Model Output Discussion - Into Summer 2020.

[johnholmes]

4 minutes ago, mb018538 said:

Its here @johnholmes

As you say - foolish to try and predict ppn totals, models often get this badly wrong.

thanks mb, not my chart but it illustrates how much rainfall this run of this model is showing. 

[Paul]

UKV going for some large totals too..

 

[Man With Beard]

Rainfall totals on the ECM this morning up until T168. I've seen drier, but also seen a lot, lot wetter. Though given the timeframe little you can do with these values except to predict there will be at least some heavy rain at some point:

 

North Scotland: 5-20mm

South Scotland: 15-40mm 

Northern Ireland: 10-20mm

North East England: 30-60mm

North West England: 10-30mm

Central England: 5-15mm

East England / E Anglia: 5-20mm

Wales: 20-70mm (higher totals on high ground)

South West: 20-70mm (highest in Cornwall/Devon)

South East: 5-15mm

 

Tempertaures are widely low to mid-twenties from Saturday onwards, so if it does rain, at least it will be mild

 

 

[Azazel]

Im terrible at reading charts - can somebody tell me if the coming weekend’s precip values will be from convection or from dynamic frontal rainfall?

[mb018538]

Heres the ecm rainfall plot @Azazel

Likely to be mainly frontal down towards the SW/Wales (high ground especially) closer to the low. Perhaps more convective if warmer/humid air comes in off the east into those areas

Edited June 8, 2020 by mb018538

[Tamara]

3 hours ago, NApplewhite said:

Two areas of Low pressure will dominate the weather week commencing 15th June 2020 and turning much colder.  No sign of any settled weather on the horizon.  Washout and zero sunshine over the weekend of 19th  - 21st June 2020. 

 

3 hours ago, NApplewhite said:

In summary - dire GFS for Heat and sunshine lovers!

 

 Will Noah visit Chipping Sodbury, or *insert town of choice* with his ark (?)  

Mood driven invective often results in loss of clarity and perspective, so some further retrospective analysis might help to we know why we have arrived where we are, and then what is set to happen over the coming days as processes keep evolving. Apologies, I admit much of this has been exhaustively dealt with previously, but  operational output "model hugging" can mean that objective facts c/o the diagnostic can get buried in translation

 So, as previously suggested during last week, there is uptick of trade winds (shaded blue on the Hovmollers plot) towards the dateline in the Pacific as convective suppression occurs in wake of the convectively coupled kelvin wave (CCKW) returned through the Western Hemisphere to the Indian Ocean.

This the cue to scrub westerly inertia from the global atmospheric circulation.   The uptick in easterly inertia across the Pacific creates a negative mountain torque response (Pacific jet retraction) across the Himalayas. Indicated in red on the Global Synoptic Dynamical Model (GSDM) plot. 

This has set up the much anticipated retrogression of the hemispheric pattern from the Pacific and a subsequent re-configuration of the downstream signature and switch from the fine warm sunny weather that stretched in to the first couple of days of June c/o our downstream ridge - to a retracted Atlantic ridge, slump in pressure across NW and central Europe and winds of polar origin. Hence the unpalatable June conditions since the end of last week that are set to continue into this week as the retrogression process continues. This allows the Icelandic trough, midweek, to slip down the eastern perimeter of the retrogressed Atlantic ridge and disrupt into the continent.

The retrogression is then completed as the  Atlantic ridge amplifies over the top of the trough and extending eastwards into Scandinavia. By the weekend, the trough is re-set to our west and south west and warm humid air advects westward and chilly rain is replaced by a much more seasonal convective variant and less by this time in terms of dynamic rainfall. Caveat for those in environs of Chipping Sodbury *she says jokingly*. (In seriousness a quaint and charming English town) x

The outlook continues to revolve around where angular momentum finds its floor and how much returning upstream momentum helps reinforce the re-set trough just to the west and south west . If momentum stays somewhat suppressed then this might invite the trough to phase from the Atlantic to the thundery heat lows close to the UK and the continent and then for another retracted amplification of an Atlantic ridge to force the humid thundery set-up further into central and eastern Europe and cooler air to arrive from the NW.

However, should there be some momentum uptick this will reinforce the re-set trough to the west and help prop up downstream high pressure to the north east and every chance of a renewed plume scenario from the south.

.....?

This is the watching brief for the extended period, but certainly a warm-up later this week and through the weekend especially into the start of next with a mix of summer sunshine, most particularly away from influences of the trough to the south west (parts of Scotland look well set for this perhaps as one example) and also with so much moisture left around in the atmosphere, the instability triggering probable development of thunderstorms particularly where and when the sun does get to work for periods of time.

Not a settled pattern, but certainly one that is more seasonal than what we currently have and also one to please weather enthusiasts

 

[Man With Beard]

GFS 06Z is curious. Up to T108, it's pretty much as before. But then the low to the SW decides to be adventurous and set sail towards to America! 

  

[Leo97t]

It feels like you don't get average spells of weather anymore it's either way above or below - always above it winter

[NApplewhite]

14 minutes ago, Man With Beard said:

GFS 06Z is curious. Up to T108, it's pretty much as before. But then the low to the SW decides to be adventurous and set sail towards to America! 

  

It sets sail for America but then gets stuck off SW Ireland and merges with another low so not much of a westward movement. Hopefully this will reduce the rain totals in England and Wales due to this and allows in a warm and humid easterly flow. 

