Model Output Discussion - Spring Has Sprung

[SunnyG]

2 hours ago, LetItSnow! said:

If it’s any consolation I think May will be warm/very warm and thundery.

The question is: where? Some areas are warm already, others are barely in double-digits and may well stay as they are for the rest of the month with brief warm-ish intervals.

[WYorksWeather]

Worth having a look at UKV for the next few days in terms of temperatures - I often find it to be much closer to the mark than the GFS once it does come into range (though admittedly it still gets things wrong from time to time).

Tomorrow looks like a poor day for temperature almost everywhere except western parts of Scotland. A particularly poor day for Wales, some central/southern counties of England and also East Anglia well below average.

A very odd pattern with temperatures generally increasing the further north and west you are, this is courtesy of a very odd 850hPa temperature distribution with the warmest air over northern England and Scotland, and surface temperatures highest in NW Scotland due to the shelter from easterly breezes. Absolute max projected at 22C for NW Scotland - very impressive for the time of year at that location. Overnight lows average to well above average away from the SW and south-central areas.

Saturday sees a bit of a change - still a warm day for NW Scotland and not quite as chilly with close to average temperatures across an irregular triangle roughly from Cardiff to Norwich to York. Wales and NW England getting the worst of the temperatures. Max of 20C for NW Scotland. Minima again average to slightly above average, well above average for NW Scotland.

Moving onto Sunday we see a slightly more 'normal' pattern with the warmest temperatures across central, eastern and southern England, caused by mixing out of the warm air plume over Scotland. Max predicted at 18C, but on that I do wonder if it might climb closer to 20C in a few places in reality if there are sufficient cloud breaks. Minima above average away from eastern coastal areas.

Similar pattern into Monday but with a slightly more favourable outcome for the south-west with cooler air moving into the London area and along the south-east and south central coasts. Slightly cooler minima but still average to above average.

Finally on Tuesday we get much more of a 'west is best' kind of day.

Summary

In short some decent weather on offer once we get tomorrow and Saturday out of the way (unless you live in NW Scotland, in which case enjoy tomorrow and Saturday!). Sunday and Monday look to be the best days further east, Monday and Tuesday better further west. 

In terms of the temperatures I'm a little dubious about the idea that with 850s into the 5-6C range at this time of year that we won't see one or two spots climb into the low 20s on Sunday and Monday - it is often the case that as a spell of high pressure gets going the ground dries out and temperatures climb a little higher.

Longer term

Looking at the ensembles we do see a trend for 850s to rise a little further into next week - this might allow temperatures to reach the low 20s more widely, with maybe an outside chance of 25C at the upper end of possibilities for one or two spots if conditions allow. However, the main expectation for the next week to 10 days seems to be consistently above average temperatures for most areas, but without any particularly impressive absolute maxima. No sign of a heatwave, but at this time of year you don't need a heatwave to still come in well above average.

 

 

[LetItSnow!]

Latest GFS run shows a slightly different but basically similar premise. 

 

After the shallow low on the 6th clears high pressure builds in by the 7th, though the remnants + weaker pressure could mean the risk of cloudier and showery weather in the southeast if this doesn’t correct southward. Then looking warm and dry from the 8th through til the 10th at least. The 10th looks particularly warm with a ridge over the country and 10C uppers in the south. I wouldn’t rule out mid-20s if that came off. Still, the trend is more things to turn more unsettled by day ten. The solution isn’t miles away from what the ECM showed earlier, the ridge breaking down with Atlantic low pressure taking over, though temperatures would still remain above average, most notably so by night.

Like @WYorksWeathersaid, nothing unusual coming in terms of absolute max, but high minima and persistently rather warm days is all it takes to get the ball rolling on a warm May. All in all, still somewhat of a signal at this time that unsettled weather may shortly return, so we may not staring at a significant pattern change to warm and dry weather but it will be a pleasant and welcomed interlude for many. The models could always however be underestimating the strength of the block though and by day ten there does seem to be a strong Azores high. Not a terrible outlook at all. 

[WYorksWeather]

 LetItSnow! In terms of the 10th specifically, it is of course beyond the range of UKV at the moment, but here is the GFS forecast.

These are typically 1-2C under, so 24-25C the likely maximum in reality.

