Model Output Discussion - Into Autumn 2019.

[knocker]

And with this evolution some notable WAA into Greenland

[Newberryone]

Day 10 on the 12z Ecm would seem to suggest, albeit tentative in nature, a general settling down in conditions again courtesy of the familiar subtropical high with temps recovering to near or normal values after the weekends cool incursion. 

[knocker]

Yes indeed and the ext EPS is again along the same lines

 

[LRD]

48 minutes ago, knocker said:

Yes indeed and the ext EPS is again along the same lines

 

Quite a cool but, alas, dry looking chart that

 

[BlueHedgehog074]

One of the GFS’s brothers, Perturbation 11, has definitely thrown too much drink down its throat tonight from zee pub!

Maybe one of the very first few runs to send the -5*C 850 hPa temperature line over the UK for the beginning of October. Thanks to its strong blast from the North! Perhaps a bit of sleet or snow in heavier showers over modest ground (this more likely at night and early morning), especially over Northern UK. While I wouldn’t mind seeing further outbreaks of warm and bright Summery weather like what’s been occurring recently, this is all for a bit of fun. Probably only something that could happen in a dream at this time of year

[knocker]

The North Atlantic 500mb and surface analysis for midnight

Quite a complex frontal system is crossing the country at the moment consisting mainly of troughs preceding the cold front  Rain from the former is current;y down the spine of the country, with some heavy bursts. but the main rain belt is on the cold front and this will track north east through the day with some heavy pulses embedded within the area of rain. It should clear from the south west, albeit with showers, during the afternoon

Sporadic rain will continue on the weakening front through this evening and overnight finally clearing northern Scotland by dawn leaving a clear night in most areas with the odd shower

But there are rapid developments in the Atlantic and the next trough has arrived west of Ireland and rain from the associated fronts is quickly into the south west early Monday morning and this will spread north east during the day reaching south west Scotland and central England by 1800.

This complex frontal system will continue to swing north east overnight Monday and through Tuesday bringing rain with some heavy bursts to most areas along with quite strong winds.

By Wednesday a complex trough covers the eastern Atlantic and the UK resulting in a windy showery day with sunny intervals but upstream amplification discussed in previous posts is getting underway

The amplification continues apace through Thursday as the upper trough in the Atlantic edges east resulting in wet and windy Weds night and day Thursday

[knocker]

According to the gfs there is much going on upstream over the next two days as the upper trough remains in situ over the UK, The amplifying subtropical high in the western Atlantic forms a cut off high cell in the Greenland area, absorbing the one west of Norway which is replaced by a trough that has tracked east north of Greenland. But that does leave the way clear for the upper flow to resume tracking across the Atlantic

Thus the upper trough formed by the phasing of the two low centres is quite quickly moved east

All of this translates into a heavy showers with longer periods of rain Frid/Sat but drier on Sunday with still the odd shower around but longer sunny intervals

For what it's worth the ten day rainfall figures

 

Edited September 22, 2019 by knocker

[knocker]

And the ecm for next weekend

[Newberryone]

Certainly the consistent signal for height rises to the south as we begin a new month (Oct) seem to be still very much in evidence with nothing too ominous looking according to the 00z Ecm run. Perhaps a typical north/south split with the latter favouring out best as usual.

[Summer Sun]

No huge surprise to see ECM backing away from the cold runs it was producing towards months end the ENS never backed it and now the Op is finally catching up

London

Southern Scotland

Edited September 22, 2019 by Summer Sun

[Frosty.]

The week ahead looks unsettled / cyclonic with some very welcome rain for the parched southeast / east anglia but longer term there is a more benign / anticyclonic / blocking signal as we get into early october, shown on the Gfs 0z operational and the mean / perturbations..no guarantee but on balance that's currently the most likely outcome.

[Methuselah]

Agreed karl; though, the rapid spread among the 00Z outcomes (especially temperature-wise) from October 1st, doesn't inspire much faith in the GFS Operational...?

   

   

High to the east, or high to the west?

[knocker]

Not an entirely settled scenario tending towards a NW/SE split which of course means drier over the latter, temps above average

Edited September 22, 2019 by knocker

[NO LONGER POSTING]

Some of the older folk might be able to answer this one..

