From the Met Office: Despite the extensive cloud and limited sunshine yesterday morning, temperatures edged up enough to trigger the forecast thunderstorms, as parts of Liverpool and Manchester will readily testify. Indeed several significant storms affected the southern half of the region yesterday afternoon and evening with rainfall totals of 67mm recorded at Denton Reservoir on the E side of Manchester and 58mm at Heaton Park reservoir on the N side of the city. Further N into Lancashire Great Harwood recorded 29mm. The atmosphere this morning is little changed from that of yesterday so the same weather risks present themselves today, although this will thankfully be the last of the really threatening downpour days albeit still with a fair bit of rain to come across the S half of the Northwest tomorrow but more on this below.
Same old story I’m afraid. The cloud is thinning and breaking in places and temperatures will soon reach the required ‘trigger levels’ for shower/storm clouds to develop. Whilst the distribution of heavy/thundery downpours this afternoon/evening will vary somewhat from yesterday, the overall message is unchanged i.e. once formed the showers/storms will tend to drift very slowly NW’wards, their slow pace and associated localised intense rainfall again allowing significant rainfall totals to build up in places with the almost inevitable surface water flooding on the roads/rail lines and perhaps too in some residential/business premises. Lightning/hail are once again additional hazards, noting the house that was struck on the Wirral in one of yesterday’s storms. Narrow urban water courses are again at risk of rising very rapidly in response to a storm. Yesterday’s yellow medium impacts thunderstorm warning has been updated (attached above) with the impact assessment rated as a low likelihood of medium impacts. The warning runs from midday through to midnight (some activity could once again linger well into this evening) and is valid across the whole of the Northwest. Please refer to the warning text for a full listing of possible impacts from the storms. As always but I’ll say it again – keep close tabs on the radar and lightning maps for the latest in terms of distribution, intensity and track of the developing showers/storms.
In the early hours of tomorrow morning a belt of rain is expected to extend westwards across the Midlands and then eventually drawn northwards towards our region. The behaviour of the rain (track/extent/intensity) is not yet totally clear cut but the prediction is that it will, during tomorrow morning, continue to extend slowly northwards across Cheshire, Merseyside, Greater Manchester and into Lancashire, some of it reaching Cumbria in the 2nd half of the day by which time it will be fragmenting and weakening. This will be more the steady variety of rain as opposed to the flash bang downpours of recent days, though a few heavier interludes could well be mixed in during the morning period. Although rainfall totals from this system will be largest across the Midlands sufficient rain could fall across the more S parts of the region to result in some low impacts and thus a new low impact (yellow) rain warning has been issued (copy above) covering Cheshire, Merseyside, Greater Manchester and S Lancashire, valid 0300 to 1200. Both the above warnings and their associated flood risk in terms of surface water and river components are reflected in this morning’s Flood Guidance Statement which I have also attached above for your information.
A few sharp showers possible on Friday then a largely dry, bright Saturday but with a belt of rain/freshening winds crossing all areas overnight followed by bright/breezy/fresher conditions on Sunday with a few scattered showers.