Model output discussion 9th April onwards

[Mike Poole]

3 minutes ago, minus10 said:

Yes it looks like HP all the way to day 10. Not warm though as you say Mike. Will have to rely on the increasing strength of the sun to provide any warmth, which, out of the wind is definately noticeable. 

However do not want this towards the end of April though on the gfs12z

This northerly signal keeps coming and going on gfs but as before is at bottom of pack in FI. Still awaiting signs of genuine warm up....

Yes, there is a signal still hinting for that on the ECM clusters, in cluster 1, the others not so, cluster 2 looks best for continued pathway to a warm up, T192-T240:

T240+ one cluster only so clearly massive uncertainty and not worth posting.

 

[Thundery wintry showers]

I've been busy moving house for the last few days so haven't been keeping up much with the model outputs, but certainly there's been a big shift over to the high pressure scenario since I last looked.  There's still potential for some scattered showers, wintry in central and northern areas, tomorrow with an upper level cold pool and the high pressure proving slow to build, but by Wednesday the high pressure should be strong enough to kill off the showery activity.

The positioning of the high and surface winds will be important, for if the high drifts to the north and pulls in an easterly flow, some rather grey and cool weather could establish across the eastern half of England with maxima below 10C and minima holding up well above freezing, as is shown for example on tonight's GFS run:

However, the UKMO/ECMWF are positioning the high pressure further south than that, resulting in a southerly flow for the west and an easterly flow only for the far south.   The ECMWF operational and ensemble mean tonight support mostly sunny weather with temperatures creeping back up to the seasonal average by day (12-14C) with frost quite widespread by night.

[I remember Atlantic 252]

1 minute ago, Thundery wintry showers said:

I've been busy moving house for the last few days so haven't been keeping up much with the model outputs, but certainly there's been a big shift over to the high pressure scenario since I last looked.  There's still potential for some scattered showers, wintry in central and northern areas, tomorrow with an upper level cold pool and the high pressure proving slow to build, but by Wednesday the high pressure should be strong enough to kill off the showery activity.

The positioning of the high and surface winds will be important, for if the high drifts to the north and pulls in an easterly flow, some rather grey and cool weather could establish across the eastern half of England with maxima below 10C and minima holding up well above freezing, as is shown for example on tonight's GFS run:

However, the UKMO/ECMWF are positioning the high pressure further south than that, resulting in a southerly flow for the west and an easterly flow only for the far south.   The ECMWF operational and ensemble mean tonight support mostly sunny weather with temperatures creeping back up to the seasonal average by day (12-14C) with frost quite widespread by night.

Aye, dreading it, sea mist could linger all day, feel freezing, E'lys are really horrid

[Jordan S]

56 minutes ago, Mr Frost said:

Beer gardens open up here on April 26th! 
Will need the thermals on if the GFS turns out to be correct for that date! 

26/04:

 

As you say though...at least it will be dry! 

Enjoy!

Hi

Does look like any warm up will be gradual during the next 7-10 days at least with a cool wind later in the week from the east/southeast for England and Wales keeping temperatures lower than normal for some and average for others, instead of a southerly that looked like a possibility for the south a couple of days ago.. plenty of sunshine throughout though ofcourse and cold nights, the chance of some areas of cloud drifting into the northwest later and possibly the south later in the week too depending on the highs position.

Ukmo..

Gfs..

Edited April 11, 2021 by jordan smith

[Cambrian]

It’s slow, but the GEFS 12z run gives some better indication that spring is coming. The graph for London shows a steady increase in day temperatures in the reliable over the next 12 days, indeed double figures maxima from the 18th onwards, continuing to benefit from the strengthening sun, solid high pressure and a dry feed. This slow warming up stalls around the 23rd, well into the unreliable. 

Here for Aberdeen, the same broad trend in the more reliable timeframe, though a more modest warming up than further south, the mean maxima struggling to get into double figures. Night frosts a possibility north and south for several days to come.

[Mike Poole]

April GloSea5 is out.  

Let’s start with 2m temps, here terciles and outer quintiles:

Looks warm, for the south at least.  

Stronger on the quintiles plot for Jun-Aug:

Z500 heights, May to Jul terciles:

This maybe shouldn’t come as a surprise - the Atlantic has not been raging at us for months, bit weird if it fired up in summer, I think this is suggesting continued mid lat blocking, and why wouldn’t it continue? What would be the driver for it not to?  

