Short range model discussion - into 2018

[knocker]

Well the gfs is sticking to it's guns with the upper low forced south through central Europe with the Azores still ridging north east into a high cell.

[chrisbell-nottheweatherman]

17 minutes ago, knocker said:

Well the gfs is sticking to it's guns with the upper low forced south through central Europe with the Azores still ridging north east into a high cell.

UK High - depending on cloud amounts could be chilly nights but warm-ish by day?

[knocker]

13 minutes ago, chrisbell-nottheweatherman said:

UK High - depending on cloud amounts could be chilly nights but warm-ish by day?

Yes, quite likely

Edited February 16, 2018 by knocker

[knocker]

At T84 the ecm has the upper low further SW than the gfs over north west Germany and with a different orientation and the upper trough is N/S over Ireland. This makes a big difference to the surface analysis with the surface low in close attendance in eastern France and the cold front down the Irish Sea. Thus with the high pressure to the NE ridging over southern Scandinavia an easterly is still initiated over southern England. The low then slips south but with the trough stationary over the Irish Sea the easterly is maintained briefly at T96.whilst the high pressure consolidates by T120

[knocker]

Just to add the T120 chart to the above.

[knocker]

The have been some major upheavals today so it's of interest how the anomalies have handled it even if at the end of the day they don't shed much light.

As it happens there is no agreement. Upstream no huge change except perhaps the Gulf of Mexico HP becoming more influential  so still the east Pacific ridge, north Canadian vortex with associated troughs SW to the south west US and the other south east onto mid Atlantic and still a strong westerly jet leaving the eastern seaboard with the very intense thermal gradient between the vortex and the high pressure to the south east.

So we have an amplified pattern upstream which continues in spades across the Atlantic (ensuring the jet gets cut off at the pass) and north west Europe but this where we run into problems. There is no agreement on the intensity or orientation of the mid Atlantic trough or the ridging north of the high pressure in the vicinity of the UK, nor indeed of the trough to south east which is a quite important player in this. Consequently, for example, there will be a significant various between the GEFS and EPS as to the orientation of the surface high and European low, not forgetting NOAA either. This will affect CAA flowing south west and then west into the UK and thus, obviously, the expected temps over the UK. Something for the det runs to sort

 

 

Edited February 16, 2018 by knocker

[knocker]

Very nice example showing different airmasses with a a front running from two upper lows acting as one major barrier,

Edited February 16, 2018 by knocker

[knocker]

Today a weak front will track south east across England and wales accompanied by cloud and patchy rain/ drizzle and perhaps some light snow on the high ground in the north, but dry with sunny intervals elsewhere but showers in N. Ireland and western Scotland, tending wintry in the latter, Temps in the 8-10C range so quite mild.

Overnight most places will be clear with frost in some places but by Sunday 00 frontal systems will have arrived in the south west bringing with them cloud and drizzle which will move slowly east during Sunday morning thus extending the murky conditions, Simultaneously in the western Atlantic explosive cyclogenenesis is taking place, courtesy of the favourable environment off the eastern seaboard, as a rapidly deepening low associated with the aforementioned frontal system tracks NNE to be south east of Greenland.

The fronts will continue to track east overnight into Monday which will be in the warm sector so generally cloudy with intermittent drizzle will be the order of the day with max temps in the 10-12C range.

Once the cold front has cleared east the Azores ridges north east and forms a high cell over the Uk whilst away to the south west a deep low that started life off the coast of the Carolina's is part of a mid Atlantic upper trough. I mention this because the trough has a role to play later.

Thus a fairly rapid transition into the next installment of the current evolution even if things look more complicated out west.

 

Edited February 17, 2018 by knocker

[knocker]

The fax chart for Tuesday 00 with England and Wales in the warm sector and the ecm still making more of the little wave and placing southern England in a weak easterly.

Edited February 17, 2018 by knocker

[knocker]

The front is though here so clear skies at moment.

 

[knocker]

Another good high res. Modis Image at 1245 showing the weak front and the cloud gathering to the west.Also the 1200 geostationary. Images courtesy of the Dundee Satellite Receiving Station.

[knocker]

This morning's fax chart for 1200 Tuesday probably ties in pretty well with the 06 Icon

[knocker]

Not a lot to add to this morning's resume vis tomorrow. A mainly clear night with frost and fog in some places but cloud and rain/drizzle associated with the next frontal systems will move into N. Ireland, Wales and the south west and track east during the day. But the fronts do not move that fast so eastern parts and Scotland could well remain dry.

Monday the UK is in the warm sector so murky with patchy rain/drizzle in places but by 1800 a wave is developing on the front and is in the vicinity of East Anglia with the cold front lying across Ireland Temps in 12-13C range

Tuesday will be reasonably dry as the wave tracks south east into central Europe, the cold front moves east and fizzles out and the Azores  high pressure ridges in from the south west and by 00 Wednesday has establish a high cell over N. Ireland Scotland.

By Thursday the high is ridging north east and thanks to the configuration of the upper troughs to the east SSE the colder air is beckoning.

 

Edited February 17, 2018 by knocker

[knocker]

The ecm varies from the gfs quite early on and at t96 it has a 170kt jet sweeping east from NE North America and all this energy puts a lot of pressure on the ridge stretching north across the UK which in turn puts pressure on the upper trough to the east.

This continues with a warm front approaching north west Scotland at T120 but equally to the point it affects the configuration and movement of the cold air to the east.

http://wxcharts.eu/?model=ecmwf&region=euratl&chart=850temp_anom&run=12&step=000&plottype=10&lat=51.500&lon=-1.000&skewtstep=0

 

Edited February 17, 2018 by knocker

[knocker]

Tonight’s anomalies will have a familiar ring about them. That being the case I will not repeat the upstream spiel except once again to emphasise the very strong westerly jet courtesy of the intense thermal gradient between the Canadian vortex and the Gulf of Mexico high pressure, exiting NE North America across the Atlantic.

Where it hits the buffers thanks to the intense amplification in the Atlantic and north west Europe. This consists of a deep mid Atlantic trough associated with the aforementioned vortex, high pressure ridging north through the UK into the eastern Arctic and another Eurasian trough extending south west into southern Europe where it semi phases with the Atlantic trough.

It is stating the obvious that the orientation of these three features is critical to the evolution of the surface analysis of which the detail the det runs need to sort and the energy leaving North America previously mentioned has no small part to play in this as it exerts pressure on the ridge/high pressure. At the end of the day how this pans out will determine the orientation and movement of the cold air and whether the CAA will impact the UK and if so, for how long. As it is we are looking at a dry period with temps below average but how much below is still up for grabs.

Edited February 17, 2018 by knocker

[knocker]

Pretty much a two way split this morning well signified by the morning temps where it is clearer and brighter in central areas, the east and north with frost in places whilst and much milder in the west which has cloud and patchy rain. The cloud, and then the patchy rain/drizzle, will spread east as the latest frontal systems do the same affecting virtually all areas by evening but particularly Scotland where the rain will be heavier.

Cloudy with patchy rain/drizzle with hill fog remains the general overall picture through tonight and tomorrow as the warm front continues east and the UK is in the warm sector with temps in the 10C range so quite mild with temps in the 11-12C range.

The one complication here is that by Tuesday 00 a wave has formed on the warm front over Kent which over the next 24 hours tracks south through eastern France en route to the Mediterranean where it is absorbed by the upper low which is part of Eurasian/ east European upper trough complex which will be a major player in future events. This movement allows the Azores high pressure to edge north east and form a high cell over the UK by Wednesday 00.

Meanwhile in the western Atlantic a lobe of the Canadian vortex has detached and initiated some intense amplification with a deep trough in mid Atlantic with simultaneously  the high pressure ridging  north into the eastern Arctic with the aforementioned upper trough channel to the east. This establishes the surface high cell further north and initiates the easterly flow into the UK and the general lowering of the temps.

But what's this lurking in the woodshed? A little intense Polar Low

 

Edited February 18, 2018 by knocker

[knocker]

As with last evening the ecm has a 160kt jet leaving the NE of North America and thus a lot of energy running east south of the detached vortex lobe which again puts much pressure on the ridge with a front affecting north west Scotland by T120. But the amplification quickly puts the kibosh on this.

http://wxcharts.eu/?model=ecmwf&region=euratl&chart=gph500_anom&run=00&step=000&plottype=10&lat=51.500&lon=-1.000&skewtstep=0

Edited February 18, 2018 by knocker

[knocker]

Currently moderate rain here, thick fog and sky obscured

http://meteocentre.com/radar/europe/?lang=en

[knocker]

[knocker]

The high resolution 1120 Modis sums it up pretty well, Courtesy of the Dundee Satellite Receiving Station

[knocker]

The 1200 geostationary showing the large warm sector and cold front to the west

 

[knocker]

The weather here today has generally been thick fog, sky obscured and intermittent rain and drizzle. This is probably emblematic of many areas particularly in the western half of the country and will continue to be the story through the night as the warm front edges east and the warm sector expands it's influence.Thus temps in the morning on the mild side. By midday the front has cleared the east coast and a wave has formed on it.Max temps up as high as 13C

Rain will linger near the east coast overnight and into Tuesday as the cold front peters out in the west giving clear periods as the high cell moves north east.

This continues overnight Tuesday into Wednesday whilst out to west the detached vortex lobe and the energy running south of it has created a split trough in mad Atlantic with the said energy hitting the brick wall of the block to the east.

It does have a partial success forcing the high cell to realign which initiates the easterly regime into southern England

The stage is now set for the cold upper troughs in the east to track south west under the high pressure establishing a conduit for the cold air which are all linked to the vortex lobe and split upper trough in the Atlantic.

 

Edited February 18, 2018 by knocker

[Sky Full]

Blimey, Knocker -  you do put in a huge amount of work here!  I try to read it most days because your forecasts are more detailed than the BBC!  Looks like you will have some company in here in a few days, though, if people migrate to the short range thread when this expected cold weather comes within 48 hours.  I will be in here to get a sensible view of developments because I think there will be chaos elsewhere....

In the short term, I am hoping for a dry spell in the next few days as pressure rises over the UK and the existing multiple fronts move out to the east by Tuesday.

[knocker]

10 minutes ago, Sky Full said:

Blimey, Knocker -  you do put in a huge amount of work here!  I try to read it most days because your forecasts are more detailed than the BBC!  Looks like you will have some company in here in a few days, though, if people migrate to the short range thread when this expected cold weather comes within 48 hours.  I will be in here to get a sensible view of developments because I think there will be chaos elsewhere....

In the short term, I am hoping for a dry spell in the next few days as pressure rises over the UK and the existing multiple fronts move out to the east by Tuesday.

 

Certainly looking quite dry for the next 10 days

[knocker]

I'm definitely losing it, forgot to include the chart