Potential Hazardous Weather Next 48 hours – Met Office Update

I have received the following email this morning from the North West Met Office.

“The radar at 0700 confirms a band of rain already spreading eastwards across the region with the heavier rain now likely to affect Cheshire, Merseyside, Greater Manchester and Lancashire, that over Cumbria at present looking lighter and more patchy.   The rain in the next couple of hours will be falling onto surfaces either still affected by old snow/ice or, if not, still close to or just below freezing.   Hence there is a risk of locally very slippery conditions developing through the rush hour.    Once the heavier rain has gone through later this morning it will leave behind a legacy of damp, overcast conditions with further intermittent light rain but with temperatures eventually rising to between +4 and +6C at low levels – hence there should be some acceleration in the rate of thaw of lying snow/ice.   Towards midnight the next band of rain will advance in from the west to reach all areas in the early hours of Saturday.   Some heavy rain is possible anywhere from this system, especially over Cumbria.   As mentioned yesterday there is a chance of the rain turning to sleet/snow for a time on the higher ground during Saturday morning with several centimetres of snow possible over the higher Cumbrian fells and the higher-lying Pennine areas.    Very difficult to put a height on the rain/snow boundary but certainly something to bear in mind.

Probably of greater significance, though, is the likely impact of the rain falling onto land, much of which is still under a substantial snow-cover.   As yesterday’s Flood Guidance Statement suggested (without actually referring to northern England), this is likely to lead to enhanced run off of rainwater, accentuated by thawing snow, which could result in localised problems.     I will try and forward today’s Flood Guidance Statement to you upon receipt (usually between 1000 and 1030).    Potential problems could also arise where snow has been piled up on roadsides/car parks etc. possibly inhibiting drainage.

Although the heavier rain tomorrow will occur prior to midday, further intermittent rain is likely through the remainder of Saturday with a proper clearance not expected until Saturday evening.    With temperatures at low levels again climbing several degrees above freezing and, combined with the rain, we should see a continued faster thaw of snow than during the recent past.

As for Sunday and beyond into next week the good news is that it looks as if we’ll be under a more typical January regime with temperatures for the time being back up towards the average.    This obviously doesn’t preclude overnight frost/fog but at least things should start to feel a little more like ‘normal’ whatever ‘normal’ is………………………”

Alan Goodman; Met Office Regional Advisor – NW England

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