Model Output Discussion - Spring Has Sprung

[MJB]

Consistency from GFS 

 

[Cambrian]

Some indications emerging now of how the aftermath of the SSW might play out in terms of the Northern Hemisphere profile over the next couple of weeks. 

The 0z ECM ensemble mean / EPS charts show low pressure centred near the Low Countries at day 4. The Scandinavian heights are being squeezed northwest towards Greenland. Strong heights in this region appear to be a feature of the next couple of weeks.

 

They are being held there at day 7 by a westward extension of the Siberian core of the PV to the north of Greenland, which reinvigorates the Greenland trough, bringing the western fringe of Europe to the eastern periphery of an Atlantic cyclonic influence. 

 

By day 10, this westward extension of the PV has developed further, forming a major trough down through eastern North America, a very cold spell looking to develop there,

 

peaking at around day 12, while Europe remains quiet with temperatures near average.

 

Indications of a change for Europe by day 15 though, as heights rise through the Atlantic and a Scandinavian trough becomes established, along with a surface low over the northern Mediterranean…

 

…bringing signs, albeit at that distant range, of scope for a northerly surface flow, picked up on the EPS MSLP charts too, flowing from the Siberian Arctic, through the Norwegian Sea, to Western Europe. 

From what has proved at times to be a quite exasperating winter, though the Atlantic might at times dabble with us, it looks like we’ll move towards and pass the spring equinox with a largely blocked setup and one more tease for prospects of cold weather, this one perhaps being directed rather than being diverted by events in the stratosphere. 

Relatively quiet it almost certainly will be. As for something notably cold later in the month, well maybe, but let’s not hold our breath!

[stodge]

Evening all

Starting to firm up the early part of next week and despite the main LP crossing northern France over the weekend, enough residual energy remains in the Atlantic to spawn new LP and keep a broadly unsettled theme going up to midweek.

Those hoping for renewed cold look like being disappointed while those looking for early warmth likewise. A little respite for the south and east in terms of further rainfall but more soakings for western and especially north western parts.

No sign of the SSW having a significant impact as yet but as it often the case in late March, northern blocking starts to show its hand to an extent. Hard to get the detail as yet but a southerly tracking jet obviously leaves southern Britain more vulnerable to further rainfall.

[Rain All Night]

10 hours ago, Rain All Night said:

0z deterministic runs, out to Thu 14th (day 7)

Must admit the crappiness of most of the later frames on these runs has taken me a little by surprise, UKMO excepted. Oh well, who needs a dry second week of March anyway, it can wait until the days are longer and the sun is stronger.

0z ensemble means, out to Fri 22nd (day 15)

ECM is continuing its newly-assumed role as the bad cop earlier on, but still offers the intriguing height rise signal - focused to the west of the UK - later on, and the other two models show some signs of this as well.

The ECM clusters from days 8-15:

12z deterministic runs, out to Thu 14th (day 7)

Today's runs are brought to you by:

Weak pressure gradients at 500hPa, and seemingly nothing going on in the atmosphere that can pump up an anticyclone anywhere in the entire Europe & North Atlantic region, not even Iberia... while the Atlantic keeps on spawning its endless lows.

12z ensemble means, out to Fri 22nd (day 15)

ECM still seeing something funky later on.

ECM clusters for days 8-15:

Edited March 7 by Rain All Night

[WYorksWeather]

Still plenty of wind direction uncertainty beyond the next few days. Looks like a strengthening easterly, then a colder spell with the wind turning more northerly (but not excessively cold). Beyond that maybe more south-easterly, and then for the second half of March all options remain on the table.

[Addicks Fan 1981]

 IDO reckon we need to keep a close eye on the MJO as @Kirkcaldy Weatheralluded us to, instead of going with our gut on NWP charts.   Proactivity towards this is to me pivotal, and according to both the GEFS/ECM the MJO be in the western Pacific, what that will mean I am not quite sure over, but a thing to monitor very closely.   

[Cheshire Freeze]

Not much comment on the ECM this evening. Not surprising.

