Weather Update

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Good afternoon,

The rain across Lancashire and Cumbria has now diminished to little more than a few patches here and there and with the situation on the ground improving so the afternoon edition of the Flood Guidance Statement was able to show a reduced flood risk from amber to yellow with a low likelihood of significant impacts still applying to both counties. In tandem with this the Met Office amber warning was cancelled just after 1500, leaving the region under a single yellow warning, the graphical bits of which are displayed below. As you can see it’s now only N/NE Lancashire and Cumbria still at risk from any significant impacts over the next 12 hours. The upcoming feature of concern is the rain band associated with the transition to clearer conditions, set to move in between approx 2100 and 2300 this evening. There’ll be some heavy rain on this, especially over Cumbria, but it should be a relatively short-lived affair and even allowing for a few showers in the early hours of Monday, additional accumulations of rain will be modest in comparison with what fell earlier today and overnight. The power of the Cumbrian mountains to generate rain when fed the right air supply never ceases to impress and the EA gauge at Seathwaite recorded 178mm in the 12 hours to 0845 this morning. However, one didn’t have to travel very far out from the central fell area of the Lake District to see the totals tail off rapidly.

As for tomorrow night’s weather system – still some uncertainty as to the northern edge of the associated rain area but hopefully it will stay wholly to the south of Cumbria and N Lancs. The next system, following quick on its heels, will likely take a more northern track and further rain looks a surer bet during Tuesday.

In the meantime have a good rest of Sunday,

Regards,

Alan Goodman; Met Office Advisor (Civil Contingencies)

Weather Update

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LATEST WEATHER SEQUENCE:
The rain, already into parts of Lancashire and Cumbria, will be generally light at first this afternoon, with the more serious rain arriving through the course of this afternoon. Then from later this afternoon through this evening a period of fairly persistent and locally heavy rain is expected for much of the region except perhaps in the south where Cheshire, especially the south of the county, may escape much of the heavier rainfall. During this evening the persistent, heavy rain will tend to become more focussed across Cumbria and the Lancashire Pennines but even further south further locally heavy outbreaks of rain may continue for a time overnight, especially across the western Pennine upslopes. Through Sunday we’ll see further rain at times across the Northwest but more especially over Cumbria and the Lancashire/Greater Manchester Pennines where some of the rain will again be heavy, albeit waxing and waning in area/extent. During Sunday evening the more persistent rain should finally depart as somewhat clearer conditions arrive from the west, though with the risk of showers through the early hours of Monday, some of which could themselves be quite sharp.
SEVERE WEATHER WARNING STATUS/FLOOD RISK:
This morning’s Flood Guidance Statement now has two area As within the Northwest where the flood risk rating is a medium likelihood of severe impacts, firstly the area of S/W/Central Cumbria which we became aware of yesterday afternoon but now in addition we have an area of E/NE Lancashire also at medium likelihood of severe impacts. The rest of the Northwest (bar south Cheshire) remains on yellow (low likelihood of significant impacts). The flood risk comprises a combination of river and surface water flooding. The amber flood risk status runs today and tomorrow with all areas reverting to yellow for Monday and Tuesday, emphasising the ongoing nature of the flood risk. The current Met Office yellow and amber severe weather warnings have just been updated and are on the Met Office website.
MONDAY/TUESDAY:
Much of Monday daytime should be dry but the next batch of rain is likely to arrive in the evening with further rain possible during Tuesday and Wednesday. However, confidence in the exact track of these subsequent weather systems, together with the extent and amount of rain they may generate, is fairly low at present and hence their effect on the flood risk is difficult to quantify at present. What I can say is that these systems should be moving through reasonably quickly. In terms of amount of rain this weekend’s event will be by some way the biggest.

Weekend Weather

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The forecast for the weekend has remained fairly consistent throughout the past 24 hours. Hence confidence is increasing now for a significant rainfall event to affect the region between tomorrow and Monday giving rise to both river and surface water flooding with further rainfall likely through the course of next week.
WEATHER SEQUENCE:
The first of the weekend’s rain will be spilling in off the Irish Sea during tomorrow morning. Whilst the first 2 to 3 hours’ worth may be relatively light and perhaps rather intermittent the rain looks like really getting going through the course of Saturday afternoon and into the evening when some heavier, more persistent rainfall could occur pretty much anywhere across the Northwest, except perhaps in Cheshire. Overnight into the early hours of Sunday the rain will continue across much of the region but gradually become more and more focussed on Cumbria and N/NE Lancashire with the rest of the region still subject to some scattered outbreaks of rain during Sunday, but with some drier interludes also developing. Over Cumbria and N/NE Lancashire the rain could continue unabated throughout Sunday with the western, central and southern parts of Cumbria catching the worst of it and the more northern and eastern areas seeing significantly lower totals as is always the case in these situations. I should add that there remains some uncertainty regarding the persistence of the rain through Sunday with some variance amongst the forecast models as to where the most persistent rain will ultimately play out. What is reasonably certain is that the final clearance should come through during Sunday evening, slightly earlier than suggested yesterday, albeit accompanied by a period of strengthening winds which could result in one or two minor impacts. Nevertheless there is scope for some very large rainfall totals over the course of the weekend and given all the evidence the decision has been made, not surprisingly, to upgrade yesterday’s initial yellow alert to an amber alert for much of Cumbria and NE Lancashire meaning that for these areas there is now a medium likelihood of medium/significant impacts arising as a result of the rain. The alert is valid from 1800 tomorrow evening to 2100 Sunday evening. Across the rest of the region we remain under the yellow alert issued yesterday and re-issued today (low likelihood of medium/significant impacts) except for south Cheshire who remain outside the alert area. A copy of the new amber and revised yellow alerts are attached above.
FLOOD RISK AND IMPACTS:
The flood risk, is a combination of potential river overspill and surface water excess. The weather warnings show both Cumbria and Lancashire on amber (medium flood risk) for both Saturday and Sunday with the remainder of the Northwest on yellow. For all river-related impacts the Environment Agency will be issuing flood alerts/warnings in due course. Their online river levels site is an excellent resource for monitoring the response of local rivers. Surface water excess will particularly impact transport networks across the region with travel disruption likely from Saturday evening onwards, particularly on the roads but possibly also on any susceptible stretches of rail line. Up until Sunday morning surface water disruption could occur anywhere within the yellow and amber alert areas. By the time we get through to Sunday morning the main focus for further surface water flooding will, like the rain, become increasingly focussed on Cumbria and N/NE Lancashire. Given the time of year leaves on the ground could play a big part in exacerbating the surface water problem, especially in urban areas. Please refer to the Met Office website for a comprehensive breakdown of the flood risk.
LOOKING FURTHER AHEAD:
Monday I’m afraid is likely to bring only a temporary respite. Further Atlantic weather systems will be queuing up during the course of next week to deliver further rainfall from time to time. Hence a good part of next week is likely to see the flood risk elevated across parts of the region. Not surprisingly therefore the warnings have kept the whole of the Northwest on yellow flood risk for Monday (when residual river impacts may still be experienced) with Cumbria and Lancashire being retained on yellow through Tuesday (as the next weather system and its attendant rain approaches).