Models, teleconnections and nowcasting

[knocker]

The anomalies this evening are indicating quite a rapid de-amplification of the Atlantic subtropical high seemingly related to the movement of the tpv, But as yet no agreement on the detail of this change

[damianslaw]

1 hour ago, knocker said:

The anomalies this evening are indicating quite a rapid de-amplification of the Atlantic subtropical high seemingly related to the movement of the tpv, But as yet no agreement on the detail of this change

In line with models showing the high moving further NW in time, with the shallow trough to the SW joining hands with the main parent trough to the NE, so possibly becoming cool and unsettled before months end, with the driest weather reserved for the NW closer to the high. 

[knocker]

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

Rain on the occlusion associated with the low to the south west, currently in the Channel, will move north through the day, but slowly petering out. Temps okay but cooler along eastern regions in the onshore wind

But once the frontal rain has cleared a trough following in the wake will bring heavy showers to southern regions through the evening and overnight, with storms in the mix, probably more concentrated in the SE by dawn

Quite a chilly day on Saturday in the brisk easterly wind but with the trough/occlusion still around more cloud in the south and a tad warmer. Possibly some heavy showers here in the afternoon

By Sunday a trough, which essentially is an extension of the main tpv lobe over Canada,  has tracked into mid Atlantic whilst high pressure becomes established to the NE. A dry and warmer day, possibly some showers in the south, but with the usual caveats re. east coast regions

Over Monday and Tuesday the Atlantic trough takes on a negative tilt as it come up against the resilient high pressure and one surface low fills as another evolves to the south which proceeds to phase with the low pressure in western Europe. All of which peps up the south easterly flow over the UK where it will mainly dry with perhaps some showery rain in the south west

 

[knocker]

According to the gfs a similar day on Weds as the Atlantic subtropical high amplifies once more in an attempt to facilitate migration of the high cell west but the tpv is still feeding troughs into the NW Atlantic via Newfoundland which thwarts this resulting in the high cell settling over the UK by Friday

[knocker]

By midday Tuesday the ecm Atlantic analysis is quite different to the gfs so a quick run through of this Wed > Friday

By Wednesday it has a breakaway trough tracking south east in mid Atlantic as the subtropical high  ridges behind. And over the next couple of days the amplification is reinforced by further major troughs dropping into the NW Atlantic, whilst the earlier trough is forced further south. All of which creates a high cell south of Iceland. As far as the UK is concerned it means that essentially the country remains in an easterly regime which abates through the week

[knocker]

There doesn't appear to be any consensus on the 500mb pattern during the move into the ext period. So to just use the EPS as an overview which suggests that once the extension of the tpv into the NW Atlantic subsides the amplification of the Atlantic subtropical high into Greenland will do likewise and then move east

[knocker]

Saturday > Monday with the 0600 ecm

[johnholmes]

19 minutes ago, knocker said:

Saturday > Monday with the 0600 ecm

Oh Joy the wind off the N sea and not just a gentle zephy either!

[knocker]

9 minutes ago, johnholmes said:

Oh Joy the wind off the N sea and not just a gentle zephy either!

Might even make gale force

[knocker]

The other anomalies will be of interest this evening as the GEFs has brought the trough into play in the last 24 hours

Edited April 17, 2020 by knocker

[knocker]

Outlook -For the next few days  high pressure to the N/NE will be in charge with most of the action taking place to the west and south

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

Very much a N/S split today as the showery rain currently over central southern and eastern England will move slowly north and fizzle out but staying generally cloudy but clearer in the north. The usual caveats re.  eastern coastal regions

A similar scenario overnight with perhaps the odd frost patch in the north

Generally much less cloud everywhere on Sunday and warming up a tad except.......well you know the rest

No significant changes on Monday but quite a lot going on to the west with troughs exiting the main tpv lobe into the Atlantic and disrupting and pepping up the low pressure in western Europe/ This may also pep up the easterly winds somewhat

.....

