Model output discussion - into July 2020

[Downpour]

11 minutes ago, swfc said:

Morning NW .What's this "det" you include in a lot of your postsI'd agree also in regard to the Azores high influence but whether it has any longevity remains to be seen with all usual caveats .tia

Deterministic run I think i.e. the op run

Edited July 12, 2020 by Downpour

[Frosty.]

Wow what an incredible GEM..of course, I only say that because it shows high pressure!..but joking aside, I’m seeing great potential from the mods, I mean the models?..the ECM 0z mean for example!...for summer fans..err, in the height of summer..ja ist gut?!!!

Edited July 12, 2020 by JON SNOW

[swfc]

29 minutes ago, Downpour said:

Deterministic run I think i.e. the op run

So it's the operational run, ok cheers.ecmw looking nay to bad today but the current fluctuations are atm are quite strong

Edited July 12, 2020 by swfc

[Tamara]

Um bom dia para todos

The switch of the tropical signal to Africa and the Western Indian ocean as summer arrived has marked the extent of the fall in global atmospheric angular momentum since the beginning of June. Registering at -2SD (standard deviations) below average, global momentum has been depicting a typical traditional La Nina type atmospheric circulation as manifested by anomalous Pacific and Atlantic ridging and downstream trough arrangement. Up to this time, this has fully underpinned the elusive nature of the Azores High in flattering to deceive with its eastward ridging to deflect Atlantic low pressure areas from moving west to east too close to the north of the UK and the complete absence of any continental influences since the very warm spell in the last week of June.

However, upward trending frictional torque tendency has continued further, which as explained previously, translates to some added forcing to tropical>extra tropical propagation processes leading to a lagged subtle alteration of the downstream pattern c/o greater rossby wave induced anticyclonic wave-breaking from the sub tropics . This process is not invalidated by the constant distractions of cent capricious numerical models, and still looks set to provide some diffusion to the unfavourable progression of low pressure areas. Mostly, NWP is now advertising this much more consistently - albeit some erratic progress towards it has still continued from one suite to another.

 

With that in mind, the latest post by @johnholmes aptly observes within his customary very experienced summary, how numerical models struggle in these situations, and why taking them at face value with their flip flopping around over the finely balances wind-flow inertia upstream is better advised to monitor over a day or two rather then drawing instant conclusions with each and every operational output. 

2 hours ago, johnholmes said:

Sunday 12 th July

An update as the models have altered some items shall we say on the chart for 6-10 days.

Ec-gfs now show differences quite markedly from the charts issues only yesterday; ec has shifted any +ve height rises well into the atlantic beneath a less marked trough and its forward part is now shown over or indeed e of the uk. Gfshas ‘lost’ any indication of height rises s of the uk, it has any very small such rises off the eastern seaboard into s Greenland, the trough is not far from its suggested position yesterday.

Meanwhile noaa has put a small area of +ve heights over the s of the uk and n france, little signal for this yesterday, and has changed the depth and position/orirntation of the trough.

All told sufficient differences in 24 hours to say the upper air pattern seems more fluid than usual and best not taken too much for granted until we get consistency over 2-3 days and both run to run and with one another. Unusual for this lack of confidence in them at this time of year.

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

Climate Prediction Center - 6-10 Day 500mb Outlook

WWW.CPC.NCEP.NOAA.GOV

 

 

To manage expectations - based on the unfavourable La Nina aspect to the global circulation,  rossby wave propagation in this sector of the NH is not going to be as effective as it was so consistently during the Spring to create long lasting anticyclonic spells. There will still be some innate tendency for NWP to want to retrogress the pattern from time to time. But the second half of July continues to hold the prospect of more settled and warmer conditions with the constant interruptions of cool air from the northern and eastern Atlantic c/o of low pressure systems passing too close to the NW, becoming fewer and further between.

 

On 09/07/2020 at 23:56, CreweCold said:

Solar min...

The jet is constantly being corrected S by the modelling as we get closer.

It will likely be the same this winter...

 

22 hours ago, 38.7°C said:

I shall believe these model runs when they're inside the five day range. They'll most likely get watered down as we approach those time frames. I saw a post somewhere else the other day suggesting that the jet stream is responding to solar minimum and it has been pushed too far south and models just aren't really getting to grips with the jet until its inside the reliable time frame. Explains why all summer we keep seeing ridging at Days 8/9/10

The essence of the upstream pattern has been due to North Pacific ridging configuring the flatter supressed jet downstream pattern and retracted sub tropical ridge. The e/QBO signature has not been ascendant, which with a La Nina type forcing would have augmented a much more definitive -ve AO signal, and also with the absence of the Azores ridge trying to adjust eastwards from time to time, a persistent southerly tracking low pressure c/o an authentic -ve NAO would develop instead. As occurred during summer 2007. Despite the jet stream following a path at a lower latitude than once might hope for, a bone fide -ve AO/-ve NAO has simply not been the case through this first half of the summer

Clearly this illustrates that low solar activity has no one size fits all correlation to a suppressed jet stream, but depends on whether the polar or ferrel cell is in ascendancy. As many posts have illustrated so many times - there has been sporadic forcing from the  equator evident so far this summer which has bolstered the ferrel cell, and while it has still not prevented the less than inspiring conditions of the last fortnight, still shows that actually it could have been  worse still than this.

