Model output discussion - first hot, thundery plume of the summer

[knocker]

Quite illuminating to compare the ecm and gfs 5-10 anomalies and it illustrates once again the dodgy business of jumping too far ahead when assessing the output

 

Edited July 17, 2019 by knocker

[weathermadbarnsleylad]

Ecm is very strange to me. Totally diff from yesterday I won't trust any model beyond 96hr. Its all to do with how the energy is placed. Its no where near sorted in my opinion. I think we will something in between the gfs and ECM warm start to next week 30+ etc but I don't think the Atlantic will come in a quick as forecasted this evening from the ecm. 

[MATTWOLVES 3]

It's not a bad mean... We have some very warm conditions still next week... Before a slight cooling from the NW later. I will leave it to you good folks to make your own mind up regarding this... Because I tend to see good things... When's it's clearly bad....

[Singularity]

The trouble is, we have a potential major heatwave that depends heavily on the behaviour of one unusually vigorous trough Mon-Tue next week.

Whatever it does, will strongly drive the weather one way or the other.

If a low digs south on the southern flank, the jet aligns south to north and the trough drives such strong amplification of the pattern that the resulting heatwave is more likely than not to have substantial duration, at least across W. Europe (the UK always has troubling caveats!).

If that doesn't happen, the jet aligns southwest to northeast, or even more toward west to east, and the heat gets shunted away from the UK within a couple of days and W. Europe generally within another day or two.

The critical period is now at 5-6 days range. We should know which way it's going to go by Friday evening. Brace yourselves - it could be a very bumpy ride!

[Frosty.]

Certainly a strong warm up across southern uk early to mid next week on the Ecm 12z ensemble mean, becoming hot and humid for a time across the s / se and then a gradual cool down..the far NW of the uk misses out completely  but there is still plenty of time to resolve who gets the heat, how long it lasts for and who misses out !!!!!!!!!!!

Edited July 17, 2019 by Jon Snow

[MATTWOLVES 3]

32 minutes ago, ANYWEATHER said:

Evening , next week's weather is out to the jury, a forecasters nightmare, but reading between the lines  a warm up for next week but with some Heavy thundery downpours  before the Atlantic air moves in.....that's my thoughts  with a human brain rather than a computer. ....

Your using the models for guidance on the warm up though. And only using what you think in your own head regarding the Atlantic breakthrough! Not having a go at you, far from it... But it seems quite a strange theory and prognosis...

Or I may have got the wrong end of the stick.. Perhaps you mean that's your thoughts completely regarding the output. And this is what you think will play out!

Edited July 17, 2019 by Mattwolves

[thestixx]

9 minutes ago, Singularity said:

The trouble is, we have a potential major heatwave that depends heavily on the behaviour of one unusually vigorous trough Mon-Tue next week.

Whatever it does, will strongly drive the weather one way or the other.

If a low digs south on the southern flank, the jet aligns south to north and the trough drives such strong amplification of the pattern that the resulting heatwave is more likely than not to have substantial duration, at least across W. Europe (the UK always has troubling caveats!).

If that doesn't happen, the jet aligns southwest to northeast, or even more toward west to east, and the heat gets shunted away from the UK within a couple of days and W. Europe generally within another day or two.

The critical period is now at 5-6 days range. We should know which way it's going to go by Friday evening. Brace yourselves - it could be a very bumpy ride

It's the start of the school summer holidays so I'd definitely back your latter summation!

[knocker]

The EPS mean anomaly is relatively progressive with the trough

Edited July 17, 2019 by knocker

[MATTWOLVES 3]

The mean certainly indicates a drop in temperature, and its slowly but surely catching the op up.... The pressure remains stable.... Shall we say!! But overall its certainly dropped away compared to more recent runs... Looks like a 50/50split either side of the mean... 

Edited July 17, 2019 by Mattwolves

[mb018538]

12z ecm op was bottom of the pack. Looks like Monday, Tuesday and Wednesday will be hot before a slow slide back down to normality. I would think a 32c/90f will appear somewhere by the middle of next week in the SE, with a small possibility of the really hot stuff wafting up for a 35c day. Could be some violent storms if the Atlantic bumps into the heat too, so we could keep plenty of people happy!

