Model discussion - March drawing to a close

[Singularity]

Some astounding strength and persistence of HLB appearing in the modelling at the moment. Even ECM's coming around to the idea of a vast high centred NW of the UK and reaching across the high Arctic.

It's hard to fathom why this is going on, though - there's no major SSW and nothing much going on with tropical forcing. Troposphere wave breaks just happen to come together in the right way to initiate the blocking and then it seems that the westerly momentum is just too low to take it down any time soon. This may be to do with the strong 'warm Arctic, cold continents' type weather pattern that's unfolded during the past week; the polar to mid-latitude thermal gradient (that drives the thermal winds i.e. jet streams) is a lot weaker than usual.

Our best hope of escaping a cool run of weather looks to be broad troughs setting up due west of Europe, which is a typical development during an El Nino April. If they move close enough, they'll drive unusually warm conditions our way - but with the risk of some lengthy spells of rain if they make it too far east.

As the month goes on, the HLB should weaken and the chances of a big flip in temperatures increase. I wonder if the second half of the month might prove a dramatic one with warmer and colder than usual airmasses colliding in the vicinity of the UK? Something to watch out for in the outer reaches of the modelling. In theory, ridging from Europe should then win out at some point... hopefully soon enough to avoid giving the UK an absolute deluge.

[Frosty.]

Insane Ukmo 12h chart..if it was winter!!

Edited April 2, 2019 by Frosty.

[SMU]

Picture postcard winter charts from the UKMO-

Even at this stage that 144 UKMO is sending the fairly deep upper air cold pool ( -10c ) SW towards the UK..

The bottom values of the GFS ens for London were around -8c --

[Methuselah]

Will the cold air from the northeast win out, or will that blob of warmer air be pushed our way, keeping the cold locked-up in Scandinavia? Prepare for the worst and hope for the best...cos it changes, a little bit, with each run...

 

And I'm not looking forward to that nasty-looking patch of sub-zero uppers...not looking like one of the greatest of weekends one could hope for, in early April?

[Frosty.]

20 minutes ago, Frosty. said:

Insane Ukmo 12h chart..if it was winter!!

Indeed now I've been able to see the icy 850's approaching...even at this stage it could deliver something memorable..hope exeter include it in tomorrow's update!!!!!!

[SLEETY]

13 minutes ago, Steve Murr said:

Picture postcard winter charts from the UKMO-

Even at this stage that 144 UKMO is sending the fairly deep upper air cold pool ( -10c ) SW towards the UK..

The bottom values of the GFS ens for London were around -8c --

why can’t we get these charts in the winter months,is the big question

[MATTWOLVES 3]

13 minutes ago, SLEETY said:

why can’t we get these charts in the winter months,is the big question

The positioning of the split vortex and the way it hung around over canada did us know favours. In 2018 it all worked to our favour! So perhaps next time it will again, cartainly know point in giving in hope! We start again in November with a clean slate!! Oh by the way.... Great UKMO charts guys!

Edited April 2, 2019 by Mattwolves

[MATTWOLVES 3]

Out to 240hrs and GFS still having us under a rather warm SEtly, low pressure to the West perhaps a cause for concern at this stage. 

[knocker]

Interesting to see what the later fax charts come up with this evening as at t96 the gfs has the Canadian train running south east of the high pressure with the developing little upper low to the east which over the next 48 hours tracks west in this very artistic pattern. This would bring some rain to much of England and Wales It then phases with the trough to the south west as another major trough enters the Atlantic to the west This results in a trough dominated Atlantic with high pressure running around it from the NW > N > .NE with the UK in a very slack easterly Temps around normal becoming a tad warmer

 

Edited April 2, 2019 by knocker

[SLEETY]

38 minutes ago, Mattwolves said:

The positioning of the split vortex and the way it hung around over canada did us know favours. In 2018 it all worked to our favour! So perhaps next time it will again, cartainly know point in giving in hope! We start again in November with a clean slate!! Oh by the way.... Great UKMO charts guys!

but that happened at end of the winter.When was the last time we had the sort of charts the ukmo is hinting at in early January for example,where the snow and cold would be mega.

 

[MATTWOLVES 3]

17 minutes ago, SLEETY said:

but that happened at end of the winter.When was the last time we had the sort of charts the ukmo is hinting at in early January for example,where the snow and cold would be mega.