Precipitation, very slightly below average, there never is a clear signal on this in the summer and again this year.  Keeps the storms enthusiasts happy that it isn’t a unanimous dry forecast at all.  

All in all, a decent summer forecast there from this model, not 2018, but very promising nevertheless...we will see...

 

Edited April 11, 2021 by Mike Poole

[Iceman2606]

Looking like we will finally have high pressure moving in over to our east.

 

This would turn things a lot more settled and bring temperatures back to to around average.

[minus10]

Same story this morning. Becoming less cold but not overly warm . Pleasant in the sun perhaps if not plagued with cloud. Towards end of month large scatter on gfs ens 0z with control then op dropping again. 

This gfs run shows a mainly easterly weather patten over us for the entire run. Not in the slightest zonal. HP rules the roost although again leaking away a bit at the end with large scatter..

A few flakes here this morning. Winter reluctant to leave the stage....

Edited April 12, 2021 by minus10

[Guest]

Its still a painfully slow transition away from colder conditions, 850's still at -5C here for another 4-6days and frosts likely almost every night. 

[Empire Of Snow]

34 minutes ago, Alderc said:

Its still a painfully slow transition away from colder conditions, 850's still at -5C here for another 4-6days and frosts likely almost every night. 

Precisely. Everything moves in a turtle pace regarding the transition from cool/cold to significant warmer conditions. A "mini" Easterly is almost nailed on affecting mainly the East coasts and south east areas, could possibly reach - 7 or - 8 850hpa uppers there and it will feel really cold especially in the night and early morning. Widespread frosts almost everywhere, some areas might see record minus temps for April under clear night skies. 

Looking further into FI I can't see major changes until the first week of May and there is always the "terror from above" lurking. I won't be surprised if a cold NorthEasterly sets up late April. 

That said, April 2021 is a strong contender for the coldest April the last 50 years or so. Need to check some historical data about this though. 

 

[Guest]

40 minutes ago, Empire Of Snow said:

Precisely. Everything moves in a turtle pace regarding the transition from cool/cold to significant warmer conditions. A "mini" Easterly is almost nailed on affecting mainly the East coasts and south east areas, could possibly reach - 7 or - 8 850hpa uppers there and it will feel really cold especially in the night and early morning. Widespread frosts almost everywhere, some areas might see record minus temps for April under clear night skies. 

Looking further into FI I can't see major changes until the first week of May and there is always the "terror from above" lurking. I won't be surprised if a cold NorthEasterly sets up late April. 

That said, April 2021 is a strong contender for the coldest April the last 50 years or so. Need to check some historical data about this though. 

 

The last sub 7C CET for April was 1989 @ 6.6C. Current CET to the 11th was 5.7C and with the current GFS 06z outlook which ends in another northerly with sub -5C 850's yet again becoming widespread it hard to see it getting above 6.5-7.0C. 

1986 (5.8C) and 1922 (5.5C) were the only Sub 6C April's of the 20th Century,  

[Britneyfan]

Can see potential for couple of 20° days in April on GFS it’s showing 18° across London area obviously with sunshine and the fact gfs undercooks temps wouldn’t be surprised to see a 20°

[Empire Of Snow]

1 hour ago, Britneyfan said:

Can see potential for couple of 20° days in April on GFS it’s showing 18° across London area obviously with sunshine and the fact gfs undercooks temps wouldn’t be surprised to see a 20°

06z is very poor if you're after 18C+ temps. Yes it will be pleasant under sun exposure but this is not how temps are officially recorded in meteorology. 

FI again but the Arctic won't stop finding its way down under this pattern. 276h+ another cold blast and after this a reload. Always a possibility for the 1st one to shift west and have a direct hit or shift east and miss it altogether. I won't be chasing this one though. I think. 

[Northwest NI]

54 minutes ago, Empire Of Snow said:

06z is very poor if you're after 18C+ temps. Yes it will be pleasant under sun exposure but this is not how temps are officially recorded in meteorology. 

FI again but the Arctic won't stop finding its way down under this pattern. 276h+ another cold blast and after this a reload. Always a possibility for the 1st one to shift west and have a direct hit or shift east and miss it altogether. I won't be chasing this one though. I think. 

If those Northerlies were in the heart of winter they’d find a way to miss us. As it is, I expect a direct hit (Northerly verifying at 276h+; and April shows December & January how it’s done!)

