Models, teleconnections and nowcasting

[knocker]

Given the marked difference between the gfs and ecm a closer look at the medium term anomalies which reveals no bog surprises.

Apparently the EPS is making much more of the cut off trough and the diversion of the upper flow which initially allows the European subtropical high to amplify NW before subsiding a rad. Whereas the GEFS does not divert much of the energy and thus a westerly upper flow is maintained with some amplification of the Subtropical in mid Atlantic. Well that's my take on it

[johnholmes]

The 3 500 mb anomaly charts still show different ideas, EC and GFS are similar with 500 mb ridging and +ve heights for the UK area; NOAA has a trough, like yesterday just west of the country lying down to off Iberia and just slight height rises east out over Europe. So no guidance there.

[knocker]

The divergence of the gfs and ecm from around t120 is causing some problems at the moment and looking at the clusters for that time period you would nor bet the woodshed on the det. run being right

 

[knocker]

Sat image at midday

[knocker]

Next batch of rain on the way as thickening Cs encroaches down here

Edited April 29, 2020 by knocker

[mushymanrob]

7 hours ago, johnholmes said:

The 3 500 mb anomaly charts still show different ideas, EC and GFS are similar with 500 mb ridging and +ve heights for the UK area; NOAA has a trough, like yesterday just west of the country lying down to off Iberia and just slight height rises east out over Europe. So no guidance there.

I must be missing something here... i dont see the Ecm and Gfs looking similar but different, with the NOAA ( 8-14) agreeing more with the Gfs , both appear to me to be suggesting an amplified azores ridge, troughing to our near southwest and down to Iberia as you say. The Ecm appears to be on its own.

To me, they all seem to be trying to bring on positive heights, but cant decide where whilst that cut off low to our near southwest is causing them headaches.

 

[viking_smb]

the bottom image is the united states not europe

[johnholmes]

44 minutes ago, viking_smb said:

the bottom image is the united states not europe

Yes we do both realise that. We have both commented on what the charts appear to suggest for the upper air pattern around the UK.I was also using the 6-10 image not the 8-14 Noaa chart.

Edited April 29, 2020 by johnholmes

[johnholmes]

45 minutes ago, mushymanrob said:

I must be missing something here... i dont see the Ecm and Gfs looking similar but different, with the NOAA ( 8-14) agreeing more with the Gfs , both appear to me to be suggesting an amplified azores ridge, troughing to our near southwest and down to Iberia as you say. The Ecm appears to be on its own.

To me, they all seem to be trying to bring on positive heights, but cant decide where whilst that cut off low to our near southwest is causing them headaches.

 

I was looking at bot Ec and GFS show +ve heights in a similar area whilst NOAA does not. 

[knocker]

Some heavy rain on the front which just appears to be clearing here

And a quick glance

 

Edited April 29, 2020 by knocker

[knocker]

The ecm this evening t120 > 144 and oh to be in Skeggy again

Edited April 29, 2020 by knocker

[knocker]

At midnight a complex upper trough is centred over the UK and stretching south west into the Atlantic

Thus today there is a surface low over NW England with the associated front bringing a band of rain to central Scotland and N. Ireland whilst south of this over much of England and Wales it will be a  day of heavy showers with some thunder in the mix and quite windy

This evening and tonight the showery activity across most of the UK will continue but there may be a touch of frost courtesy of the clear interludes

More persistent rain over northern Scotland on Friday thanks  to the odd front running around in the circulation bur elsewhere probaly plenty of sunshine but still some heavy showers around mainly concentrated in the vicinity of the trough

A dry day for most on Saturday but still some showery rain across Scotland, perhaps extending down the NE coast of England but there are developments in the Atlantic as the upper through splits under pressure from the amplifying high zones

A dry and relatively sunny day on Sunday but cloud could creep into NE coastal regions and cloud and rain from fronts associated with the trough to the south west will encroach south western regions during the afternoon and effect much of England and Wales overnight

The rain will clear by Monday as the system moves east leaving a dry day with sunny intervals a but quite a N/S split regarding temperature

[knocker]

