Model Output Discussion - Spring Has Sprung

[ANYWEATHER]

11 minutes ago, Alderc 2.0 said:

there is nothing remotely warm about that chart. Don’t really need the showers either. 

You're right.  But would provide some great cloudscapes, just bog standard showers we don't want ,but some pyrotechnics yes I would like!

[Sherry]

Pretty much all gfs members keep us above average 

I think people need to forget about SSW events clearly not one of them did anything in the past winter! And everyone said the background signals were good! 

[LightningLover]

15-16c 850hPa temps encroaching on the 06z GFS. Broadly the same synoptics as the last run!

[Met4Cast]

5 minutes ago, Sherry said:

I think people need to forget about SSW events clearly not one of them did anything in the past winter! And everyone said the background signals were good! 

Background forcing has been against the idea of colder weather since the mid January cold spell, a marker divergence appeared around the 22nd January when I (and others) noted the likelihood of a cold February was diminishing. 

Indeed, background forcing remains unfavourable for strongly blocked/colder patterns with the Iberian high continuing to play a larger role in the broadscale patterns (despite major SSW)

April however does show some tendency towards higher latitude blocking as the MJO continues to progress into phase 7-8 but by this point does anybody really want colder blasts of air? Probably not. 

[Cambrian]

We are ten days away from the spring equinox. Looking at the 0z ECM ensemble mean for day 10 shows a much depleted PV. 

If we imagine a line running west-east across the Arctic dividing the hemisphere between the Greenwich meridian half and the International Date Line half, a continuation of 90 degrees west over the pole to 90 degrees east in longitude, we see that the PV is entirely on our side of the hemisphere. 

An Alaskan ridge extends all the way through to the far east of Russia so the core PV is being squeezed to the Greenland-Svalbard-Kara Sea region. 

  

The core cold sits further west over northern Greenland. There are two main zones of polar troughing being orchestrated, also shown nicely on the 0z EPS chart, one running south through the Norwegian Sea, and a really handsome one, with an easy run south for the cold air over the continuous ice / land mass of the Canadian Arctic down into the eastern United States, much easier than over the long sea track down into Western Europe. 

As a result, the T850 -4 degree isotherm and 540 dam heights contour runs from Washington DC at 39 degrees North to just north of the central belt in Scotland at 57 degrees North. 

Nevertheless, in this same broad setup, that is maintained for a fair few days thereafter, especially when the trough sets in just that little bit further east over Scandinavia, there are possibilities for incursion of cold air into Western Europe too, as here on the 0z ECM control at days 11 (a clean northerly shot there) 

 

and day 13/14 (a bit more messily cyclonic but still cold).

  

I’m enjoying the longer and brighter days at the moment and it’s interesting to see some warmer southerly episodes cropping up in the ops.

However, I really like the ECM for the way that it typically keeps the control (in effect the post day 10 op) synoptically coupled to the mean, even at the longer ranges - it’s better than the other models in this regard - so for me, with this polar setup, and in many ways, typical for the time of year with waning PV and marked long wave troughs, some colder weather is still very much a distinct possibility for the last third of the month.

Indeed, in keeping with the above, it would be little surprise to see stark and sudden transitions between warm and cold spells over the next few weeks. Happy Mother’s Day.

[damianslaw]

The models are moving away from any scandi height rise having an influence - a theme of the season as a whole. Instead there continues to be a signal for height rises albeit weak to our NW. This has the affect of sharpening the atlantic trough in combination with heights to our SW, again the theme of the season.

End result, a return to a milder but wetter flow from between south and west, but no long draw warmer feed as yet.

Longer term we may well see the atlantic trough anchor east and with a lot of cold polar air on its flank, we may see some of this spill down into the UK, indeed ECM output very plausible in this respect. GFS as well is playing around with a switch to locking the UK on the colder side of the jet as we move into latter third of March, but all too far away to call at this stage.

For the foreseeable its all quite dull model viewing for weather enthuiasts who like something interesting, but March can entrench itself in quite uninteresting terrain for lengthy spells, same as the other shoulder month, September. April is the month for more sudden marked changes and interesting synoptics with the still cold arctic polar air doing battle with the ever increasingly warm tropical/continental air. 

Edited March 10 by damianslaw

[KTtom]

06z ens also flipping around wildly from mid month. Operational goes from the warmest member to the coldext in 48hrs! General consensus is a mild and wet week to 10 days especially in the west then just maybe one of those classical switches from warm to cold we used to get in Spring.

[Anthony Burden]

 Cambrian Hi excellent summary.

[Rain All Night]

On 09/03/2024 at 10:41, Rain All Night said:

0z deterministic runs, out to Sat 16th (day 7)

Yes please ECM. The other models also show more heights to the east than were evident yesterday, so there's more hope of less rain for us.