Edited April 12, 2021 by Northwest NI

[knocker]

Interesting Arctic blast at t276 on the 06 gfs

Edited April 12, 2021 by knocker

[Britneyfan]

1 hour ago, Empire Of Snow said:

06z is very poor if you're after 18C+ temps. Yes it will be pleasant under sun exposure but this is not how temps are officially recorded in meteorology. 

FI again but the Arctic won't stop finding its way down under this pattern. 276h+ another cold blast and after this a reload. Always a possibility for the 1st one to shift west and have a direct hit or shift east and miss it altogether. I won't be chasing this one though. I think. 

The gfs does provide 18° and from experience in any sun you can record temps up to 20 officially as gfs usually under does temps so even on the gfs 2m temps it shows 17 or 18 

[Methuselah]

The GEFS 06Z temperature ensembles are awful. And think of those poor boozers, chipping the ice of their pints of Boddingtons:

    

They'll be whingeing in the streets of Raith, if that one verifies!

[minus10]

Well at last the gfs 12z gives us a little hope compared to the 6z

Not getting carried away here but are we seeing a break in this cold patten?

Ens will be of interest later...

 

[Cambrian]

The 16-day outlook from NOAA for precipitation and temperature. Going on the flavour of the ECM and GFS over the last few days, scratching my head as to where as much as 25 mm for parts of Ireland is going to come from over the next 8 days. I’m assuming the 5-7.5mm for the hills of Northern England and Wales fell earlier today. More rain expected for England and Wales in the second week. 

       

The temperature chart optimistically shows a warm-up to near average for the UK for the second week, typically 2-4 degrees higher than the first week, away from the Northern Isles, supported by the flatlining GEFS 06z temperature ensemble for Shetland. But in general, UK for the next week cold and dry, the following week a bit warmer and a bit wetter, fits nicely with the ensembles.

Desperately seeking something more eventful (!) - just joking, I will enjoy this dry spell and a slowly emerging spring gives us a bit more time to appreciate the turn of season - though changes in Europe are more striking in terms of heralding the spring, at least an 8 degree lift in day-night average for Southern Germany in the second week and a loss of sub-zero temperatures over the Alps - should get the edelweiss going. Some heavy rain over Northern Italy and Croatia in the first week extends westwards into Spain and Morocco in the second week, cooling Spain and Portugal down a tad while Sicily and the rest of the Med basin steadily warm up. 
 

 

[I remember Atlantic 252]

Just now, minus10 said:

Well at last the gfs 12z gives us a little hope compared to the 6z

Not getting carried away here but are we seeing a break in this cold patten?

Ens will be of interest later...

 

Still not happy with GFS, big rain event next Monday, EC didn't have that on the 00Z

[minus10]

10 minutes ago, I remember Atlantic 252 said:

Still not happy with GFS, big rain event next Monday, EC didn't have that on the 00Z

Speaking as a gardener I wouldnt mind some rain as the ground is pretty dry now and some rain before a (potential) warm up would be good planting/growing weather. Understand though not so good for the outdoor pubs etc...

Edited April 12, 2021 by minus10

[Mike Poole]

Decent run from ECM 12z.  T120 has the high to our east with ridge from the Azores, but then corrects to a UK high by T240.  

Uppers not that bad, so chance to develop some home grown heat with this scenario, T240:

Wonder how this evolution sits in the clusters.  Edit - no help at all from the clusters, just one cluster from T96 onwards.

Edited April 12, 2021 by Mike Poole

[minus10]

Well the Gfs ens show that the 12z op was almost a warm outlier of admittedly a wide spread towards the latter stages of the run.

With the ecm looking a little better maybe a little more hope now of some warmth ( less cold? ) towards latter stages of April...

[Mike Poole]

Given the clusters gave one result, that can mean one of two things, either there is a degree of confidence in a single outcome (unlikely), or there is so much uncertainty ECM algorithm can’t identify separate clusters.  

So worth looking at the mean directly for ECM at T240:

10 day mean with big 1025 area looks like confidence in the outcome to me.  If it gets to 1030 at 10 days out we will know for sure.  

[Frosty.]

As we are now on the cusp of mid spring (meteorologically) speaking, these charts from the GEFS 12z mean look jolly decent to me, Scandi high, Scandi / Azores high link up.....it could be worse?...although this weeks high isn’t quite strong enough to prevent a few showers here and there, it’s still decent as there should be some pleasant sunny spells although nights still look chilly but we should see temperatures for some of us gradually recovering to average during the second half of this week which would make for more pleasant surface conditions for many.