Quite windy on Tuesday as the country is squeezed between the high and low pressure

The easterly wind easing a tad on Wednesday

Edited April 18, 2020 by knocker

[knocker]

According to the gfs from this point some rapid pattern changes get underway so caution is advised regarding the detail

In a nutshell the tpv lobe northern Canada starts to lose it's influence but not before ejecting further troughs in the NW Atlantic which track east. This initiates ridging by the subtropical high north east whilst high pressure in the north east dissolves. All of which means that by Saturday there is a completely different picture with the UK in a showery westerly. Await the ecm

 

Edited April 18, 2020 by knocker

[knocker]

A quick look at yesterday's EC weeklies update for the middle two weeks of May

8 > 15

Ridging NW North America adjacent to a weak tpv with a relatively benign trough into the NW Atlantic. A westerly upper flow abating considerable in the east under the influence of some positive anomalies Dry with temps above average

16 > 23

Little change upstream but more pronounced ridging in the east confirming the drier spell

 

Edited April 18, 2020 by knocker

[knocker]

The ecm also eliminates high pressure to the north east through the latter part of next week but unlike the gfs it proceeds with significant migration to the north west. Despite the disagreement on the detail of the change the upshot is that the UK still likely to manage to hang on to a ridge of some description

 

[knocker]

The forthcoming pattern change in the ext period is a slam dunk but agreement between the anomalies most certainly is not. A glance at the different handling of the trough associated with the vortex lobe over northern Russia by the GEFS/EPS says it all really

[knocker]

Sunday > Tuesday with the 0600 ecm

[Zak M]

Sunday is looking dry for the majority of the UK, with the exception of the odd shower. Temperatures in the strong sunshine will climb into the high teens.

   

Monday is also looking dry with temperatures a few degrees above average for the time of year

   

Tuesday and Wednesday will be the exact same as Monday, with everywhere being dry and temperatures still above average for the time of year.

   

   

[knocker]

Quite a difference in 12 hours with a move towards this morning's ecm

[knocker]

The North Atlantic 500mb and surface analysis for midnight

Apart from Scotland there is a fair amount of cloud around this morning but this should thin and largely dissolve through the day and get relatively warm albeit getting a tad breezier. Possible the odd shower in the south west during the afternoon

A mostly clear night with the odd frost patch by morning but the H/L squeeze is underway so wind increasing

A dry and sunny day on Monday, perhaps some cloud in the south west from the wee trough and windy in southern regions. Quite warm with the usual caveats re. eastern regions

A similar story on Tuesday with the easterly wind the only issue

Not a lot of change over the next couple of days except the wind does abate by Thursday. But the NH picture is in transition with the tpv lobe and trough to the NE developing and further troughs exiting the eastern seaboard tracking east resulting in the high pressure to our north starting to migrate west to Greenland

 

Edited April 19, 2020 by knocker

[knocker]

According to the gfs this process continues slowly over the next three days with the UK generally in a very slack gradient but the detail is tricky so not putting too much credence to this at the moment without seeing the ecm or the ens

[johnholmes]

2 hours ago, knocker said:

The North Atlantic 500mb and surface analysis for midnight

 

Apart from Scotland there is a fair amount of cloud around this morning but this should thin and largely dissolve through the day and get relatively warm albeit getting a tad breezier. Possible the odd shower in the south west during the afternoon

 

A mostly clear night with the odd frost patch by morning but the H/L squeeze is underway so wind increasing

 

A dry and sunny day on Monday, perhaps some cloud in the south west from the wee trough and windy in southern regions. Quite warm with the usual caveats re. eastern regions

 

A similar story on Tuesday with the easterly wind the only issue

 

Not a lot of change over the next couple of days except the wind does abate by Thursday. But the NH picture is in transition with the tpv lobe and trough to the NE developing and further troughs exiting the eastern seaboard tracking east resulting in the high pressure to our north starting to migrate west to Greenland

 

 

 

A ;lovely sunny start for Sunday here. Roll on Thursday and the chuffing flow off the N Sea desists!

 

[knocker]

Overcast here, hopefully it will clear

The medium term GEFS anomaly merely confirms the transition to a more unsettled period, albeit nothing drastic with the slack gradient

[knocker]

Apparently there have been a few problems with the ecm this morning so just  some surface charts illustrating the transition to more unsettle next weekend

The cloud is clearing down here

 

[knocker]

The EPS this morning showing the transition over the weekend and the medium range anomaly

[knocker]

Monday > Weds with the 600 ecm

Current sat image