Model output discussion - after the beast, what next?

[Derecho]

7 minutes ago, Faronstream said:

GFS continues to be an outliner with unrealistic outputs with cold uppers down to -15, absolutely impossible and nothing to expect since ECMWF continues to show mild westerlies and no sign of " east from the beast". GEM is something in between

ECM continues to show mild westerlies? You may not like the look of the 00z....

And what is an outliner?

Anyway it seems like the 06z was still keen on cold although it was a bit more sluggish as with other members because it took longer to get some deep cold pooling into Scandinavia.

This is to do with uncertainty as to how much pressure builds to our north.

For those wanting Spring the best chance of anything is a west based -NAO I think drawing up warm air from the south.

Edited March 21, 2018 by Quicksilver1989

[Singularity]

As far as I'm aware, a weak polar vortex located over Siberia is pretty much the ultimate setup for placing deep cold airmasses E/NE of the UK and then allowing ridges from the Atlantic sector to pull some of that SW or W toward and potentially right across the UK.

Sadly for those who prefer this to happen in the heart of winter, only the most powerful vortex splitting events are able to bring about such a weak vortex in that area during Dec-Feb, yet due to the seasonal warming-out, it only takes a weak event to do so in late March or early April. 

Anyway - combined with albedo feedback from the extensive snow cover across NE Europe and W. Russia, it means we're at risk of unusually cold air imports until either the vortex fully winds down and stops drawing deep cold together beneath it, or the cold air warms out under the increasingly strong sun, or tropical forcing such as the MJO can force the ridges from the Atlantic to stay at lower latitudes.

The warming of the global climate will be focused away from the N. Europe to NW. Asia regions during this time, hence it's not out of the question for record levels of cold to be challenged in these areas.

I am of course just highlighting the potential here; even with the higher than usual risk, there's still quite a good chance of escaping another import of air as anomalously cold as we've received twice this month already. The ensembles do have me concerned for the welfare of our wildlife though!

Edited March 21, 2018 by Singularity
Wrong Word Woes

[karyo]

Stunning 12z gfs brings the cold from the northeast by Wednesday next week!

The UKMO appears much slower.

[JamesL]

UKMO slower yes but looking like the low around Iceland has nowhere to go but move SE as a trigger low sending all that cold over Scandi southwestwards 

 

Edited March 21, 2018 by JamesL

[Summer Sun]

GFS now wants to bring the high back into play around Easter

12z

06z

 

[DIS1970]

Anything beyond 6 days should taken with a pinch of salt, as there is nearly always a completely different outcome after this.

[Frosty.]

6 minutes ago, Summer Sun said:

GFS now wants to bring the high back into play around Easter

12z

 

 

 

Yeah the high / ridge lasts about 5 minutes and then low pressure for Easter!

[Summer Sun]

GFS taking a different route this afternoon with less cold air arriving just in time for Easter quite wet at times and windy but any snow would be restricted to the highest ground in the north

[ICE COLD]

37 minutes ago, Faronstream said:

GFS continues to be an outliner with unrealistic outputs with cold uppers down to -15, absolutely impossible and nothing to expect since ECMWF continues to show mild westerlies and no sign of " east from the beast". GEM is something in between

Mild westerlies ???? ????. 

ECM days 7,8,9 and 10 below . 

Cant see mild westerlies there ? ? 

So the GFS has support from the ECM for a coldish spell . How cold ? Will have to wait and see . 

[Faronstream]

2 minutes ago, ICE COLD said:

Mild westerlies ???? ????. 

ECM days 7,8,9 and 10 below . 

Cant see mild westerlies there ? ? 

So the GFS has support from the ECM for a coldish spell . How cold ? Will have to wait and see . 

It has support for just one run

[phil nw.]

Both GFS and UKMO models show the weak heights around Greenland/Iceland at day 6 but the difference lies further south .

