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Model output discussion 9th April onwards


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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.

Today's GFS 00Z 'promises' a very mixed bag; though, as it's (for the most part) a warm mixed bag, thunder potential could be quite good:

h500slp.png     h850t850eu.png

h500slp.png     h850t850eu.png

h500slp.png     h850t850eu.png

GEFS 00Z temp. ensembles:

t850Suffolk.png   t2mSuffolk.png

Edited by Ed Stone
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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.

I can't think why (⚡) but things have gone rather dead, in here, this morning . . . The GFS06Z is suggesting some real heat might be headed this way, towards/around month's end.

h500slp.png    h850t850eu.png

h500slp.png    h850t850eu.png

h500slp.png    h850t850eu.png

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

Most of the Gfs 12z operational is instantly forgettable but it does have a happy ending...well, happy if you like high pressure!  

As for the longer term GEFS 12z mean, it’s not terrible and probably represents a typical north / south split?, it’s fair to say there are some very unsettled and cooler members but there’s a few peaches too  

I guess it’s so quiet in here because many are on storm watch? ...May the force be with you

533A9DC5-345B-40FC-8A7C-58FC7AF80EB3.thumb.png.d4f17357928845863264def4e37e36fa.png5EEFFCD6-3606-458F-95EE-F4EE5471180A.thumb.png.90812dc1ac830e86dfb1d00ad89715c6.png822E1BDE-7664-4FC3-8967-284EBB3BD44A.thumb.png.95ae1a53781c73b55bdaeeda6aa89d41.png3E37A87E-0C5A-452C-BDE6-41BE942183AC.thumb.png.633dcdaaa255e6882efa696df23ad210.png925D47B9-15D4-4BC9-8EB7-08A795D36DFB.thumb.png.4f8a089aaad6c5b8f615c2de515d8ed9.pngA5D31C27-8F2F-4096-85F4-6A846A0F0484.thumb.png.a0341fc8ba5fc075290d38dd07a793c0.png8D607186-0358-421C-BB41-23348DFECD73.thumb.jpeg.26f8e1a8dab88a4916707105e3087b74.jpeg

 

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Posted
  • Location: East Ham, London
  • Location: East Ham, London

Evening all

The mid month breakdown was pretty well advertised by the models and is at hand.

Looking further ahead, the T+168 charts from the 12Z suite this evening:

image.thumb.png.aeadcca93da05eaff99985b1e8707e74.pngimage.thumb.png.5876f0c8bacbabcbf9e4dc8b1be6c802.pngimage.thumb.png.27093d0a696ede78537c465b7ad2c414.pngimage.thumb.png.0f3549c3315641e5fadd6ba117d56439.pngimage.thumb.png.83a864d21ae15a0b81ec95f37c0b2952.png

So that's GEM, JMA, ECM, GFS OP and GFS Control.

None of that screams hot, dry and settled if I'm being honest. Winds generally from the west or perhaps north west so not excitingly warm and while the Azores HP ridge is trying to push across the south, it's all a bit half-hearted. 

The problem is the large block over Russia is going nowhere and hot air is pumped north and west over Finland (28c over Helsinki tomorrow) with the usual heights to the south west, the trough ends up over northern and western Europe with lower heights over the Mediterranean as well.  That's a recipe for unsettled weather for the British Isles - nothing dramatic - we aren't dealing with vigorous Atlantic storms by any stretch and there's no chance of a "plume" scenario.

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Posted
  • Location: Cambridge, UK
  • Weather Preferences: Summer > Spring > Winter > Autumn :-)
  • Location: Cambridge, UK
1 hour ago, Singularity said:

The broad theme of turning ‘a bit unsettled’ this weekend into next week but then starting to recover by late next week befits the modest fall of AAM to weakly negative before rising again.

Those details matter; it’s not just negative versus positive AAM driving weather patterns, but how AAM is changing and where the cycles peak and bottom-out.

We’re a long way from the very low AAM orbits that drove persistent UK troughs in 2012 and 2007, so I’ve been viewing model runs featuring such with great suspicion.

Don’t think we’re headed down that path at all as you say. Least year was very low -AAM dominated due to Nina, and the incoming drop isnt anything like the same.

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Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl
1 hour ago, Singularity said:

The broad theme of turning ‘a bit unsettled’ this weekend into next week but then starting to recover by late next week befits the modest fall of AAM to weakly negative before rising again.

Those details matter; it’s not just negative versus positive AAM driving weather patterns, but how AAM is changing and where the cycles peak and bottom-out.

We’re a long way from the very low AAM orbits that drove persistent UK troughs in 2012 and 2007, so I’ve been viewing model runs featuring such with great suspicion.

Welcome more knowledge on the AAM, and what drives it. Can other factors cancel it out, it seems to be a barometer of unsettled vs settled, when high it promotes ridging, when low a trough.. however, our weather isn't that simple!

All models in firm agreement of a change taking place now to a more unsettled outlook, with the atlantic trough winning the battle, and the jet taking a nosedive south. Whether this is an embedded change or a shortlived blip remains to be seen, however, the theme of the last 6 months or so, has been generally locked in settled and unsettled spells (of more than 2 weeks duration apiece at least, not 3-4 days or dry then wet then dry etc), and not a more typical fluid pattern. Look at the settled to unsettled then settled switch combo of last 3 months (roughly 3-4 week duration).

Edited by damianslaw
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Posted
  • Location: North West
  • Weather Preferences: Anything but the prevailing wind!
  • Location: North West
1 hour ago, Singularity said:

The broad theme of turning ‘a bit unsettled’ this weekend into next week but then starting to recover by late next week befits the modest fall of AAM to weakly negative before rising again.

Those details matter; it’s not just negative versus positive AAM driving weather patterns, but how AAM is changing and where the cycles peak and bottom-out.

We’re a long way from the very low AAM orbits that drove persistent UK troughs in 2012 and 2007, so I’ve been viewing model runs featuring such with great suspicion.

Yes James I’ve often noticed it’s often the ‘direction’ AAM is taking can be the driver or impetus behind changes in U.K. weather patterns - especially when other forcings are lesser such as  in midsummer.
 

ECM and GEM both hint at heights building over the top of the trough by day 10

image.thumb.gif.26fa9cc72ed38de9a62de4c624dae263.gif
Best case scenario for dry sunny weather lovers there and not well supported yet...

But equally there are some really quite disturbing members of the GEFS showing extreme northern blocking and a deep downstream trough. Here’s the control, representative and dismal:

image.thumb.png.c14b7115a8679cc824eedcb55b5e271e.png

EPS at day 10 shows the low further S and weaker, and an AR / Scandi link up not full on -NAO (didn’t we see this pattern an awful lot in midwinter???)

image.thumb.png.c1b675f357eb9c68103668bb5979c5f8.png

image.thumb.png.bcc2dfac8e62b5981bda897c9b0e8034.png

Spreads show main uncertainties include the position of the trough to the SW (crucial) and the extent, if any, of ridging to the E extending towards eastern U.K.

We actually had a very similar pattern develop in mid June last year

image.thumb.png.f35b99667f13b9ede400eb3fbdf42d35.png

That ended up quite a thundery week, if the low stays rooted SW of Cornwall then expect more sunshine / thundery showers later in week 2. That is the trend this evening but it’s fledgling and we await further clarity.

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Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire

GFS still showing some very heavy rain pushing N through Saturday night. Hopefully some embedded cells. Love that type of rainfall…the lightning just comes out of nowhere amongst the deluge.

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Posted
  • Location: manchester
  • Weather Preferences: Summer
  • Location: manchester

Not sure if this means anything or boosts chances for a warmer dryer summer but Quasi Biennial Oscillation is currently in an Easterly phase.  Summer 2018 was in an Easterly QBO phase. 

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Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl
12 minutes ago, CreweCold said:

GFS still showing some very heavy rain pushing N through Saturday night. Hopefully some embedded cells. Love that type of rainfall…the lightning just comes out of nowhere amongst the deluge.

Will be our first proper dose of rain all month, we've had a few light falls or just drizzle since end May. Indeed cant remember last proper wet day.

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Posted
  • Location: Brongest,Wales
  • Weather Preferences: Stormy autumn, hot and sunny summer and thunderstorms all year round.
  • Location: Brongest,Wales
2 hours ago, CreweCold said:

GFS still showing some very heavy rain pushing N through Saturday night. Hopefully some embedded cells. Love that type of rainfall…the lightning just comes out of nowhere amongst the deluge.

Yes I have just seen this mentioned on the latest BBC weather forecast as well, so although tonight has been a bust for storms hopefully it maybe our turn in the west to get something on Saturday night.

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Not the best output this morning. Green snot returns to the UK as the trough solution looks to get locked in. GEM offered so hope last night but to be honest it’s even worse than GFS this morning. Concerning given how the pattern seems to be going recently and once something gets in it rarely moves before 3weeks or so. ie April cold & sunny (4 weeks), May cold & wet (4 weeks), end of May and start of June dry and generally warm 3weeks. 
 

GFS ensembles becoming pretty tightly packed, and zero warmer solutions until at least day 10-12. Not a good sign IMO. 
 

746052615_gfs-bournemouth-gb-505n21.thumb.jpeg.63d117854d7cd75ccb8ca143ffa1c2c8.jpeg

Edited by Alderc
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Posted
  • Location: Maldon, Essex
  • Location: Maldon, Essex

Nothing overly worrying IMO. There are some good background signals. The problem with the NWP models is that they sniff a pattern and go hell for leather to continue it.

