Model output discussion - deep cold inbound?

[Notty]

Look at that for a temperature gradient in Europe !

Actually looks a little ridiculous

Edited February 5, 2021 by Notty
Addition

[Updated_Weather]

MetO have issued a large 3 cold weather alert until Wednesday at least.

also come on people take an op run as gospel, things will change a lot throughout this week, I doubt it will just all be gone just like that..

[ianmm94]

in FL, but it's trying to throw up heights into the atlantic and up into the Greenland/Iceland area here

 

[Djdazzle]

6 minutes ago, radiohead said:

Increasing confidence with each run that milder air will push in from the southwest from Thursday. There is still time remaining for that to change, it's still 6 days away and we all know how much the 144 charts can change, but I do think it looks likely at the moment. There seems to be little in terms of blocking to prevent the Atlantic pushing in. Our best hope is for the low pressure to slide south and hopefully we will see hints of that cropping up on the models soon. But whatever happens, at least the cold spell from the weekend to Thursday does look 100% locked in at this change and some places will be seeing signifcant snow.

I'd still give it no more than 50:50 at this range.

[Updated_Weather]

I will quote what EssexWeather have said regarding prolonging of the cold

“There will always be brief milder interludes on the south-western quadrant of the block when lows approach, but the cold will fight back. Unlike in 2018, we have an extra month of the season in our favour. UKMO 30 day forecast is way more crediable than any one model at T+192”

also said this

“Weather models continue the cold theme with a strong easterly in place from Sunday. With the jet stream south of the UK, the dense cold air mass will not be going anywhere fast. A lengthy cold spell on the way, coldest of the winter so far”

Edited February 5, 2021 by Vadoseflame

[geordiekev]

16 minutes ago, KTtom said:

Very lttle battleground with the gfs 06z once again, mild air pushes through quickly to cover all areas by this time naxt week. Hard to believe how quick the transition takes place?!

According to 0z ECM the snow line remains at zero ASL up till midnight Next Sunday, for most of us, so I wouldn't say quick & as most know things can easily change in the space of 10 days

Edited February 5, 2021 by geordiekev

[ICE COLD]

This run looks interesting around day 10 ? 
 

 

Edited February 5, 2021 by ICE COLD

[Liam J]

No point looking for trends from the GFS atm especially the OP. 
 

00z

06z

Edited February 5, 2021 by DisruptiveGust

[frosty ground]

Just now, ICE COLD said:

This run looks around day 10 ? 
 

 

Once chase ends another begins. 

[Don]

15 minutes ago, Notty said:

Look at that for a temperature gradient in Europe !

Actually looks a little ridiculous

Talk about quick transition from winter to spring!

[geordiekev]

2 minutes ago, ICE COLD said:

This run looks around day 10 ? 

My giddy Aunt the potential reloads are spoiling us & not to be unexpected with a smashed vortex 

Edited February 5, 2021 by geordiekev

[IDO]

You can see the potential from the gfs 06z run at d6 with battleground snow, although this is in fact a snow to rain event on this run:

If we could get the Atlantic to slowdown and stall, somewhere will get copious amounts of frontal snow. Each run, as we would expect, currently offering a different take on Thursday "battle". No real trend yet apart from the date when the low gets close. We can see from the post-d8 charts that background processes are occurring so this is very dynamic, even entropic ATM? Just compare the d8 0z and 06z gfs op charts:

A watching brief and the weekend should resolve this better?

[sheikhy]

Gfs your hilarious!!!talk about inconsistency!!!something is defo brewing for the end of next week!!a sudden growth of scandi heights and cold air pushing back westwards?!

[Don]

1 minute ago, DisruptiveGust said:

No point looking for trends from the GFS atm especially the OP. 
 

00z

06z

Chalk and cheese!  FI day 6 ATM, as we don't know if and how the breakdown will occur?

[ICE COLD]

T270 looks even more interesting . 
 

@frosty ground lol they’ll definitely be another chase . 

[Tim Bland]

1 minute ago, frosty ground said:

Once chase ends another begins. 

I think it’s quite likely the next chase won’t be too far away given the background signals. I still doubt we can avoid a brief milder spell from next weekend though 

[That ECM]

On your marks,  get set, go!! And we are off on another chase. Looks a bit marginal in the south east corner.

Edited February 5, 2021 by That ECM

[pyrotech]

5 minutes ago, DisruptiveGust said:

No point looking for trends from the GFS atm especially the OP. 
 

00z

06z

Especially trying to compare Apples v Pears

Trends show comparing 0z v 0z or 06z v 06z

 

[MildCarlilse]

12 hours ago, Ice Day said:

Beautiful at 120 - low gone under, cold still completely in charge

 

Today’s profile with next Sunday...

[Purga]

Interesting (like Steve Davis ) GFS 06z brings back blocking and an easterly after D10.

Another twist to the drama?

 

[Battleground Snow]

I don't think we are done with this cold spell just yet,  MOGREPS is hinting the breakdown won't occur until day 9 or 10. It's really frustrating we are not able to access this data.

Attached GEFS up to 150, incredible spread even at day 3 and 4.. op generally above the mean.

