Model output discussion 10/02/21

[zubzero]

Forgetting the crazy odd cold run in lala land. Some of the uppers shown on the GEFS are insane some show +12c. I think peoples perceptions of  March cold are based on the recent cold ones this past Decade. Most cold spells away from the North are rare, and brought about by northerly toppler type cold not rare raging easterlys.

[Don]

13 minutes ago, MATTWOLVES said:

Blimey Don your updates are getting as inconsistent as the mets..last night the roller coaster was in for repairs,24hrs later and its decommissioned for a year!! You won't get many visitors to your Theme Park this year mate..

Lol!  The roller coaster hasn't been decommissioned yet, but there are technical issues which are proving to be difficult to rectify!  I will post an update on the situation tomorrow evening..... 

[Tim Bland]

12z Vs 18z the definition of uncertainty

[MATTWOLVES 3]

7 minutes ago, Tim Bland said:

12z Vs 18z the definition of uncertainty

Worlds apart Tim...just clock that cold pool...

 

 

 

[Mizzle]

As one who is slowly learning I like to check the models, decide what I think it means and then check in here to see if my interpretation was correct. Tonight I see this! What would this FI weather be because I can't work it out.

[drm]

15 minutes ago, Mizzle said:

As one who is slowly learning I like to check the models, decide what I think it means and then check in here to see if my interpretation was correct. Tonight I see this! What would this FI weather be because I can't work it out.

If your after cold you'd certainly want the low to the north of Scotland 500 miles further south,the weather on the day of the chart would most likely be cold rain 

Edited February 15, 2021 by drm

[zubzero]

1 hour ago, Mizzle said:

As one who is slowly learning I like to check the models, decide what I think it means and then check in here to see if my interpretation was correct. Tonight I see this! What would this FI weather be because I can't work it out.

If you want to learn the models I'd focus on the ens, in the 5+ day range its pointless trying to pin down any details on individual charts 10+ days away. Use high res models in the 24-48 hour range even then its hard to pin down. Snow events /Thunderstorms ect. With any great detail.

Edited February 16, 2021 by zubzero

[Cold Winter Night]

1 hour ago, Mizzle said:

As one who is slowly learning I like to check the models, decide what I think it means and then check in here to see if my interpretation was correct. Tonight I see this! What would this FI weather be because I can't work it out.

Taken at face value, the weather with this chart would be very cloudy, rainy and chilly. Not much wind though (isobars far apart). Unpleasant weather for most still.

There would be some discussion in here about what the heights near Scandi will do, if they increase, they could move the cold West.
The Greenland High is retreating and will not help much, but the jet and the train of lows that accompany it are on a very Southerly trajectory, so it will remain on the colder side, rather than milder. Technically not a West-based negative NAO, but the effect is the same.

However, this is so far in FI, you might as well take out your own crayons to create a nice looking chart and it would be equally likely to become reality.

If you want to learn how to "read" the developments, look at closer timeframes, in the Northern hemisphere view mode.
Look at how Highs and Lows interact, look at other charts, like the 850 hPa temperature charts, the jet stream chart to see how the flow is tilted in a direction that either promotes blocking (buckling jet) or a flatter, zonal pattern (high speed, straight jet stream).
Then try to predict what every next frame will look like and see where you were right or wrong.

[syed2878]

1 hour ago, Tim Bland said:

12z Vs 18z the definition of uncertainty

can you please explain the uncertainty because the GFS only showing on called in the ensemble and UK but has now totally drop the cold forecast in their extended outlook they going more to wards mild than cold

[Mizzle]

@Cold Winter Night and @zubzero thank you for those great tips, much appreciated.

[Jordan S]

A very early post from me so morning

It will be very unsettled this week and likely particularly wet for some Friday and especially Saturday.

Rain moving northeast tomorrow and more once again on thursday, a low pressure system will develop to the south of tomorrow's low and move northeast, becoming very windy for England and Wales as this moves across..

Then on friday a large low pressure system approaches bringing a very windy day for many and mild, it will become very wet for a time for south and perhaps west Scotland, and also western parts of England and Wales with 50-80mm likely on some higher ground and possibly upto around 100mm in the wettest places by the end of Saturday.. 

The jetstream making slow progress east during the weekend for a time as higher pressure building to the southeast slows this process along with the rain.

Mild in the south and east but dependent of the progress of the rain in western areas temperatures of 12-14c and a very mild 15-16c is a possibility locally. 

