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He has since posted this, discussing the rest of today using up-to-date output charts and the latest FAX:
An update on today. Quite heavy rain later with snow in Scotland and high ground in the north of England and strong winds across Wales and the southern half of England.
And need to keep a storm watch, and possible snow watch, next week as the Atlantic depressions gear up
The westerly influence is reflected in the precipitation distribution
When you have eyesight like mine there is no other wayI presume those who are interested in doing so are clicking on the thumbnail images within the posts I'm quoting in order to examine them at full size?
I can't see anything useful from the images unless I expand them either!When you have eyesight like mine there is no other wayP.
Today and tonight
The low and fronts associated with yesterdays bad weather have scooted away east leaving the UK in a a strong, unstable, north westerly airstream. This will mean frequent wintry showers of rain, sleet and in particular snow in N. Ireland and western Scotland. The showers will initially be confined to these areas plus Wales and the western coasts of England but increasingly further inland as the day progresses and the snow showers may well slip further south as well. Some reasonable accumulations could occur. There is always the chance of more persistent precipitation with the odd trough embedded in the flow. The showery activity will continue overnight, but perhaps more confined to northern areas with the wind backing a tad, but with ice an added danger Monday morning with a widespread frost. Feeling very cold in the strong wind
Monday another day of sunshine and showers, these confined to the west, but not feeling as cold as the wind abates. But by 12 a deep low 971mb is south of Iceland with associated fronts lying N/S west of Ireland and by Tuesday 00 they have tracked east to be over Ireland backing the surface wind over the UK to a strong south westerly accompanied by a band of rain. This is probably going to be another marginal affair with snow on the higher ground to the north.
The band of rain/sleet/snow clears to the east by 1800 Tuesday leaving the UK in a transitional weak ridge with showers in the west but there is an occlusion out at 20W associated with a deep depression 954mb south east of Greenland that is poised to move track east, which it duly does, and by 1800 Wednesday has brought more rain and strong winds to the UK. At the moment it would appear unlikely to bring snow apart from perhaps on high ground in Scotland.
Once cleared the UK is back in and unstable westerly with frequent wintry showers in the NW once more. The Atlantic is dominated by the cold upper trough but changes are afoot with the Bermuda high pressure beginning to amplify and surge north in the western Atlantic but there we must leave it. This is of course according to the gfs.
Having had a quick glance at the ecm for the purposes of this thread no significant difference to the gfs. I say no more.
Naming criteria are complex, it isn't purely based on windspeed but also on calcilated impact. That said, there has already been a deep low this season so far that "bombed" over the UK but which wasn't named as the forecasts all indicated that it wouldn't deepen that rapidly until it was over the North Sea. Forecasting is incredibly difficult and there will always be mistakes as the complexity of the interactions between various drivers and influences over even 24 hours mean that, though the overall set up is fairly predictable, trying to determine whether something will happen over the UK or in the North Sea can come down to 20 miles either way, which to the layman seems quite a generous margin for error, but, with current data and computing power is a very narrow margin.Well, last night's winds were worse than the so-called/named storms we've had so far this year.
Between 17:00 Sun 11th and 10:00 Mon 12th
Icy patches are expected to form on untreated roads, pavements and cycle paths on Sunday night and Monday morning. This is likely to lead to some injuries from slips and falls.
Between 00:05 Sun 11th and 23:55 Sun 11th
Frequent, heavy hail and snow showers are expected through Sunday and will lead to snow accumulating on many surfaces. Longer journey times by road, bus and train services are likely while some vehicles could become stranded. Ice is likely to form on untreated pavements, cycle paths and roads leading to some injuries from slips and falls. Power cuts may occur and other services, such as mobile phones, may be affected.
Wednesday is looking windy tooWell, last night's winds were worse than the so-called/named storms we've had so far this year.
Today will start with a reasonable severe frost in many places compounded by ice in many western and northern areas where snow showers have persisted overnight. These showers will continue during the morning in these areas, more particularly west Wales, N. Ireland, NW England and Scotland whilst most other areas will be quite sunny if a little cold. The showers will become less frequent later as the surface wind backs south westerly with arrival of the occlusion west of Ireland associated with a depression 972mb to the NW
By midnight the front is over Ireland with the triple point over Cork and the band of rain, sleet and snow will move steadily east overnight and through Tuesday. There could well be some significant snow falls in Scotland and perhaps the north, mainly on the higher ground but not exclusively, with some quite strong winds in the south. Clearer weather behind as the front clears to the east with some wintry showers mainly in the north west
But by 0600 on Wednesday there is a deep low 944mb SWS of Iceland with the associated fronts just to the west of the UK with the wind once again picking up from the south west. By midday the frontal systems are over the UK along with the associated precipitation.
The question is once again will the precipitation be of snow in places and the answer is probably some preceding the front in the north but in general the temps/dew points will be too high and rain will be the order of the day.
Once all of this has cleared to the east a strong westerly wind prevails with frequent wintry showers in western Scotland with cold Pm air dominating the Atlantic By Friday quieter weather will have arrived in the south as the westerly abates with the arrival of a little high cell
Yup huge winds at mine too, absolutely howling up the valley.Well, last night's winds were worse than the so-called/named storms we've had so far this year.