I would also note that there's some substantially warmer air, around 12-13C 850hPa only 100 miles or so to the south of the UK. At this range it would take only a tiny adjustment to bring that into southern England, and then you could even have quite widespread 24-25C with that and possibly an odd spot reaching 27C. At this time of year the lapse rates can reach around 1C per 100m or even 1C per 80m, which under the right circumstances can allow a total differential from the 850hPa level to the surface of 15-20C.

Again though, that does require the upper end of possibilities. It will be interesting to see UKV's verdict in a couple of days and also see whether we do get any double digit 850s into the UK more consistently, which looks like it would require an adjustment north from the current position, though as I've said not a particularly large one.

[danm]

 SunnyG your location was at 20c+ on both Tuesday and Wednesday 

[LetItSnow!]

Still a build of high pressure shown for the 7th on the 0z though a little cooler than the previous run. The high is oriented a little differently, the uppers are cooler and there is slight less thickness, though still I imagine would get the temperatures into the upper teens/low twenties in favoured spots, particularly come Friday. Some pretty cool nights with suggested minima around 5-6C in parts. After that, still a trend to introduce lower pressure by the 12th.

You can't get nicer weather than that to be honest. Fair, sunny weather by day with temperatures in the upper teens/low twenties and cool single digit minima. The perfect balance between sunny and comfortable.

The model is experimenting with slightly different orientations of high pressure, some warmer some a bit cooler. The previous run was quite warm and showed potentially our first 25C by about the 10th. This one is a cooler example.

[minus10]

Well another dull morning to wake up to..10mm more rain having fallen during the night...over 45mm of rain just in the last 3 days here !...

Are we still on course for some more settled weather...?..yes as others have stated looking better for next week...after the bank hol of course..

Latest gefs mspl goes from this on Monday..

..to this by Wednesday...

...rise in pressure pretty certain now..

..

...orientation not though which will determine how settled and warm it will be..however temps above average looks a fair bet according to gefs 0z 850s mean heading into mid May and beyond..

...also noticeable the rise in minema over the period..

..so while the week after next is still uncertain re wet/dry hopefully there wont be any shocks now re colder temps again..

..indeed the gfs control going for the heat later in the run..

 ..trough over spain and wrap around of warm air to the north..like current set up however further south..

..hoping the easterly  'rain' train terminates soon as ground is like putty and difficult to work with when gardening..so...drier weather...bring it on..cant come soon enough..have a good day and good weekend if you can...

 

 

[danm]

Can't really complain about the output this morning, we seem to (hopefully) be on a countdown to a week of settled and increasingly warm weather. 

UKMO

 

ECM

 

GFS

 

GEM

 

[Howie]

 danm couldn't come any sooner!

[Alderc 2.0]

 danm  let’s just hope surface conditions respond to the build in pressure and we get some nationwide sunshine and warmth. 

 

Edited May 3 by Alderc 2.0

[SunnyG]

 Addicks Fan 1981

 

Back to reality and it did get downgraded as we got closer to the 5th May. And here we are, back in winter wonderland lmao

Edited May 3 by SunnyG

[damianslaw]

Near term, a slow moving shallow low trough will aid shower development over the bank holiday. Unusually the warmest air currently is over NW locations, quite a strange set up. Some places will escape with a fine weekend, others could see a fair amount of rain. Western parts will see low cloud and drizzle tomorrow. Temps average or above for all. Sunshine could be fairly limited for most. Could be alot worse but also a fair better.

Next week likely to bring the first nationwide fine warm dry spell, warm but not especially so, hopefully lots of sunshine and under the ridge with light winds will feel very good indeed.

Difficult to pinpoint cloud amounts and where will see the highest temps. Later in the week, SE parts may see more appreciable warmth.

Where we go as we head into the middle of the month is questionable, longer range models were suggesting a retrogressive high and a cooler northerly flow, but are now showing the ridge sink SE allowing the atlantic to move through. No obvious signal we are seeing the foundations for a lengthy warm dry spell, but I guess most will be happy to experience a few days of such conditions at least.

Here, we have seen a preety decent couple of weeks other than Monday its been dry, often can be the case NW is best at this time of year.