The first half of next week staying mild for most with values of 12-14c likely for England and Wales and potentially as high as 16-17c in a few places, also remaining wet at times probably mostly for northern Ireland and Scotland.

After Wednesday next week its more likely that things become drier but possibly colder at night in particular.

Here's a Gfs overview for the next few days..

Edited February 16, 2021 by jordan smith

[Daniel*]

Not greatest direction we appear to be heading for warm and fine weather, increasingly UKMO charging jet stream right as us.

 

GFS also not really interested this morning too much strength in upper low.

[mb018538]

1 hour ago, Daniel* said:

Not greatest direction we appear to be heading for warm and fine weather, increasingly UKMO charging jet stream right as us.

 

GFS also not really interested this morning too much strength in upper low.

Was going to post the same @Daniel. The amplified very warm southerly and high temperatures is just being chiselled away as the models have underestimated the strength of the Atlantic. Could just end up fairly mild, wet and windy instead of very mild and drier.

[bluearmy]

The gefs are still sniffing around a retrogression of the mean ridge late week 2 .....whether it can get far enough west is the question but the upstream vortex extension has shown signs of pulling back towards Newfoundland which does allow for a griceland height rise ..... Then we have to look at what happens to our south and east ..March cold is tougher than feb .........

[NewEra21]

Ensembles definitely not as mild as they have looked in previous days

[DavidS]

1 hour ago, mb018538 said:

Was going to post the same @Daniel. The amplified very warm southerly and high temperatures is just being chiselled away as the models have underestimated the strength of the Atlantic. Could just end up fairly mild, wet and windy instead of very mild and drier.

Yes the much warmer upper uppers looking to be kept just to the south and or east of the UK. Past D10 the GEFS are suggestive of something cooler.

[Empire Of Snow]

Morning all. Too much uncertainty in FI but early signs indicate the deep cold reforming in NE Russia. Where this cold ends is still up for grabs but as it stands now a shift west is not favorable. Classic pattern again for another blast to SE Europe. Even though chances are slim right now for us, let's wait another 2-3 days. METO didn't drop completely the possibility of a return to cold/snowy conditions in their extended forecast. 

[SqueakheartLW]

Not a lot of cold showing up in the GFS 18z, 00z or GEM 00z. I have however picked out the best charts I could find across all 3 models

GEM 00z

GEM 00z is in general mild all the way if you base it purely on the ensemble mean. I have however picked out the best cold charts of a generally bad set of ensembles

GEM 00z Member 17     +360 hours away     850hpa temp -8.7

Cold uppers here with a weak surface low pressure. Could see some snow here but mostly at night when temps are lower and any sun during the day soon melting any of the snow or even turning the snow back to sleet or rain in the daytime maxes

GEM 00z Member 10     +384 hours away     850hpa temp -9.2

A cold anticyclonic option here. Cold sunny days but some decent frosts by night. Probably colder than the above option overall due to colder nights.

GFS 18z

GFS 18z like the 00z to come have in general maintained their less mild theme compared with GEM and some of the colder options are really decent too but the problem is that there are few of them. I have picked out the best ones I could find on the 18z

GFS 18z Member 9     +180 hours away     850hpa temp -8.8

If you are that desperate for something colder to turn up in closer range then this is the best I could come up with I'm afraid. A besterly is the best thing on offer here with some quite cold uppers heading in from the west. Could produce snow here with sea surface temperatures probably around the lowest for the year. Could be good news for those who missed out on snow in the latest easterlies in the west.

GFS 18z Member 28     +306 hours away     850hpa temp -13.8

A fairly decent cold easterly here and generally anticyclonic in the north and less so further south where snow showers could be a factor with decent uppers too. Could produce some more significant falls if parameters fall right at the time

GFS 18z Member 30     +330 hours away     850hpa temp -18.0

Feast your eyes upon this beast. -18 uppers which is just slightly colder than the 2018 beast. This one is very close to the one that featured in the 12z. A real snow maker here with the large temperature contrast between the North Sea and those -18 uppers. Even some western areas could get in on the act with this setup

GFS 00z

How does the GFS 00z fare in terms of cold fantasy charts compared with the 18z. Quite a few more cold charts showing up in the 00z but like with the 18z all are in FI territory. I have ordered these charts from least cold to coldest at the end.

GFS 00z Member 30     +360 hours away     850hpa temp -9.8

The joint least cold option and this one is generally high pressure dominated so a cold and sunny option here with overnight frosts. Maybe small risk of wintry showers in the SE of the UK here.