 

09/ and 2010 to some point, Estlys were quite frequent in the 80s, then kind of died a death in the 90s and 00s, they most likely come in sequences, wouldnt be surprised to see a glut of them from 2020 onwards! It's Impossible to be sure but things do tend to pan out a certain way. In the meantime perhaps a bit of a standoff in the later frames of GFS, much warmer to our SW, and much colder to the NE! I'm not fussed either way... Its been to long a season in fairness, and it's gonna take a while to dust meself down and get ready for the next chase in just...... 7months! Amazing how quick it comes around... In the meantime bring me another summer to remember!

Edited April 2, 2019 by Mattwolves

[Methuselah]

37 minutes ago, Mattwolves said:

Out to 240hrs and GFS still having us under a rather warm SEtly, low pressure to the West perhaps a cause for concern at this stage. 

And right at the death, those annoying blobs of once-bottled-up-by-the-PV leftovers are finally starting to lose their intensity...Still, there's maybe a chance of a quick freeze-up before proto-summer fully takes hold?

  

[Frosty.]

The Gfs 12z parallel is flying it's cold bias flag loudly and proudly, there be snow in them there hills!!

[MATTWOLVES 3]

Perhaps the first signs of the cold plunge from the N/NE around day 10 on the para, which is running o so slowly this evening! 

Sweet jesus, there's some seriously cold air bottled up to our North, it getting a move on as well! 

-16 uppers anyone!! Or is the chase dead!! 

Its along way off but its packing a punch! 

A thoroughly entertaining run from GFSP! 

Edited April 2, 2019 by Mattwolves

[Frosty.]

Looking at the extended GEFS 12z, the arctic could still be a threat ( as the parallel also shows on my post further up)..but such is the duality of spring, there could be some continental warmth from southern europe or indeed a warm anticyclone over the uk.

Edited April 2, 2019 by Frosty.

[Mike Poole]

ECM 12z at just T144:

Well you just couldn't make it up, just like Brexit!  Pretty much nailed on easterly after the cold of winter is gone.  But an easterly is more likely in April than winter, much more likely.   Few tweaks on this and a significant cold shot is still possible though. 

However, I'm looking a bit further forward, who reckons on a sudden shift cold to warm around mid month, happened last year and I think there is reason looking at the GWO with Atmospheric Angular Momentum expected to rise to expect it again.  I'll do a post on this when I have more time. 

Edited April 2, 2019 by Mike Poole

[Frosty.]

Remarkably similar to the ukmo 12 @ T+144 mike.

[MATTWOLVES 3]

7 minutes ago, Frosty. said:

Remarkably similar to the ukmo 12 @ T+144 mike.

And 2 of the best models to have on board guys!

[Frosty.]

Coldies are still in the game, a few tweaks and the Ecm 12z would have been sensational but those heights transferring to the NW around the Greenland area is impressive, something I crave for in winter.

[Methuselah]

A hint of a southeasterly, according to the FV3:

 

But will it turn into a northeasterly, farther down the line? Anywho, it's sleeting at Molineux(sp?) COME ON YOU WOLVES!!!

[Methuselah]

Uppers like these aren't too shabby, for April; and, neither is the heat building to our south!

 

The T850 ensemble doesn't clear much up, either... 

[ANYWEATHER]

Evening! Serious Northern Blocking from the ops. Ecm and Gfs show a few mild blips , but overall some very cold synoptics on the cards, So Aprils cold today , looks as though this will be the theme for April, some of those charts show some damaging frosts , any growers need to take notice,,,,

[Mike Poole]

Some short range output from me, ARPEGE 12z and HIRLAM 12z cumulative snow fall up to T48:

Snow looks restricted to higher elevation in the usual places.  

Longer term ECM T240 mean looks dead set on the easterly:

Uncertainty over temperatures in the south, here's the spread:

So to sum that up the north looks likely to get some coldish weather from the easterly, but for the south there is quite a lot of uncertainty.

 

[knocker]

The general theme of the latter part of the em det run is to track the high pressure west to the Greenland area with some complex energy flows south of this which even involves an arm of the subtropical jet resulting in troughs being promoted across the Atlantic under the block. And one such deep low ends up in the eastern Atlantic bringing heavy rain and gales to the UK

Putting aside the detail of the end of the run which will not verify but remembering the general evolution then this evening's EPS 8-13 mean anomaly is not with out interest. The vortex is in the Franz Joseph area and high pressure around Greenland and the north west Atlantic resulting in the reasonably strong westerly flow exiting the eastern seaboard across the Atlantic being further south than usual with quite impressive negative anomalies in mid Atlantic. This could perhaps add some traction to the idea of systems tracking into the UK from the south west despite the upper flow losing some impetus. Just an observation as I suspect pinning down the detail will not be simple. Temps a tad below average

[Frosty.]

Stunning Ecm 12z ensemble mean..what an Easterly!!