Model Output Discussions 12z 08/03/17

[Fourty Point Three Degrees]

5 hours ago, East_England_Stormchaser91 said:

The same thing happened on July 1st 2015. We got 37.1c out of the 20c isotherm, and it could've got even higher, had it have not been scuppered by a period of mid level cloud trundling by. I remember it so well! 

May record could be under a serious threat if we keep getting upgrades like this! 

I think you got confused with the August 1990 hot spell:

August 4 1990 - 37.1 at Cheltenham 

July 1st 2015 - 36.7 at Heathrow,  

 

[knocker]

Haven't had time to look at the 12z output but after a quick glance the obvious change in the evolution is it bringing the next thundery low north on Monday which, if it materializes in this manner, it would create some interest. But it's a long way off at the moment.

Edited May 21, 2017 by knocker

[Scorcher]

3 hours ago, 40*C said:

I think you got confused with the August 1990 hot spell:

August 4 1990 - 37.1 at Cheltenham 

July 1st 2015 - 36.7 at Heathrow,  

 

0.4C- not that much of a difference

[SizzlingHeat]

So... The downgrades have begun. Was as late as sunday/Monday yesterday now the latest 12z has the breakdown during Saturday. So the traditional 3 fine days and a thunderstorm it is then. Knew it was too good to be true. Never mind. It's still early days in the season.

[SizzlingHeat]

Such a shame. Still time for changes but looking progressively down hill from Friday onwards now as opposed to Sunday or Monday this time yesterday.

[Comandante]

5 minutes ago, SizzlingHeat said:

So... The downgrades have begun. Was as late as sunday/Monday yesterday now the latest 12z has the breakdown during Saturday. So the traditional 3 fine days and a thunderstorm it is then. Knew it was too good to be true. Never mind. It's still early days in the season.

It's a cool outlier. Most show the heat lasting into Monday. It's a dangerous game assuming one run in isolation will be correct. Best to hang fire and see the full data set before getting the razor blades out.

Edited May 21, 2017 by Comandante

[Comandante]

4 minutes ago, SizzlingHeat said:

So... The downgrades have begun. Was as late as sunday/Monday yesterday now the latest 12z has the breakdown during Saturday. So the traditional 3 fine days and a thunderstorm it is then. Knew it was too good to be true. Never mind. It's still early days in the season.

I link you to the ensembles...

[knocker]

Although this is academic at the moment the ecm is not looking follow the gfs lead and track the second Iberian low north on Monday. Still 26 -28C on Saturday.

[Summer Sun]

1 hour ago, SizzlingHeat said:

Such a shame. Still time for changes but looking progressively down hill from Friday onwards now as opposed to Sunday or Monday this time yesterday.

 

 

ECM keeps the heat till Sunday then fresher air sweeps through on BH Monday

Edited May 21, 2017 by Summer Sun

[stainesbloke]

2 hours ago, SizzlingHeat said:

So... The downgrades have begun. Was as late as sunday/Monday yesterday now the latest 12z has the breakdown during Saturday. So the traditional 3 fine days and a thunderstorm it is then. Knew it was too good to be true. Never mind. It's still early days in the season.

The GFS 12Z is a cool outlier and not supported. No need to start the doom mongering just yet as we know how keen the GFS is to bring in the Atlantic. Fingers crossed the ECM is correct as it would deliver a lovely spell of weather including much of the BH weekend.

[Mokidugway]

Like loosing a tenner and finding a twenty but mourning for the tenner,let's wait and see .

[Britneyfan]

Going by the EMC and it's ensembles it looks like the breakdown won't happen till Monday! Especially in the south east! Should stay in the mid to high tweenties across the south east all weekend 

[knocker]

The EPS 850mb mean temp and contours

Edited May 21, 2017 by knocker

[East_England_Stormchaser91]

Think we are lucky, infact very lucky to even see the 15c isotherm visiting our shores so early on in the season. Can't remember the last time in May bar 2012 that it happened? 2006?! 

Lets just make the most of it while we can. We all know what our summers can be like! Not impossible that we may not even see it again..! 

Edited May 21, 2017 by East_England_Stormchaser91

[SizzlingHeat]

Definitely looks like Saturday being the warmest day now. High twenties likely in places. A thundery low spills north and east overnight with a renewed surge of high pressure thereafter. Temps back into low twenties for Sunday and Monday with sunshine and some cloud but dry for most. Brilliant weekend considering. Would have been nicer to keep the heat through Sunday but looking increasingly unlikely.

 

There have been signs however of a renewed surge of high pressure into Tuesday and Wednesday next week. Worth keeping an eye on for sure 

[knocker]

Perhaps one thing worth a comment vis the gfs this morning that is at variance with last evening and that is the second Iberian low is no longer tracking north and impacting the country on Monday with thundery outbreaks but rather has renewed ridging from the south west a la ecm. The question of cloud amounts is always tricky in these situations as it depends are quite a few variables such as geographic position  linked to wind direction (precise position of the HP). My broad take on it as a general overview, and this is just my opinion , is the latter part of the week could well be better as drier air from the SE becomes prevalent

Meanwhile just to quickly reiterate,

Weds sees the high cell covering the UK with just the very north of Scotland looking at cooler and a tad unsettled. There is a big latitudinal temp spread of 12C - 26C.

