Model Output Discussions 12z 08/03/17

[mb018538]

6z broadly similar....pattern emerging of heat, slight breakdown as low pressure passes by sunday/Monday, before a re-build of pressure into next week.



This is what we want to see! Nice blues and a big trough over Iceland/Greenland, and no massive polar heights giving us cool muck.

[knocker]

3 hours ago, Glacier Point said:

Sounding a lot like my seasonal outlook there ! 

Within the shorter and medium range we are beginning to get the influence of an Atlantic trough signal and somewhat split flow over Europe giving a tendency to mid latitude high pressure. As a real positive, a colder than normal upper stratosphere over the Arctic and low heights developing through the upper and middle stratosphere is a recipe for fine spells increasingly developing into June.

Excuse me being somewhat thick here GP but I'm not sure I understand why this is. By that I mean what is the correlation between low heights in the middle and upper stratosphere ( colder than normal) and pressure distribution in the troposphere in the N.Atlantic/NW Europe in summer? Or even make that the NH. Essentially what mechanism is at play here that overrides other signals?

Edited May 22, 2017 by knocker

[Frosty.]

A fabulous early taste of summer this week as high pressure builds in and becoming hot later in the week as our high migrates to the east enabling hot and humid continental air to waft north across the uk with temperatures reaching 30-32c 86-90f during the weekend across southern uk and very warm further north too..enjoy it..not even summer until later next week!

[northwestsnow]

Fabulous output again today and looks very warm into the weekend, im hoping the ridge following the thundery low late saturday proves more stubborn than the metoffice are suggesting, clearly they expect this ridge is going to be swept away very quickly by the Atlantic and they are anticipating a poor start to June, presumably by an unwelcome active Atlantic..

[mb018538]

Latest BBC lunchtime forecast is going for a 30c on Saturday, which ties in with the output we are seeing, but not the modelled predicted temps! Should be a scorcher, and a pretty early first 30c of the year?



I'd say at the moment there isn't a clear signal into June.....and let's not forget how this has caught everyone out too! A third of the ensemble members are over 10c at the end of the run, so we can't rule anything in or out yet. These thundery lows etc are notoriously hard to model and predict.

[northwestsnow]

5 minutes ago, mb018538 said:

Latest BBC lunchtime forecast is going for a 30c on Saturday, which ties in with the output we are seeing, but not the modelled predicted temps! Should be a scorcher, and a pretty early first 30c of the year?



I'd say at the moment there isn't a clear signal into June.....and let's not forget how this has caught everyone out too! A third of the ensemble members are over 10c at the end of the run, so we can't rule anything in or out yet. These thundery lows etc are notoriously hard to model and predict.

Absolutely! The metoffice update has actually suprised me given that momentum seems to be building for a re establishment of the azores high they are actually really bullish on Atlantic gunk into next week. Still, a decent spell of warm even very warm weather is not to be sniffed at, i'll be on the bank rod in hand when my night shift finishes fri morning..:-)

[knocker]

48 minutes ago, northwestsnow said:

Absolutely! The metoffice update has actually suprised me given that momentum seems to be building for a re establishment of the azores high they are actually really bullish on Atlantic gunk into next week. Still, a decent spell of warm even very warm weather is not to be sniffed at, i'll be on the bank rod in hand when my night shift finishes fri morning..:-)

It is not that much of a surprise as the anomalies are all indicating the HP slipping east with the Atlantic trough becoming more influential.Cannot post the ext EPS

[Atmogenic]

1 hour ago, Knockers said:

A fabulous early taste of summer this week as high pressure builds in and becoming hot later in the week as our high migrates to the east enabling hot and humid continental air to waft north across the uk with temperatures reaching 30-32c 86-90f during the weekend across southern uk and very warm further north too..enjoy it..not even summer until later next week!

Now that's the stuff I wish to see all the time during the summer but with some thundery activity from time to time to cool down from the heat and humidity 

[Frosty.]

