Models, teleconnections and nowcasting

[knocker]

There appears to be a tad more upstream amplification of the NW North American ridge/tpv trough combination this evening resulting in some amplification of the mid Atlantic subtropical high Thus the strong upper flow exiting the eastern seaboard swings around the latter towards the UK where it abates and diverges courtesy of the west Russian ridge and the trough to the south west of the UK. All of this tends to indicate a relatively quiet period of weather with temps around average but the det. runs will need to sort the detail

Edited May 22, 2020 by knocker

[knocker]

The North Atlantic 500mb and surface analysis for midnight and sat image

The heavy rain over N Ireland and much of Scotland will persist through this morning along with the very strong winds before easing a tad but further rain will encroach N. Ireland late on courtesy of the next frontal system associated with the new trough in the western Atlantic. Further south frequent showers in the quite breezy westerly

The rain over N. Ireland will track NE into SW Scotland overnight whilst the showers will dissipate in the south resulting in a clear night.

By Sunday the Atlantic trough re-orientates as the subtropical high zones amplify either side. Over the UK the weakening fronts bring cloud and patchy rain to the north and some central areas but high pressure is pushing north and temps start to rise

Over Sunday night into Monday the pattern continues to develop and the trough tales on a positive tilt stretching a long way south with the centre over Iceland as the ridge extends north east over the UK. Thus sunny and warm in most areas but the NW of Scotland still breezy with some patchy rain

By Tuesday the Atlantic trough has disrupted as further amplification of the subtropical high occurs in the west and closer to home some cloud and light patchy rain as a couple of weak fronts are forced across the country

And this is the position on Wednesday with the weak front trailing across the country bring cloud to some areas

Edited May 23, 2020 by knocker

[knocker]

To continue over the next three days with the gfs

The shallow low in the southern quadrant of the Atlantic trough is quickly absorbed by further movement of the latter and then the previously described process is repeated but this time the amplification of the subtropical high north east has more traction and a separate trough is created to the south west of the UK. All of which results in the eastern Atlantic becoming a pretty inert area with the UK in a col

Edited May 23, 2020 by knocker

[knocker]

The ecm evolves along similar lines as the gfs but not surprisingly differs with the detail

Edited May 23, 2020 by knocker

[knocker]

Some pretty extreme above average temps in Siberia at the moment

[knocker]

A quick update of this morning's ext anomalies. The precise position and intensity of the key downstream elements, Atlantic ridge; west Russian ridge and trough to the south west of the UK, will dictate the surface analysis effecting the latter

[johnholmes]

And to add how things are looking for the 6-10 day period using the 500 mb anomaly charts

Saturday 23 May

Ec and gfs and both show a flattish westerly into the uk with +ve heights to the south; the trough shape north of this differs between them but not by that much flow over the uk itself, so possibly a nw-se split with any frontal activity mainly in the nw. How warm would depend on what shape and position any surfave high may take up in the 6-10 day period.

Turning to noaa and it is quite similar to the pattern shown on the other two. Thus we can have a reasonable degree of confidence that the 6-10 day 500 mb charts will generally be pretty similar. So the comments on ec-gfs cover noaa as well.

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

 

Climate Prediction Center - 6-10 Day 500mb Outlook

WWW.CPC.NCEP.NOAA.GOV

 

 

Edited May 23, 2020 by johnholmes
spelling

[knocker]

Interesting massively warm ascent from a Russian station on the edge of the arctic circle yesterday and then a little radiation inversion

[mb018538]

1 hour ago, knocker said:

Interesting massively warm ascent from a Russian station on the edge of the arctic circle yesterday and then a little radiation inversion

I saw this - crazy heat for the arctic circle in May. Very dry heat too with that dewpoint. More like a desert sounding!

[knocker]

Midday frontal cloud over northern UK and deep convection in south

[knocker]

Looking familiar

[knocker]

This evening's ext anomalies are indicating a quite amplified Atlantic/Europe downstream from a quite intense tpv trough over NE north America bur there is no agreement on the intensity or alignment of this which is quite critical when it comes to the surface analysis involving the UK. Suffice it to say at the moment there is nothing obvious lurking in th woodshed and the indications are for a warm and dry period

Edited May 23, 2020 by knocker

[knocker]

The North Atlantic 500mb and surface analysis for midnight and sat image, Note the new trough has tracked into the western Atlantic

A fairly cloudy start to the day in many areas with some patchy rain/drizzle over N. Ireland and NW regions.This will tend to move north east and fizzle out through the day whilst further south there will be sunny intervals with maybe a few showers

There follows a clear night for most with some mist/fog patches forming and even a spot of ground frost

By Monday the subtropical high zones have amplified and the, now, positively tilted trough is centred over Iceland. Fronts associated with this will bring cloud and rain with strengthening winds to the NW during the day whilst it is getting a tad warmer elsewhere.

