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All data are provisional and may be subject to revision. The views expressed in this document are not necessarily those of t he

Environment Agency. Its off icers, servants or agents accept no liability for any loss or damage arising from the interpretation or

use of the information, or reliance upon views contained herein.

Weekly rainfall and river flow summary

Weekly bulletin: Wednesday 29 April to Tuesday 5 May 2020

Summary: Most areas have seen some rainfall this week with more falling across

southern areas. River flows have decreased at most of the key sites we report on

in comparison to last week.

Rainfall

The past week has been generally wetter than the previous week apart from in central England where it was drier. Rainfall totals ranged from 9mm in north-east and central England to 25mm in south-west England (Table 1 and Figure 1). Cumulative rainfall totals for April ranged from only 14% of the monthly long term average (LTA) in north-east England to 83% in south-east England (Table 1).

River flow

River flows have decreased at four-fifths of the key sites that we report on, compared to the previous week. The latest river flows are classed as normal or lower, for the time of year, at the vast majority of sites including 2 sites across Cumbria which remain exceptionally low. Flows are only above normal or higher in 3 groundwater dominated catchments across southern England (Figure 2).

Outlook

Thursday, Friday and Saturday are expected to be predominately dry with the risk of showers, some locally, heavy, developing particularly on Friday and Saturday afternoon. A weakening band of rain will move south across northern areas on Saturday night and into Sunday. Monday and Tuesday are expected to remain dry. Author: National Water Resources Hydrology Team

Geographic regions

Latest Week:

29 Apr to 05 May 2020

Latest month to date:

May 2020

Last month: Apr 2020

Last 3 months: Feb to Apr 2020

Last 6 months: Nov 2019 to Apr

2020

Last 12 months: May 2019 to Apr

2020

Total (mm) Total (mm)

% LTA Total (mm)

% LTA Total (mm)

% LTA Total (mm)

% LTA Total (mm)

% LTA

north-west 12 3 4 21 30 388 159 744 123 1,549 129

north-east 9 4 7 8 14 230 124 486 113 1,080 129

central 9 1 2 27 50 206 127 468 128 1,015 141

east 11 <1 1 24 51 128 98 334 113 744 124

south-east 17 3 5 43 83 211 132 502 131 912 125

south-west 25 8 12 45 73 308 133 728 128 1,302 127

England 14 3 5 28 50 232 128 522 122 1,058 128

Table 1 Latest rainfall summary information (Source: Met Office © Crown Copyright, 2020)1

1 Notes:

LTA = long term av erage rainf all f or 1961 – 1990.

Data f or the current month are calculated using MORECS (Met Of f ice Rainf all and Ev aporation Calculation Sy stem); data f or pas t months are prov isional v alues

f rom the National Climate Inf ormation Centre (NCIC).

The data is rounded to the nearest millimetre or percent (except when v alues are less than 1).

Recorded amounts of rainf all are likely to be underestimated during snow ev ents.

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Rainfall

19 to 25 February 26 February to 3 March 4 to 10 March

11 to 17 March 18 to 24 March 25 to 31 March

1 to 7 April 8 to 14 April 15 to 21 April

22 to 28 April 29 April to 5 May

Figure 1 Weekly precipitation across England and Wales for the past 11 weeks. UKPP radar

data (Source: Met Office © Crown Copyright, 2020). Note: Images may sometimes include straight lines originating from the centre of the radar, resulting from tall trees and buildings located near the radar installation affecting its performance. This does not reflect actual conditions on the ground. Crown copyright. All rights reserved. Environment Agency, 100024198, 2020.

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River flow

‘Naturalised’ f low s are provided for the River Thames at Kingston and the River Lee at Feildes Weir.

Figure 2 Latest daily mean river flow, relative to an analysis of historic daily mean flows,

classed by flow percentile for the same time of year2 (Source: Environment Agency). Crown copyright. All rights reserved. Environment Agency, 100024198, 20203.

2Flow percentiles describe the percentage of time that a particular f low has been equalled or exceeded compared to the historic f low record f or

that site f or the time of y ear. Flow percentiles presented relate to an analy sis f or the time of y ear and not a whole y ear. 3The f low sites in this report are indicator sites prov iding a National ov erv iew and a subset of a wider f low monitoring network.

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River flow categories Exceptionally high Value likely to fall within this band 5% of the time Notably high Value likely to fall within this band 8% of the time

Above normal Value likely to fall within this band 15% of the time Normal Value likely to fall within this band 44% of the time Below normal Value likely to fall within this band 15% of the time

Notably low Value likely to fall within this band 8% of the time Exceptionally low Value likely to fall within this band 5% of the time

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