For heat seekers, the Ecm 00z ensemble mean is a dream later this week and especially during the weekend with high summer conditions in late spring..temps could be pushing 90F in the south of the uk at the end of this week and widely into the 80's..hopefully we will see plenty more mean charts like these during the next 12-14 weeks..so, expect increasing amounts of sunshine and sizzling temps later this week, perfect BBQ weather and also a growing risk of thundery showers as the humidity soars once we tap into the hot / humid continental airmass!..Bliss

Edited May 22, 2017 by Knockers

[SizzlingHeat]

Subtle changes again on 12z. Pressure slipping away faster to the east. South and west likely to have heavy showers from Saturday afternoon as a result. If this high slips away to the east any quicker, the very warm temps are only likely to last Wednesday through to saturday. Could be an outlier like yesterday however.

[I remember Atlantic 252]

30 minutes ago, SizzlingHeat said:

Subtle changes again on 12z. Pressure slipping away faster to the east. South and west likely to have heavy showers from Saturday afternoon as a result. If this high slips away to the east any quicker, the very warm temps are only likely to last Wednesday through to saturday. Could be an outlier like yesterday however.

not sure about that! looks t'other way if anything, heat holding on through Sunday

[Captain Shortwave]

As many have stated the GFS isn't exactly reliable in delivering accurate highs, though the first few days of the warm spell are now in range of the arpege which was very good at getting within a degree or so of the actual maximum.

Thursday/Friday highs

   

25-27C widely on both days and by that I mean pretty much anywhere in the UK away from coastal areas where onshore breezes will develop. 

Still interest in how things will breakdown over the weekend, worth noting the GFS takes that low so far west that the southeastern third actually avoids this and stays very warm until Monday when a weak cold front moves south east across the UK. UKMO a little quicker perhaps with fresher air moving eastwards during Sunday.

  

There is enough evidence that after this spell we could see another warm up during the middle of next week as the Azores ridge moves north east allowing another southerly source airflow.

ECM differs again this evening and rebuilds the Euro ridge over the weekend with Sunday hotter still in eastern areas, in fact these areas remain hot and sunny throughout the whole bank holiday weekend, the west always at risk of thundery downpours.

Edited May 22, 2017 by Captain Shortwave

[Frosty.]

The Ecm 12z really hots up later this week, sunday looks hottest..great charts and you know it's going to be very summery when the 564 dam is into the uk. and to think..it's not even summer yet!

Edited May 22, 2017 by Knockers

[Frosty.]

Stays hot for BH Monday too!  a wonderful spell of hot continental weather looks to be on the way.

[Scorcher]

Wow what a run from the ECM tonight, there is not really a breakdown at all on this run. In fact it shows some of the hottest air of all still hanging around in the east at midday on Monday:

Slightly cooler from then on but with high pressure remaining influential, conditions should remain very pleasant for Tuesday and beyond. There seems to be good agreement for high pressure to re-establish itself after the weekend now.

[Singularity]

   

I wonder why ECM has such a habit of handling plumes in different and more exciting ways to all but the (legendary/infamous) GEM?

Seems like the SE would stay toasty right out to Tuesday on this run, depending on surface details regarding cloud and showers.

I must say, as that low lifted out so far west on Sunday, I feared the Atlantic could just march right in early next week, but even this run manages to avoid that. So what are the Met Office seeing I have to wonder? Even the ensembles look less changeable-looking than 24 hours ago, although there are a fair few shallow low scenarios - yet this favours the south for rainfall which just takes us further from the Met Office guidance. Very curious indeed!

I'm now going to be naughty and leave some CFSv2 weekly ensemble mean temperature anomaly charts here 

 

This forum probably isn't big enough to hold the size of caveat that comes with these. Except perhaps it is these days, as this model has done surprisingly well in recent months 

[Scorcher]

I really am wondering about the Met Office and their predictions in spells like this, particularly with maximum temperature predictions.