From here the upper trough to the west deconstructs (relevant to the evolution next week) with yet another cut off low established, the surface high tracks east initiating the southeasterly flow, and the shallow Iberian low tracks north into southern Ireland. Temps generally still in the 24C-26C range.

This low moves away rapidly NE and deepens with a weak band of showery rain crossing the country Sat/Sun before renewed ridging from the south west and another battle between this and  the major Atlantic trough and the Iberian low pressure into next week.

So in a nutshell some dry warm weather for the rest of this week, small hiccup on Saturday, then a continuation of dry but temps nearer normal next week.,

Edited May 22, 2017 by knocker

[Man With Beard]

ECM 00Z continues to be a little different. It doesn't develop the breakdown low for Saturday night that much, and as a result has a much slower clearout of the hot air. Sunday and Monday therefore still potentially in the 80sF. But most other models seem to be going with a Saturday night breakdown.

[mb018538]

That's ok with me! A nice week, warm/hot thu/fri/sat and maybe sunday....potentially a new high pressure building in next week too. It's May, and an absolute bonus. Enjoy it people, a week ago we were shown deep lows over the UK this week! I present exhibit A:



Versus what we are actually going to get:



I for one will be enjoying every minute. Have a good week!

[Gordon Webb]

1 hour ago, knocker said:

Perhaps one thing worth a comment vis the gfs this morning that is at variance with last evening and that is the second Iberian low is no longer tracking north and impacting the country on Monday with thundery outbreaks but rather has renewed ridging from the south west a la ecm. The question of cloud amounts is always tricky in these situations as it depends are quite a few variables such as geographic position  linked to wind direction (precise position of the HP). My broad take on it as a general overview, and this is just my opinion , is the latter part of the week could well be better as drier air from the SE becomes prevalent

Meanwhile just to quickly reiterate,

Weds sees the high cell covering the UK with just the very north of Scotland looking at cooler and a tad unsettled. There is a big latitudinal temp spread of 12C - 26C.

From here the upper trough to the west deconstructs (relevant to the evolution next week) with yet another cut off low established, the surface high tracks east initiating the southeasterly flow, and the shallow Iberian low tracks north into southern Ireland. Temps generally still in the 24C-26C range.

This low moves away rapidly NE and deepens with a weak band of showery rain crossing the country Sat/Sun before renewed ridging from the south west and another battle between this and  the major Atlantic trough and the Iberian low pressure into next week.

So in a nutshell some dry warm weather for the rest of this week, small hiccup on Saturday, then a continuation of dry but temps nearer normal next week.,

I can live with this

[knocker]

16 minutes ago, Man With Beard said:

ECM 00Z continues to be a little different. It doesn't develop the breakdown low for Saturday night that much, and as a result has a much slower clearout of the hot air. Sunday and Monday therefore still potentially in the 80sF. But most other models seem to be going with a Saturday night breakdown.

As you say the ecm is different and doesn't have the low as a well defined feature on Saturday and before the next ridge it runs a small perturbation north east from the Iberia/cut off low region to dissect Britain midday Sunday with cooler thundery region to the NW and the dry in the S/SE. A very marked temp gradient with 28C-30C in the latter and 12C -14C in the north and even 10C in Aberdeenshire

Edited May 22, 2017 by knocker

[Summer Sun]

UKMO extended shows a new area of high pressure trying to develop at D7

[Andy Bown]

55 minutes ago, mb018538 said:

That's ok with me! A nice week, warm/hot thu/fri/sat and maybe sunday....potentially a new high pressure building in next week too. It's May, and an absolute bonus. Enjoy it people, a week ago we were shown deep lows over the UK this week! I present exhibit A:



Versus what we are actually going to get:



I for one will be enjoying every minute. Have a good week!

That in a nutshell shows the complete fallacy of getting hung up on model runs anything other than 5 or 6 days ahead. At less than a week ahead that forecast chart is horrendously inaccurate!

So with that in mind, next Sunday is as far away on today's runs!

[Singularity]

Pretty neat how a low is predicted by all models to slide SE into Iberia even as the preceding one (however shallow it is) drifts N into/through the UK, with this new feature 'propping up' a decent new ridge from the SW early-mid next week.

This is of course how a reloading pattern of fresher settled - increasingly warm/hot settled - thundery - fresher settled can be achieved. Well - with a bit of luck...! 

[Glacier Point]

5 minutes ago, Singularity said:

Pretty neat how a low is predicted by all models to slide SE into Iberia even as the preceding one (however shallow it is) drifts N into/through the UK, with this new feature 'propping up' a decent new ridge from the SW early-mid next week.

This is of course how a reloading pattern of fresher settled - increasingly warm/hot settled - thundery - fresher settled can be achieved. Well - with a bit of luck...! 

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.

[mb018538]

Also worth noting that human input is valuable with regard to temperatures in times such as this:

 

GFS only going for 23/24c in the SE Saturday with 850s over 15c, very little cloud, no rain and a slack southerly flow. I think we all know we can add 3-5c on to these figures. BBC currently showing 28c, but if it verifies as shown, I wouldn't be surprised to see somewhere nudge 30c.