Edited May 3 by damianslaw

[Bats32]

 damianslaw Purely from an IMBY POV, from the 00z ECM anyway, it looks like rain could skirt around the high to the NW. I'd like to see the high a bit further north next week. 

[Rain All Night]

On 02/05/2024 at 12:36, Rain All Night said:

0z ensemble means, out to Fri 17 May (day 15)

The high looks as though it could stay in place over the UK throughout next weekend, which would be a real blessing. After that, the means blur out any clear signal, but the high perhaps now looks more likely to sink than to retrogress.

0z deterministic runs, on Thu 9 May (day 7)

9th May is the one day that has been producing eye-catching ensemble mean charts for ages... will it now deliver?

0z ensemble means, out to Sat 18 May (day 15)

It looks likely that the new Atlantic trough will have pushed our high away by around the 13th/14th, by which point we may have had around five days of fairly settled weather nationwide (depending on specifics of the surface high), including a weekend.

Beyond that there are signals both for Atlantic ridging, and for shallow troughing to our immediate west.

The former signal for direct retrogression of our high into the Atlantic with cold trough formation to our east is gone now.

0z deterministic runs, on Fri 10 May (day 7)

There's that new Atlantic trough in development, while we are under the influence of the high, which is looking a bit squashed.

Edited May 3 by Rain All Night

[damianslaw]

 Bats32 Yes perhaps the far NW will be exposed to a damp atlantic flow.

[Don]

3 hours ago, SunnyG said:

And here we are, back in winter wonderland lmao

Oh yeah, where's all the snow then?!   

[Sherry]

Lovely set of runs this evening 

[Scorcher]

Not as good from the ECM to be honest. Hopefully an outlier. The GFS is a cracking run tonight right through next weekend for most of us.

[I remember Atlantic 252]

Only 240 chart is crap! hopefully low held out further west, 240 on EC ever been close to actual?

[Addicks Fan 1981]

 Scorcher I would imagine that deterministic chart is in a very small cluster though, let's allow @Mike Pooleto shed some light on it and see if I have his back on this.   

[WYorksWeather]

Worth noting that the GFS ensemble is continuing to extend the overall warmer than average spell. Still room for this to change as we saw in April, but increasingly signs that the first third or even first half of the month will come out notably above average.

[WYorksWeather]

Quick look at UKV for the next few days.

We can now see through to Wednesday. It looks like a gradual build in both the extent and level of warmth - from 18C tomorrow up to low 20s by Tuesday and Wednesday. Over the next few days it seems like most areas will have a chance of seeing at least one or two warm days, with the exception of Scotland.

Right at the very end, there does appear to be some warmer 850hPa air moving, which under the right surface conditions might raise the temperatures still higher later on next week.

For example, the GFS 12z was raising temperatures to 23C next Friday and Saturday. In practice, a first 25C of the year might well be possible given usual underestimation.

Summary

In short, it looks like we'll see a general improving trend if it's warm and dry you're looking for through the course of the weekend into early next week, and by the middle to end of next week most areas should have seen at least a couple of days of pleasantly warm conditions.

Again, nothing notable on the horizon by daily maxima, but consistently very mild to warm is all we need at this time of year for things to end up well above average temperature wise. A very warm first third of May is highly likely.

No heatwave on the cards, but certainly a decent spell of weather on offer for many of us. Of course, as is always the way with these things, some areas will probably end up getting it better than others, but that level of precision is probably not worth worrying about beyond the next 2-3 days.

 

 

[WYorksWeather]

Final post for tonight most likely - an update to my regular posts on North Atlantic SSTs. Last time you may remember I noted a very rapid warmup due to take place in the North Atlantic - let's see how it is progressing.

Here are the SSTs in absolute terms at days 0, 5, 10 and 15:

And here are the anomalies:

Overall there are a few areas to look at. To our north nothing especially unusual going on, so if we do get chilly northerlies these shouldn't be moderated excessively. However, if we do go into a south-westerly pattern yet again after the high pressure next week, we may well see some absolutely turbo-charged mildness, especially by night. SSTs in the Azores area generally continuing around 1-2C above average. Flat westerlies would be closer to average.

Closer to home, there is a very striking warm anomaly around our immediate coasts and towards the near continent as well - this will likely result in a greater propensity for mild nights and less moderation of any warm or hot continental airflows around the middle of the month.

