Model Output Discussion - Spring Has Sprung

[Scorcher]

 LetItSnow! I'm not denying it's going to be chilly but one poster in particular is keen to emphasise how exceptionally bad this is going to be- so I stand by my hyperbole comment.

[LetItSnow!]

 Scorcher It’ll all depend on preferences and location. If areas in the east get stuck with cloud, showers and temperatures in the upper single digits to low teens then it may feel exceptionally bad. In your location and further west, perhaps not as much. Standard spring fare, but not want people are wanting to see given where we’ve been. 

On a local note,  even the past few days have seen showers and the unstable N/NE type flow being picked up on could affect the southeast disproportionately. I wonder if April will turn out yet another really wet month for the southeast in particular.

Edited April 17 by LetItSnow!

[Josh Rubio]

 LetItSnow! I believe the same thing happened last year(?) for those of us in the East Midlands and East side of the country. I remember we were plagued with low cloud and mist, with suppressed temperatures, whilst the South West had lengthy sunny spells and respectable temperatures. 

[Derecho]

Whether we get temperatures slightly below normal or more substantially colder then normal, will depend on cloud cover. Cloudy days will suppress maximums a lot with the cold uppers.

You can imagine a setup with the same T850s... cloudy days and clear nights will return much colder values then sunny days and cloudy nights.

[Cambrian]

This appears to be quite a telling moment in the development of this spring. The Atlantic jet stream is heading very decisively north before fragmenting, here on the 0z ECM op for the next 10 days.

The 0z ECM mean anomaly shows an impressive build in heights not only north through the Atlantic but also west into Greenland. The low pressure over the pole is lost as heights link up through the Arctic to the Siberian side. So the pattern is getting locked down.

 

From the meridional 5-wave hemispheric pattern we’ve been looking at recently, we might have seen the next stage involving injection of some energy to incorporate a couple more waves, reduce the amplification and introduce a more mobile setup, but instead we’re seeing the opposite happen - the Atlantic build is so substantial that it serves to carve out one of the waves altogether. 

This is shown nicely by the 0z GEFS jet stream charts, the 5-wave starfish at day 5 being replaced by a 4-wave cross at day 10, the jet stream actually bending back on itself with a northeasterly component as it dives south towards the UK and Ireland. 

 

The surface flow will be very much in the northeast for several days, following the contour lines in the mean heights charts (below) from around day 5 onwards. 

So we’re moving towards a more static setup towards the end of the month, drier than it has been, but with suppressed temperatures. The stronger sunshine when on offer could make for some pleasant weather all the same, especially further west with shelter, though as discussed, the onshore breeze could be quite the dampener in eastern parts at times. 

 

One more thing, looking through to day 10, the upper trough remains uncomfortably close by to the east, even steadily working its way further west - so small systems beginning to run down the western flank of the trough, picking up moisture through the Norwegian Sea, might well become an added complication later on next week. 

[Sun Chaser]

Out in the west this spell doesn't look bad at all. Good levels of sunshine, most days in the mid teens, completely dry, almost April 2021-esque. For the east though this looks like a nightmare! Days struggling to reach even 10c, yet more slate grey skies, possible showers, and windier to boot. A reversal of fortune from the first half of the month which saw the east warmer and drier than the west, although still very dull everywhere.

I'm genuinely wondering if this could turn out to be one of the dullest Aprils of all time in the east seeing as most locations have only recorded 40-60 hrs of sunshine so far (in the west it will probably end up average). And given the outlook for places like east Anglia and London which is still almost entirely cloudy - what's the dullest April at Heathrow out of interest?

[minus10]

Working outside yesterday was a case in point...one minute when the sky cleared and the wind dropped it felt like early summer...next the gusts returned and the big shower clouds moved in it was suddenly late winter/early spring again..

..fairly clear consistent signal now shown by eps 0z 850s for below average temps for probably rest of April..

...ens showing reasonable certainty with restricted spread..

..what is also certain is the spell of higher pressure from the weekend for 3 or 4 days...

...although from a south eastern point of view would like to see it a bit further east perhaps..

..should be able to look forward to relatively drier weather and yes..in any sunny breaks should feel pretty decent with less wind...

...longer term ..yes..that north easterly...

..for eastern/south eastern areas risk of cloud/dull/drizzle/ showers but still chance i say to see some sunny breaks...more chance further west...

..rainfull distribution also shows that south western areas will fayre best for driest weather perhaps..

..but for all areas should be drier than has been of late so that has to be an improvement..

...all in all could be better however i think there will still be some decent weather to be had..certainly some good gardening weather..(watch out for frosts though)

 

[Metwatch]

The most important thing to keep in mind is how much drier the outlook is. We've finally lost those damp westerlies and south westerlies off the Atlantic. The upcoming northerlies and northeasterlies will carry less moisture, particularly with high pressure still quite close to the country. It's unlikely to be bone dry, showers sometimes in the mix or light patchy rain, but for farmers or anyone (which is pretty much everyone) who is sick of the flooding and non stop rainfall, this is very good to see. The sun is as strong as it is at the end of August now, and with afternoon temperatures in the 10-13C range, that would still feel quite pleasant and accelerate evaporation following any rainfall.

Expecting low 20s and no rain through most of April is a very high expectation, and recent Aprils have spoiled a lot of us and exceeded said expectations. April usually isn't a month for something that contains prolonged warmth or non stop sunshine. Though something warmer and sunnier will probably come into May or early summer though, it has to!

Edited April 17 by Metwatch

[Rain All Night]

9 hours ago, Rain All Night said:

12z deterministic runs, out to Tue 23 Apr (day 7)

ECM machine learning model - yes please! GFS - no thank you!