0z ensemble means, out to Sun 24th (day 15)

The ECM mean resembles its op earlier on, and while the signal isn't as strong as a few days back, it still has interest in an Atlantic height rise later. The other two means look like garbage unfortunately.

0z deterministic runs, out to Sun 17th (day 7)

Just catching up, and I see this week's not looking too bad for me down here now, which is a relief. Not much sunshine on offer though.

0z ensemble means, out to Mon 25th (day 15)

Possibly something ridge-like hinted at around the equinox, but otherwise not much interesting going on.

Edited March 10 by Rain All Night

[phil nw.]

Good to see a change from this chilly feeling and damp easterly setup as by Tuesday we are all into the milder south westerlies as the Iberian ridging shows it's  hand -the change well established by mid-week.

Looking further on gfs to day 8 continues with this

so although the pv is gradually shrinking,it's still back to business on our side of the pole with a return to our usual Atlantic pattern.

Probably it's still too early to see the effect of the spv reversal lower down.I am not wishing a poor Spring by any means but it wouldn't surprise me to see northern blocking become a feature in charts before March is out. 

CFS for April height anomalies suggest anomalies over Greenland with Atlantic troughing underneath.

 

[Frosty.]

According to the Daily Express! ..we will be covered in snow soon! ..more likely mild with rain as the Gfs 12z op indicates! …sorry guys, but I’ve had enough of this.. roll on summer! …I’m sure it will be a record breaker! 

[minus10]

Well if its dryer weather you are looking for i think the 12z gefs is looking reasonable...

..the accumulated precip until 25th showing an improving picture with a return to more standard fayre with the north west south east distribution of rainfull..

...also temps look reasonable with average to only a degree or so below average for 850s by the last week of March..

..which results in actual average to above average 2m temps given time of year...

...on a broader scale the gefs not really showing any dramatic response to the current ssw if its (poleward) blocking you are looking for.. (yet)

...current predicted height anoms showing mild to warm for the uk i would think...

..benign and fairly warm in the south as is shown on the gfs op 12z..

...of course it could still change for the end of the month...with the ongoing ssw, however really hoping now that this being modelled is the way forward..

..the ens mean show next week warmer then back to lt average or just below which at this time of year is pretty reasonable...less rain spikes to..

..after todays Mothering Sunday washout i really hope for warmer and drier weather...the cold weather ship has sailed as far as i am concerned and i am a coldie ...also as a gardener really do need to see some drier weather at least as the ground is still saturated around here and in the south generally.. ..hope springs eternal...

 

Edited March 10 by minus10

[Frosty.]

Looking at the cfs,  further into March looks rather blocked with high pressure in the ascendancy meaning benign conditions for the majority…then I’ll skip April and look forward to early May! …call me a traitor coldies… I’ve had enough of this abysmal / pathetic / rotten excuse for a  so called winter season already!…bring on the sun! ️ 

 

Edited March 10 by Frosty.

[DaveF]

Almost no sunshine on offer right across the UK this coming week. Some glimpses on Friday in some areas but that's about it. Not sure I've ever seen a chart like this for Tuesday:

Edited March 10 by DaveF
clarification

[WYorksWeather]

Definitely looks like a milder week to come, and fairly dry as well. Temperatures finally nudging up to something a bit above average here after what has been a poor weekend (including yesterday, unlike for many of you further south).

Beyond that, we have a fairly standard outlook again - huge amounts of scatter from mid-month, smart money on near average temperatures but a lot of variation.

For a bit of fun though, let's do crazy ensemble of the day - one cold, one warm.

Cold ensemble of the day - GFS 12z P08

After a fairly non-descript first 7 days or so, around the 17th we get an absolute classic northerly. Probably one of the coldest late March spells you're ever like to see in an ensemble.

By day 8, we have a strong block over Greenland, and cold begins to flood southwards.

By day 11, almost the entire country is in a severe cold spell. Mild air cannot re-establish as the Atlantic is firmly blocked by the mid-Atlantic ridge. All except the far south under the -8C isotherm and northern areas at -12C, Scotland at -14C. Crazy.

Even later on at day 14, the pattern is still persisting. The cold has moderated somewhat, but the combination of both depth and duration of cold on this chart is really quite remarkable for so late in the extended cold season. 

Warm ensemble of the day - GEM 00z P11

This is a completely different event to the above cold event - much more localised to the south. But the intensity of the warmth is simply phenomenal. Meteociel doesn't have the ensembles, so using Wetterzentrale for this.

All relatively normal at day 7...

Bit of early heat into southern Europe at day 9...

OK this is a bit unusual at day 10, what's that doing over France?

In the hours that follow, we briefly get the 20C isotherm touching the south coast, and at midday Wednesday 20th a huge swathe of the country is under the +15C isotherm. It clears away pretty quickly though.