When was the last time a dry spell like this in the south was reported? I read somewhere last weel that some places are 300% below normal rainfall for the last 2 years. I'm not sure how you get to a static like that I'm trying to find the post on Facebook from a weather page that poped up.. 

But if this week is just a blip of unsettled and we revert back to high pressure again surely if you said look at days this year with pressure above 1000mb it would be quite an impressive figure.. 

Or does it just feel dry because of last years very hot and dry summer.. 

 

 

 

 

[knocker]

You can find the monthly rainfall stats for the climate stations, and others, on Roger Brugge's site

http://www.met.reading.ac.uk/~brugge/CURR.html

And a bit wet for the rugby

Edited September 22, 2019 by knocker

[Froze were the Days]

50 minutes ago, Surrey said:

When was the last time a dry spell like this in the south was reported? I read somewhere last weel that some places are 300% below normal rainfall for the last 2 years.

Can't remember what year it was might have been 2011 or 2012 which had a dry autumn which lead onto a dry winter, 2016 was pretty dry and warm by the time September ended if memory serves me right.

[knocker]

Current sat japan

Edited September 22, 2019 by knocker

[Methuselah]

So, the GFS Operational continues to seesaw between a warm-and-humid NW-SE split, and cooler/more unsettled generally? I guess the NW-SE split would be the more likely -- though, by no means nailed-on -- outcome?

   

[Derecho]

7 minutes ago, Ed Stone said:

So, the GFS Operational continues to seesaw between a warm-and-humid NW-SE split, and cooler/more unsettled generally? I guess the NW-SE split would be the more likely -- though, by no means nailed-on -- outcome?

   

Recent model runs (especially the GFS, the hurricane has been there on the last 4 runs at least) have been particularly bullish about developing a hurricane in the tropical North Atlantic and maintaining some strength towards the Azores.... which is a bit unusual given this is quite a long time away.

Given models often underestimate the strength of hurricanes I think this may be worth watching. The 06z resembles a similar pattern to Ophelia in October 2017 though as the recent model output uncertainty with a northerly has shown, any option for T192-T240 should be taken with a large pinch of salt.

Edited September 22, 2019 by Quicksilver1989

[Methuselah]

And, for the 06Zs, the Op has moved to the warm end...Where will go next?

   

   

Would certainly be a splendid run, were things to go that way!

[MATTWOLVES 3]

The ECM mean shows a marked improvement towards day 10,with high pressure gaining control to the South, and becoming warmer again!! Can't help but notice that lovely cold pool to the NE though.... Kind of dribbling at the mouth... But small things satisfy small minds.. Nothing to significant from the extended ensembles out to day 14 at this stage.... The mean in the South around 7C...The slp around 1016mb...very early days though yet... Hopefully a winter of Interest to follow. 

[knocker]

Some large Cu building to Cb here this afternoon, with a moderate rain/hail shower recently. The potential for cloud tops to around 20, 000 ft on the Camborne sounding

[SMU]

12z ICON presents a very blocked polar picture at 180 with a reverse flow across Russia -

It appears to be deeply -AO however due to the overwhelming heat ridges over some of the mid lattitudes it does temper the measure- 

Impressive for the time of year on the back of 2 startling statistics

- 2019 Record breaking year with the most consecutive number of negative NAO days

- 2019 highest 500MB height anomalies ever recorded over the Arctic region in the summer.

This in itself is enough to encourage winter lovers for the UK 2019/20 Winter.

Edited September 22, 2019 by Steve Murr

[feb1991blizzard]

Some quite staggering charts showing for this early, not even really out of the closed season yet, of course its arbitrary when it ends and not really a definition, but i would say its the point at which its scientifically possible for low level snow not just in the North to come into GFS range.

[Frosty.]

12 minutes ago, feb1991blizzard said:

Some quite staggering charts showing for this early, not even really out of the closed season yet, of course its arbitrary when it ends and not really a definition, but i would say its the point at which its scientifically possible for low level snow not just in the North to come into GFS range.

It's a recurring theme in that range..hope it's right..bring on the Arctic!!!!❄

Edited September 22, 2019 by JON SNOW