10 day rainfall totals widely approaching 2 inches for many.

[Addicks Fan 1981]

 Cheshire Freeze think our el niño decline is doing this to be honest, the question now on everyones lips is whether we get into neutral and I think when we enter ENSO neutral we should I'd say see something a bit more normal come the second half of April.    

[Sherry]

Still no sign of anything cold in the models and they now go out to late march! 

[KTtom]

 Sherry indeed, in fact post SSW the pattern looks very familiar if UKMO has got it right...south westerlies and euro high.

 

[Bogman]

 Sherry I think you can call it now. The last rites have been read on what was supposedly winter, time to look for the green shoots of spring/summer.

Looking like more of the same down here - rain, rain, and then to put the cherry on the cake, more rain.

At least it looks like the north of the country may start to dry out a tad.

[Mike Poole]

I’ve been wondering for a couple of days now whether we are starting to see the effects of the strat reversal now in the extended clusters:

I think if we do, the likely area for blocking appears to be Greenland, as shown in clusters 2 and 4, maybe also 3 by day 15.  One to watch, if this does happen it will be against the backdrop of the flabbier pressure patterns of spring rather than winter, and of course very late for any cold, but if the right pattern evolved, an interesting Easter weekend is still very much a possibility.  

 

[Bogman]

 Mike Poole Be about right. Got the first BBQ booked in for the Sunday. Remember one year building a snowman on Easter Sunday........................

But I expect the weather will revert to type.

[Stephen W]

@Mike Poole Will be interesting to see if this SSW does indeed produce GH blocking and a cold period for the UK. However, looking at the NWP output, it’s a familiar story with some tantalising cold in FI on some ensemble members only for the complete opposite to be the reality in near time! Wouldn’t surprise me if we end up with an early plume of warmth courtesy of the familiar euro/iberian heights which we just can’t shake off for long. Or, just more rain! GFS ensembles this morning look more unsettled to me which I was surprised about.

[CoventryWeather]

Anyone fancy an early season plume?

Has been gaining interest in recent model runs. The GEM tries something at day 10. 

[Rain All Night]

12 hours ago, Rain All Night said:

12z deterministic runs, out to Thu 14th (day 7)

Today's runs are brought to you by:

Weak pressure gradients at 500hPa, and seemingly nothing going on in the atmosphere that can pump up an anticyclone anywhere in the entire Europe & North Atlantic region, not even Iberia... while the Atlantic keeps on spawning its endless lows.

12z ensemble means, out to Fri 22nd (day 15)

ECM still seeing something funky later on.

ECM clusters for days 8-15:

0z deterministic runs, out to Fri 15th (day 7)

0z ensemble means, out to Sat 23rd (day 15)

The Atlantic height rise signal in deep FI on the ECM ensemble mean doesn't seem as strong this morning.

[Howie]

Tbh I'm ready for warm and sunny weather now. Winter can wait until November 

[feb1991blizzard]

Now that would be special for time of year.

Edited March 8 by feb1991blizzard

[feb1991blizzard]

In fact tell a lie, that would be something special once every 10 years in Jan in SW England.

[CoventryWeather]

 feb1991blizzard bank it in Jan, not now.. 

Anyways a further increase in warmer ensembles on the GEFS 06z. I'd expect a cluster on tonight's ECM. 

P5 looks nice.

I do wonder if we will have a warm snap then a cold snap towards Easter. A typical spring mix.

Edited March 8 by CoventryWeather

[Jordan S]

On 07/03/2024 at 11:14, Jordan S said:

The Gfs seems to want to go with this above quote to a large degree in its latter frames, with the increasing chance of northeast winds into the north with snow showers and the risk of more persistent wintry precipitation once again being possible from advancing weather fronts moving northeast into northern areas from the south, with higher pressures tending to float around to our immediate north/northwest ie more Greenland as said previously, the wettest weather which will probably be all rain still looks to be for southern UK overall, with very mild air trying to establish further north into the UK aswell still likely, on the whole it does still look like often being drier in the north with some pleasant spring sunshine in the latter part of March but some colder nights could be a feature in any absence of winds from our south, potential is still there for southern and southeastern areas to tap into some warmer than average temperatures after mid month in an otherwise cyclonic wet spell, but there will be some drier days even here ofcourse, so yes looks wetter than average for March here but not as much as February.

