Low Flood Risk for 24 and 25 September

Flood Forecast Area 24 and 25 SeptemberA major development now taking place well to the southwest of the UK will result in a deep low pressure centre tracking NE’wards into the country over the next 36 hours. Copious rainfall will be generated by the system across a good swathe of the UK, some places also at risk from strong to gale force winds, and the Met Office has Yellow Alerts in place for the whole of northwest England throughout Monday and Tuesday.
There remains some uncertainty as to exactly where will see the heaviest and potentially most disruptive rainfall, but the latest predictive sequence I can offer is as follows;
TODAY (23 September):
Outbreaks of rain will spread from the south later today, reaching Cheshire late this afternoon or early this evening then pushing on northwards to remaining areas this evening. There will be further rain at times across the region through the night but, borne on a freshening E to NE wind, I expect the Pennines to ‘do their job’ and filter out most of the heavier rain, hence no disruption is anticipated in the overnight period with some drier interludes quite possible.
MONDAY:
The main threat of any disruptive rainfall arrives through the course of tomorrow when areas of more persistent and, at times, heavy rain spread northwards. The main risk time for this heavier rain looks like being through Monday afternoon and early evening, before drier conditions follow from the south through the evening. Hard to specify exactly where will catch the heavier stuff so I’m afraid it’s a blanket warning at the moment. Thereafter the remainder of Monday evening along with Monday night does not appear to pose any additional threat from rainfall although winds could become quite strong for a time on Monday night, more on this aspect tomorrow morning.
TUESDAY/WEDNESDAY:
As the low begins to lose power we’ll be looking at a couple of potentially showery days, especially Tuesday. There will still be the potential for one or two sharp downpours, something to bear in mind, although the risk of any associated disruption should steadily diminish through this period.
FLOOD GUIDANCE STATEMENT:
Today’s Flood Guidance Statement, attached above, has the whole of NW England at Yellow (Low) flood risk for both tomorrow and Tuesday. I refer you to the ‘Specific areas of concern’ maps on page 2 for amplification of the flood risk. Needless to say, any bursts of really heavy rain (particularly I’m thinking of radar image pixels shaded red, pink or white), have the potential to result in localised surface water flooding, as we have witnessed too many times already this past ‘summer’. Hence my message again is to keep an eye on the radar tomorrow, be it via Hazard Manager or the Met Office website  http://www.metoffice.gov.uk/  (click on rainfall on the ‘UK Weather’ map then click on ‘Get detailed rainfall for the UK and pan and zoom accordingly).
I will be out and about for much of today but will be able to take calls or at least reply to them. An update briefing will be issued as and when appropriate but most likely early on tomorrow morning.
Kind regards,

Alan Goodman;

Met Office Advisor (Civil Contingencies)

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