Corporate report

Flood Forecasting Centre: annual review 2023 to 2024

Published 14 October 2024

Applies to England and Wales

1. Introduction

The Flood Forecasting Centre (FFC) 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 performance

• insights we have gained from our users

• improvements and changes we have made in our services

• information on our modelling capabilities and people

2. Main weather and flood features

Overview

The year was very wet and stormy overall. There were 17 named storms - 11 named by Met Office and 6 by other Meteorological Services during the winter period.

The winter was the 3rd wettest winter flood period on record in the last 10 years. This meant that FFC and local forecasting and warning teams were extremely active.

May 2023

On 9 May there were significant surface water impacts in Somerset and Devon as thunderstorms generated very intense short-term isolated rainfall totals:

• in Devon 53 residential properties flooded in the village of Newton Poppleford - with further flooding affecting surrounding villages

• in Somerset a major incident was declared with 50 residential properties evacuated

• notable road and rail disruption also occurred in both locations - along with some instances of rivers overtopping their defences

• some river flooding impacts were recorded in this event - though most impacts were driven by surface water

• minor impacts on transport and some property flooding occurred in other parts of the country due to the thunderstorms

June 2023

On 12 June thunderstorms led to minor surface water flooding in southern and central England:

• 17 properties flooded in Buckinghamshire

• there was flooding at Luton and Dunstable hospital in Bedfordshire

• the railway line between Gloucester and Swindon was closed until the following day

On 18 June thunderstorms led to minor surface water flooding in the north of England, in particular in Wrexham, Greater Manchester and South Yorkshire. Impacts included:

• motorway closures

• a football stadium evacuated due to structural damage

• an elderly lady rescued from her home

• many drivers rescued from cars

July 2023

On 8 July significant surface water flooding occurred across Derbyshire and the West Midlands:

• in Derbyshire 15 commercial properties were flooded

• in the West Midlands an estimated 80 properties were flooded

• widespread minor surface water flooding impacts were seen across Lancashire, Cumbria, Merseyside, Wrexham, Flintshire, Cheshire and South Yorkshire - with disruption to transport networks 

August 2023

On the evening of 26 August significant surface water flooding was recorded in Liverpool.

Rainfall accumulations during this event were not unusual. Isolated flooding in Queens Road was mainly caused by infrastructure issues at a known flood hotspot, where the road dips under a rail bridge.

However, this event was assessed as significant, largely due to the depth of water. This resulted in cars becoming stranded and sadly 2 fatalities.

In addition to this incident, heavier rain further south overnight into August 27 led to internal flooding of 6 properties in Ellesmere Port.

September 2023

On 17 September heavy thunderstorms brought some large, short duration rainfall accumulations leading to widespread flooding impacts across Somerset and Devon:

• significant surface water flooding of 120 properties across 28 communities in Devon - including commercial properties, a school in Exeter and Exeter Airport

• river flooding of 30 properties and widespread disruption to transport - with railway line closures and flooding of A roads

On 18 September further thunderstorms lead to significant flooding in Swindon where up to 100 properties flooded, the vast majority from surface water.

October 2023

From 18 to 21 October Storm Babet resulted in the most severe and widespread flooding disruption of 2023:

• heavy, persistent and widespread rain affected much of England and Wales - with 100mm falling widely and high flows across many river catchments

• multiple severe flood warnings were issued by the Environment Agency - with over 1,000 homes in England affected by flooding across Yorkshire, the East Midlands and Humber areas

• in Derbyshire, around 300 homes were flooded with several hundred homes also evacuated

• there was major transport disruption on road and rail - with significant impacts persisting for several days in some areas

Later in October, a period of strong winds, large waves and storm surge brought the potential for widespread minor coastal flooding impacts. Significant flooding impacts were observed in parts of Cornwall and around 75 properties were affected in Looe, Mevagissey, Fowey, Perranworthal and Polperro.

November 2023

Storm Ciarán followed soon after on 1 to 2 November with strong wind speeds and localised flooding affecting many communities in the south of England.