A fast downwelling e/QBO would have had profound effects on stratospheric downwelling  of negative zonal winds and coupled with low angular momentum and low solar forcing - creating  a locked in cool and unsettled pattern. Whilst some for whatever reason, are evidently dreaming of this even in high summer, despite the disappointing end to June and first part of July, the pattern is not locked in this way, with some warmer drier spells evidently appearing in the modelling.

 This subject has been previously discussed and outlined in detail at least a couple of times in recent weeks as to the plethora of factors that are interactable and determine the macro scale pattern. There is simply no one size fits all x=y correlation. Much of this though is related to weather preference bias (especially when out of season winter aspirations keep being referenced).

Obrigada e cumprimentos

 

[johnholmes]

Re your post commenting on my earlier one Tamara

Thanks for your usual in depth input. 

What puzzles me re the 500 mb anomaly sets, and not just this morning, it has already happened twice if not three times in the past 2-3 weeks, it is whatever the long term pattern and teleconnections may or may not show, in 10 years of daily watching and logging them into my weather files on my pc I cannot recall them being so unreliable this early in summer. One of their 'weak' spells is at the northern hemisphere seasonal change over, winter to summer and summer to winter. Another weak period is the north Atlantic main hurricane season. Note I write main, so I rarely see this happening before late August at the earliest. I have no idea why it is showing this weakness in reliability for predicting the main trough-ridge pattern, perhaps some change in logarithmic input into the main models is causing this, just a thought. 

What would you speculate might be a possible reason, or indeed anyone else that posts in heer?

 

 

[Frosty.]

Wow, not the best Gfs 6z operational, however, for the south there’s plenty of ridging for most of the run so nae so bad darn sarf but for the north it’s a bit of a bum deal..ps..great post as always from Tamara, sorry tams, can’t add anything at this time.

ps..no disrespect to southerners, my dads an eastender!

Edited July 12, 2020 by JON SNOW

[Guest]

GFS 06Z Ops run a pretty big outlier in the south however I still don't like the continual tendency for almost every GFS & ECM Ops to be an outlier currently, very little consistency beyond 5days. Still the mean 850s for GFS above 10C for 4 or 5 days down here from the weekend although again the coming week less than straightforward with fronts, cloud and drizzly bit of rain coming around and over the top of our high pressure and cooler 850's that'll only be mixed out in a slack pattern.

[Zak M]

Nice to wake up to a positive set of runs!

Thought I would include the 00z ECM clusters @144:

And feast your eyes on the GEM... 

[Frosty.]

Well, looking at the GEFS 6z mean I’m seeing what is essentially a north / south split although some would see this as a simplified assessment, I think it’s about right although this is only based on the 6z mean, there is tons of other model output which may be telling a different story?..anyway, for southern u k, especially southern England it’s probably quite a decent outlook, increasingly naff the further north you go!?

charts not in the correct order..I’ve been drinking, I actually enjoy posting more when I’ve had a few..less inhibitions !!!.hiccup..

Edited July 12, 2020 by JON SNOW

[mushymanrob]

2 hours ago, johnholmes said:

Re your post commenting on my earlier one Tamara

Thanks for your usual in depth input. 

What puzzles me re the 500 mb anomaly sets, and not just this morning, it has already happened twice if not three times in the past 2-3 weeks, it is whatever the long term pattern and teleconnections may or may not show, in 10 years of daily watching and logging them into my weather files on my pc I cannot recall them being so unreliable this early in summer. One of their 'weak' spells is at the northern hemisphere seasonal change over, winter to summer and summer to winter. Another weak period is the north Atlantic main hurricane season. Note I write main, so I rarely see this happening before late August at the earliest. I have no idea why it is showing this weakness in reliability for predicting the main trough-ridge pattern, perhaps some change in logarithmic input into the main models is causing this, just a thought. 

What would you speculate might be a possible reason, or indeed anyone else that posts in heer?

 

 

Could it be down to disruption caused by unusually deep, early,  tropical storms in the western Atlantic injecting more energy then usual into the North Atlantic mix?

