There was some very lively weather over the weekend with heavy rain, thunderstorms and hail the size of marbles!
The thunderstorms on Saturday night were unexpected and were caused by a big difference in temperature. The air over Wales came from the tropics so it was very mild and moist.
To the west of Ireland, though, the air was colder and drier and this difference in temperature created 'potential instability' in the atmosphere. This was released and led to thunderstorms.
Thunder can happen at any time of the year but the storms on Saturday night were unusually severe for January.
Violent thunderstorms normally occur during the summer months when there is more heat and humidity available in the atmosphere.
Yesterday the air over Wales originated from Greenland so it was cold and as it passed over the warmer waters around Wales and Ireland the air became very unstable. This meant huge towering Cumulonimbus clouds, hail and thunder.
Several impressive pictures were sent to me on Twitter yesterday including Cumulonimbus clouds and Mammatus.
https://twitter.com/jessvoyce/status/295577573423984641/photo/1
https://twitter.com/Kristian14_/status/295572069201104896/photo/1
https://twitter.com/HattonWillow/status/295575918498443266/photo/1
Hail the size of peas and marbles fell from the sky and a hailstorm caused an accident on the M4 motorway.
Pictures of hail:
https://twitter.com/NiaJon/status/295648058589454336/photo/1
https://twitter.com/MissyLeyMeek/status/295514996056670208/photo/1
In July 1968, hail the size of a tennis ball fell at Cardiff Airport!
I wouldn't rule out more hail and thunder later this week but before then we have more heavy rain and gales to deal with.
Met Office heavy rain warnings are already in force for tomorrow including an amber warning for parts of south Wales.
Rainfall totals of 20 to 30mm are expected with over 50mm, 2 inches, on higher ground.
This means a risk of further localised flooding given the ground is saturated from previous rainfall and from melting snow.
Rivers are already swollen. At the time of writing, there is one flood warning in force in the Lower Dee Valley from Llangollen to Chester and 7 other flood alerts.
Strong winds combined with high tides may also result in large waves and spray overtopping the coast.
The reason for the heavy rain and gales tomorrow is a deep area of low pressure over the Atlantic.
A warm front will bring very mild air from the tropics with temperatures rising as high as 13 Celsius but the air will also be very moist so expect lots of low cloud, mist and hill fog. Visibility will become poor, especially on higher ground.