In short, not only  are we in for a warm start to May, all the ingredients are there for it to continue well beyond that, even if a cloudy and/or wet south-westerly type pattern would limit daytime maxima. Only a significant northerly outbreak as we saw in the second half of April is likely to prevent another notably above average month by mean temperature.

[Kirkcaldy Weather]

Linking to the post above we've seen the natural progression of La Nina sea surface temperatures which began in the ENSO 1 and 2 Regions gradually move westward with a continuation of El Ninò sea surface temperatures across the western ENSO Regions in particular, there are some websites which claim an ENSO Neutral to be with neither El Ninò or La Nina being present however I generally disagree as my view is when we have a La Nina emerging from the East and the natural movement of El Ninò sea temperatures westward this gives both events simultaneously and therefore gives overall ENSO values into Neutral values.

NOAA

Tropicaltidbits 

On 21/04/2024 at 02:04, Kirkcaldy Weather said:

There may be opportunities for some high pressure extending toward the UK and Ireland at times though there isnt any concrete signal for this in current modelling though the 00z GEPS did hint toward the latter part of May week 1.

 

On 21/04/2024 at 02:04, Kirkcaldy Weather said:

Overall really pleased with the above posts given current and future evolutions a la the teleconnective feedback already shown, I decided to look into ENSO Neutral for recent MJO Progression.

Credit JMA

Nearing 3 months since my previous in depth post on future ENSO evolution.

 

And again reposting my thoughts from January 

'We'll continue seeing patterns which link to El Ninò throughout March and I'd favour potentially the first few weeks or so of April, following that time it's a gradual move into ENSO Neutral with some themes continuing of heading into La Ninà by late spring and particularly Summer 2024.'

Very pleased with the above

Looking at individual model outputs.

CFS

ENSO 1&2 Regions

Currently showing a Moderate >> Strong Nina in the East over the next few months followed by a weakening / less cool SSTs in Autumn followed by a second intensification of La Nina in Winter.

Nino 3 and 3.4 Regions

Corresponding with the weakening in the East the natural progression of the initial Moderate >> Strong La Nina conditions moves westward during Autumn heading toward Winter.

ENSO 4 Region

NMME [8th April data]

CANSIPS 

Some notes I'm making

• Whilst a Moderate - Strong Nina is suggested overall, a Super Nina cannot be discounted, an important lesson from last year.
• Whilst a majority of focus & attention will be on the Atlantic for cyclone & hurricane development my attention is drawn immediately toward the West Pacific and possibly the Indian Ocean too for a number of reasons.
• Cross model agreement showing part of the El Ninò SST heat moving West Northwest toward Melanesia and Southeast Asia

• CFS has the MJO being most prominently active from Africa progressing across the Indian Ocean > Maritimes and into the West Pacific / Pacific from July through January.

Certainly suggestive to me of heightened Monsoon, tropical rainfall and cyclone / typhoon developments.

Focusing on the Pacific a bit further, the area of warm Sea Surface Temperatures toward East Asia and Japan is part of the -PDO with a cooling of Sea Surface temperatures along the Alaska, Northwestern and Western America Coastline.

Credit Researchgate 

Credit 

The role of the Pacific Decadal Oscillation and ocean-atmosphere interactions in driving US temperature predictability

WWW.NATURE.COM

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npj Climate and Atmospheric Science - The role of the Pacific Decadal Oscillation and ocean-atmosphere interactions in driving US temperature predictability

Credit 

Spatiotemporal vertical velocity variation in the western tropical Pacific and its relation to decadal ocean variability | Progress in Earth and Planetary Science | Full Text

PROGEARTHPLANETSCI.SPRINGEROPEN.COM

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Abstract Prior to the cold phase of the Pacific decadal oscillation (PDO), sea surface water in the western tropical North Pacific is heated. To evaluate the impact of the subsurface water on the...

Interesting that the CFS for August is a really great match with the smoothed Tropical Cyclone Frequency from NMME forecast via Tropicaltidbits 

Hopefully this has been insightful and helpful for everyone and learners / newbies KW

[Alderc 2.0]

Poor output this morning for the coming week, despite a build in pressure lots of cloud and drizzle possible everyday next week in parts of E&W