Model Output Discussion - early October

[Daniel*]

Abandon all hope, ye who enter here.. major flooding looks to strike again day 5-12 period looks very unsettled and actually cool at times. One thing of note in ext EPS no real indication of a mighty vortex?

[Man With Beard]

2 hours ago, jordan smith said:

ECM accumulated rainfall for the next 10 days yes very wet particularly for England, Wales and Ireland.. 

GFS ensembles still very unsettled after Wednesday.

 

Could be even more trouble ahead with flooding if latest charts come off. 100mm in 10 days - while not extreme - have to bear in mind the quantity of rain already fallen in places. Besides - the ECM charts for D6-D10, if verified, are ripe for something even more significant to arise. 

[Jordan S]

4 minutes ago, Man With Beard said:

Could be even more trouble ahead with flooding if latest charts come off. 100mm in 10 days - while not extreme - have to bear in mind the quantity of rain already fallen in places. Besides - the ECM charts for D6-D10, if verified, are ripe for something even more significant to arise. 

They have been pretty consistent the last couple of days.. I agree could be a signal for even wetter conditions than currently indicated which is wet enough.. 

[Frosty.]

I think I can say without fear of contradiction that tonight's Ecm 12z ensemble mean is heading in an unsettled direction!

[Cheshire Freeze]

19 minutes ago, Man With Beard said:

Could be even more trouble ahead with flooding if latest charts come off. 100mm in 10 days - while not extreme - have to bear in mind the quantity of rain already fallen in places. Besides - the ECM charts for D6-D10, if verified, are ripe for something even more significant to arise. 

A lot of the country doesn't realise how wet it is across parts of Wales, the Midlands and N England. Nantwich, about 5 miles from here, has been under water the past couple of days as the River Weaver burst its banks. The modelling hardly fills me with joy right now.

Cheshire floods cause more chaos across county - Cheshire Live

WWW.CHESHIRE-LIVE.CO.UK

---

There has been a further day of chaos caused by flooding

 

Edited October 27, 2019 by CreweCold

[Catacol]

1 hour ago, knocker said:

Just to repeat what Nick said earlier

The intensification of now Hurricane Pablo continues. Despite moving over 15-20C SSTs, cloud tops continue to cool & the eye has cleared out further. In the modern satellite era, it is unprecedented to have a hurricane this far north & east in the NATL basin (42.8N/18.3W).

H/t Philippe Papin

Which does, in itself, raise a number of questions. Hurricane/Typhoon development is an area I know next to nothing about - apart from the obvious bit about warm oceans sparking things off and sustaining them. Given we have already had one record breaking atlantic hurricane hit the Azores this season, and we currently have yet another record breaking storm sitting off the west coast of India (and forecast to do much to enhance a downstream meridional jet pattern over the coming period) there are variables at work that fall outside of known parameters I would suggest. Ryan Maue has recently tweeted an opinion that the pattern that has led to a cut off cold pool east of California, and encouraging the winds that are doing so much to create chaos there, has its origins in arctic forcing due to ice loss.

It's too early for me to get excited yet about winter prospects - the next 2 - 3 weeks will be key in setting up the early winter context and at that point I might take a punt - but the salient point to make here I think is that our weather is fast becoming extremely unpredictable. Maybe it is because I am looking for examples....maybe it is because the media gives us eyes we didn't have in the past - but maybe not. Instead it may actually be the case that we are now on an ever steepening gradient towards weather extremes and some aspects of modelling may become less rather than more accurate in this context. I'm far from convinced (yet) that a significantly +NAO winter is approaching - though at some point 88/89 or 98/99 will happen again...but I am increasingly convinced that extreme cold events are going to become a part of NH winters to come and while they may be outnumbered 5:1 in frequency when compared to extreme mild/wet episodes when they strike they will be severe.

Much to ponder in our global weather at present. Anyone with knowledge of hurricane formation got information on how a hurricane can be sustained over such relatively cool SSTs in the atlantic?

[Ross90]

20 minutes ago, JON SNOW said:

I think I can say without fear of contradiction that tonight's Ecm 12z ensemble mean is heading in an unsettled direction!

 

The low doesn't look quite as deep on that run as it has on previous runs.990mb on Nov 5th, i'm sure it was 975mb yesterday...

[Robbie Garrett]

14 minutes ago, Catacol said:

Much to ponder in our global weather at present. Anyone with knowledge of hurricane formation got information on how a hurricane can be sustained over such relatively cool SSTs in the atlantic?

I believe this is the discussion from NOAA/NHC.

"It is likely that cold upper-level temperatures have allowed the cyclone to maintain deep convection and lead to the formation of a warm core, while Pablo continued strengthening over cool water temperatures where tropical cyclones normally weaken. Still, the current SSTs underneath Pablo are so far below those usually needed for tropical development, that Pablo must be incredibly efficient at extracting heat from the ocean surface below (as well as low-level surrounding air, probably)."

