Model Output Discussions 12z 01/06/2017

[mb018538]

Sadly not much buckling in the polar jet is forecast, as such there is quite a tight flow keeping the cooler air to the north, warmer air to the south, without too much meandering. Head to the med for your sun!

[phil nw.]

After a cool and cyclonic week signs of some improvement over the weekend as the complex low finally moves away to the east.

No great shakes i know but somewhat of a warmer feel with some brighter skies at times with cold north easterly wind dropping off and gradually turning to to the west early next week.

Overall though modeling still not showing any return to any heat or prolonged sunshine as the jet flow continues to run across our latitude.

The ECM mean charts for days 5/10 continue to suppress any prolonged movement north of the Azores high because of the influence of the Icelandic/Greenland trough

This pattern also showing from last nights CPC Ht anomalies forecast

http://www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php

The type of pattern often seen in the UK Summer with the usual split between the drier and warmer conditions further south and east  generally speaking.However the interplay between the trough to the north west and the occasional ridging from the AH will no doubt leave room for more widespread finer weather on some days.

[Frosty.]

There's still a lot to be optimistic about regarding the second half of July with summery weather potentially returning widely across the uk so the seasonal models, Ec32 / GloSea5 must still be showing enough good signs for Exeter to keep the encouragement going for those of us waiting for our next taste of summer! 

In the meantime, the models indicate a generally NW / SE split with the best chance of warmer sunny spells further south-east but still with a risk of thundery rain at times but the most unsettled,  cooler oceanic conditions look likely further north-west. As for this weekend, it looks rather drier, brighter and warmer than most of this week and early next week also looks best further s / e.

Edited June 29, 2017 by Frosty.

[DTHFCJ]

These are not too bad,i know its London mind...

also not majorly wet-average...

and like Frosty has said the weekend looks half decent especially down south-as per usual. 

 

[Frosty.]

The GEFS 6z mean indicates a decent window of largely fine and warmer weather across southern areas in particular during the weekend and early next week due to a ridge of high pressure but continuing more changeable further n / nw. Looking further ahead the general rule of thumb is look south for the drier warmer spells thanks to occasional Azores ridging but remaining generally cooler and more unsettled further north-west where the lower heights persist.

Edited June 29, 2017 by Frosty.

[Gael_Force]

Week 3 and 4 looking better on latest JMA monthly.

 

[Summer Sun]

UKMO doesn't look too bad for next week at least it will be warmer and the bulk of any rain will be mainly in the north and west of Scotland

[Frosty.]

I'm searching for hints of a marked pattern change towards mid July but the GEFS 6z looks pretty awful around mid month..this is the best one in that range that I could find..however, at least southern uk has a spell of largely settled and pleasantly warm weather to look forward to during this weekend and potentially well into next week thanks to a ridge of high pressure.

Longer term..fingers crossed for a spell of widespread summery weather for weeks 3 and 4 of July which continues into August!

Edited June 29, 2017 by Frosty.

[Singularity]

 

GFS (left) with a shallow low moving steadily east to cross the UK overnight into Tuesday.

UKMO (right) with the same disturbance fading into oblivion just north of the Azores.

 

That is some impressive disagreement for just 4 days range! 

 

While GFS keeps a fairly flat jet across the UK, maintaining the changeable westerly regime as a result, UKMO allows the Azores High to slowly but surely extend a ridge across the UK, thanks to the lack of disturbances in our vicinity. It looks good going forward, with the next Atlantic trough in no position to find a way over to the UK.

Glancing at GEM, it continues to side with GFS. Will ECM stay close to UKMO this evening to maintain a standoff between the N. American and European continents? Fascinating to have such markedly different options on the table from such an early point in time - but frustrating if you've got forecasts to make!

 

[I remember Atlantic 252]

28 minutes ago, Frosty. said:

I'm searching for hints of a marked pattern change towards mid July but the GEFS 6z looks pretty awful around mid month..this is the best one in that range that I could find..however, at least southern uk has a spell of largely settled and pleasantly warm weather to look forward to during this weekend and potentially well into next week thanks to a ridge of high pressure.

Longer term..fingers crossed for a spell of widespread summery weather for weeks 3 and 4 of July which continues into August!

12Z 0perational shows, probably more realistic, spectators watching ladies final in coats/gloves

[Frosty.]

Not a bad Ukmo 12z for the weekend into next week, certainly compared to the unseasonably cool / very unsettled autumnal filth recently. A welcome ridge of high pressure will settle our weather down in time for this weekend, becoming largely dry with sunny spells and pleasant temperatures across most of the uk, certainly the southern half with temps into the low 20's celsius across the s / se.

[DTHFCJ]

start of a trend?..I Hope so

[Frosty.]

26 minutes ago, DTHFCJ said:

start of a trend?..I Hope so

As I'm sure most of us do, I would have liked to see the following few days, pity the Ecm stops at T+240 but encouraging hints that the azores high could be our friend before mid july!?

Edited June 29, 2017 by Frosty.

[Frosty.]

As with the Ecm 12z operational, the 12z ensemble mean ends with the azores high ridging in..in fact, most of the run indicates plenty of decent weather, especially further south with some warm dry days and sunny spells.

