Short range model discussion - into 2018

[Rocheydub]

Met Eireann named it storm Fionn

[Paul]

That's a different storm, and not really on topic, but take a look at  Jo's blog for more info on the storm naming over the last couple of days

https://www.netweather.tv/weather-forecasts/news/8685--wheres-my-storm-name-wild-winds-and-snow-tempetedavid-orkantief-friederike

[sawan]

Knocker, what's its trajectory please, couldn't sleep last night due to strong gusts of wind. I am sure it will spare central England this time. 

[alexisj9]

5 minutes ago, Rocheydub said:

Met Eireann named it storm Fionn

Nah that was a different storm the night before that gave Ireland a bit of a blow. It also gave Cornwall some gusts around 50-60 mph.

[Rocheydub]

20 minutes ago, Paul said:

That's a different storm, and not really on topic, but take a look at  Jo's blog for more info on the storm naming over the last couple of days

https://www.netweather.tv/weather-forecasts/news/8685--wheres-my-storm-name-wild-winds-and-snow-tempetedavid-orkantief-friederike

 

17 minutes ago, alexisj9 said:

Nah that was a different storm the night before that gave Ireland a bit of a blow. It also gave Cornwall some gusts around 50-60 mph.

Apologies people, I though you were talking about that one! Now, back on topic!

[knocker]

33 minutes ago, sawan said:

Knocker, what's its trajectory please, couldn't sleep last night due to strong gusts of wind. I am sure it will spare central England this time. 

Sorry I'm a bit lost here. There are no storms tonight merely an unstable north westerly surface wind which might be a bit breezy on the coasts but nothing to bother you in the Midlands.

[knocker]

There is a fair bit going on weather wise over the next few days so need to restrict the waffle and keep this reasonable succinct.

Firstly a quick overview of the general synopsis at 1800 today. The major upper trough that has been the main influence of our recent weather is slipping south east whilst further troughs in the western Atlantic are entering the picture and starting to move east driven by the enery flows from the Canadian vortex lobe and around the southern US. Whilst at the same time the Azores high pressure is pushing north in mid Atlantic.

So a bit more meat on the bones.

Today a continuation of wintry showers in western areas but particularly in the north where they are likely to be of snow whilst the rest of the country will be sunny but cold. Quite breezy in western coastal areas, Later a wave forming on the front lying to the west will track south east and bring rain to the far south west.

So during Saturday the south west remains cloudy and in the milder air but elsewhere, particularly in the north, the gradient becomes slack as the low pressure fills and moves away and colder air pools with a marked temp contrast being established. This is important because the aforementioned warm front is moving steadily north east overnight on Saturday and during Sunday bringing with it wet and windy conditions but as it comes up against the colder air along the norther edge this could fall as snow in northern regions. Just where and how much still to be ascertained.

This could be further complicated if little perturbations form on the front and also as can be seen another little wave is forming south west of Ireland and that tracks swiftly east bringing more rain to southern England and Wales overnight Sunday and into Monday.

And by now the previously mentioned energy emerging upstream has coalesced into a complex upper trough covering most of the Atlantic to the west

Edited January 19, 2018 by knocker

[knocker]

Not surprisingly the ecm is very similar so just the surface analysis for T24,48,72

[knocker]

And regarding today the METO have issued an amber warning for snow and ice

https://www.metoffice.gov.uk/public/weather/warnings

[chrisbell-nottheweatherman]

6 hours ago, knocker said:

Today a continuation of wintry showers in western areas but particularly in the north where they are likely to be of snow whilst the rest of the country will be sunny but cold. Quite breezy in western coastal areas, Later a wave forming on the front lying to the west will track south east and bring rain to the far south west.

Am I correct in assuming that the front to which you are referring is the warm front to the south-west rather than the occlusion draped across northern England?

[knocker]

8 minutes ago, chrisbell-nottheweatherman said:

Am I correct in assuming that the front to which you are referring is the warm front to the south-west rather than the occlusion draped across northern England?

Yes that's correct Chris, probably badly worded. The latest fax charts show it in greater detail

[bluearmy]

Icon 12z seems to think we may be looking at a snowy slider tomorrow !!!!

[knocker]

Ignoring your lapse into unseemly terminology yes a second wave forming on the front? A high ground event?

Edited January 19, 2018 by knocker

[bluearmy]

‘Snowy slider’?  Unseemly?  

Surely not!

anyway, will be interesting to see how far north ecm and the NNM are on this - a correction south a bit and maybe not just high ground !

[Nick L]

7 minutes ago, bluearmy said:

‘Snowy slider’?  Unseemly?  

Surely not!

anyway, will be interesting to see how far north ecm and the NNM are on this - a correction south a bit and maybe not just high ground !

ECM and UKV have a slushy cm or so above 250m or so, diddly squat elsewhere.

