Corporate report

Flood Forecasting Centre: annual review 2022 to 2023

Published 2 November 2023

Applies to England and Wales

1. Introduction

The Flood Forecasting Centre is a working partnership between the Met Office and Environment Agency. Its primary aim is to contribute to national resilience across England and Wales.

We seek to continually evolve our services and capabilities, to improve our value to our stakeholders.

This review aims to provide:

• a brief overview of flood conditions experienced across England and Wales
• a summary of our operational performances
• insights we have gained from our customers
• improvements and changes we have made in our services
• information on our modelling capabilities and people

2. Overview

The main weather and flood features of the year 2022/23 were:

• conditions were generally drier than average at the start of the year
• in mid-May heavy showers and thunderstorms brought minor surface water impacts to the south of England
• there were also a few heavy shower events in June, with some surface water impacts
• Criccieth (north Wales) which saw minor impacts from 98mm falling in 5 hours on 03 June
• heatwave conditions in early July broke down later in the month, with heavy showers and thunderstorms
• thunderstorms from 20 to 23 July led to raised surface water flood risk, and localised flooding in the north of England
• August started wet with frontal systems affecting the north-west of England and Wales
• a thundery breakdown in mid-August led to surface water flooding impacts
• 16 and 17 August saw impacts in southern and central parts England and the south of Wales, including roads and the tube in Greater London
• heavy showers and longer spells of rain on the 5 and 6 of September led to an increased surface water flood risk over parts of England and Wales
• heavy rain along the coasts of Sussex and Kent on the 23 and 24 September lead to a threat of significant inland flooding
• thundery plumes in October brought the potential for significant surface water impacts
• during November, successive bands of frontal rain brought several discrete periods of flood risk
• above-average rainfall totals recorded through much of Wales and the south-east and south-west of England
• wet conditions during the second half of December caused minor impacts on several across parts of south Wales and the south of England
• the mild, unsettled and very wet theme continued into January, which was our busiest time of the year
• prolonged heavy rain through 10 to 13 January led to localised significant impacts in parts of South Wales and south-west England
• approximately 40 properties flooded in Devon
• despite much drier conditions during January, groundwater levels continued to rise due to the wet weather
• a prolonged period of minor groundwater flooding impacts seen across parts of the south of England into early February
• March bought wet unsettled weather with successive bands of heavy rain across England and Wales
• spring tides that peaked on 23 March brought some minor coastal flooding to Cornwall and Ceredigion
• on 31 March successive heavy showers brought numerous minor impacts across the south of England

2.1 Thunderstorms 17 August 2022: flooding across London and south-east England

This was the third consecutive day of thunderstorms across England and Wales. The result was widespread surface water flooding across London and the south-east. In London torrential downpours led to more than 30 mm falling in less than 2 hours across large areas. Many significant impacts were observed across parts of Surrey, London, Essex and Suffolk. This included closures to tube stations and the flooding of several major roads with parts of the M25 becoming unpassable. Other less populated areas saw over 60 mm of rain. Minor impacts were observed across Isle of Wight, East Sussex and Kent. The Flood Guidance Statement (FGS) initially forecast significant impacts (very low likelihood) for this day on 14 August. A small area was upgraded to amber (medium likelihood of significant impacts) on the morning of 17 August.

3. Performance

3.1 Timeliness

FGS to be issued on-time, and in full, by no later than 11:00 local.

3.2 Table 1: highest forecast flood risk from all flood sources for any Flood Guidance Statement (FGS) issued for each calendar day for 2022 to 2023

Month 22/23	Green	Yellow	Amber	Red
April	30	0	0	0
May	27	4	0	0
June	25	5	0	0
July	29	2	0	0
August	28	2	1	0
September	28	3	0	0
October	28	3	0	0
November	19	11	0	0
December	26	5	0	0
January	6	25	0	0
February	24	4	0	0
March	27	4	0	0

The timeliness measure is verified on the first Flood Guidance Statement (FGS) issue of each day which includes any low flood risk or above. This is presented graphically as a 3-month rolling average for the last 12 months, with supplementary detail around the number of FGS issued displayed in the bar chart.

It was a perfect year with no late issues of the Flood Guidance Statement.

3.3 Probability of Detection (POD)

The percentage of observed impacts that were forecast at a county scale.

