Cold Spell & Snowfall Discussion Part 2 (Eagle says Polar Low) Wednesday/Thursday

M.T. Cranium wrote: »

Hello again, I had another look at this Thursday snow potential, can't say that it amounts to very much, but it may bring a covering to places that have not seen much yet (recently at least).

What we have is a rather weak wave on the arctic front which days ago pushed out to the west of Ireland and just stalled in the maritime north to northeast flow that has been endlessly circulating around the Greenland-Iceland high.

This wave only amounts to a 1022 mb feature with 5-10 knot wind field around it, so frontal mechanism will be weak. The track is predicted to be almost due south past the outer coasts of Galway (about 1500h) and Kerry (about 1800h), and in a few days this will be off Portugal spinning up a stronger low down there (won't be a factor in Ireland's weather at that point).

It seems likely that a double-wave structure will develop, one dropping south along the coast, a second and very weak feature forming north of Donegal and dropping south through west-central Ireland. Now, east of that wave, temperatures will not warm up very much due to the dense mass of cold air recently chilled by tonight's likely -8 C lows. There could be a weak and diffuse band of light snow running from north to south and including counties between around Roscommon to Tipps and Cork (petering out beyond Fermanagh to Laois). I wouldn't even try my hand at a map for this as I think it's going to be a patchy 2-3 cms here, trace-1 cm there sort of a business, with light winds and a sort of misty, foggy ambience to it. Further west, between the two wave tracks, the air may become warmer than 2-3 C in low elevations, at least briefly, in a very light SW wind that turns SE then NE, all of which may mean sleet, light hail, or cold rain, but not in very large quantities, 3-5 mms possibly. Higher hills in Galway and Mayo could see fresh falls of snow.

I don't see this reaching the east coast at all, but there is a second low moving south in the North Sea, so with a weak trough connecting the features, you can't rule out a brief flurry almost anywhere, in almost calm wind conditions.

As generally stated by other forecasters, Friday and Saturday, generally high pressure is too close and too strong for snow production and the bone-chilling overnight lows will become the bigger story.

Sunday, looks promising for locally heavy snow in the southeast and possibly even snow-starved south coast locations, the air will be very cold at higher levels and winds picking up to a 20-30 knot gradient from the ESE this time, so streamers would form south of Wales and head for Wexford and south Wicklow, possibly weaker features in sync near Dublin and even near Waterford and Cork. Although a few places could see 10-20 cms from this activity, 3-5 cms might be a reasonable guess for potential in general. It won't be as likely north of Dublin but sometimes Co. Down gets hit pretty well with this wind direction too.

Looks to me as though the following week could see slight moderation in temperatures. But I am not totally convinced this is the case yet.