Summary

Mostly a benign set of charts yet again - milder for the next few days then possibly closer to average. But as the charts I've shown above illustrate, we can go back into the freezer or get a full on plume later this month, so I really don't have much confidence in predicting anything past late next week!

 

 

 

 

 

 

 

 

 

[Addicks Fan 1981]

 phil nw. to me Phil it wouldn't be an overly cold april and consisting with SW winds a lot, just unsettled but coming out of an el niño would cause implications.  Reckon we are in a similar place to what we were in 2016, I remember the spring of 2016 being very iffy up until May.   

[mountain shadow]

As ever, any proper cold stays past day 10, so the risk of snow and ice remains very low.

In fact, I'm seeing more evidence that the Iberian ridge will have more influence than Northerly blocking. 

[CoventryWeather]

 Don it wasn't meant to come across that way, simply an opinion. To be fair I'd take anything over this cloud fest we get this week. I'd prefer a warm Easter for a change though. 

Overnight modelling going for something warmer, following the GFS runs from yesterday. No sign of blocking or anything colder from my view in the reliable. 

Edited March 11 by CoventryWeather

[Stephen W]

@mountain shadow Yes, seems to be the theme through the entire winter..despite another SSW ongoing, no strong evidence of northerly blocking in the NWP output other than throwing out a few outside the reliable timeframe..  In fact, as you say, the opposite seems to be the case once within the reliable with the Iberian ridge having more influence and resulting in well above average temps, not helped by warmer than normal SSTs in the North Atlantic.  I had thought this current SSW may prove otherwise and perhaps it still will towards month end but no sign yet of any increased ensemble members heading in that direction post day 10. The trend, if anything, is less towards northerly blocking so other factors must be at play still.

[Derecho]

You wouldn't want to be to the north of Iceland if that came off!

[Rain All Night]

18 hours ago, Rain All Night said:

0z deterministic runs, out to Sun 17th (day 7)

Just catching up, and I see this week's not looking too bad for me down here now, which is a relief. Not much sunshine on offer though.

0z ensemble means, out to Mon 25th (day 15)

Possibly something ridge-like hinted at around the equinox, but otherwise not much interesting going on.

0z deterministic runs, out to Mon 18th (day 7)

Outlook about as uninteresting as it gets, from what I can see...

0z ensemble means, out to Tue 26th (day 15)

Other than the mean surface low shifting eastwards very late in these runs, there is not a lot to comment on.

[Cambrian]

Next weekend looking quite reasonable on the 12z GFS op as some decent heights encourage a ridge of high pressure to nose up from the south in between the two low pressure systems on Saturday. This establishes a gentle southwesterly flow travelling up all the way from the Azores for all of the UK and Ireland by Sunday. 

 

Largely dry away from the west of Scotland bar a light shower or two. Temperatures responding - into double figures generally by the afternoon.

  

Warm for many parts of England, 14-16 degrees, some 5-7 degrees above average for the time of year on the anomaly chart. Sweaters optional. 

Edited March 11 by Cambrian

[Metwatch]

6 minutes ago, Cambrian said:

Next weekend looking quite reasonable on the 12z GFS op as some decent heights encourage a ridge of high pressure to nose up from the south in between the two low pressure systems on Saturday. This establishes a gentle southwesterly flow for all of the UK and Ireland by Sunday. 

I'd say a weekend of 2 halves, that's most likely what will happen but it's still a little far out so changes will occur before we get there. Most of the output is showing Saturday to be the wetter day, then an improvement on Sunday.

The best mini break in the rain will be in the middle of this week, otherwise staying mild but mostly dull. Other than that the best way I can put it is a simply disgusting vile outlook towards the latter part of March.

[Met4Cast]

On 02/03/2024 at 12:46, Met4Cast said:

The direction of +AAM anomalies is equally important and we're seeing +AAM anomalies moving poleward as the previous cycle completes, this is suggestive of a stronger jet and is further evidence of a quicker flattening of the pattern.

Unsurprisingly the blocked model outputs from a week or so ago didn’t really materialise, here was a run for today vs how things actually looked today; 

The teleconnections are sometimes rubbished on this forum if it doesn’t snow in X location but once again they’ve proved a very useful tool in viewing NWP outputs with added context, as they have done for the majority of this winter. 

It seems instead we’re in for a fairly prolonged period of above average temperatures with the March CET likely coming out above average if the current direction of travel continues. 

Perhaps signs of something a little colder thanks to Atlantic ridging late March/early April as the MJO continues to progress eastwards through the Maritimes & into the Pacific with AAM tendency fairly positive at the moment as a result.

[CoventryWeather]

Now the ECM 12z goes on yesterdays GFS route. Drier and warmer, traps a heat low west of Portugal. 

It's starting to trend in the right direction, let's head this down towards day 5/6.