This time the emphasis was on the wind,
with gusts reaching 69 m.p.h. at South Uist on the 21st. The
warmth was maintained with the temperature rising to 17 °C at
Lossiemouth.
On the 24th high pressure developed over the British Isles
and the North Sea with sunny periods developing. The
temperature rose to 19 °C at some eastern locations on the
25th and 26th.
On the 27th the anticyclone transferred west into the
Atlantic, low pressure developed over Europe and
north-easterly winds blew across Scotland. In the east it was
cloudy with periods of rain and the temperature reached only 8
°C at Charterhall on the 29th. In the west there were sunny
periods with showers in the north-west on the 28th and
29th.
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Statistical details (using
best available data/estimates): Updated September 2004
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Scotland Mean Temperature Series
(series began in 1961).
The final value for the month was
7.4 °C, which is 2.0 °C above the 1961-1990 average, which
is in the exceptionally above average category. 2nd warmest in series, warmest 2003 with 8.1 °C.
Scotland Rainfall Series (series began in 1961).
The final total for the month was 122.9 mm, which is 152%
of the 1961-1990 average, which is in the well above average
category. 3rd wettest in series, wettest 1977 with 126.2
mm. Wettest since 1994.
Scotland Sunshine Series (series began in 1929).
The final total for the month was 104.9 hours, which is 76%
of the 1961-1990 average, which is in the well below average
category.
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| Warm and wet. |
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Diary of Highlights
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Temperatures were again above normal - especially at night
with positive anomalies of 1 to 3 degrees. Rainfall was above
average, though by varying degrees due to the often showery
nature of the weather. Sunshine values were generally near or
a little below average.
The first three weeks were unsettled with showers or some
longer spells of rain at times. Some of the showers were heavy
with hail and isolated thunderstorms were reported locally on
the 3rd and 6th.
The Easter holiday period was relatively quiet with a lot
of cloudy, dry weather and any rain was mostly insignificant.
Clearer spells at night, however, did allow some ground frosts.
Like March, the most unsettled period occurred around mid-month
and active fronts brought 10-15 mm of rain to many areas overnight
on the 14th. This was followed by a couple of brighter days
with good sunny spells but some heavy showers with hail and
thunder. Another very active front brought a further 15-20
mm of rain on the 17th and this was driven along by strong
and gusty winds. It was cold too with some sleet/wet snow
reported in the Omagh area as afternoon temperatures struggled
between 4 and 6 °C.
By the evening of the 20th, more rain was arriving as a
deep depression tracked northwards along the western coast of
Ireland. 5-10 mm occurred in many areas and southerly winds
increased to gale force in many areas on the morning of the
21st with inland gusts reaching or locally exceeding 50
m.p.h., causing some minor damage to trees.
By the 22nd pressure was rising and a spell of warmer,
sunnier weather arrived for the last weekend of the month with
temperatures on the 24th and 25th reaching 17 or 18 °C inland,
the highest of the month.
The remainder of the month had a good deal of dry and sunny
weather though it felt quite cool as northerly winds
strengthened.
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Statistical details (using
best available data/estimates): Updated September 2004
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Northern Ireland Mean Temperature Series (series
began in 1961).
The final value for the month was
8.4 °C, which is 1.3 °C above the 1961-1990 average, which
is in the well above average category. 5th warmest in series, warmest 2003 with 9.0 °C.
Northern Ireland Rainfall Series (series began
in 1961).
The final total for the month was 78.5 mm, which is 118% of
the 1961-1990 average, which is in the close to average category.
Northern Ireland Sunshine Series (series began
in 1929).
The final total for the month was 135.3 hours, which is 93%
of the 1961-1990 average, which is in the close to average
category.
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| Homogeneous
series based upon selected station data: |
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Central England Temperature (series begins in
1659).
CET
Index
England and Wales Rainfall (series begins in 1766).
EWP
Index
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| Note: Diary values are provisional based on data available at the time. |
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