3.4 Table 2: POD for all sources of flooding, April 2022 to March 2023

Source	Lead Time	Probability of Detection	No. Observations
Surface Water	Day 2	79%	170
River	Day 3	74%	75
Coastal	Day 3	71%	7
Groundwater	Day 3	92%	96

POD scores were good overall this year, albeit with some reduction in scores for surface water and coastal (falling from 87% and 93% since last year respectively). The POD score for river flooding remained steady with a 2% increase. As is typical for groundwater flooding, a high POD score was achieved given the tendency for groundwater flooding to be long-lasting once it has started.

3.5 Table 3: POD rolling 36 month

Source	Lead Time	Probability of Detection	No. Observations	RAG Status
Surface Water	Day 2	81%	1036	Green
River	Day 3	77%	539	Green
Coastal	Day 3	72%	37	Green
Groundwater	Day 3	91%	129	Green

3.6 Lead time of first correct forecast

Lead time of first correct forecast is the longest lead time typically provided when the forecast is correct.

3.7 Table 4: target lead time April 2022 to March 2023

Source	Target Lead Time	Actual Lead Time	No. Forecasts
Surface Water	Day 2	Day 4	151
River	Day 3	Day 5	68
Coastal	Day 3	Day 5	5
Groundwater	Day 3	Day 5	95

Lead time of first correct forecast remains above the target. The actual lead time of surface water flooding decreased by 1 day to 4 days relative to last FY. This could be due to a change in procedures where the lead time for convective surface water events is now limited, on the whole, to day 3.

4. Stakeholder engagement

A summary of stakeholder engagement activities carried out in 2022/23:

• launch of redesigned Flood Outlook, supported by new training material
• Stakeholder User Group held in December
• hosted visitors, including Government ministers (Kit Malthouse and Steve Double), Malaysian Government officials, colleagues from DLUHC and Cabinet Office
• also hosted Directors and Deputy Directors from our parent organisations
• implemented hydrometeorologist ‘train the trainer’ training
• delivered training across all stakeholder groups
• delivered FGS user guide
• recorded and published new suite of training videos to support users

Results of the 2022 User Survey delivered. Satisfaction with the FFC and its services remained high:

• 86% of responders were satisfied with the service provided by the FFC (with 42% very satisfied and 44% fairly satisfied)
• 92% of those who receive the FGS are satisfied with it (with 45% very satisfied and 47% fairly satisfied)
• although there has been a significant drop in overall satisfaction levels compared to 2019 from 91% to 86%
• the most common, and the preferred way to receive the FGS continues to be by direct email
• looking ahead, data suggests that many more will be turning to mobile
• current receipt of the flood outlook is low (16%), but a significant proportion (71%) have indicated that they would find it useful
• most are currently unaware of the range of training and resources available from the FFC
• of those who are aware, only around half tend to use the resources, but these responders do rate the training and resources very highly

5. Product and service development

5.1 Flood guidance services

Following user feedback, the FGS is now available on Resilience Direct. Shortly the FGS email attachment will be replaced with a download link. This allows us to improve security and future proof FGS dissemination. 

We have carried out our annual development phase of the FGS production and verification tool. This included creating and implementing a new customer registration system. 

We are exploring a collaboration with the Met Office to develop a system to produce and share both the:

• National Severe Weather Warnings
• the Flood Guidance Statement

The aim will be to improve efficiency and resilience, delivering a system that is strategically fit for the future. 

5.2 Flood Outlook Services

In May the redesigned Flood Outlook was launched. Flood Outlook is now available via Hazard Manager and Resilience Direct. We also launched a video briefing to accompany each issue of the Flood Outlook. This complements the training videos already available.

5.3 Surface water forecasting

SWFHIM (Surface Water Forecasting Hazard Impact Model) is one of our key forecasting tools to help us assess the risk of surface water flooding impacts. Work on SWFHIM has been ongoing to:

• deliver new application developments
• correct ‘frequently flagging counties’, with consistently high false alarm rates
• carry out verification of SWFHIM
• build confidence in output and enhance accuracy through targeted future development

Further improvements to SWFHIM this year through the Surface Water Flood Forecasting Improvement Project will help to improve our surface water flood forecasting capability. 