GFS 00z Member 26     +384 hours away     850hpa temp -9.8

This one looks brilliant even if 384 hours away and is a much better position than the first option. May be down at the least cold end of the scale as the beast is only just getting going by the looks of this chart and much colder weather is yet to come. An increasing risk of snow here and it would be good to see how this one would progress beyond 384 hours away. As the GFS extended appears to be based on an 00z run I wonder if this run will feature in the extended either today or tomorrow.

GFS 00z Member 8     +342 hours away     850hpa temp -10.0

Slightly colder than the first 2 options but also the driest option so far with high pressure generally centred over the UK so a cold and dry option here with frosts at night. Would be even colder if snow already on the ground but with how things are before this stage then that is unlikely.

GFS 00z Control     +318 hours away     850hpa temp -11.0

A bit of a beasterly option here, at least for the south anyway. Cold uppers and a cold easterly flow here. Most likely generally dry due to the SE element to the wind direction but significant wind chill the most likely situation in the south and frosts in the north under the high pressure.

GFS 00z Member 29     +366 hours away     850hpa temp -11.0

A proper Arctic shot here on Member 29 with decent uppers and a real risk of snow showers in the N and E and with this proper convection under the unstable northerly so some decent falls of snow in the exposed locations. Northern Scotland the most favoured area of the at risk regions.

GFS 00z Member 21     +348 hours away     850hpa temp -12.2

Northerly number 2 here and an even more potent one than the previous option. This one similar to above but more likely even greater snow risk with stronger winds driving the snow further S and W than in the first northerly option.

GFS 00z Member 4     +294 hours away     850hpa temp -13.0

Member 4 is the start of what is a cold run from this point right out to 384 hours away so overall the run I would pick out for longevity of the cold rather than a short sharp burst of extreme cold. May be generally high pressure dominated here at the start but low pressure does feature at times during the rest of the run so snow chances are present.

GFS 00z Member 18     +384 hours away     850hpa temp -14.2

Finally the best one of them all, at least for having the coldest uppers already in the UK. Beast from the east unleashed here with a decent shot at some significant snowfall from convection. Could be a chance of something more persistent in the south near the low pressure area. I'd either take this Member 18 option or I would take Member 26 knowing what was about to arrive soon after the chart showing

[mb018538]

Most of the longer term ECM 00z clusters keep high pressure very close to/over the UK at day 10-15. Exact position would of course determine surface temps.

[feb1991blizzard]

Here she comes!!

EDIT : good run this, it now shows how even a very slightly West based setup is possible which is good news, given every half decent ruun lately has ended up showcasing a miss to the East, problem still remains though, just not sure how the atmosphere is primed for a ridge that far North, whatever longitude it is.

Edited February 16, 2021 by feb1991blizzard

[DavidS]

Will it go up?

 

[DavidS]

3 minutes ago, DavidS said:

Will it go up?

 

I’ll answer my own question - yes. Big time!

 

[feb1991blizzard]

Pity its a big outlier because if it wasn't, we would be into territory of looking at these charts again.

https://images.meteociel.fr/im/6857/gfseuw-16-360_gtb9.png

 

[Empire Of Snow]

Decent 06z by GFS. If I'm not mistaken it's the first one bringing us back in game even at 300h+. Good to see the +10 and +12 uppers scenarios dropped for now. Save them for late spring and early summer. 

[Slippery When White]

10 hours ago, Cold Winter Night said:

Taken at face value, the weather with this chart would be very cloudy, rainy and chilly. Not much wind though (isobars far apart). Unpleasant weather for most still.

There would be some discussion in here about what the heights near Scandi will do, if they increase, they could move the cold West.
The Greenland High is retreating and will not help much, but the jet and the train of lows that accompany it are on a very Southerly trajectory, so it will remain on the colder side, rather than milder. Technically not a West-based negative NAO, but the effect is the same.

However, this is so far in FI, you might as well take out your own crayons to create a nice looking chart and it would be equally likely to become reality.

If you want to learn how to "read" the developments, look at closer timeframes, in the Northern hemisphere view mode.
Look at how Highs and Lows interact, look at other charts, like the 850 hPa temperature charts, the jet stream chart to see how the flow is tilted in a direction that either promotes blocking (buckling jet) or a flatter, zonal pattern (high speed, straight jet stream).
Then try to predict what every next frame will look like and see where you were right or wrong.

Thank you CWN, that was a really useful post about model watching/interpretations