Storm Debi brought further strong winds and heavy rain to England and Wales on 13 November. There were some localised minor flooding impacts across parts of England and Wales.

December 2023

December saw further named storms (Elin, Fergus and Gerrit) and a prolonged period of raised flood risk across England and Wales:

• groundwater flooding became an increasing concern during this period through parts of the south of England

• flooding affected the larger and slower responding rivers such as the Severn and Trent

• significant impacts were observed on both the 4 and 7 December - with minor impacts recorded most days for the remainder of the month

January 2024

Storm Henk on 2 January resulted in:

• an afternoon issue of the Flood Guidance Statement (FGS) going amber for Billing Aquadrome, a caravan park in Northamptonshire - where park wide evacuations took place

• river levels on the River Trent in Derby and Nottinghamshire, on the lower reaches of the River Severn and on the River Thames rising to significant impact levels

• multiple properties flooding in Lincolnshire, Leicestershire, Nottinghamshire, Northamptonshire, Somerset, and Gloucestershire

• isolated property flooding in Wiltshire, Derbyshire and West Berkshire

The Environment Agency reported that around 2,000 properties flooded in the first week of January.

February 2024

During February:

• the FGS showed raised flood risk for 24 out of 31 days

• Billing Aquadrome was evacuated again on 10 February, with the park closed for the much of the remainder of the month

• there were many instances of minor river and surface water flooding impacts as modest amounts of rain fell on wet catchments

It was the wettest February on record in the south of England meaning that ground water levels were high for much of March.

3. Performance

As well as issuing the FGS on time, accuracy and lead time are critical to allow for emergency responder planning and resourcing.

The following information provides an insight into FFC performance across these metrics.

3.1 Timeliness

The FGS is an important part of emergency responder decision-making. We aim to publish it every day by 10:30hrs so that customers receive it by 11:00hrs. Our timeliness target is 95%.

Table 1: highest forecast flood risk from all flood sources for any FGS issued for each calendar day for 2023 to 2024.

Month (2023 to 2024)	Green	Yellow	Amber	Red
April	30	0	0	0
May	30	1	0	0
June	18	12	0	0
July	27	4	0	0
August	25	6	0	0
September	19	11	0	0
October	11	11	9	0
November	21	9	0	0
December	2	28	1	0
January	4	21	6	0
February	8	21	0	0
March	7	24	0	0

The timeliness measure is verified on the first FGS issue of each day which includes any low flood risk or above.

The FGS was issued on time 100% of the time, an improvement on recent years.

3.2 Probability of Detection (POD)

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

Table 2: POD for all sources of flooding, April 2023 to March 2024

Source	Lead time	POD	No. Observations
Surface water	Day 2	83%	403
River	Day 3	73%	404
Coastal	Day 3	82%	23
Groundwater	Day 3	82%	234

Table 3: POD rolling 36 month

Source	Lead time	POD	No. Observations	RAG status
Surface water	Day 2	84%	867	Green
River	Day 3	73%	558	Green
Coastal	Day 3	84%	46	Green
Groundwater	Day 3	85%	330	Green

3.3 Lead time of first correct forecast

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

Table 4: Target lead time April 2023 to March 2024

Source	Lead time	POD	No. Observations
Surface water	Day 2	83%	403
River	Day 3	73%	404
Coastal	Day 3	82%	23
Groundwater	Day 3	82%	234

4. Stakeholder engagement

To meet the needs of users and understand expectations of key stakeholders, the FFC undertakes a range of activities, including:

• visits
• user group sessions
• open days
• research

4.1 Visitors

The FFC hosted visitors from:

• DLUHC

• Defra

• Environment Agency

• Australian Bureau of Meteorology

• Jersey Met Service

• Malaysian Met Service

• DESNZ (Department for Energy Security and Net Zero)

4.2 Other engagement activities

The FFC also:

• attended careers fairs at Plymouth and Exeter Universities to promote opportunities for careers in the FFC

• held an open day in November 2023 - hosting, amongst others, the Environment Agency and Natural Resources Wales

• supported and attended numerous winter readiness calls to improve preparedness and resilience

• compiled post-event reports for Storms Babet and Ciaran

• produced tailored reports for Defra (Secretary of State Review and Flood Outlook Performance Report)

• held user group meetings in June and December - expanding the number of attendees and ensuring all Local Resilience Fora (LRF) are now represented

4.3 Responder survey

The 2023 responder survey was sent out in February. The results will be published in the next financial year.