Quote

000 WTNT43 KNHC 272032 TCDAT3 Hurricane Pablo Discussion Number 9 NWS National Hurricane Center Miami FL AL182019 500 PM AST Sun Oct 27 2019

Pablo continues to have a remarkably impressive appearance for a tropical cyclone over such cold waters. The hurricane's eye remains evident in most satellite imagery channels, with a solid ring of cloud tops colder than 50C surrounding it. This maintenance of the deep convection can be attributed to an environment of very cold temperatures aloft, which can allow for the hurricane to remain intact over waters colder than those typically observed. The latest subjective Dvorak intensity estimate from TAFB remains unchanged from 6 hours ago, while the objective estimates from UW-CIMSS have increased slightly. The initial advisory intensity has been increased to 70 kt, and this could be a little conservative.

There are strong low-level easterlies associated with a baroclinic zone and frontal boundary located a couple hundred miles north of Pablo. The hurricane is expected to begin interacting with this zone soon, which combined with even cooler waters should make the cyclone lose its tropical characteristics within the next 24 hours. The system is then expected to become absorbed by the circulation of a much larger low as it approaches from the west in a couple of days.

The initial motion is now 020/20 kt. There is significant spread in the model guidance beyond 24 hours, as the ECMWF and UKMET turn the post-tropical cyclone to the northeast, while the remainder of the guidance turns it northwest. The official forecast follows the majority of the guidance and the previous forecast. In this scenario, Pablo is expected to turn northward and slow its forward motion tonight as it approaches the frontal zone. Then, a turn toward the northwest on Monday is expected as the larger low to its west begins to steer the cyclone. FORECAST POSITIONS AND MAX WINDS INIT 27/2100Z 44.7N 17.2W 70 KT 80 MPH 12H 28/0600Z 46.5N 16.8W 60 KT 70 MPH 24H 28/1800Z 47.7N 17.2W 55 KT 65 MPH...POST-TROP/EXTRATROP 36H 29/0600Z 49.0N 18.0W 50 KT 60 MPH...POST-TROP/EXTRATROP 48H 29/1800Z...DISSIPATED $$

Forecaster Latto

 

[knocker]

31 minutes ago, Catacol said:

Which does, in itself, raise a number of questions. Hurricane/Typhoon development is an area I know next to nothing about - apart from the obvious bit about warm oceans sparking things off and sustaining them. Given we have already had one record breaking atlantic hurricane hit the Azores this season, and we currently have yet another record breaking storm sitting off the west coast of India (and forecast to do much to enhance a downstream meridional jet pattern over the coming period) there are variables at work that fall outside of known parameters I would suggest. Ryan Maue has recently tweeted an opinion that the pattern that has led to a cut off cold pool east of California, and encouraging the winds that are doing so much to create chaos there, has its origins in arctic forcing due to ice loss.

I

 

The record breaker at the moment is Tropical Cyclone Kyarr in the Arabian Sea and be wary of quoting Maue as he is prone to sarcasm when it comes to linking climate change with current events

 

[Mike Poole]

So it is flatfish time for the vortex on the GFS 18z, here T138, one eye over N America, one on Siberia, where's yer money?  

The tail might beat against the water, but I don't think it will stop us getting a right soaking!

Edit, no getting round this one it seems, every model has it, T186:

Oh dear! Flush, please!

Edited October 27, 2019 by Mike Poole

[feb1991blizzard]

Steady as she goes on this run maintaining the status quo from the 12z more or less up until 150.

[Ross90]

The gfs has been pushing that low further south over the last couple of days, any further and it'll be over the channel.The ecm has it centred about 300 miles further north...

[feb1991blizzard]

Frigid cold filtering down into Scandi nicely ready for later in the run hopefully.

 

If only we could get a clean separation of energy here we would be right in business

Edited October 27, 2019 by feb1991blizzard

[booferking]

8 minutes ago, feb1991blizzard said:

Frigid cold filtering down into Scandi nicely ready for later in the run hopefully.

Here she comes.

[feb1991blizzard]

Here she comes 

EDIT : Beaten to it!

Edited October 27, 2019 by feb1991blizzard

[Mike Poole]

Pub run T312:

Not saying it is gonna happen, but these situations are in the  game from now on, just have to roll the dice....

[phil nw.]

Good to see 2/3 days of crisp Autumn weather to allow some drying out but the latest fax charts show another wet spell is on it's way later in the week.

The day 5 NH 500hPa chart shows the southerly tracking jet is doing us no favours really firing more Atlantic rain bands at the UK.

[Jordan S]

1 hour ago, JON SNOW said:

I think I can say without fear of contradiction that tonight's Ecm 12z ensemble mean is heading in an unsettled direction!

The GFS chart looks very good and dry for early November actually..

Oops sorry wrong year this is it yeah very wishy washy (unsettled) ..

JMA for example.. 

On a more serious note this is a soggy end to Halloween into November for all parts..

