Up to 80 mile an hour wind gusts possible from ex-hurricane Gonzalo

The remains of hurricane Gonzalo is due to strike the British Isles tonight resulting in widespread rainfall and wind gusts up to 80 miles an hour tomorrow morning.

Gonzalo travelled over the island of Bermuda earlier this week, but has since been decreasing in energy and is now downgraded from hurricane status to an extra-tropical storm. The video below, from the Met Office, shows ex-hurricane Gonzalo undergoing extra-tropical transition into an Atlantic low pressure system.

The Met Office has issued a severe weather warning for wind for large parts of the UK. The worst disruption is expected on Tuesday morning when high wind gusts coincide with the morning rush hour.

The Environment Agency has asked people to be flood aware and prepared, Although the strong winds might help drive low coastal flood risk on Tuesday and Wednesday. You can keep up to date with updated flood warnings on the Environment Agency’s website: http://apps.environment-agency.gov.uk/flood/142151.aspx


More information:
[1] The Met Office warnings: http://www.metoffice.gov.uk/public/weather/warnings/
[2] The Environment Agency flood risk map: http://apps.environment-agency.gov.uk/flood/142151.aspx
[3] More about hurricanes, typhoons and cyclones: https://climateandgeohazards.wordpress.com/2013/10/07/cyclones-hurricanes-and-typhoons-whats-the-difference
[4] The latest BBC news report at time of writing (21:37 Mon 20th): http://www.bbc.co.uk/news/uk-29685066

Flash Floods in the Holy City of Mecca

The holy capital of the Islamic religion is the ancient and beautiful city of Mecca. Located in the desert climate of Saudi Arabia, with temperatures often exceeding 45 degrees Celsius, this is the last place you would expect to experience heavy floods.

However, since the city is located in a low-lying region it is threatened by seasonal flash floods despite the low amount of annual rainfall. A flash flood is a very rapid flooding event often occurring with little warning.

Heavy rainfall over the past week has resulted in significant flash floods in the city of Mecca today. At the time of writing the floods are ongoing. The pictures below show streets inundated by flood waters and a number of vehicles being swept away by the currents.

All images courtesy of Zakhir Hussain.






INCOMPASS – Investigating The Dynamics Of The Indian Monsoon

CGS’ Doug Parker and John Marsham have won a major research grant as part of a joint UK-Indian consortium studying the dynamics of the Indian Monsoon. The INCOMPASS project will involve a large-scale field campaign in India and over the adjacent oceans, in the year 2016, and a programme of computer modelling, with the specific aim of improving predictions of the monsoon.

A topographic map of India. The brown regions are high topography, which act as barriers to moisture rich air from the Indian ocean to the south.

The brown regions are high topography, which act as barriers to moisture rich air coming from the Indian ocean to the south. Image: Wikimedia Commons

The Indian Monsoon is one of the most significant climate systems on Earth. The seasonal changes in the monsoon winds, which bring the annual rainfall to most parts of India in the summer, are one of the most intense and robust patterns in our climate system. However, computer models show very large errors for this region, whether predicting the weather a few days in advance, or representing the current climate of India. Climate projections for future Indian rainfall also have significant uncertainties.

The INCOMPASS project aims to explain the physical processes which lead to these errors in models, and to derive strategies to represent the processes more accurately. In particular, the project will explore the ways in which the land surface, and the patterns of land-use, lead to responses in the regional climate.

Monsoon rains over Mumbai. Wikimedia Commons

Monsoon rains over Mumbai. Image: Wikimedia Commons

The project will support a 3-year postdoctoral research position in Leeds. The research group at Leeds will contribute to the airborne research programme and will lead the analysis of new high-resolution models of the monsoon, using the Met Office forecast model. Airborne observations will be made with the UK Facility for Airborne Atmospheric Measurements (FAAM) BAe146 research aircraft, and will be supplemented by a large number of extra balloon-soundings from the operational weather stations across India. A network of ground stations will measure the water and energy budgets at the surface, and how these change during the seasonal progression of the monsoon. High resolution models, which capture the dynamics of individual storms, will enable researchers to evaluate the feedbacks between the land surface and the atmosphere, which are governed by these storms.

