UK Heatwave Advice – Tower HamletsAugust 12, 2020 3:13 pm
Yellow Thunderstorm Weather Warning
Here is an update on the weather over the next few days. Today looks like being the last of the really hot weather but the risk of thunderstorms continues.
Very heavy showers and thunderstorms are expected in places over the next few days leading to the flooding of homes and businesses from surface water, disruption to transport, power outages and damage to buildings.
– Yellow THUNDERSTORM Warning (Very Low Likelihood of High Impacts) valid until 2359 today.
– Yellow THUNDERSTORM Warnings (Very Low Likelihood of Medium impacts) covering the potential impacts over the next few days.
– Heat-Health Watch level-3 for SE England is out until 0900 on Friday 14th August.
– The Daily Hazard Assessment is Amber for the wildfire risk for the next five days.
– The poor Air Quality risk is moderate to high today and tomorrow.
Heavy Showers and Thunderstorms:
Many of us have missed the showers and thunderstorms in the last few days but a few have popped up here and there with one in Oxfordshire yesterday evening giving 25 mm of rain in a fairly short space of time. The risk of seeing showers and thunderstorms will be higher in the next few days so more of us could see heavy or torrential downpours accompanied by lightning, hail and strong gusty winds.
After a generally fine start to today the high temperatures will trigger the development of heavy showers and thunderstorms. As with any situation like this it is very difficult to pinpoint exactly where the showers and thunderstorms are likely to develop but we are expecting them to be more widespread than yesterday. The risk of further showers and thunderstorms continues through the evening and into the night with the possibility of further thunderstorms developing or moving north.
The risk continues, or possibly increases, tomorrow and on Friday with further showers and thunderstorms expected. Saturday currently looks like being the quietest day of the week with only isolated showers in places but the heavy shower and thunderstorm risk returns for Sunday and Monday.
Where the showers and thunderstorms do occur we could see torrential downpours, frequent lightning, large hail and gusty winds. There is the potential of seeing 30-40 mm of rain in less than an hour and as much as 60-70 mm or more in the space of just 2-3 hours. This could lead to impacts such as difficult driving conditions, flooding of homes and businesses from surface water, disruption to transport, power outages and damage to buildings. The Met Office have issued Yellow THUNDERSTORM Warnings (see above) to cover the potential impacts from showers and thunderstorms over the next few days. Details of the warnings can be found on the Met Office website or on the Met Office App.
Message from the Environment Agency (London):
The potentially heavy thunderstorms could see some rivers react quickly depending on the location and intensity of rain. Small or flashy river catchments could see a more significant fluvial reaction. In the event of heavy isolated rain, we would expect that the principle source of flooding will be from surface water. We have cleared trashscreens and we have put additional resources in place to manage the heightened flood risk.
It looks like we will see a couple more days of the very hot weather before a gradually decline in the temperatures over the following few days. We will see temperatures still into the low to mid-30s Celsius quite widely today and generally the high-20s to low-30s Celsius tomorrow. The Level-3 Heat-Health Watch remains in force until Friday morning. The temperature is then expected to be lower from Friday with temperatures generally in the mid-20s Celsius although one or two spots may still get into the high-20s Celsius.
Due to the current weather conditions the Daily Hazard Assessment shows an Amber risk for wildfires across SE England and moderate to poor Air Quality.