GFS. 

Edited October 27, 2019 by jordan smith

[Duane S.]

Two things to watch for me over the coming weeks, an increasingly southerly tracking jet and very little appetite for a sustained euro high. We may well have to endure a (further) period of VERY wet conditions but I think thereafter things could get interesting.

With a fierce vortex spinning up in the strat but likely to struggle to propagate downwards with ease and couple with the TPV, I can see future major disturbances afoot. Strong warmings and wave activity.

This is shaping up to be fascinating start to the season...

Edited October 27, 2019 by s4lancia

[Catacol]

3 hours ago, knocker said:

The record breaker at the moment is Tropical Cyclone Kyarr in the Arabian Sea and be wary of quoting Maue as he is prone to sarcasm when it comes to linking climate change with current events

 

And meanwhile, back on topic, the anomalies for Bonfire Night not yet showing the +NAO imprint that modelling is touting....but it is early days yet. As said earlier the next 2-3 weeks will begin to give us a steer.

[knocker]

Outlook - Most areas will have a respite from the unsettled weather for the next three days, the exception being Cornwall and the far reaches of the south west courtesy of Pablo dragging the old front back north, the indications of which can be seen on the Camborne midnight sounding.

A little more detail starting with the North Atlantic 500mb and surface analysis for midnight and the 0400 UK chart

As can be seen a frosty start in many areas with the odd fog/mist patch around but once these clear a dry and sunny day for most areas. Perhaps some showers along the north east coast in the northerly wind and cloud and light rain will ingress Cornwall during the day as already mentioned

A similar story overnight with frost and mist/fog patches and becoming a tad breezy in the south west

A similar scenario on Tuesday, quite windy in the south west with a now quite complex frontal system quite adjacent as the pattern that has previously been discussed begins to unfold

Overnight Tuesday through Wednesday the unfolding continues resulting in an elongated trough with positive tilt to the west of the UK, with the high cell that has been influential for a couple of days, being shunted east as further troughs are poised to exit Canada.Much of the country still sunny and dry after another morning frost, but the cloud and patchy rain in the south west will move a tad further north east

By Thursday the high cell is removed from the scene to the east as the trough comes under increasing pressure from the west. All of which results in fronts crossing the country thus sunny intervals and periods of rain

By Friday the two troughs have almost merged and a quite intense surface low has arrived over southern Ireland with the associated fronts sweeping across the country bringing rain and quite strong winds, albeit accompanied by a rise in temperature,

And to digress for a moment. In case a comment I made last evening is misconstrued (heaven forbid that should happen in this thread, I am fully aware of the possible connection between Arctic warming and a meridional jet and future extreme weather events as Dr Jen Francis and others have written papers on the subject in recent years.In case some are not familiar with some of these:

https://royalsocietypublishing.org/doi/pdf/10.1098/rsta.2014.0170

https://www.carbonbrief.org/qa-how-is-arctic-warming-linked-to-polar-vortext-other-extreme-weather

 

[knocker]

From this point we are on dodgy ground because the gfs has the new trough approaching from the west undergoing explosive cyclogenesis near the left exit of a very strong jet which is not indicated by the fax but of course this is where the fax charts end. I'm not happy with this so just the weekend and really just to note at the moment before a look at the ecm

 

Edited October 28, 2019 by knocker

[knocker]

The ecm is pretty close to the fax midday Friday but it too has a trough undergoing explosive cyclogenesis as it tracks quickly down from the Labrador Straits south of the low near the tip of Greenland

Run this on over the weekend and this development is obviously something that has to watched quite carefully

[bluearmy]

7 hours ago, s4lancia said:

Two things to watch for me over the coming weeks, an increasingly southerly tracking jet and very little appetite for a sustained euro high. We may well have to endure a (further) period of VERY wet conditions but I think thereafter things could get interesting.

With a fierce vortex spinning up in the strat but likely to struggle to propagate downwards with ease and couple with the TPV, I can see future major disturbances afoot. Strong warmings and wave activity.

This is shaping up to be fascinating start to the season...

It’s been the marker of the autumn thus far that the week 2 modelling has promised a strengthening pos AO and NAO yet this hasn’t managed to stick .....

 now we see a trend whereby week 2 begins to show the opposite ........ it’s going to be November ......... I’m starting to get a little bit interested, especially as the Sod’s law that tends to  govern uk winters means that the strengthening SPV will eventually take control - is an early front loaded winter our chance for 19/20 ???  

[Blessed Weather]

The ECM and GFS 8-10 Day 500mb Height Anomalies ending 5th Nov in agreement that the strong negative EPO pattern continues in the Pacific with a strong ridge over Alaska. The downstream consequence is the deep trough over the UK and Europe.

8-10 day hgt anom:

GFS charts for the 5th Nov showing the strongest 500hPa pressure anomalies in the NH are the Alaskan ridge and UK trough and the UK on the cold side of the jetstream as it dives into Africa: