Model Output Discussion - May and Early Summer!

[BlueHedgehog074]

Greetings to you all!

A glistening new thread for the month of May and early Summer!

As we head deeper into Spring and into Summer (though I guess for some, May could be classed as a Summery month), a number of us hunt for warm weather with sunshine, thunderstorms and plumes. For some, you may be after some cool and wet, or cool and dry weather instead. That time of year where trees become thick of yellow, green and purple foliage, and flowers burst into life all over the place!

A little glance at the models and you can see, using the GFS 18Z as example, that it's painting a chilly picture over the UK later this week with a cool flow developing from the North. This is thanks to High Pressure to the South-West of the UK linking up with the high heights over Greenland with a trough dropping down to our East from Scandinavia. But before that happens, a puny Low Pressure system to the West of Ireland, currently sandwhiched between both the High Pressure to our South West and the High Pressure over Greenland, will track South-Eastwards to join up with the Low Pressure to our East later this week. The Low will fill as it does so and become a wave feature.

This helps out with High Pressure amplifying to our West in the Atlantic. That little cyclone will bring some showery rain over the UK today as it makes its journey South-Eastwards, with further rain and showers on Thursday.

With regards to that Northerly following after (see charts below), the best of the driest conditions would most likely be over Western UK closest to that High Pressure. Chiller conditions likely further North and East you are with a chance of showers, possibly with some longer spells of rain and hill sleet and snow. Probably not much precipitation about, but some of the showers may have a wintry flavour to them. Most likely over Northern high ground and maybe to lower levels over Scotland. The 850 hPa temperatures the GFS shows below could certainly be cold enough to support some wintriness over Northern areas. Could be quite windy too, especially towards Northern and Eastern coastal districts.

Did feel back in April that one or two of the chily outbreaks the models were showing would have been the last shot for the cold and snow enthusiasts. Nevertheless, this would very likely be the last chance to squeeze out some wintriness for the cold fans before next Winter. Their may also be enough room for the Northerly to back a little further West allowing lower heights from the East to become more influential and increase the instability for more widespread, potent, (wintry) showers. Equally, the Northerly may just get shoved further East with the High Pressure over Western UK giving the Scandinavian troughing a bit of a kick - more of the UK ends up staying dry and bright. There is a risk of some night time frosts later this week and into the weekend, which may cause some disruption to plant growth and farmers. Perhaps, though, nothing too servere and hopefully not much damage is caused. Still looks as though it would be a fairly dry period overall, particularly again over Western UK spots.

Later on into the outlook, and it looks as though Low Pressure to the West of that Atlantic and Greenland ridging will try to take over. (Quite possibly with ridging over Southern UK hanging on):

At 192 hours, the 18Z GFS, 12Z ECMWF and 12Z GEM generally show the UK under the Atlantic and Scandinavian's troughs spell!

Some strong heights over Greenland maintained with Atlantic Lows directed over the UK. Could stay quite cool, especially over Northern UK areas, and maybe become more unsettled during this period next week. Since it is 192 hours away, things may still improve for those wanting to see more in the way of warm, settled, weather (including myself). However, it would be fair to say some rain is likely needed in some places still, considering how mostly dry its been for some parts, especially for the South East of the UK. Both the 6 to 10 day and the 8 to 14 day CPC/NOAA 500mb mean charts following similar ideas as the above operational runs with blocking continuing over Greenland and Low Pressure in the Atlantic. Perhaps some ridging influencing Southern areas of the UK at times (especially with the higher than average heights over Western Europe), so probably nothing majorly unsettled. Maybe a possibility some of the operational runs, such as that 12Z GEM, over-doing Low Pressure over the UK.

https://www.cpc.ncep.noaa.gov/products/predictions/610day/500mb.php

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

I suppose it will be interesting to see how the models continue to develop things.

 

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Alternative Threads:
To chat more generally about the Spring weather, please head over to the spring thread:

https://www.netweather.tv/forum/topic/91223-spring-2019-moans-ramps-chat-etc/

The Summer one: https://www.netweather.tv/forum/topic/91676-summer-2019-moans-ramps-chat-etc/

And to post tweets about the models (although you're still welcome to use the Model Output Discussion thread), please see this thread:

https://www.netweather.tv/forum/topic/87130-model-tweets/

For the Met Office outlooks, please use this one:

https://www.netweather.tv/forum/topic/64157-meto-uk-further-outlook/

 

Model Output And Charts On Netweather:

GFS
GFS FV3 (Parallel)
GEFS Ensembles
ECMWF
ECMWF EPS
NetWx-SR (3km)
NetWx-MR (9km)
Met Office (UKMO)
Fax
GEM
GFS Hourly

Model Comparison
Golbal Jetstream
Stratosphere

 

Previous thread:

Thanks a lot all!  

[knocker]

Outlook - Due to become colder by the end of the week but the weekend should be sunny for most with light winds. After that still a tad uncertain with the energy flows jockeying for position. The percentage play is for the Atlantic trough to win on points. The 300mb wind field at midday Monday illustrates this quite well

The 500mb NH profile and the Atlantic surface analysis for midnight and the 0300 UTC UK chart

A clear start to the day in the east and N. Ireland and this will remain the case pretty much during the day, albeit clouding over somewhat. But the cold front that is causing patchy rain in western regions at the moment will move slowly east with the patchy rain becoming increasingly showery. during the afternoon a trough will bring more showers to N. Ireland. The temp spread reflects all of this with the south east becoming quite pleasant

The showers will peter out through the evening and overnight but will continue a while in northern Scotland and the south east of England. So generally a clear night with the odd fog patch by morning. But note the trough over Scandinavia is getting organised and the associated cold front is on the way south.

Thursday will be a day of sunshine and heavy showers but the cold front is now tracking down Scotland so a belt of more persistent rain here and colder air in it's wake

Over Thursday night and through Friday the cold front stalls across the country as the subtropical high amplifies in the west so essentially a cold day with frequent heavy showers,

The cold front clears the south coast during Friday night as the ridge moves east resulting in Saturday being a sunny day with temps a tad below average after a frosty start, Not feeling that bad in the very light winds. But showers will still effect eastern coastal regions as troughs track down the North Sea in the northerly flow

by Sunday we are getting to the tricky time, After a widespread frost a generally sunny day with temps still a tad below average but still possible showers in eastern regions. And another cold front is on it's way south and is just north of Scotland

On Monday the gfs has the front tracking down the country some some rain and showers around with temps still a tad below average

 

Edited May 1, 2019 by knocker

[knocker]

And then the energy in the west delivers the knockout blow

[knocker]

The ecm much the same through Monday and the trough then comes into play Tues/Weds but runs a little south with the fronts pushing north east across the country

[joggs]

All in all it's safe to say these charts are 3/4 months too late with a poor outlook over the next 7/10 days if its warmer weather you're after.

Very dissappointed atm.

[johnholmes]

Looking at the anomaly charts and  a change from just a few days ago with all 3 now show troughing as the main 500 mb feature over and around the UK, the EC-GFS in particular have it from a cold source, so little signal for much warmth 6-14 days from now, and probably mainly unsettled or changeable.

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

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

 

[Methuselah]

Today's 00Z looks to be (after the weekend's unpleasantness) something of an improvement. Should the chance of seeing some warmer (or at least less cold) temperatures and rainfall be your thing:

 

[knocker]

The cold front is lowly passing through here at the moment

 

Edited May 1, 2019 by knocker

[Polar Maritime]

A cold end to the week coming up with a Northerly flow pushing South over the UK. -10c windchill for some spots with sharp frosts & snow showers for the North/Pennines.

 

[Singularity]

A sense of deja vu with the models depicting a change in the HLB orientation next week, from Pacific-Atlantic to Asia-N. America, that opens the door to south-tracking lows crossing or passing just south of the UK from west to east.

It didn’t come around this week after they predicted it last week, so it will be worthy of note (for future forecasting) should the same misfire be observed again this time. Usually though, it proves to just be a case of the models having been too quick; the change does occur in the end.

Remains to be seen whether the lows track fat north enough to affect the UK. It’s possible that as the CCKW crosses the Indian Ocean and contradicts the Nino base state, SLP will fall further south across Europe than currently modelled.

I have a feeling we’ll end up looking to the E or SE again for a decent warm-up. Often happens for a time during HLB-dominated Mays; 2012 a recent example (hopefully not a harbinger for the summer months!).

[Frosty.]

Signs of improvement longer term on the Ecm 00z ensemble mean but before that a lot of cold weather is indicated, especially for scotland and damaging frosts can be expected from later this week.

Edited May 1, 2019 by Frosty.

[Methuselah]

Not the greatest of BH Monday's coming up...if only those deep Atlantic depressions were a few hundred miles further east?

[northwestsnow]

44 minutes ago, Singularity said:

A sense of deja vu with the models depicting a change in the HLB orientation next week, from Pacific-Atlantic to Asia-N. America, that opens the door to south-tracking lows crossing or passing just south of the UK from west to east.

It didn’t come around this week after they predicted it last week, so it will be worthy of note (for future forecasting) should the same misfire be observed again this time. Usually though, it proves to just be a case of the models having been too quick; the change does occur in the end.

Remains to be seen whether the lows track fat north enough to affect the UK. It’s possible that as the CCKW crosses the Indian Ocean and contradicts the Nino base state, SLP will fall further south across Europe than currently modelled.

I have a feeling we’ll end up looking to the E or SE again for a decent warm-up. Often happens for a time during HLB-dominated Mays; 2012 a recent example (hopefully not a harbinger for the summer months!).

Yes i think may 1996 had some northern blocking and the June that followed was fabulous.

That is one straw i'm holding to in the face of some dreadful charts, i posted last week about the potential for a really poor spell of weather when the models were signposting HLB ..