INCOMPASS is a consortium of UK and Indian partners, led by the University of Reading and by the Indian Institute of Science (IISc), with the University of Leeds, the NERC National Centre for Atmospheric Science (NCAS) and Centre for Ecology and Hydrology (CEH), the Indian Space Research Organisation (ISRO), the National Centre for Medium-Range Weather Forecasts (NCMRWF), the CSIR National Aerospace Laboratories (NAL), the Indian Institute of Technology (IIT), the India Meteorological Department (IMD) and the Met Office. The project is jointly funded by NERC and the Indian Ministry of Earth Sciences (MoES). Two sister projects were also funded, to study Indian Ocean dynamics, and to study atmospheric aerosol processes in the monsoon system.

The extreme flooding in the summer of 2010 was due to high volumes of rainfall during the monsoon season that year.  Image: NASA

The extreme flooding in the summer of 2010 was due to high volumes of rainfall during the monsoon season that year.
Image: NASA



More information:
[1] http://earthobservatory.nasa.gov/IOTD/view.php?id=45177
[2] http://www.see.leeds.ac.uk/admissions-and-study/research-degrees/icas/indian-monsoon



Large Low Pressure System In The Atlantic = More Rain And Floods

Large Low Pressure System In The Atlantic = More Rain

An area of low pressure has been moving up from the Atlantic over the past few days. At the moment it is located off the west coast of Ireland.

This weather front will move into the UK later today and could result in strong winds creating large coastal waves, coastal flooding and storm surges. The north-western coasts of Scotland are expected to be hit the worst.

However, according to the latest Met Office forecast the weather should improve over the week as the storm moves north-east past the UK.

This beautiful screen shot shows wind speeds at 1000 hPa with the values shown for the small green circle (Leeds). The large low pressure system is clearly seen in the Atlantic.


Future flood losses in the world’s largest coastal cities


Over the next few decades climate change induced sea level rise and subsidence due to ground water pumping is expected to affect a greater proportion of people living in low lying  regions. Coupled with economic growth and increasing populations in coastal cities this trend will result in higher annual losses from flooding.

A recent Nature Climate Change article estimates that the average annual losses from flooding in the world’s largest coastal cities could rise from about $6 billion per year in 2005 to over $1 trillion per year by 2050. Even if investments are made to maintain flood probabilities at current levels, subsidence and sea level rise alone will increase annual losses to around $63 billion by 2050.

The top 20 coastal cities with the most Average Annual Loss increase in 2050.

The top 20 coastal cities with the most Average Annual Loss increase in 2050. Hallegatte et al. 2013

The above figure, from the article, shows the 20 cities where Average Annual Losses (AAL) increase the most (in relative terms in 2050 compared with 2005) if adaptive measures are taken to only maintain present defence standards or flood probability. Note that this assumes a relatively optimistic sea level rise of about 20cm. Many coastal cities are expected to have much higher sea levels of ~60cm by 2050.

Another way to look at flood risks is to rank them in order of how much much damage is expected from a 100 year repeat flooding event with respect their annual GDP. The table below lists the top 10 cities ranked by 2005 losses as a percentage of its GDP.

City Country AAL (% of GDP)
1 Guangzhou China 1.32
2 New Orleans USA 1.21
3 Guayaquil Ecuador 0.95
4 Ho Chi Minh City Vietnam 0.74
5 Abidjan Ivory Coast 0.72
6 Zhanjiang China 0.50
7 Mumbai India 0.47
8 Khulna Bangladesh 0.43
9 Palembang Indonesia 0.39
10 Shenzen China 0.38

China currently occupies three of the top 10 positions in this table. Which is why the Chinese government is actively investing in flood defence technologies and climate change research. Many of the countries where the annual losses are a significant proportion of the annual GDP are developing nations. These countries will continue to suffer with greater losses in future years unless something drastic is done to improve their flood defence systems.

It is worth noting that Hallegatte et al. (2013)  do not consider the other issues a rising sea level will have on coastal populations. Higher sea levels coupled with rising temperatures will result in a greater frequency and/or magnitude of coastal storms and cyclones. Historically these single events have been the cause of the greatest loss of lives and damage to infrastructure.

It is clear that flood risk and exposure needs to be reduced to below current levels if we are to avoid large financial and human losses in the future.

CGS academic Professor Nigel Wright explores the links between flood vulnerability and climate change and is currently helping to develop a Coastal City Flood Vulnerability Index (CCFVI) based on exposure, susceptibility and resilience to coastal flooding.

Read more about his recent work here: http://link.springer.com/article/10.1007/s11069-012-0234-1