[Derecho]

39 minutes ago, Singularity said:

The trouble is, we have a potential major heatwave that depends heavily on the behaviour of one unusually vigorous trough Mon-Tue next week.

Whatever it does, will strongly drive the weather one way or the other.

If a low digs south on the southern flank, the jet aligns south to north and the trough drives such strong amplification of the pattern that the resulting heatwave is more likely than not to have substantial duration, at least across W. Europe (the UK always has troubling caveats!).

If that doesn't happen, the jet aligns southwest to northeast, or even more toward west to east, and the heat gets shunted away from the UK within a couple of days and W. Europe generally within another day or two.

The critical period is now at 5-6 days range. We should know which way it's going to go by Friday evening. Brace yourselves - it could be a very bumpy ride!

The ECM ensemble spread agrees, large uncertainty in SLP to our west early next week 

Standard deviation near to 10mb to the North of the Azores.

Edited July 17, 2019 by Quicksilver1989

[MATTWOLVES 3]

Interesting tussle going on here, the Gfs legacy bringing the core of the heat straight into the UK at 150hrs. The FV3 is shunting that heat East by this stage, although it does manage to become very warm/hot in central and SE/E areas for a time. Be interesting to see wether the models downplay this plume tomorrow morning, or indeed strengthen it.. 

 

 

 

[Catacol]

6 hours ago, Tamara said:

In terms of my own 'at home' observation as a fascinated pattern watch observer, there is no doubt in my mind that these sub tropical ridging patterns, whilst always a feature of greater trade wind phases, and typically subject to seasonal wavelength changes and Annular Mode variations, are becoming more and more dominant as part of shifts in long term global changes. With the tropics forcing one way, due to anomalous extra heating, set against the destabilised polar profile creating larger swings in AO responses as the sea ice patterns distort feedbacks there, a new way of interpreting composite analyses for H500 patterns is certainly required.   

...

The UK's fate, in terms of tapping into continental increases in heat, rests as usual in the actual wavelength that the sub tropical ridge amplifies. All tied into that primary wavelength dictated by frictional torque tendency within the Pacific, as just discussed according to the controlling tropical wave(s). But also the polar profile determining the latitude the ridging sets up.

 

Thanks Tamara for the detail and effort in this post. My eye was drawn in particular to these 2 paragraphs, both of which chime with my current thoughts. The twice mentioned polar profile to me is a key factor, not only for the potential impact of SSW events in the winter but also in helping "guide" the wave pattern over the atlantic as the jet exits the US landmass at any time of year. We have seen a long period of +NAO impact on our weather for the last 2 or so years, with low pressure over Greenland helping to reinforce the NE atlantic Azores ridge. Earlier this summer a rather dramatic switch to extended -NAO conditions with pressure high over Greenland helped suppress that same ridge...and while southern counties have become dry there has been a fairly constant stream of convective action for the northern half of the UK. There is a dance being played out here I think - particularly for the attempt to provide some kind of accurate forecast for the UK within the bigger GSDM global envelope - and that dance is becoming less predictable as you say. Ice melt in the arctic is reducing the temperature gradient overall, and changing energy feedbacks are making atlantic forecasting extremely tricky. What odds yet another SSW event this winter regardless of QBO and ENSO phase? I have a feeling we are going to see more winter warmings....and in turn feedbacks that will impact on following seasons.

In the end it's all fun. The context is ever changing, and the science ever improving. I'm happy if I can cling to the coat tails of those at the cutting edge of the debate, as I think is the case with your ability to grasp the complex interactions within the GSDM.

[Captain Shortwave]

   

  

Well the UKMO has turned up the heat on this with a much slower progression of that trough. Mid thirties by Wednesday if this came off.

   

   

GFS not a million miles away either, probably slightly less hot and more unstable as the trough approaches. But so far the models have suggested that this spell might last a little longer than yesterdays 12z suite.

[northwestsnow]

1 minute ago, Captain Shortwave said:

   

  

Well the UKMO has turned up the heat on this with a much slower progression of that trough. Mid thirties by Wednesday if this came off.

   

   

GFS not a million miles away either, probably slightly less hot and more unstable as the trough approaches. But so far the models have suggested that this spell might last a little longer than yesterdays 12z suite.