[knocker]

Today sees the transition to a different weather pattern over the UK, as the low pressure to our north fills and slides south east and systems from the Atlantic move in. Thus today it's more or less a Scotland and the rest split. The former will be quite clear and dry, perhaps the odd wintry shower in the west whilst England and Wales and just about N. Ireland will be cloudy with outbreaks of rain as a front tracks east with little waves running along it which last most of the day in most places. Not feeling particularly warm either and quite windy in the west.

Overnight drier weather pertains with quite a severe frost in Scotland but the next front(s) arrive in the early hours, Associated with a deep depression in mid Atlantic, and they sweep quickly north east bringing rain to many areas but along the leading edge quite possibly some significant snow in the north and Scotland and also very windy for a time over the latter before the fronts clear overnight. Behind the fronts much milder air.

During Monday the Azores HP attempts some transient ridging north east but fails to stop another little wave that has formed to the west running quickly east up the channel bringing rain to the south, albeit it clears very quickly.

From this point through midweek the controlling factor is the upper trough in mid Atlantic as it moves east, initially bringing a strong, mild, south westerly flow over the UK but the question is, what happens when it disrupts later?

If I may make an observation here which is outside the remit of this thread so MODS please remove if deemed inappropriate, But simply the anomalies of late have been indicating the Azores being much more influential in the medium term as the forecast pattern change occurs in the North Pacific. This is again indicated by this morning's GEFS.

Edited January 20, 2018 by knocker

[knocker]

The current synopsis showing the front and waves. Cloudy with slight rain here with wind gusting 30mph from the west.

 

Edited January 20, 2018 by knocker

[Summer Sun]

Snow upgrades from GFS

00z yesterday

00z today

[knocker]

A clearance here in the last hour, not that it will last that long

Cloud top frontal/surface 700mb on the 12 sounding?

Edited January 20, 2018 by knocker

[knocker]

Now that the rain is clearing England and Wales tonight will be a cold night, particularly in Scotland with a severe frosts in many places. I suspect those ICON temps could well be under cooked in some areas.But by early morning rain from the approaching front(s) will be into N/Ireland, perhaps snow briefly, and Wales and the south west.

The precipitation and fronts track east during the day and the rain will increasingly fall as snow as it meets the colder air. The trick here is knowing how far south and how extensive it will be with dew points being very marginal the further south, Certainly looking at snow down from Scotland to the east Midlands as being quite likely.

Edited January 20, 2018 by knocker

[knocker]

The ecm this evening has a wave running through the Channel into northern France bringing some rain to the south early Monday morning before the Azores ridges north east. This is just a brief interlude as the deep upper trough has tracked southeast of Greenland and with a strong jet running NE to the west of Ireland it is quite quickly suppressed and by 1200 Tuesday the UK is in a strong WSW surface flow but more to point a nasty looking depression is forming in the southern quadrant of the main low west of Ireland. This 'bombs' rapidly north east to be north of Scotland 957mb by midday Wednesday bringing with it heavy rain and severe gales to N. Ireland, northern England and Scotland.

[knocker]

Same low on the gfs 1800

Edited January 20, 2018 by knocker

[knocker]

With a very slack gradient over the UK last night has been cold for most with frost, severe in Scotland, Altnaharra down to -10.5C at 0300 and Loch Glascarnoch -8.6C, But change is already well underway. Fronts associated with the deep depression south of Iceland are already impacting N. Ireland and the western side of the main island with rain, perhaps some snow on the high ground and this will spread east as the fronts do likewise.There will likely be some snow in some areas as the front hits the colder air, mostly on high ground but certainly in lower regions to the east and particularly the north, but it will be quite transient as the warmer air behind the front arrives. A bigger danger may well be ice as rain falls on very cold surfaces. I wont bother with model snow charts best keep an eye n the radar.

The fronts will clear to the east this evening followed by some transient ridging from the Azores HP which actually doesn't rule out another little wave nipping past the the south west in the early hours of Monday and another low tracking east over Scotland  Otherwise a much drier day for all.

I said transient ridging because come Tuesday the deep upper trough in the western Atlantic has moved east to be south east of Greenland with an associated complex surface low pressure area to the west of the UK with the latter in a strong, mild and moist, south westerly airstream  And just to complicate matters another wave is forming in the general circulation west of Ireland and is 990mb by 1800

The low tracks quickly north east and traverses Scotland overnight en route to southern Norway bringing with it strong winds and heavy rain, snow on the mountains, whilst the associated front tracks south east across the rest of the UK during Wednesday clearing the south by the evening.

But by now the upper trough has moved further east along with complex surface area of surface area of low pressure and amplification is taking place with Azores ridging in mid Atlantic. Where will it all end? Perhaps as still being indicated by the GEFS anomalies this morning.

Edited January 21, 2018 by knocker

[knocker]

The ecm is still running Weds Low as an intense little feature north west of Scotland 960mb which briefly could bring severe gales to western Scotland gusting in the 60-65kt range.

 

[knocker]

Looking at a forecast sounding for the NE Midlands is quite a good illustration of the marginality of snow. The warm upper air encroaching from the west,600mb temp only -10C and the colder air in the boundary layer