Alternate Model Discussion - into 2022

[mushymanrob]

1 hour ago, phil nw. said:

Looking ahead to days 5/10 on the ECM mean 500 charts and 850s anomalies.Northern hemisphere view.

We can see the pattern changing as the Canadian trough, which has seen Canada and parts of the northern states in deep cold, move east into the Atlantic 

Downstream of this trough the Azores high ridges ne with milder air enveloping much of western and northern Europe by day 10.

 

Itll be interesting to see if the NOAA charts support this, currently they still retain the TPV over North Canada

[knocker]

No significant changes with the medium term anomalies this evening. The salient points remain; Aleutian trough  and ridge western North America extending to Siberia adjacent to the main tpv lobe northern Canada. A very strong 180kt jet exiting the eastern seaboard at the beginning of the period which initiates some trough disruption in mid Atlantic which in turn promotes the Azores HP, resulting in a more settled period, particularly in the southern half of the country, Temps rising above average

Edited January 4, 2022 by knocker

[knocker]

A quick glance at the rapid cyclogenesis this morning as the low deepens 36mb bertween midnight and 1800

And then after a widespread frost Thursday morning, fronts associated with this will bring rain and transient snow down to quite low levels, as they track east across the country. Friday a day of sunny intervals and squally showers

And the unsettled weather continues on Saturday and the beginning of next week with temps now rising to around average

Edited January 5, 2022 by knocker

[knocker]

Both the gfs/ecm have the tpv lobe dropping some very cold air down eastern North America/NW Atlantic next week, which pumps up the Atlantic jet and to a certain extent the Azores ridge, Thus the southern half of the country becoming more settled

[knocker]

Atlantic satellite 0740

[knocker]

Some snow on Thursdays front and the showers that follow

Edited January 5, 2022 by knocker

[phil nw.]

A pretty cold night to come countrywide under the ridge.

.

As can be seen the next system is approaching out west and this will move rain and snow across the UK on Thursday with temperatures still on the cold side for many especially away from the far south west

[knocker]

Early next week both the gfs/ecm continue to indicate cold Arctic air, associated with the tpv lobe, dropping down NE North America, pumping up the jet, splitting the upper trough and creating a cut off upper low, and promoting the Azores ridge.

 

[knocker]

Snow on the leading edge of the front today followed by squally snow showers down to quite low levels once the front clears to the east

[knocker]

Although reasonable agreement on the cold plunge NE North America, pumped up Atlantic jet and promotion of the subtropical ridge next week, the subsequent detail still to be sorted

[knocker]

The salient points of the ext mean anomalies this morning. Ridge western North America extending into Siberia adjacent to a realigned tpv NE Europe > northern Canada; Strong upper flow exiting the eastern seaboard swinging around some amplification of the subtropical high mid Atlantic; Temps around average, possible a tad below and pretty dry with a NW/SE bias

[johnholmes]

One can understand why the graphics one can see on tv show so much snow in the showers behind the cold front later today looking at the GFS predictions coming out for the 6-18 hours after the front, -7 C widely predicted over even some southern parts of England.

[knocker]

The concentration of snow showers overnight and then this little feature brings more persistent rain to the SW tomorrow with snow over the moors

Edited January 6, 2022 by knocker

[cheshire snow]

@knocker good to see you posting again your contribution is much appreciated on this forum Always my first port of call in the morning this thread plain and simple as it should be without getting lost in all the hype on the other side.

[phil nw.]

A general summary of how things look to develop over the next few days.

A couple of fax's for Friday and Saturday showing the unsettled pattern as fronts move across the UK associated with a deep low pressure near the south west of Iceland.The GFS chart for 12z Saturday shows a pretty active Atlantic jet stream.

UKV charts plenty of showers around in the cold westerly tomorrow with snow in some places as temperatures remain quite low.Saturday sees another system moving east with a brief mild sector with mainly rain and temperatures somewhat higher especially further south.

Looking towards Sunday and Monday on the ECM 00z shows a rather cold day again on Sunday with some showers before the start of higher pressure building from the south bringing in milder air again.

Modeling shows the high is expected to continue to build north into next week and the interest then will be where it situates as this will influence surface conditions for the UK going forward. 

