Short Term Model discussion 03/01/19 onwards

[phil nw.]

A new thread to discuss model output in the shorter term usually to around day 4 where generally we get good agreement.

This thread then is useful to summarise the near term outlook and highlight any interesting features. 

[phil nw.]

The 12z UKMO charts show the high settled over England and Wales tomorrow so where the skies clear long enough quite a sharp frost looks likely.Still quite cold into Saturday but something of a change looks on the cards as the high gets a little squeeze from the west as a front approaches.

We see this Atlantic frontal system working it's way into the high weakening as it does but bringing some light patchy rain and less cold air for a time as it works it's way south.

The front becomes stationary over the far south by Sunday though before we see a developing wave depression running up the west (seen on the fax) and over the top of the high by Monday day 4 shown on a chart from 12z GFS.

This would bring a short,sharp spell of wind and rain across the UK as it looks to head quickly south east into the low countries.

[phil nw.]

Tomorrow sees that squeeze on our high as a weak front comes into it but by that time very little rain left more just an area of cloud.

It's the wave depression out to our west that becomes the next player moving up around the high and across to the north of Scotland and heading down the North Sea towards Denmark with some rain and wind briefly for the north.

As the low moves away it pulls down polar air from the nw to it's rear.Much of any rainfall looks like missing the UK maybe just skirting eastern coastal areas on it's way south. 

T72hrs-Tues 12z

T96hrs Weds 12z on meteociel UKMO 850 hPa/500 hPa

shows eastern and central districts receiving the western extent of the colder air with the main thrust of this heading into much of the continent.The high returning to our shores from the west.

After a milder 2/3 days we will see something of a colder couple of days mid-week with temperatures back down to below normal.

 

[knocker]

Outlook - The influence of the ridge/high cell slowly declines during the period as the center slips south west which heralds a pattern change to more unsettled and cooler conditions.

Back to the here and now and the NH 500mb and surface analysis for midnight and the WV 0300 sat. image.

Central areas will start the day cloudy with perhaps the odd spot of drizzle courtesy of the warm front associated with the deep depression north of Iceland. Further south, with less cloud, rather chilly. During the day the front will drift slowly south accompanied by the patchy rain/drizzle leaving clearer conditions in it;s wake, so sunny intervals in the north.

The patchy rain will persist through this evening before the front clears into the Channel whilst with clearer intervals further north just a chance of some frost in some places.

Friday will be dry, perhaps some drizzle over western hills, but generally cloudy day under the auspices of the ridge but cloud and rain will arrive in the north west late on courtesy of a cold front associated with another low in the Denmark Straits

The cold front will traverse northern parts through the early hours of Saturday accompanied by rain and quite strong winds as the wave tracks east into southern Norway.whilst the south remains dry. Quite a mild day with temps above average

By Sunday the cold front is still straddled across central parts of England as it stretches from southern Norway to another system way out in the Atlantic so another breezy day with sunny internals and showers with the latter tending to be concentrated in the north west.

Monday finds the ridge stretching north east once more thus a drier and quieter day with light winds but this is transitional as the aforementioned unsettled period gets underway beginning with some light rain in the west from the approaching warm front.

And the NH profile at T120

 

[knocker]

Quite chilly in the south this morning with some mist and fog around

[knocker]

As the warm front continues to drift south still quite chilly in the far south at 1600 On another note a nice morning in these parts, despite some thick Ci, so will have added to the one hours sunshine we have had already this month

[knocker]

According to Finnish met. men this is an exceptionally deep low passing across Lapland tomorrow

 

[knocker]

Outlook - very similar to yesterday with the high cell slipping south west allowing systems to swing around it thus more unsettled, albeit nothing drastic. But it is the forerunner of a more unsettled period. The precipitation for the period illustrates this quite well.

The NH 500mb and surface analysis for midnight.

With yesterday;s front out of the way today will be mainly dry, but cloudy, with perhaps patchy drizzle in western areas whilst the north east stands the best chance of sunshine. Temps around average or a tad above. But by 1800 more persistent rain from the cold front associated with the wave over Iceland will be effecting N. Ireland and western Scotland.

During this evening and overnight the front and rain belt will track south east leaving squally showers in their wake whilst further south, with cloud persisting, a relatively mild and frost free night

The front, and by now patchy rain, will clear the south coast by lunchtime tomorrow but by now more cloud and rain is starting to effect the north west once more from a warm front associated with another wave in the Denmark Strait. This will move e/se during the afternoon but become quite patchy. Still quite cloudy elsewhere with the best chance of sunny spells in the east. Still relatively mild with temps above average but a quite lively north westerly wind.