 

[SqueakheartLW]

Now that we appear to have established a cold spell is almost certain now my main focus now is on when it is likely to come to an end. After yesterday's 18z GFS completed the set of sub -10 850hpa temperatures for the peak of the cold spell with a -10.6 which is -7.2 below the long term mean and my 2nd coldest value so far. From today's 00z my focus switches to when the average 850hpa temperature moves back above -5 at 850hpa which to me is the end of the colder spell. This followed by the predicted peak average temperature of this milder spell

What I will be looking for here is how much the end of the colder spell gets pushed back and also how much the milder spell can be watered down until it doesn't exist.

00z GFS

Today the first assessment of the end of the colder spell brings this in at 162 hours away. Here are the average charts for this time period.

As you can see here, low pressure on average bringing a switch from SE to SW winds and no doubt a transitional snow event as the milder air makes its way back in. 850hpa temperatures at this point are -4.0 which is -2.3 below the long term average. The anomaly chart clearly shows up the transition zone with the blues retreating to the north and the yellows and oranges waiting to move in from the south.

The peak of this milder spell comes at 240 hours away. Here are the average charts for this time period

Very much back to standard Atlantic weather again with SW winds and low pressure parked in a typical spot to our NW. The 850hpa temperatures at the mild peak are 1.6 which is +3.9 above the long term mean. The anomaly chart shows this up well with the yellows and oranges covering the UK.

00z GEM

How does the GEM fare against GFS in terms of the end of the cold spell. On the 00z GEM it comes at 174 hours away. The 850hpa temperature at this time is -4.9 which is -3.0 below the long term mean. No doubt just like GFS there will be a transitional snow event as this takes place.

The peak of the milder spell comes at 234 hours away with 850hpa temperatures at 1.1 which is +3.2 above the long term mean. Slightly less mild than the GFS but then no surprises there really with the mild Atlantic bias the GFS has compared with GEM.

GFS Extended

When does GFS Extended bring in both the end of the cold spell and the milder peak. The end of the cold spell on this run comes at 186 hours away.

A slightly better looking chart for the pressure pattern compared with the 00z GFS. This one has a chance to become a slider event instead with the angle of the low pressure on average. Milder air already into the SW but with 850hpa temperatures over Scunthorpe still at -4.8 which is -3.1 below the long term mean then we are still in with a chance of extended cold. The anomaly chart is making less of the milder conditions to the south compared with GFS 00z. Hope the Extended is more on the mark than the main GFS runs.

The peak of the milder spell on GFS Extended comes at 288 hours away

A typical SW wind chart with low pressure out to the NW comes with this milder peak. 850hpa temperatures here are 0.5 which is +2.7 above the long term mean. This is less mild than the main GFS run so is a watering down process already under way. I hope so. The anomaly chart also reflects this less mild setup with more yellows than oranges near the UK.

[ICE COLD]

2 minutes ago, That ECM said:

On your marks,  get set, go!! And we are off on another chase.

The chase is on . Should count down with no dramas really

[geordiekev]

1 minute ago, ICE COLD said:

T270 looks even more interesting . 
 

@frosty ground lol they’ll definitely be another chase . 

I would have thought many will take pole position for the next chase, if Atlantic rise follows on so quickly after this spell.

As there are still many spots still with cover from 3 days ago, my lawn has only just cleared today.

Just remember to look out the window now & then

[johnholmes]

39 minutes ago, Jayces said:

Always enjoy your refreshing down to earth analysis @johnholmes but with many on here often talking about FI being five or so days ahead and sometimes even less than that in these unusual (for us) situations how confident are you that the cold will clear in 9-10 days?  

An interesting question, I'm just about to post the 500 mb anomaly charts, and they, to me, do suggest that the 'cold' is likely to end the following weekend. So some 10-12 days ahead. the charts, especially those from NOAA, are not often wrong but I do prefer to see a 'run' of at least 2-3 days before I feel confident in the upper air pattern being what they show. Today is the first time all 3 are suggesting the return of the Atlantic. They are supported though by the ECMWF charts I've started to use. At the moment I would say, if I was a betting man (I'm not!), about 40-50% likely.

Anyway below is the text to go with these charts

Anomaly charts Friday 5 February

Ec –gfs and noaa

Both show a stronger atlantic flow into the uk and from s of west.

Noaa shows similar especially its 8-14 chart, and the exit of the n’ern portion of this flow over the eastern atlantic is diffluent which suggests lows running quickly along the atlantic then deepening, on current charts, about 20 west, thus turning ne off, most of the time, nw Scotland? This would imply milder air over much of the UK.

However, models are no better at predicting cold break downs than we were before the advent of computers. Cold air is dense to milder air (less dense) finds it not easy to move it. Time will tell, as ever!

sorry my pc, for some reason, has stopped letting me run more than one window at once, so will post the links as I can

http://www.meteo.psu.edu/fxg1/ECMWF_0z/hgtcomp.html

Climate Prediction Center - 6-10 Day 500mb Outlook

WWW.CPC.NCEP.NOAA.GOV

 

 

 

 

Edited February 5, 2021 by johnholmes