 

[Methuselah]

11 minutes ago, northwestsnow said:

Yes i think may 1996 had some northern blocking and the June that followed was fabulous.

That is one straw i'm holding to in the face of some dreadful charts, i posted last week about the potential for a really poor spell of weather when the models were signposting HLB ..

Indeed, NWS...Today's charts may not look all that pretty, but crap weather between late April and early June is hardly unheard of.

 

!975, 1983, 1989, 1995 and 1996, to name but five, all had spells of nastiness during Spring...But they all turned-out quite well?

[Scorcher]

Awful outlook this morning from all the main models, very deflating. I thought we were done with raw feeling days with bitter wind chills after that spell in April. A big shame really, I had high hopes of a similar May to last year but it's looking like this upcoming bank holiday will be in stark contrast to last year's with the very warm conditions.

Hard to see a way out of the current pattern, but we also felt that in April when the month started cold. Hopefully things will shift over the next few days.

[Scorcher]

1 hour ago, Singularity said:

 

I have a feeling we’ll end up looking to the E or SE again for a decent warm-up. Often happens for a time during HLB-dominated Mays; 2012 a recent example (hopefully not a harbinger for the summer months!).

I really hope we don't get a repeat of May 2012, which was for the most part an awful month. Yes there was the late (and beautiful) warm spell but we really had to suffer for it before that with such a cold first half of the month. 2012 really was a miserable year for warm weather fans with the exception of March and a couple of brief spells here and there. Even the autumn was bereft of any warmth.

[MP-R]

Many a May have had a cold and/or unsettled first half, only to improve markedly into the second half. One May that was Atlantic-based pretty much throughout until the last week was 2003, and we all known what followed. 2004 was very poor to start but quickly improved after midmonth (although we don't want a mid-May to mid-June prolonged settled spell if it means a deterioration by July). 2010 is a good example of a predominantly cold but not too unsettled first 2/3 of May that like a switch turned hot and sunny around the 21st. As said above, even the unsettled May of 2012 managed that super spell in the final week.

Anyway, a cool or cold outlook, with temperature struggling to average let alone above. Rain looks variable though so by no means a washout and Bank Holiday looks usable at least, if a bit unseasonal. If we were getting these charts around the time our summer base state tends to set in, then I'd be a little more concerned.

[Frosty.]

Reading all these sad posts makes me want to get my violin out!

The models are looking increasingly cool and changeable / unsettled but it's still spring for another month so no damage done..apart from the frosts on the way.

[Methuselah]

But, as is nearly always the case, the end of the run is better than the start. Nowt all that settled (yet) but warm-and-unsettled is better than cold? And some of us need some proper rain!

 

[MATTWOLVES 3]

32 minutes ago, Scorcher said:

Awful outlook this morning from all the main models, very deflating. I thought we were done with raw feeling days with bitter wind chills after that spell in April. A big shame really, I had high hopes of a similar May to last year but it's looking like this upcoming bank holiday will be in stark contrast to last year's with the very warm conditions.

Hard to see a way out of the current pattern, but we also felt that in April when the month started cold. Hopefully things will shift over the next few days.

How can you fail to see a way out of the current output! Firstly the models may look completely different inside the next 24/48hrs, and secondly its the 1st of May! Alot of fine lengthy summers come on the back of cold/cool unsettled spells in late spring. It's hardly throw the towel in is it! I would be more worried if we was locked into a continued heatwave through May! For example it peaking to soon. This is a slight blip in what is sure to be a summer of many fine, very warm spells! Let's remember folks, it's the 1st of May, not the 1st of July! I thi k to many have got lulled into a false sense of security because of the last couple of very warm spells!! Let's not forget those spells were a tad premature! Refrain from towel throwing just yet folks..... Please!!! 

[Methuselah]

45 minutes ago, Scorcher said:

Hard to see a way out of the current pattern, but we also felt that in April when the month started cold. Hopefully things will shift over the next few days.

The first real 'summer's over' post of the new season!

But, it's not really like that: how much change would it really take, for things to improve?

 

[MATTWOLVES 3]

2 minutes ago, Ed Stone said:

The first real 'summer's over' post of the new season!

But, it's not really like that: how much change would it really take, for things to improve?

 

Well it's simple Pete, high pressure devoloping from the azores, or even becoming stationary over scandy, allowing for a warm E/SEtly. I dread this time of year, just like I dread December! A couple of days or a week or so of the wrong weather type, and it will be summer is over, or winter is over... Before it even gets going! There seems to be a serious lack of patience, let's be honest here Pete, we were long overdue a colder unsettled interlude... Its best it comes now, rather than summer proper if you ask me..

[Frosty.]

The longer term GEFS 6z mean looks increasingly settled and warmer.

[Methuselah]

Back end of the FV3 shows definite signs of improvement; though hardly a heatwave:

 

 Precip spikes too! 

[mb018538]

ECM clusters also looking much more settled at the end. Here's day 13:



High pressure building. One to keep an eye on. The first 10-12 days of the month looking unsettled and cool, no getting away from that.