For one reason and another I couldn't do the usual medium term anomalies up date last evening so for the sake of conformity and because of the interesting times and recent major pattern changes just a quick run through this morning.
Everything is now more amplified and upstream still a Siberian vortex lobe (blue are top left in the Northern Hemisphere images below), strong Aleutian ridge into the Arctic (red/pink area between Alaska and eastern Russia, bottom left) and still an active Canadian vortex (blue lower section of the same two images) with a trough running SW through central canada to the SW United States and still with a strong westerly flow leaving NE North America. So far so good but not so downstream where there is disagreement as to the the orientation of the Atlantic trough/ridge duo (bottom right corner of the images, in mid-Atlantic) and consequently the trough to the east/south east as well. This will obviously impact on the det (deterministic) runs and the subsequent surface analysis so I'll just leave it here for the time as it will be updated today.
Back to the here and now.
The occlusion is currently over western parts (moderate rain here) and it and the developing wave will move east during the morning bringing with it strong winds, snow sleet and rain. Fairly significant snowfall in central and southern Scotland even at low levels and perhaps down to the north of England and higher ground further south but here it will essentially be rain. A case of radar watching. behind the front still windy in the north and wintry showers, particularly in the north west but everything will die down later with a quiet night ensuing with a widespread frost by morning.
so a quiet start to Wednesday but by 1200 the next frontal system has arrived over Ireland, SW Wales and Cornwall heralding very much a replay of today with strong winds and rain, sleet and snow tracking east The snow is again likely to be in the north and favouring the higher ground but as always this doesn't rule out some further south and again probably down to radar watching
The occlusion will have cleared the east coast by 00 Thursday leaving most of the UK in a fresh, west/south west airstream with frequent wintry showers, particularly in the north but the triple point is still over east Anglia so the rain will persist in the south east for a while
The westerly showery routine continues through Thursday and Friday but ridging in the Atlantic is becoming more influential
And by the weekend a more settled and drier regime is on the cards with temps around average albeit quite a diurnal variation.
Well get tomorrow out of the way and we might see a few days of drier, quieter and warmer weather (relatively speaking), excluding the north at first but then maybe everyone.
But first tomorrow. A fairly clear night tonight tonight for most places with frost in many areas but by 0600 cloud and rain associated with the next frontal system will already have reached N. Ireland, western Scotland, west Wales and Cornwall. The band of rain, heavy at times will track east during the day, perhaps some snow preceding it in the north leaving showers in it's wake predominately in the north west.
So by Thursday 1200 after the fronts are out of the way the UK is in a very breezy westerly and quite sunny but frequent wintry showers in the north west. But away to the south west the high pressure is shaking a tail and beginning to stretch north east and by 1200 Friday has become much more influential with drier and quieter weather in most places apart from remnants of a front affecting the NW of Scotland
Much the same on Saturday with max temps around 8C in many places (according to the gfs so pinch and salt applies) and Sunday in the southern half of the UK but windier with showers in the north courtesy of a weak front.
I didn't know you were an astronomer, Colum! I must admit I've never found astronomy that interesting, though I do appreciate a clear night when they're in view - sadly, being only a few miles south of Norwich, the northern sky is obscured by a constant glow after dark.Fantastic stars last night and a good layer of frost this morning. Unfortunately the stars were too twinkly to make it worth an hour with the telescope but hey ho. Less wind and rain sounds good.
This morning's update is not significantly different to yesterday afternoons. Essentially becoming dryer and calmer for most by the weekend but before arriving there some wet and very windy weather to negotiate.
At midnight there was a deep depression in mid Atlantic with the associated fronts lined up to the west of the UK. After a frosty start in many areas the rain from these fronts, which is already impacting the south west, will move steadily east during the day preceded by snow on the high ground in Scotland, where there could be blizzard conditions for a while, and northern England. Perhaps even some snow north Wales and the Pennines. Some very strong winds also in some areas with 50-60mph gusts not out of the question. The rain will clear to the east late on and through the early hours and the gales will abate except possible the far north west where wintry showers will be frequent. Milder in the south west with temps reaching 11C
So by 1200 tomorrow the UK is in a very breezy westerly with frequent wintry showers in the north and west and feeling quite cold in the strong winds, less so in the south
Friday sees the start of a drier period as the high pressure to the south west pushes north east. This will initially exclude Scotland and N Ireland as showers and perhaps some drizzle will run around the tip of the ridge/high cell on the south westerly wind.
Thus the warmer. drier airmass is established by Sunday but with it comes a fairly large diurnal range with frosts in the morning. The temp charts not to be taken as definitive.
The ecm appears not quite so blasé about a dry weekend and has a weak front tracking SE Friday night (to be fair the gfs does indicate this as well) but by Sunday 00 it has a wave that has developed to the west over Ireland. which brings an area of patchy rain to Wales and England Sunday morning.
The 0600 fax where they now have the first occlusion as an upper feature, I should have mentioned earlier the rain in the south west might be slightly more complex with proximity of the triple point but it will be clarified by the radar. Or not,
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