[johnholmes]

I think that has to a possible even probable  reason mushy, but then why are they so early?

[Frosty.]

As I mentioned already, the last third of July may be preety decent across southern parts of the u k as these GEFS 6z charts show, of course this doesn’t preclude that more of the u k won’t see some summery weather to!..it’s very quiet in here..is everyone busy watching England lose at cricket (as usual)?

[mushymanrob]

31 minutes ago, johnholmes said:

I think that has to a possible even probable  reason mushy, but then why are they so early?

I have no clue, lol, good question though.. perhaps the Azores high is weaker then usual? due to AAM being weak? maybe @Tamara may have some insight into this , as, if i understand her last post correctly (and i may be well off) it would suggest so?... Total guess, but maybe these early vigorous TS energy/influence may have been lessened IF the Azores high was stronger, as in being held in position longer but if whatever drives the AZH is weak then its protective influence is reduced?

I dunno.... im just thinking out loud and may be miles off...

[MATTWOLVES 3]

2 hours ago, JON SNOW said:

Well, looking at the GEFS 6z mean I’m seeing what is essentially a north / south split although some would see this as a simplified assessment, I think it’s about right although this is only based on the 6z mean, there is tons of other model output which may be telling a different story?..anyway, for southern u k, especially southern England it’s probably quite a decent outlook, increasingly naff the further north you go!?

charts not in the correct order..I’ve been drinking, I actually enjoy posting more when I’ve had a few..less inhibitions !!!.hiccup..

You say its quite in here Karl... Just a thought most people are lapping up the sun after 3 weeks of crap, rather than sitting infront of the box watching England trying to play cricket... Just a thought..

Icon looks rather good, even suggests an Azores/scandy link up... Better output it as to be said... Beautiful here today... More mixed through till. Midweek before improving later in the week and warming up towards the weekend...

[northwestsnow]

Superb UKMO this evening...

Nasty troughing sent packing as the Azores high flexes  it's muscles, must of had some spinach..

Peak summer too,couldn't have been timed better...

 

Edited July 12, 2020 by northwestsnow

[Zak M]

[Djdazzle]

Jet looks to be trending further north, which can only be a good thing.

[Guest]

UKMO looks decent @ T144 but the pattern is starting to get squeezed and flattened and the GFS output after a couple of warmer days in the extreme south (Fri & Sat) turns to a northerly, we'll be very unlucky to end up with that.....

[Djdazzle]

2 minutes ago, Alderc said:

UKMO looks decent @ T144 but the pattern is starting to get squeezed and flattened and the GFS output after a couple of warmer days in the extreme south (Fri & Sat) turns to a northerly, we'll be very unlucky to end up with that.....

I don’t see how the UKMO 144 chart can’t lead to a prolonged warm spell. The jet is to the north and there is a positive tilt to the Azores high ridging in. Not bothered what GFS does with it!

[I remember Atlantic 252]

2 minutes ago, Djdazzle said:

I don’t see how the UKMO 144 chart can’t lead to a prolonged warm spell. The jet is to the north and there is a positive tilt to the Azores high ridging in. Not bothered what GFS does with it!

Key EC coming up then, GFS is awful

[MATTWOLVES 3]

12 minutes ago, I remember Atlantic 252 said:

Key EC coming up then, GFS is awful

Why is it a key ECM! I'm pretty sure we had this conversation on here the other day when just because we had a dodgy GFS run, some were saying big ECM run coming up! Does GFS ever put 2 or 3 runs together the same! I think this model is becoming pretty pointless tbh, pergaps it's time it had another upgrade, cause the last one seems to have Downgraded the model. 

I was almost waiting for your most favourite comment of... Hey the Atlantic always dominates in July and August.. UKMO looks good.. I look forward to Mondays EC46.. Don't get to stressed over GFS it really is struggling. 

And talking about some good runs... Not a bad GEM out to day 7..

Edited July 12, 2020 by MATT☀️

[Tim Bland]

Massive ECM coming up. Could be life changing!!!

[summer blizzard]

GFS and UKMO are essentially arguing about the low near Iceland. It starts to deepen before weakening and the differences in the strength and timing are why the models disagree. Very strange at such close range but then it's strange to deepen then weaken. 

[Guest]

21 minutes ago, Djdazzle said:

I don’t see how the UKMO 144 chart can’t lead to a prolonged warm spell. The jet is to the north and there is a positive tilt to the Azores high ridging in. Not bothered what GFS does with it!

Famous last words, all you’d need is the eastern extension of the high to build further and pressure would drop over the U.K

[Mike Poole]

So T144, key time, here’s UKMO, GFS, GEM, 

I’m thinking a UKMO/GEM blend will be the result, we will see...