.

Over Monday night and through Tuesday the weakening fronts will slowly track south east accompanied by cloud and some intermittent rain but another sunny and warm day south of this

Over Wednesday/Thursday high pressure is in charge with the centre moving into the North Sea. Still a little patchy rain in some places on Weds and a tad cooler in the north but by Thursday generally warm and sunny with the usual caveats vis some coastal regions

[knocker]

Over the weekend the gfs has movement within the tpv lobe over northern Canada which initiates the tracking of a trough east across the Atlantic whilst simultaneously the Atlantic subtropical high amplifies north east towards the high zone northern Scandinavia.This deconstructs the trough and isolates a showery surface low over the UK Need to see what the ecm makes of this

[knocker]

Just been fpr a 90minute walk. now knackered but the show must go on

The ecm has similar idea but a different execution with the high pressure to the east being more resilient, thus the trough deconstructs further west which is a much better solution for the UK

[knocker]

An update of the ext anomalies this morning without further comment

[knocker]

My interpretation of the clusters at t192, and I freely admit I'm no expert, is that cluster two is a distilled version of the det run whilst cluster one probably has the UK in a col

[knocker]

The North Atlantic 300mb wind field and surface analysis for midnight

Some early morning mist patches will quickly clear and from then on a sunny and warm day with light winds for virtually all areas. But the frontal system nudging in from the west will bring cloud and light rain to N. Ireland and western Scotland during the afternoon

The rain will slide a little further south east though tonight but become quite patchy. Elsewhere clear with some mist/fog patches by dawn in the south

On Tuesday the cloud and very patchy rain/drizzle will move further south over central regions whilst remaining sunny elsewhere and quite warm in the far south

The high cell is centred over the country on Wednesday so another dry and sunny day but the weak front is still trailing across the country so perhaps cloudy in the regions effected

By Thursday developments involving the trough in mid Atlantic are putting pressure on the ridge and the high cell moves east into the North Sea/ But still another fine day and feeling warm with the usual caveats regarding some coastal areas

This scenario continues to evolve through Friday so although another sunny and warm day for most cloud, and possibly some thundery rain, could effect some western region during the afternoon/evening as fronts grind slowly east

Edited May 25, 2020 by knocker

[knocker]

To continue over the weekend with the gfs

Still some rain over Scotland on Saturday as the upper trough to the west deconstructs under further amplification of the subtropical high leaving a rather messy surface analysis in the eastern Atlantic

Over the next couple of days the subtropical high continues to ridge strongly north east towards the high cell northern Scandinavia whilst the perennial cut off upper low develops west of Iberia. Probaly continuing warm with light winds with some showery interludes but not to get too immersed in detail at this range

 

[knocker]

This from a tweet by Alicia M Bentley which may be of interest. Or not

Quote

The multiple cutoff lows that will be located over/near N America this week are the result of an amplified flow pattern that allows for the "tails" of PV streamers to get removed from the midlatitude waveguide and stuck (i.e., cutoff) at lower latitudes.

 

[knocker]

The ecm has this position Saturday

To continue over the next two days skipping the repetitive comment.

In summation the week, barring the odd regional hiccup, is looking dry and warm

[knocker]

The ext anomalies this morning are on the same page, albeit with some differences, which given the expected pattern is understandable

Upstream the tpv centred over northern canada with trough extension south east adjacent to the subtropical high now amplifying over the cemtral areas. A strong westerly upper flow exiting the northern section of the eastern seaboard but this abates in mid Atlantic as it swings around the Atlantic subtropical high ridging strongly north east, and diverges, mainly courtesy of the trough that has been established close to Iberia.With the other part of the flow trying to track north east thanks to a ridge northern Scandinavia the UK is likely to become fairly becalmed with light airs and temps above average. Of course how this pans depends on precisely how all of these elements fall into place

 

Edited May 25, 2020 by knocker

[knocker]

Frontal cloud creeping into the NW at midday

[knocker]

The upper cloud advancing on the Castor Bay sounding

 

[knocker]

The gfs deconstructs the trough twice!