5.4 River flood forecasting

We continue to upgrade our national-scale Grid-to-Grid (G2G) model in conjunction with the Centre for Ecology and Hydrology (CEH). This will ensure that we make the best use of an expanding network of real-time rainfall and river flow observations. We also continue to work towards the movement of the G2G model to new Met Office and Environment Agency computer platforms. The key aims of this are to:

• improve efficiency in maintaining our models
• develop model capability in partnership

5.5 Medium to long-range flood forecasting

‘Decider’ model is a medium to long-term weather forecast tool developed by the Met Office. It supports our river and coastal flood risk assessments for the Flood Outlook service. In the summer a new ‘multi-model’ version of Decider was launched and is now used in FFC operations. This combines the information from four different weather ensemble forecasting models and we use it to:

• improve our flood risk assessment for the 6 to 30 day period ahead
• aid early identification of the potential for extreme events

5.6 Flood impacts: social sensing

In collaboration with the Met Office, we procured a new social sensing system (FloodTags). This system geolocates flood impacts using Twitter. The aim is to enhance situational awareness and improve the flood impact collection and verification process.

5.7 Planning our improvements

Key improvements to FFC working structure this year were:

• introducing a more efficient way to plan and prioritise our work
• being clearer on team and individual accountability across the Centre
• incorporating stakeholder engagement across all aspects of our work

6. People

6.1 Staff movements

We said farewell to our Head of Centre in January, and a new Head of Centre has recently been appointed.  

In September we welcomed a new Operations Officer. We also contracted in a Met Office Product Owner for the first time this year to help provide more consistency with our product lifecycle work.  

We said goodbye to our 2021/22 Industrial Placement student, who has since gained a place on the Met Office Graduate Development Scheme.

We also welcomed our 2022/23 Industrial Placement Student. Emily says, “I have been able to experience a wide breadth of what the FFC has to offer. I have interacted with customers, overseen improvements to FFC products and aided operations. I have enjoyed visiting offices, in Exeter, Birmingham, Leeds and Bristol. Additionally, I have attended and helped present in various workshops which have allowed me to gain a clear picture of FFC remit. I have really appreciated my time at the FFC and all the people who work here.”

6.2 Staff development

This year we started taking a more holistic and strategic approach to our recruitment and staff development. We considered succession planning, staff development and improving equality, diversity and inclusion within the team. We will continue to progress this work this year. 

Two of our FFC hydrometeorologists have started 50:50 opportunities in the Met Office. They are researching Elevated Instability with Foundation Science and looking into extreme events with Verification Impacts Post Processing Team. As well as utilising our hydrometeorological skills and expertise across the wider organisation, this will also bring skills and knowledge back to the FFC team.

We’ve needed to slow and pause our operational hydrometeorology and flood forecasting RQF qualification given staffing challenges within the FFC . However, we are now exploring opportunities to pick up momentum. We are drawing on a qualified assessor from outside the FFC as well as verifying a candidate from within the FFC.  This is especially timely as we look to welcome new trainee hydrometeorologists.

7. Forward look

As we head into our 15th year of operation it is remarkable to think of how far we have come as a centre and the experience the team can now draw on. Our funding business case  is agreed until 2027, with our current strategy in place until 2024. This year will see us deliver against that current strategy and start to refresh our approach for 2024 to 2027.

Maintaining operational delivery is the core of our service. This has evolved from day-to-day delivery to new monthly flood outlook products and video briefings to help the nation prepare for flood events.

The FFC now has four main national modelling approaches:

• coastal
• river
• surface water
• groundwater

These all need maintenance and development through our improvement programmes. Our team work offline in organised blocks to focus on this project work.

We are also stepping into larger project management on behalf of parent organisations:

• developing surface water capabilities for the Environment Agency (funding via Defra)
• working with the Met Office on integrating our guidance with the NSWWS service

To deliver this work we have an ambitious programme of recruitment and people development. We will need to promote what we do and our careers more widely to continue to attract the best candidates to join us.

Our next strategy will be benchmarked against the newly published international standards for forecasting and warning. These are developed by the WMO (World Meteorological Organization) . This will ensure we continue to improve and demonstrate we are leaders in flood forecasting.

I am delighted to be leading this chapter of the FFCs development through this key time.

Russ Turner

Head of Centre