12z ensemble means, out to Wed 1 May (day 15)

Wow, it looks like we will be under a reversed, initially northeasterly flow from the middle of next week through to the end of the month. That's not going to bring the warm conditions I've been hoping for, but at least it's something interesting.

I don't remember the last time the UK experienced a northeasterly flow. Does anybody know when it was?

0z deterministic runs, out to Wed 24 Apr (day 7)

Harmony up to day 7 from the models this morning. There will be a cold pool sliding under the southeast during the first part of next week.

0z ensemble means, out to Thu 2 May (day 15)

The northeasterly flow looks like it will continue for quite a while. Not quite clear yet whether the Atlantic heights are going to endure into the beginning of May.

[Frigid]

For a 10 day chart, a pretty strong signal for a mid Atlantic block, making its way to Greenland. Virtually all members go for this idea. 

Shame we didn't see more of this during winter..

 

 

Edited April 17 by Frigid

[Addicks Fan 1981]

 Frigid I'd say there isn't full confidence in anything at this stage and I would suggest that more runs are needed.  We need to approach these charts with caution as things stand.   

[raz.org.rain]

 Addicks Fan 1981 I'm sure there were multiple occasions during winter when the models were all dead set agreed on a certain outcome in the reliable and it still fell apart.

[Addicks Fan 1981]

 raz.org.rain absolutely that and I think @Tamarasays we should look at all the proxies rather than taking all NWP output at face value.  Its times like this where her input is greatly appreciated.   I think in two weeks time or second half of next week it is scheduled to be showery but not especially cold and will feel quite nice in the sunshine.   

[SunnyG]

 Addicks Fan 1981 The eldorado is always 10 days' away and when we get closer it's still the same old rubbish.

[SunnyG]

4 hours ago, Metwatch said:

April usually isn't a month for something that contains prolonged warmth or non stop sunshine. Though something warmer and sunnier will probably come into May or early summer though, it has to!

Has to? Why? The weather doesn't seem to be very interested in our 'has to's'. I said it elsewhere: it won't settle down before autmun. Summer will be more of the same. Better be prepared

[In Absence of True Seasons]

 Sun Chaser Exactly the same situation happend in 2023. Cloudy and cool East with warmer and clearer West. 

Very interesting that it's playing out *again* the following year, like clockwork....

[damianslaw]

Models holding firm on a generally more settled theme compared to anything since mid January. I say 'more settled', not exclusively settled which I would describe as dry throughout. After tomorrow's frontal features work through, high pressure looks set to osscilate in our vicinity, first to the west, then building through the UK over the weekend and then advecting north west, pulling in a north easterly flow.

I'm waiting for the often used phrase at this time of year 'west is best', all very common synoptics second half of Spring. Look back at the weather archives and you will see this type of synoptic feature often in many years, and often for quite some time. Northerlies and easterlies reach their annual peak hereon until June. For someone in the 'west', its why I rate May my favourite month of the year, most likely to experience less in the way of dank westerlies and southwesterlies, by May the sun is just as strong as in high summer but air temps are tempered. 

Edited April 17 by damianslaw

[*Stormforce~beka*]

 In Absence of True Seasons It was hell for me. I was under the cloud from the East then that cleared and the west went under cloud and I got that too!!! For mooooonths ...

[Howie]

Yeah I remember we were absolutely fuming lol

[Daniel*]

10 hours ago, Scorcher said:

LetItSnow! I'm not denying it's going to be chilly but one poster in particular is keen to emphasise how exceptionally bad this is going to be- so I stand by my hyperbole comment.

If you’re talking to me at least @ me thanks. In what way I have done that? All I’m saying temperatures are indicated to be well below average for late April, no one has mention snow and freezing temperatures and what can be expected at this time of year. You said about me being antagonistic, I think you should look at yourself, all you do is purposely try to undermine messaging, if anything cool is mentioned, it’s a repeated pattern from you. It’s as if it upsets you personally, I find it very odd it is just the weather. 

Edited April 17 by Daniel*

[WYorksWeather]

 Daniel* To be fair the outlook has changed somewhat since my last comment - less of a warmup now predicted for the weekend. I'd now bet on this week being about 1-2C below the 1961-1990 average for most areas.

[Scorcher]

 Daniel* You're the one always calling other people out and ridiculing them.

Just because the coldies like all your posts doesn't mean there aren't a lot of others that are thinking exactly the same as me.

You called one poster out for playing down the cold and stated that temps wouldn't reach double figures in Manchester. I feel in making your point you majorly exaggerate at times.

Edited April 17 by Scorcher

[WYorksWeather]

There continues to be no real signal for a significant warmup at any point during the current run - at most you could say the turn of the month looks to return closer to average. 

A clear lack of any significantly warm runs is obvious, though. It's a pretty strong signal for below average temperatures at least for this week, then a bit more uncertainty for later next week but below average the likely outcome until then.

 

[danm]

2 hours ago, In Absence of True Seasons said:

Exactly the same situation happend in 2023. Cloudy and cool East with warmer and clearer West. 

Very interesting that it's playing out *again* the following year, like clockwork....

To be fair, it’s a pretty common synoptic set up at this time of year. It’s happened during many a Spring. Hence why the NW often see their driest weather between April and early June. 

[raz.org.rain]

15 minutes ago, WYorksWeather said:

A clear lack of any significantly warm runs is obvious, though. It's a pretty strong signal for below average temperatures at least for this week, then a bit more uncertainty for later next week but below average the likely outcome until then.

James Peacock on Twitter had commented that he was dubious of how prolonged the cooler spell is in the outputs and suggested it may only last one week as opposed to over a fortnight.