The UK model disrupting the trough a little further north as the Azores high pushes east thus holding back the southward track of the cold.

GFS continues to bring the cold right down just after this with the ideal angle of attack from the ne (polar continental air)by day 8.By that time we would see sub-zero dew points quite widely with snow probably at quite low levels if this was to verify.

 

 

 

[Summer Sun]

GEM shows an unsettled start to Easter with quite a bit of rain at times but at least it wouldn't be overly cold for the majority

Edited March 21, 2018 by Summer Sun

[Tim Bland]

GFS still showing lots of cold and snow for Easter and beyond ...

 

[ICE COLD]

6 minutes ago, Summer Sun said:

GFS taking a different route this afternoon with less cold air arriving just in time for Easter quite wet at times and windy but any snow would be restricted to the highest ground in the north

Just a quick question . Why do you seem so pleased when the outputs show mild wet weather  ? I can understand people wanting mild/warm dry weather as I can understand people wanting cold and snow (me included) . But being happy with mild and wet for Easter is a bit weird. ?

[nick sussex]

The issue going forward is whether you get a breakaway shortwave rather than waiting for the whole low pressure and associated shortwave energy to clear.

You really need a GFS trend and that chunk of low heights on the tip of Greenland to stay there.

Waiting for a total clearance is going to take time and the angle isn’t great.

[johnholmes]

Comical really but quite confusing for new folk. One post version  just above here around Easter showing mild and wet and another showing cold and snow.

 

[Stationary Front]

Not that confusing - posts clearly state 2 different models Gem and GFS

[johnholmes]

2 minutes ago, Stationary Front said:

Not that confusing - posts clearly state 2 different models Gem and GFS

Nope, Tim Bland GFS and SS GFS I was referring to

 

[Tim Bland]

Difference is SS points out the average  wet weekend which is preceded by and followed by cold and snow. 

[feb1991blizzard]

1 minute ago, johnholmes said:

Nope, Tim Bland GFS and SS GFS I was referring to

 

All you have to do is look at the dates to decide which one is correct, one is just before the Easter period, SS refers to the Easter weekend and he is right. not desperately cold at all, to be fair to Tim Bland though. I think he was anticipating that the Thursday chart would equate to cold for 5 days afterwards.

[ICE COLD]

GFS 12z is a very cold run again starting next Wednesday to Saturday-

it turns less cold for the Easter weekend and wet ?

And then the cold comes back , especially for the east of the country . It carries on until day 16 .

[Summer Sun]

Looking at the GFS mean any snow over the Easter weekend (30th to 2nd) would be in the north and mainly for higher ground certainly so during the day temperatures for the majority are too high.

[Frosty.]

18 minutes ago, Summer Sun said:

Looking at the GFS mean any snow over the Easter weekend (30th to 2nd) would be in the north and mainly for higher ground certainly so during the day temperatures for the majority are too high.

Yes you're right about Easter SS..if the GEFS 12z mean is right of course!, temps across the southern half of the uk are around 7-10c but nearer 3-6c across most of scotland, lower still over scottish highlands with a risk of snow.

Edited March 21, 2018 by Frosty.

[Derecho]

Swingometers updated again and it looks like as though we have a stand off for the last week of March.

Will the cold air reach us, or will low pressure systems keep it away? Sometimes the GFS deepens lows too much so it may be too progressive.

However the potential for low pressure to keep the cold air away can't be ignored. A few runs take the low to our SW and keep it stick there bring warmer air from the south. There is even something close to a plume at the start of April on one member (check out P15 Summer Sun).

So will the cold air remain bottled up to our east, or will it be released to head our way?

A final thing to note is that unlike the last two easterlies which progressed very quickly, this one is less clear cut so has less widespread cold uppers heading our way on the colder ensemble members (for now!)

[Purga]

Excellent - snow showers across the bulk of the UK!

A very brief milder blip and then the April Beast strikes again

 

 

Edited March 21, 2018 by Purga