UKMO is el scorchio!!

Look at the uppers at 144!!

[Cheshire Freeze]

Looks like the potential for a very hot and thundery few days next week...BUT we've been here before!

[northwestsnow]

7 minutes ago, CreweCold said:

Looks like the potential for a very hot and thundery few days next week...BUT we've been here before!

Agreed.

UKMO surely would be very hot and very unstable if it comes off of course!

[knocker]

The North Atlantic 500mb and surface analysis for midnight and the 0300 UK chart

After a cloudy and muggy night in many areas (see chart) the front(s) associated with the low south east of Iceland will slowly clear the south east this morning but it remains quite warm here so showers, perhaps thundery,  will pop up during the day. Fresher elsewhere now but from the start frequent heavy showers will effect N. Ireland and western Scotland which will spread east during the day and possibly reach as far south as the north of England. All courtesy of a trough embedded in the circulation of the low.

Apart from the west coast of Scotland any showers will fizzle out this evening but by the ear;y hours the next frontal system is arriving from the south west and cloud and rain will be effecting Cornwall and south west Wales by 0600.

The frontal system will continue to track north east through Friday and rain will effect all areas, apart from the south east by evening. There could well be some heavy pulses across the Midlands and south with thunder in the mix and becoming quite windy as well in southern areas. Feeling much cooler than of late

Over Friday night and through Saturday the front(S) clear to the east leaving a day of frequent heavy showers courtesy of a couple of troughs embedded in the circulation. But things are afoot way to to west as another upper trough has dropped into the Atlantic.

By Sunday the new trough has merged with our in situ one to the north and we are now entering the critical phase of the energy distribution and the alignment of the trough and subsequently the amplification of the subtropical high. Thus we have surface frontal system running SW > NE bringing some rain to N. Ireland and western Scotland whilst elsewhere remains dry and warming up a tad

By Monday the trough is just about positively tilted to the west of Ireland and the amplification is well underway to the east so the UK is in a warm south westerly flow but is now trending very much towards a NW/SE split with a freshening wind and rain over the former

Edited July 18, 2019 by knocker

[knocker]

I should point out that the gfs surface analysis on Monday did not precisely coincide with Exeter

Anyway by Tuesday the trough is now digging a fair way south and become slightly negatively tilted  and thus the upper flow backs somewhat and warmer air is advected from the south

Over Tuesday night and through Weds the trough nudges east and cooler showery conditions prevail in western and north western regions

By Thursday the trough is over the UK and thus frequent showers but still quite warm in the south east

All of this is of course subject to change

Edited July 18, 2019 by knocker

[mb018538]

Epic ukmo run today, with 850s up to 23c by Wednesday. Looking more likely as we draw closer that it will be a plume followed by a low pressure breakdown, but there’s potential for 35c by midweek if that verifies.

We're also starting to see some ensemble grouping which is good news:



Looking hot Monday-Thursday/Friday before we start to head back down towards average. Still a few runs prolonging the heat, but the form horse looks to be a roughly 4 day event before a breakdown. Not too bad at all.

Edited July 18, 2019 by mb018538

[mb018538]

ECM also has a southerly by 144 hours with 850s above 20c in the SE:


 

Midweek looking very hot for quite a big slice of the UK.
 

[mb018538]

Also just to note:



The NAO is about to break it's 90 day streak of negative values. I *think* it has been the longest negative stretch of NAO in recorded history?

[northwestsnow]

EC 00z looks warm to hot, then warm and thundery..

By friday morning the uppers are still 12/13 across the SE ..

The uppers peak at around day 7 , and they are spicy, 21/22 into the SE.. temps into the low 30s i would guess, and probably be wrong.

 

Edited July 18, 2019 by northwestsnow

[knocker]

The movement and change of alignment of the upper trough in association with the jet and the subsequent movement of the ridge according to this morning's ecm. Thus very hot on Tuesday with temps noted in the low 30s in much of England before the cooler air moves in. This could be be a classic Spanish Plume scenario with the cooler air moving in from the west , mixing with the hot air in situ,  and thus increasing instability

Edited July 18, 2019 by knocker

[northwestsnow]

Then the run goes faulty as a low scoots across the UK from the south west- all the while a decent scandy high is in place..