The warm front clears the east coast by midnight, leaving the UK briefly in the warm sector, but the cold front quickly sweeps south east leaving much of Sunday in a stiff north westerly with squally showers that will be mainly concentrated in the north west. Temps still holding up well

Monday will be a much quieter day with a transient ridge,with perhaps some sunny intervals, particularly in the east, but with a chance of patchy drizzle in the west. But out in the Atlantic things are stirring with a lot of energy exiting the eastern seaboard and a warm front associated with an intense depression south east of Greenland is nudging the west coast of Ireland and will bring cloud and rain to western regions during Monday evening. Temps still a tad above average.

The warm front quickly crosses the country on Tuesday as the low tracks east south of Iceland but the cold front develops a wave and thus more persistent rain, snow on the higher ground, effects the north west Still temps a little above average but cooler air creeping into the north, a sign of things to come.

And the NH profile at T120, We have come a long way in five days

[knocker]

Quite an interesting Sc 'sheet' to our west at moment with a fairly well defined edge and in parallel rolls

[knocker]

Interesting cloud on the high res/ MODIS at 1320

Oops sonde failure but the Sc layer below the inversion is illustrated

[knocker]

Interesting. I've never thought to look recently but it would appear Camborne and Lerwick are using high altitude balloons at midday

 

[knocker]

Remaining cloudy this evening and overnight with bits and bobs of rain in western regions, But by early evening rain associated with the cold front will have reached north west Scotland and this will track south east overnight but becoming fragmented as it reaches the high pressure. Behind the front frequent squally showers in the freshening north westerly wind. Courtesy the cloud and rain a frost free night except perhaps for the odd spot in north east Scotland

[knocker]

Outlook - Unsettled, quite windy at times, and becoming colder as the influence of the high cell wanes

The NH 500mb and surface analysis for midnight and the 0500 surface chart.

A cloudy and mild start to the day with some patchy rain around central England and Wales at the moment as the cold front continues to drift south during the morning. Further north frequent showers over western Scotland. But more persistent rain will arrive here, and to regions a little further south, by late morning and track east through the afternoon, albeit becoming intermittent, courtesy of the warm front associated with the system tracking rapidly east from southern Greenland, Still mild but becoming quite windy in Scotland.

The rain will then pep up over Scotland through the evening and then further south as the triple point passes close by and the cold front starts tracking south east. Meanwhile the rest of the country stays cloudy, but mild, in the warm sector.

Through Sunday the cold front will continue to track south thus essentially splitting the country with cloudy warmer air south of it and windier with some heavy showers in the north as the wind veers more northerly introducing much cooler air.

Overnight the cold front quickly clears the south coast so Monday a much quieter day, cloudy with perhaps some sunny intervals, but much less wind as wind courtesy of a transient ridge. But by early evening patchy rain will start effecting western regions as a warm front, associated with a another low near the southern tip of Greenland, edges east.

Some light patchy rain/drizzle on Tuesday as the weakening warm front crosses the country but very mild in the warm sector.The one slight complication is the cold front waves a tad so perhaps some more persistent rain over Scotland for a time

On Wednesday the subtropical high amplifies in mid Atlantic which diverts the little complex frontal structure south east over Scotland which will track south during the day bringing patchy rain to most areas with snow on the high ground in Scotland. At the same time introducing cooler air once again as the wind veers.

And the NH profile for T120

[knocker]

Currently still some rain on the warm front. mainly around central areas of England, and this will push east during the evening clearing the east coast by 2300.  Meanwhile while most of the country is in the warm sector and remaining cloudy, heavier rain will effect north west Scotland courtesy of the cold front. This will track slowly south during the night with the rain becoming sporadic but frequent squally showers will occur along western Scotland in the quite strong north westerly. No frost

[knocker]

outlook - Little change from yesterday; unsettled becoming colder later

The NH 500mb profile and surface analysis for midnight and the WV image for 0300

As can be seen it's very cloudy over much of England and Wales with the odd spot of rain around, and this will remain the case through much of the day as the cold front tracks slowly south., clearing the south coast by early evening. But in the clearer conditions behind the front, particularity over western Scotland, squally wintry showers will be quite frequent with perhaps snow on the mountains, pepping up later as another cold front slips south.. Quite strong north west wind, perhaps touching gale force in exposed areas, before easing. A relatively mild day

Things will calm down through the evening and overnight although the wintry showers will persist in the north and down some east coast regions. With variable cloud and lighter winds a much cooler night with a frost in some areas in the north.

After the chilly start Monday will be a relatively pleasant day with light winds and variable cloud  But by early evening rain will effect north western parts as a warm front associated with a low east of the southern tip of Greenland edges east. Temps still a tad above average

Over night and through Tuesday the warm front does struggle across the country but weaken as the ridge retains some influence so mostly dry if cloudy. But a wave forms on the cold front and tracks NNE to be west of Scotland by midday initiating some quite heavy rain over north west Scotland. Temps still above average.

