Ongoing risk of disruption from persistent rain

25 Sept 2012 Warning Map
25 Sept 2012 Warning Map

The latest forecast information is now to hand and the scenario overnight is largely unchanged with further outbreaks of rain affecting much of the region for a good part of this evening and overnight, the driest conditions liable to be located towards north and west Cumbria where currently things are dry. Although the majority of the rain will be in the ‘light to steady’ category there remains the potential for one or two heavier interludes this side of midnight. Hence, although the rate of rainfall accumulation will be generally slow there is still the potential for another 10-20 mm of rainfall across a wide swathe of the North West with the risk of ongoing flooding-related impacts lasting well into the night. By midnight we should be seeing the rain area start to withdraw from the north so Cumbria will be first to ‘dry up’ with Lancashire expected to follow later in the night. By breakfast time tomorrow what rain there is still affecting the region is likely to be largely confined to Cheshire and Merseyside with perhaps the odd pocket still affecting Greater Manchester and south Lancashire. Through tomorrow morning this residual rain should peter out but the low pressure centre responsible for the last two days of rain will not be very far away and as skies tend to brighten up and temperatures nudge upwards so a few sharp showers are possible by lunchtime/early afternoon, more especially across Cheshire, Merseyside and Greater Manchester. There is also a low probability of cloudier skies and some patchy (mainly light) rain feeding back over the Pennines and into the same areas at risk from showers but neither these nor the showers are expected to contribute much in the way of significant additional rainfall. Tomorrow night and Thursday look dry and settled. Continue reading “Ongoing risk of disruption from persistent rain”

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.
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.
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. Continue reading “Low Flood Risk for 24 and 25 September”