The detail for the middle of next week has been causing the models some grief and from where I'm sitting it appears to have much to do with the energy distribution, and thus movement of, around the cut off low to the south west of the UK. And this morning the gfs has the low pushing NE against the ridge bringing unsettled weather to western regions but also some marked regional temp variations

[knocker]

The same general overview applies to the ecm but is more agressive with the amplification of the European subtropical zone and the low does not encroach NE. albeit an associate front does to some extent. Gradually getting a tad warmer but the usual caveats re. eastern coastal regions

[johnholmes]

1 hour ago, knocker said:

The same general overview applies to the ecm but is more agressive with the amplification of the European subtropical zone and the low does not encroach NE. albeit an associate front does to some extent. Gradually getting a tad warmer but the usual caveats re. eastern coastal regions

I like the look of Thursday, not the others though thanks to the area of water to my east!

[knocker]

The ext anomalies this morning are on the same page albeit not word for word

Tpv/troughs  eastern Europe and NE North america with strong ridging in the NW. Downstream the subtropical high amplifying in mid Atlantic adjacent to the trough in the Iberia region. Patently the Atlantic/European analysis is not a done deal and it's important how this develops but broadly speaking it's looking pretty dry with temps around average

 

[johnholmes]

32 minutes ago, knocker said:

The ext anomalies this morning are on the same page albeit not word for word

Tpv/troughs  eastern Europe and NE North america with strong ridging in the NW. Downstream the subtropical high amplifying in mid Atlantic adjacent to the trough in the Iberia region. Patently the Atlantic/European analysis is not a done deal and it's important how this develops but broadly speaking it's looking pretty dry with temps around average

 

Yes I would agree there k, EC and GFS are very similar in most respects; NOAA, well we could say it is 2/3 in agreement! By that I mean the western trough and ridging but less so for the eastern trough. Although it is always difficult to make out just how much troughing is occurring when it is on the edge of the chart.

[knocker]

Not bad agreement between the det and clusters t132 > 156 albeit the enclosed high cell is not a done deal

 

[knocker]

The midday sat image

 

[knocker]

[knocker]

The ecm amplifies the European subtropical high NW between the troughs from t96 > 120 and by 144 has done enough to very much slow down the east bound energy and the Atlantic trough only impacts western regions

 

Edited April 30, 2020 by knocker

[knocker]

Outlook - the story over the next few days is essentially one of the positively tilted upper trough, currently aligned across the UK, splitting under pressure from the amplifying subtropical high zones and creating a cut off low to the south west. From this point it is about the movement of the latter and the energy flows around the amplifying European ridge north west towards Greenland

At the moment the country is still under the influence of the trough as the above process gets underway so another day of showers and sunny intervals,not so frequent as yesterday, but still heavy at times and more concentrated in northern and eastern regions with the SW and S having a quite pleasant day with less wind

The showers in the east will tend to fade away tonight but still a few in the north and north  west, otherwise a dry night

By Saturday the UK is between troughs, so to speak resulting in a generally dry day with sunny intervals but some showers in the north and east courtesy of a stray occlusion

By Sunday the cut off upper low to the south west is established with the UK in a slack gradient and another day of sunny intervals and showers

On Monday the now influential high cell is centred near the Hebrides so a generally sunny day but with some marked regional temp variations courtesy of the North Sea and the onshore wind

By Tuesday the high pressure has become quite elongated as the trough to the south west  pushes north and the associated front brings rain the south and generally a much cooler day

 

 

Edited May 1, 2020 by knocker

[knocker]

The gfs for the rest of the week is pretty much along the lines of the opening comments above with the net result being that the systems in the Atlantic struggling east against the ridge and not being very successful

[knocker]

Obviously with variation of detail but the ecm along the same lines

Edited May 1, 2020 by knocker

[knocker]

Nothing particularly meaningful to be discerned from the ext anomalies this morning. The overall NH pattern is much as was discussed yesterday. But until the jockeying for position of the two major east/west troughs, the mid Atlantic amplification of the subtropical high, with the added complication of the trough near Iberia, settles down, then a watching brief is the percentage play