[sheikhy]

Much less rain fall on ecm today again!!not bothered with the gfs any more lol!!!ukmo looks pretty good but a risk of more widespread showers at 144 hours!!!

[Guest]

15 minutes ago, Man With Beard said:

GFS 06Z is curious. Up to T108, it's pretty much as before. But then the low to the SW decides to be adventurous and set sail towards to America! 

  

Not for long though and get squeezed back towards the UK with northerly blocking showing its face. While much warmer in the south east and drier in near term its never going to be a synoptic pattern that settles us down longer term. Just appears to be one of the many possible outcomes. 

 

[NApplewhite]

3 minutes ago, NApplewhite said:

It sets sail for America but then gets stuck off SW Ireland and merges with another low so not much of a westward movement. Hopefully this will reduce the rain totals in England and Wales due to this and allows in a warm and humid easterly flow. 

Looks very unsettled for the next 16 days though! up to +384

[MATTWOLVES 3]

GFS 6z not heading in a pretty direction, with low pressure stuck over us at day 8-10,also noticing Heights over Greenland... Not to say this spells doom but the low pressure is struggling to go anywhere fast. This could be an outlier again as it rarely agrees with its mean. In the shorter term ECM hi res shows potential rainfall amounts this week.. And the rainfall tends to look more scattered come the Weekend... But let's face it someone out there is going to cop a deluge. 

[NApplewhite]

2 minutes ago, NApplewhite said:

Looks very unsettled for the next 16 days though! up to +384

I dont like this chart for this Wednesday! 

[mb018538]

By day 6 most ecm members have the trough just about at arms length to the SW. the real issue then is shown by this day 7 chart - how much can the high to the east fight back and push it away?

[StormChaseUK]

06z is good, if the high to the east can keep the low at bay and we get stuck in warm flow , excellent outcome.

[Guest]

The Ops run is again a cold outlier for several days against a pretty tightly grouped ensemble pack - however as we saw just a few days ago the GFS ensembles showed universal agreement against anything unsettled so feels kinda pointless looking at them.

[mb018538]

2 minutes ago, MikeC53 said:

It shows the low edging in giving copious rainfall to Western areas for about a week.

It’s not that bad - 25-50mm widely across 10 days. Nothing like the 100mm other runs were showing.

As others have said - it’s not worth worrying about the run to run rainfall variance at this range. The fact that it can change by 20-40mm from one run to the next tells you all you need to know. 

[johnholmes]

5 minutes ago, MikeC53 said:

It shows the low edging in giving copious rainfall to Western areas for about a week.

Fact rather than your fiction, if anyone would like to check on the Net Wx Extra rainfall accumulation charts for 168h (7 days) ahead, and it actually shows somewhat less than the 00 z.

Why are you doing this please?

[northwestsnow]

4 minutes ago, Alderc said:

The Ops run is again a cold outlier for several days against a pretty tightly grouped ensemble pack - however as we saw just a few days ago the GFS ensembles showed universal agreement against anything unsettled so feels kinda pointless looking at them.

I concur.

Its becoming ridiculous the number of GFS ops that are outliers to the suite..

In fact, after another disaster as early as t96 recently one can't help but wonder if GFS just needs unplugging.

All that said , trying to get a handle on this troughs behaviour will not be easy for any of the models ..

[johnholmes]

It is a very unusual low especially its track. I cannot recall, at any time of the year, someone please correct me if they find one, that follows this track. Well the track predicted by the UK Met O Fax charts. It deepens in not much more than 48 hours from 1012 mb to 996 mb as it traverses from northern Scotland down into the Bay of Biscay. No wonder the models are having issues with its track, depth, and what rain falls out of it.

A very interesting spell of weather for all we weather enthusiasts. Let is just hope that no area suffers too much from the rainfall that does fall from its passage.

 

With maximum temperatures depressed below the expected values for this time in June, imagine a similar low in mid winter!

Edited June 8, 2020 by johnholmes
spelling

[Iceaxecrampon]

CAPE for this weekend - as predicted last Tuesday.

[Guest]

5 minutes ago, johnholmes said:

It is a very unusual low especially its track. I cannot recall, at any time of the year, someone please correct me if they find one, that follows this track. Well the track predicted by the UK Met O Fax charts. It deepens in not much more than 48 hours from 1012 mb to 996 mb as it traverses from northern Scotland down into the Bay of Biscay. No wonder the models are having issues with its track, depth, and what rain falls out of it.

A very interesting spell of weather for all we weather enthusiasts. Let is just hope that no area suffers too much from the rainfall that does fall from its passage.

 

With maximum temperatures depressed below the expected values for this time in June, imagine a similar low in mid winter!

I  certainly don't anything like this, its unusual in that it is certainly a different process of how we end up with troughing or near the UK. The only thing more odd I can conjour up is if you had a low moving into the UK from the south east from say central Germany but that's me completely making something up!  

But you are certainly right, if it were mid January the excitement would probably be too much to handle! 

Edited June 8, 2020 by Guest

[MikeC53]

19 minutes ago, johnholmes said:

Fact rather than your fiction, if anyone would like to check on the Net Wx Extra rainfall accumulation charts for 168h (7 days) ahead, and it actually shows somewhat less than the 00 z.

Why are you doing this please?

I was referring to after that time period the Low to the West edges back in from T180 onwards.

[ChannelThunder]

From memory, I seem to recall a few low pressures taking this track down the years, so this one doesn't strike me as all that bizarre, but unusual, yes.