The results from the 2021 responder survey suggested many users were unaware of the training offered by the FFC. Therefore, the following activities were carried out:

• FGS matrix training delivered to over 40 responders in October 2023

• ‘FGS in action’ training webinar held in February 2024 reaching over 90 people

In total, the FFC trained over 800 people this year.

5. Product and service development

5.1 Rapid Flood Guidance trial

The FFC has been working on a trial Rapid Flood Guidance service.

For summer 2024, FFC plan to:

• issue updates to Flood Guidance Statement (FGS) users during days when flooding could develop rapidly (less than 6 hours)

• use the FGS to flag days on which additional guidance will be produced

• work with Met Office Expert Weather Hub to produce the guidance

• work with a panel of FGS users to evaluate the trial

In the longer term, the FFC plan to:

• work closely with the Environment Agency to add more value to this service - using new scientific data to identify areas at particular risk

• refine the service based on user feedback

• integrate the service into new technology for faster production

• include new capability for providing accurate short notice forecasts

5.2 End to end ensembles

The goal of this work is to provide an objective and consistent assessment of flood risk uncertainty. It is hoped that this will lead to:

• more consistent flood forecasting practices
• proportionate flood incident management decisions
• overall service efficiencies

The discovery stage of the project was carried out from January to March 2024. This focused on a few catchments with the Environment Agency and coastal reaches with NRW. The analysis and reporting take place between April to May 2024.

Next steps involve conducting a pilot though winter 2024 to 2025 which will be on a larger scale than the discovery phase. This will test the latest ensemble data feeds and drive hydrological model applications.

The work is being supported by the FFC-Met Office-Environment Agency Joint Development Group.

5.3 Surface water flood modelling

The FFC successfully completed the development phase of the new operational release of the Surface Water Flooding Hazard Impact Model (SWFHIM). This involved working closely with UKCEH, HSE and the Met Office Weather Impacts team.

5.4 Digital Flood Guidance Statement

The project will build a new FGS IT system. It will be digital-first, providing more flexible outputs for users to combine with other information in their systems. The system will have:

• a common warnings framework

• improved customer offering

• updated code and IT framework

• common components with National Severe Weather Warning Service (NSWWS)

• a common API format.

This year the full business case was completed and submitted for initial review.

5.5 Flood Outlook verification

The aim of this project is to provide a routine verification process for the Flood Outlook product. This will include regular product performance reports and evidence for future developments. So far, the team has:

• undertaken scoping work with the Met Office verification team
• drafted a survey for a small sample of customers, duty managers and hydromets

6. People

Our successes this year have included:

• new Met Office hydrometeorolgists onboarded and operational

• 2 senior hydrometeorologists Duty Manager trained

• 3 industrial placement students have supported us this year with 3 more successfully recruited for the coming year

• securing a Met Office Graduate to carry out a 3 month placement in FFC next year

Our challenges this year have included:

• 17 named storms since August 2023 leading to prolonged periods of heightened operational activity
• long-term industrial action
• large project resourcing affecting shift rosters
• challenges in recruitment, particularly on the EA side
• sickness absence affecting resilience through the winter

Team wellbeing remains a priority and regular topic of conversation at team meetings.

7. Forward look

The year 2023 to 2024 marked 15 years of FFC operations. This year we have delivered to our current strategy. Next year we will look to refresh this taking forward our priorities:

• wellbeing of our staff

• maintaining operational delivery and resilience

• continual service improvements projects

• development work carried out in our science, users and operations theme areas

This is both a challenging and exciting time for the FFC as we look ahead to next year.

Russ Turner

Head of Centre