[knocker]

As previously mentioned, the gfs/ecm still indicating very cold air associated with the tpv lobe dropping down the NE of North America early next week, pumping up the Atlantic jet, splitting the upper trough, and creating a cut off upper low, whilst promoting the subtropical ridge north east over the UK

 

Edited January 6, 2022 by knocker

[knocker]

Following on from the above the gfs/ecm medium term anomalies are in reasonable agreement upstream but differ greatly on the handling of the Azores ridge amplification north east into Euro and the subsidiary tpv lobe and extended trough northern Russia Essentially the ecm has the latter extending down into eastern Europe which curtails any further amplification of the subtropical ridge that the gfs favours, This obviously needs sorting before the detail for this period can be viewed with any confidence. NOAA apparently favoring the ecm interpretation

Edited January 6, 2022 by knocker

[knocker]

Frequent squally heavy showers around at the moment, mainly in western regions, of snow down to quite low levels in the north west. Likely to get less frequent as the day progresses but a littler frontal feature will track south east over south Wales/sw and southern England around lunchtime bringing rain and snow over the moors

Edited January 7, 2022 by knocker

[knocker]

The position of the tpv lobe/trough northern Russia during the latter half of the ten period continues to be paramount regarding the European detail as illustrated by the gfs/ecm this morning

[knocker]

The main clusters indicate a fairly mobile Atlantic flow with the next batch giving a tad more influence to the Atlantic subtropical HP. A reasonable summation of the ext period at the moment

Edited January 7, 2022 by knocker

[knocker]

The frontal system tracking east across the country tomorrow with some snow on the leading edge and then perhaps some snow showers on the higher ground in the north behind the cold front

 

[BlueHedgehog074]

The are some differences, but there is a chance for things to start drying out a bit over the UK just after this weekend with the rain, hill snow and wintry showers, as the models show High Pressure, in some form, moving in over the UK into next week. And Low Pressure and low heights getting pushed away further North. 

You can see, as an example at 120 hours, that the models shift the Azores High from our South-West over the UK:

00Z GFS

00Z ECMWF

00Z UKMO

 

The general pattern seems to be their for the build of pressure, but the above 3 models do address some uncertainty as to how far North the High moves over the UK from the South-West. The GFS looking the most keen to its North-Eastward progression of the High over the UK at that time-frame, where as the ECMWF, while still influential for most of the UK, has the main part of the High Pressure more suppressed to our West-South-West. Allows more of a keen Westerly flow spilling over the top for Northern Scotland. UKMO, I would say, kinda somewhere in between. 

At 144 hours, and we can see that because of the GFS’s keenness over its North-Eastwards build of pressure, the centre of the High Pressure pulls over to our East into the continent and a chance of a chilly light Easterly to South-Easterly flow developing for Southern parts of the UK. ECMWF keeps the High over South/South-Western UK and the UKMO has the High being pushed and squashed over to South-Eastern parts of the UK. The latter of which allowing tropical maritime air from the South-West to spill over the top of the High from the through the UK with some milder weather.

00Z GFS

00Z ECMWF

00Z UKMO

So it does seem like some details to still be resolved, but the likelihood, especially for Southern parts of the UK, to see a more cyclonic (edit: sorry, meant anti-cyclonic) spell. The latest ensemble pressure mean from the GFS 06Z, does signal a build of High Pressure and increased upper heights over a large portion of the UK from the South-West. Which the 96 and 120 hours time-frame illustrates well:

You can really see it build over the UK at the 120 hour mark. The ensemble mean showing the High Pressure continuing to progress Eastwards towards 144 hours, but still in good control over the UK. 

 

Some, particularly Southern areas, I can imagine would be wanting the GFS sort of solution, for that possibility of some chillier, and perhaps frostier, conditions to develop from any continental flow on the Southern flank of the High Pressure. Further North the High goes, and the more places that could see more of a continental flow. Either way a more settled spell, again, looks evident, although exactly where the High moves and settles in affecting where the distribution of the milder and/or chillier conditions occurs as well as the distribution of cloudier and brighter spells of weather. 

Edited January 7, 2022 by DiagonalRedLine
Accidentally used the word cyclonic, but meant anti-cyclonic

[johnholmes]

28 minutes ago, knocker said:

The frontal system tracking east across the country tomorrow with some snow on the leading edge and then perhaps some snow showers on the higher ground in the north behind the cold front

 

Hi K

Are you able to give the link to this 3 km model please?

[knocker]

1 minute ago, johnholmes said:

Hi K

Are you able to give the link to this 3 km model please?

http://hebweather.net/wrf/wrf.php?run=00z&region=BritishIsles&chart=Overview&time=1

[johnholmes]

1 minute ago, knocker said:

http://hebweather.net/wrf/wrf.php?run=00z&region=BritishIsles&chart=Overview&time=1

Thanks for that, not seen it, well not tried to use it, so will keep an eye open for how it does. Have you formed any opinion on it?