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UPDATE, 06.15HRS, WEDNESDAY 27 JAN. 2010:

Much as expected, the latest Met Office modelling continues to suggest a minimal risk of any snow for the West Country from Thursday overnight into Friday. Thus, myÌýcomments belowÌýfor this to be a largely (or wholly) wet - rather than white - event for our regionÌýremain valid.

The latest models are still keen to develop a convergence zone early on Saturday descending southwards from the Irish Sea into SW England (again, see original thoughts on this below).

Our expectation is for showers from this featureÌýto fall as snow anywhere above 100m inland from the north coasts of Cornwall, Devon and parts of West Somerset - notably over Exmoor. Given the direction of prevailing flow, I think it's very unlikely for showers to extend any further eastwards to affectÌýother parts of our region. Worth stressing that icy roadsÌýcould be a far bigger issue across parts of the SW Peninsula affected by these showers, rather than any actual accumulations of snow.

The weekend continues to shape-up as largely bright and dry, with a quite significant NNW breeze at times making things feel decidely chilly. The cold weather continues into next week too, with growing signs of another cold (perhaps very cold) easterly flow establishing once again.Ìý Ice scrapers at the ready....

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(ORIGINAL BLOG ENTRY FOLLOWS, TUES. 26 JAN. 2010)

In my last blog, I briefly alluded to developments later this week, with a potential for further snowfall across parts of the British Isles later on Thursday and into Friday.

So let's start by also adding Saturday to the broaderÌýperiod of interest. More on that in a moment.

For the time being, the essential theme is one of colder air establishingÌýon a northerly flow across the country progressively through Thursday and into Friday. And later on Thursday, we'll watch an Atlantic system -Ìýcombined withÌýa set of highly complex atmospheric variables and a 'wave-like'ÌýdisturbanceÌý- yield a risk of snow for some parts of England overnight into Friday.

I stress some.

It's a set-upÌýunlike any of the 'snowy synoptics' seen so far this year. For us in the West Country, the impact currently remains very tricky to call, so I've been suitably circumspect on our TV and radio broadcasts.

I'm largelyÌýinclined to downplay this one, if I'm honest. My first stab - with the usual forecast caveat that things could change (inevitably, in my profession!) -Ìýis for this Thursday-Friday evolution to yield a small snow risk for most (if not all)Ìýof us across the region.

Indeed the latest Met Office modelling is increasingly paintingÌýthe greatest snow potential out across northeast and central-eastern England, with a broader swathe of rain and sleet the more probable resultÌýacross most of our area.

Nonetheless, there's still a great deal of uncertainty, not least on the exact track of this feature as it sinks southeastwards late on Thursday. So, until the Met Office sees better continuity in model output, it'll wisely hold-off issuing any sort of public advisory until confidence improves regarding the regional bias of possible disruptive impacts.Ìý

The real forecast headache forÌýme and my colleaguesÌýcomes as this featureÌýdrops away southeastwards into Friday morning.

As it does, the northeasterly (rear)Ìýflank of precipitation, steadily pulling in colder air, will readily lower the Wet Bulb Freezing Level (WBFL, see explanation containedÌýin this blog here) down to around 200 metres or so... offering a greater chance of (wet) snow.

I've attached hereÌýtwo Met Office graphics belowÌý-Ìýmany of you who read my blogÌýwill now be familiar with these and how to interpret the WBFL contours and precipitation symbols.

You'll note (above) how by midnight into Friday,Ìýthe crucial blue sectors lie muchÌýfurther to the east andÌýnortheast in these frames, suggesting the snow risk will lie further off in those regions.

ÌýHowever, as the rain/sleetÌýmoves southwards - indicated by the midday Friday graphic (above)Ìý- we could still see a spell of transient snowfall into some of our districts, rather akin to the short-lived but partially disruptive experiences ofÌýlast week in the likes of Gloucestershire and Wiltshire. Also, any rainfallÌýprior toÌýa transition to snow could wash salt off the roads, increasing the risk of an early ice problem, depending on the timing of this feature slippingÌýaway to the south during Friday morning.

Now, perhaps of greater regional interest for usÌýis during earlyÌýSaturday, when - with a distinctly cold northerly flow blowing across us all - we're watching for a set of factors toÌýcombineÌýand feedÌýa succession of snow showers, plus merged areas of precipitation,Ìýinto parts of the southwest off the Irish Sea. Shown on theÌýright here is how the Met Office's Global Model offers a first stab at this possible development by the start of Saturday.

It's through a process termed a and the Met Office modelling is suggesting a fair swathe of snowÌýpotentially establishing east-southeastwards off the Irish Sea and extending down into parts of the SW Peninsula.

But that's still a long way off... I'll keep you updated on the latest forecast thoughts, as ever. It's shaping-up to be an interestingÌýspell of weather for us by the weekend; for sure, a distinctly cold-feeling one -Ìýif not necessarily aÌýguaranteed snowy one!

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