The couple of updates I made recently on those northeast winds after mid month over the UK looks “nailed” on.. lol ofcourse not, and no doubt will show a different theme by this afternoon (that won’t alter outlook thoughts in this post though) but the Gfs update this morning highlights the anticipated Greenland heights, very mild/warm air trying to establish from our south and colder conditions trying to establish from our northeast very well past mid month.

The synoptics over the UK unlikely to look as extreme or as south shifted in terms of cold air and wintry precipitation as the Gfs is currently showing in reality and my updates recently have eliminated southern UK being in with a chance of wintry precipitation after thinking this could happen just after mid month when I did an update in the first couple days of March, but for northern UK, there is still a reasonable chance of colder (though not exceptionally cold) northeast winds trying to establish past mid month especially post 18th March to put a bit more detail on it,  which is my 25th birthday.

Due to the very cyclonic/unsettled nature of the weather over southern UK and across the “southern portion” of the Atlantic Ocean that looks to still feature throughout the second half of March and likelihood of high pressure nosing into western and Central Europe on occasion this is what will probably prevent colder than average conditions for the most part in central and especially southern UK, very wet at times still and that’s been highlighted well but with much more of the showery unsettled variety than the winter obviously due to increased convection so rainfall totals may actually vary somewhat from place to place here but could see some big showers developing, these wintry at times in the north, shower risk is though highest in the south with that ever strengthening sunlight especially in cooler upper air temperatures that look to be a feature behind southerly tracking lows that bring very mild air ahead of them either close by or over southern regions of the UK.

Thought I’d add a confidence rating to my posts now so you can have an idea how confident a weather event or forecast per day may be to me atleast..

Confidence rating for the post mid month period attempting colder spell development in north UK: 50% so moderate confidence, most of the excess uncertainty coming from how much influence low pressure has in the north,high pressure more often than not largely close by here and that has been the consistent signal but there will be unsettled interludes in the north of the UK too with a continued risk of wintry showers along with dry drier days.

Highs over/close to Greenland a 90% chance of that occurring at frequent intervals for the rest of the March.

Confidence rating of 75-80% for southern regions seeing the wettest conditions overall and a bit milder with a consistent cyclonic pattern with low pressures moving mainly west to east being anticipated but also on occasion northwest to southeast and south to north through the rest of March bar fleeting high pressure systems that swiftly move across the country settling things down on occasion trying to form blocks elsewhere across our part of the northern hemisphere. 

Confidence rating of 60% that the synoptic pattern over west Europe will allow a temporary much warmer than average spell of temperatures into France and southern and southeastern England atleast once before the end of March, overall they look to be fleeting.

The very end of March the Greenland heights may move and weaken slightly south and in the process bringing much colder upper air temperatures south across the whole of the country and into France, bringing the risk of a brief spell of below average temperatures with a bit of sleet/snow in places potentially including the south. Confidence rating for the very end of March potential colder than average blip nationwide, 30-40% with the main uncertainty being time frame given this is 3 weeks away, but to a lesser extent on exact trajectory of potential brief north/northeast air streams widely and whether they stay east of not around end of March.
 

Have a lovely day

[ANYWEATHER]

 Bogman the drying trend will continue

[bluearmy]

 Mike Poole finally signs on the gfs ops that the reversal will downwell into the trop in two weeks time 

Given that gfs has done a decent job in the strat this winter, I’d be expecting some impressive fi output from some ens members across the models.  Be interesting to see how the AI models get on with this if it does gain momentum

[Bogman]

 ANYWEATHER

[Dancerwithwings]

5 hours ago, feb1991blizzard said:

Now that would be special for time of year.

Reminds me of March 2013….on the 20th I end up with 20cm in my backyard