 

Edited June 29, 2017 by Frosty.

[Frosty.]

Well in the short term, isn't it great that this weekend is looking dry with sunny periods across England and Wales as a ridge of high pressure builds in..for the southern half of the uk it looks like a good weekend, compared to the recent autumnal dross!

Edited June 30, 2017 by Frosty.

[mb018538]

Extended output this morning shows a continuation of the westerly theme, though the jet is further north than this week - thus low pressure is deflected away rather than barrelling straight over the UK. Probablt won't be a bad week at all across the south next week, slightly wetter and breezier to the NW, but no washout.

[knocker]

In sustainable terms it would appear at the moment that improvement of the weather in general will come via the interface of the cooler/warmer air to shift slowly north and at the same time weaken. There are signs that this is currently the percentage play as we get into July but prior to that we still have the fluidity of this set up to contend with next week with the detail of the evolution still being elusive. So what of the ecm this morning?

We finally get rid of the low pressure east that has been the cause of the foul weather over the last few days and the Azores ridges in from the SW over the weekend bringing drier and more settled weather. Apart from Scotland that is as low pressure is never far away and there will be periods of rain in the brisk westerly wind until 00z Tuesday when the ridge will influence all.

But a little shortwave is forming to south west as can be noted on the chart above which tracks rapidly ENE to bring rain to England from the north Midlands south over Tuesday  Temps a tad cool in the Midlands in the 15C Range. This perturbation departs as quickly as it arrived and ridging again exerts it's influence over all until the major trough to the north west, or more particularly it's associated fronts, approach the north west Thursday which heralds some more rain for Scotland but also this movement opens the door for another system to sweep in from the west and bringing more general rain to Britain on Friday. Temps generally around average.

 

[Frosty.]

Really what the models are showing is a return to normal summer weather with a typical n / s split compared to the very unseasonably cool wet spell during recent days. Hopefully the second half of July will see another very summery spell!

 I think normal will feel good following the last few days.

Edited June 30, 2017 by Frosty.

[Glacier Point]

Quite like the output at present.

Next week looking very pleasant, particularly the further south and we are starting to get good hints of lowering heights over Greenland and the sub-tropical ridge beginning to exert itself in a poleward displaced position north of the Azores. Next week also advertising the low cutting south-east  through Iberia and Southern France, something long range modelling just didn't show.

With a strengthened Azores ridge and low heights over Greenland, bear in mind that the models will probably not pick up disturbances in the upper level flow interacting with the subseasonal signal for troughing in the North Atlantic. The GFS also probably going to have too much bias for low angular momentum (compare its MJO forecasting with other dynamical forecasts), and it will try to shift the Azores ridge westwards over time. Net result, shift the ridge signal further east in the 10-15 day timescale. I would favour ridge development across Iberia and sufficient to influence at least Southern UK in this time frame. For this time of year, that equates to fine and dry for much of the southern half of the UK.

[Frosty.]

The Gfs 6z operational doesn't look bad at all next week, especially further south with plenty of Azores high / ridge influence and temperatures climbing to comfortable levels into the low 20's celsius which would feel very pleasant in the strong July sunshine..not completely settled but a BIG improvement on this week..and a much nicer weekend too!

Edited June 30, 2017 by Frosty.

[mb018538]

Yes the 6z looks fair, the Azores high desperately trying to ridge in but not quite being able to make it! Warmer than recently, with temps back into the low twenties. This will feel much more pleasant than the mid to upper-teens unsettled trash we've had to endure this week!

[knocker]

36 minutes ago, Glacier Point said:

Quite like the output at present.

Next week looking very pleasant, particularly the further south and we are starting to get good hints of lowering heights over Greenland and the sub-tropical ridge beginning to exert itself in a poleward displaced position north of the Azores. Next week also advertising the low cutting south-east  through Iberia and Southern France, something long range modelling just didn't show.

 

I'm sorry I'm not quite following that. I'm not sure what you mean by 'starting to get 'lowering heights over Greenland' as low heights over N. Canada  and Greenland have been around a while now and look like continuing according to the EPS, In fact they have been a blasted nuisance as they have helped to promote the strong thermal gradient in the Atlantic being a) too strong and b) too far south.

I agree that the way forward is for the Azores to become more influential

 

[Glacier Point]

Latest 500mb height anomaly shows no low heights over Greenland.

It's not until day 7 we get proper widespread -ve height anomalies across this region..

 

[knocker]

12 minutes ago, Glacier Point said:

Latest 500mb height anomaly shows no low heights over Greenland.

It's not until day 7 we get proper widespread -ve height anomalies across this region..

 

Well the latest gfs det and GEFS do and the EPS so I'm still unclear as to what you mean/

Edited June 30, 2017 by knocker

[Frosty.]

The GEFS 6z mean is much easier on the eyes than recently, next week looks decent, particularly further south with pleasantly warm sunny spells thanks to Azores ridging..in fact, the AH influence becomes even stronger into week 2..much improved picture compared to the recent sub standard muck!

Edited June 30, 2017 by Frosty.