Surely in Manchester with a setup like this for Friday, we have to do better than 23C?

Looks like a SE flow with not much in the way of cloud and upper air temperatures around 11-12C. Surely 26/27C is possible from such a setup in NW England. Or maybe they know something I don't.

[Mokidugway]

Just now, Scorcher said:

I really am wondering about the Met Office and their predictions in spells like this, particularly with maximum temperature predictions.

Surely in Manchester with a setup like this for Friday, we have to do better than 23C?

Looks like a SE flow with not much in the way of cloud and upper air temperatures around 11-12C. Surely 26/27C is possible from such a setup in NW England. Or maybe they know something I don't.

Temperatures are almost always undercooked, I'd expect 25to27c widely in the northwest.

[Scorcher]

Just now, Mokidugway said:

Temperatures are almost always undercooked, I'd expect 25to27c widely in the northwest.

You'd think if anything though, it would make sense for the Met Office/BBC to overcook the temperatures as they are maximum temperatures after all- so surely better to be a bit high than too low? 

[Mokidugway]

1 minute ago, Scorcher said:

You'd think if anything though, it would make sense for the Met Office/BBC to overcook the temperatures as they are maximum temperatures after all- so surely better to be a bit high than too low? 

You would think so ,but they probably have their reasons 

[Frosty.]

Looking excellent..here comes summer..

[Mokidugway]

1 minute ago, Knockers said:

Looking excellent..here comes summer..

Hope the giant 30 shifts , might be dull in my location 

[Ross Andrew Hemphill]

26 minutes ago, Singularity said:

   

I wonder why ECM has such a habit of handling plumes in different and more exciting ways to all but the (legendary/infamous) GEM?

Seems like the SE would stay toasty right out to Tuesday on this run, depending on surface details regarding cloud and showers.

I must say, as that low lifted out so far west on Sunday, I feared the Atlantic could just march right in early next week, but even this run manages to avoid that. So what are the Met Office seeing I have to wonder? Even the ensembles look less changeable-looking than 24 hours ago, although there are a fair few shallow low scenarios - yet this favours the south for rainfall which just takes us further from the Met Office guidance. Very curious indeed!

I'm now going to be naughty and leave some CFSv2 weekly ensemble mean temperature anomaly charts here 

 

This forum probably isn't big enough to hold the size of caveat that comes with these. Except perhaps it is these days, as this model has done surprisingly well in recent months 

What is this caveat you speak of?  And if those charts came off, it wouldn't only be this forum in meltdown! Lots of positive signs for really great weather in the next few weeks, everything just has to fall into place for us for once. 

[knocker]

The ecm quite interesting tonight. the first shallow thundery low does indeed travel north over Ireland and is over the Hebrides by 06z on Saturday. Some brief ridging follows before the next low and thundery activity arrives over Ireland, courtesy of the cut off upper low west of Iberia, .This also tracks quickly north before more sporadic rain arrives on Monday affecting most of England. Despite this activity or actually because of this, as it has mostly been confined to the west, the temps over much of England, (emphasis on England), are set to be very high over the weekend.. Around 28C - 30C on Saturday and 30C, possibly even 32C on Sunday. But again, to emphasize the difference, as low as 12C in Scotland.

The far south east keeps the very warm temps on Monday before a return to normal and by Wednesday the Atlantic trough is starting make inroads and unsettled weather beckons for the first week of June. I seem to recollect that's precisely what the METO are saying.

Of course all of entails a pretty precise evolution and small adjustments over the next couple of runs could well make some significant changes

Edited May 22, 2017 by knocker

[Fourty Point Three Degrees]

58 minutes ago, Mokidugway said:

Temperatures are almost always undercooked, I'd expect 25to27c widely in the northwest.

Depending on cloud Manchester could easily hit 30c if sunshine can remain constant.