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Posted
  • Location: Cambridge, UK
  • Weather Preferences: Summer > Spring > Winter > Autumn :-)
  • Location: Cambridge, UK

image.thumb.png.82c828fae6a41cead731e23ada6dc0dc.png

Probably the most unsettled 0-240 hour model runs we've had since May this morning. Low pressure and rain the order of the day for many, and for a change Scotland is perhaps the driest place to be. 

Seen a few comments re AAM. It's a very difficult subject to understand fully, but is driven by changes in global circulation like the MJO/Mountain torque events etc that have downstream effects on weather around the globe. Definitely not as simple as high AAM = settled weather and low AAM = unsettled though. It's way above my paygrade to explain properly.

This little explainer (c/o Matt Hugo's twitter page) gives a good understanding of what goes on with the Global Wind Oscillation (GWO) though.

image.thumb.png.dbe268d1640f14f9eefa56d29fd40ce9.png

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Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
10 hours ago, 38.7°C said:

Not sure if this means anything or boosts chances for a warmer dryer summer but Quasi Biennial Oscillation is currently in an Easterly phase.  Summer 2018 was in an Easterly QBO phase. 

The QBO in summer 2018 was in a mature easterly phase against the backdrop of a Nina to Nino flip. 

The QBO this summer has just turned negative but is essentially near neutral with upper ocean heat content looking like it may turn negative again.

Not comparable even before factoring in the PDO being much more negative this year.

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Posted
  • Location: Woodchurch, Kent.
  • Weather Preferences: Storm, drizzle
  • Location: Woodchurch, Kent.

I belive this is called the lull.

Where nothing much happens except sunshine and rain with no real winner. 

 

h500slp (3).png

h500slp (5).png

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Posted
  • Location: Woodchurch, Kent.
  • Weather Preferences: Storm, drizzle
  • Location: Woodchurch, Kent.
12 hours ago, Uncertainy said:

 

We actually had a very similar pattern develop in mid June last  year

image.thumb.png.f35b99667f13b9ede400eb3fbdf42d35.png

That ended up quite a thundery week, if the low stays rooted SW of Cornwall then expect more sunshine / thundery showers later in week 2. That is the 

Remember that, had my only direct hit from an Import that Day. 

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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.

According to the GFS00Z, there'll be plenty of 'interesting' weather coming up:

h500slp.png    h850t850eu.png

h500slp.png    h850t850eu.png

h500slp.png    h850t850eu.png

If the ensembles are anything to go by, grotty weather will alternate with not-so-grotty weather . . . All pretty normal, I'd say?

t850Suffolk.png    t2mSuffolk.png

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Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth

One day I will get my head around AAM / GWO ... until then I'll stick with analysing ensemble sets! 

The ECM clusters this morning, in general, are setting up the UK trough magnet, the ruiner of many a long summer period, but fortunately there are still potential get outs!

Even at T72 the precise details for the UK are for discussion - some clusters hold back the trough to the west long enough to keep pumping up warm air which will feel hot *if* any sunshine 

image.thumb.png.863dfd417c74c29cb3df8b46b63f605d.png

Delaying the inevitable, though - by T120 there's no escape from a UK based trough. Temps probably average or below if rain is prolonged

ec-ens_nat_z500scenarios_2021061700_132.

It doesn't stay deep for long, and with ridging anomalies all around, there's half a chance we'll be back in more settled conditions (or at least less unsettled) by the end of weekend

image.thumb.png.284d4ea233d5850fdcb4273393b3bae1.png

Not really worth considering beyond D10. The forcing on any remaining trough is very unclear. Forced to the south, and a heatwave may follow for the end of the month, forced to the north and cooler settled weather will come, or nightmare scenario cluster 1, the trough stays bang over the UK even until this point. That's not a good set of odds to work from for the average forecaster.

image.thumb.png.6140697e54ede530f553c35b9aae791f.png

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Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

12z models starting to roll out now however looking at the 0z models the outlook to day 9 was pretty dire before divergence albeit the GEM model had a more unified trough.

GFSOPEU00_216_1.png

GEMOPEU00_216_1.png

ECMOPEU00_216_1.png

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Posted
  • Location: Pendle, East Lancashire, North West England
  • Weather Preferences: Not too hot, not too cold
  • Location: Pendle, East Lancashire, North West England
6 hours ago, Ed Stone said:

 

If the ensembles are anything to go by, grotty weather will alternate with not-so-grotty weather . . . All pretty normal, I'd say?

t850Suffolk.png    t2mSuffolk.png

The 2m temps for Suffolk look a bit uninspiring to say the least.

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