By Wednesday the wave has deepened and tracked north of Scotland whilst the cold front runs south east across the country. Thus a fairly wet and windy day for most with the chance of snow later over Scotland as colder air and squally showers are introduced behind a stray occlusion tracking south.

The showers will continue for a time on Thursday but it will gradually become quite a reasonable day as a transient ridge builds but late on more cloud and rain will arrive in the west as the next frontal system approaches. Quite a cold day in northern and eastern regions.

And the NH profile at T120

 

 

[knocker]

Just musing as one does on a breezy and cloudy Sunday morning and noted that yesterday Lerwick was just on the edge of the 10mb 'high' cell. Not particularly cold with a light easterly

[knocker]

The 1130 MODIS. Showers western Scotland and waves over the Welsh mountains

[knocker]

The cloud and patchy rain should clear the south early this evening as the front moves into the Channel leaving much of England and Wales mainly dry with broken cloud through the night, Further north the frequent squally showers will continue over Scotland becoming quite wintry with snow possible down to lower levels, and they may move a tad south east later. The gusty winds will continue fora time but will slacken as the transient ridge builds north east. Ergo cooler than last night but frost probably restricted to the north east/

[knocker]

The gfs tracks the wave north east across Scotland  into southern Norway Weds/Thurs and there could be some snow on high ground in the north as the wind veers northerly/ This is followed by a transient ridge but the next low and and associated fronts then swing in from the north west through Friday as the high amplifies to the west. this could also bring some snow on the higher ground in the north

[knocker]

The ecm has quite a messy set up with trough Weds/Thurs; quite wet and windy with perhaps snow on the high ground in Scotland  before a transient ridge on Thursday and a very cold day with temps in the 3-4C range apart from the south west

On Friday the next low arrives west of Ireland but the front and rain stall more or less along the Irish Sea. Temps on Friday 3-5C

[knocker]

Outlook - Unsettled, but not drastically so, with a NW/W bias as indicated by the precipitation chart. Getting colder.

The NH 500mb profile and surface analysis for midnight and the Lerwick sounding

Quite a cold start to the day, particularly in the north east behind the occlusion, (note the cold midnight Lerwick sounding) but dry with broken cloud over England and Wales but further north still showers around that have spread down the north east coast  Some may be of snow over the high ground in Scotland. These will die out during the morning leaving a generally dry day in most places with temps about average but colder in the north But by late afternoon cloud and rain from the approaching warm front will be effecting N- Ireland and western Scotland.

During this evening the warm front will track east and the rain will become light and fragmented  But the triple point will pass quite close to northern Scotland and this and the cold front will bring more persistent and heavier rain to western Scotland through the night which generally will be pretty mild.

The weakening warm front continues to drift, more south than east now, through the day, leaving a mild and cloudy day in most places with some patchy drizzles, But a wave has formed on the cold front which pushes north resulting in the front going nowhere fast and the persistent and heavy rain will continue over north and west Scotland all day

Through Tuesday night and Wednesday morning the wave deepens and tracks north east across northern Scotland into southern Norway resulting the cold front now tracking south east down the country clearing the south during the afternoon. Thus a breezy day with a belt of rain moving south with the front leaving colder air following on in the north with some wintry showers, possibly of snow on the high ground

A much brighter and colder day on Thursday after an early widespread frost as a ridge builds from the south west. But the Atlantic is not inactive as pressure is brought to bear and a low tracks up the western flank of the ridge

A cold start to Friday leading to a fairly calm and quiet day with broken cloud with temps around the average, a tad colder in the north, But the aforementioned low has tracked east against the ridge and the associated occlusion is across Ireland and Cornwall by midday bringing some rain and strengthening winds to western regions with perhaps snow on the higher ground

And the NH profile at T120

[knocker]

Interesting it appears that Friday's low arrives on the scene courtesy of hitching a ride on a branch of the subtropical jet as it splits the ridge on Thursday

Twenty four hours later the low is over Ireland having been diverted a tad south east by strong ridging to the west,and the associated fronts have brought rain to western regions with some snow on the higher ground and even lower down as dew points are quite low in northern regions

From here the ridge comes under intense pressure from the west and the low is forced further south

This is of course according to the gfs

 

[Seasonal Trim]

It's a pity this thread isn't really used. I'm not really interested in 144+ charts. But it's all that seems to get posted in the other thread. 

[mincemeat]

We like it the way it is, thank you  

[knocker]

As ever when the influx of Artcic air becomes a real possibility polar lows pop up everywhere/ A reminder

Polar lows explained

https://www.barentswatch.no/en/services/polar-lows-explained/