Model output discussion - into the start of Winter

[sheikhy]

Ive got this 80s feel right now!a week or so of cold dry frosty weather to get the ground temps ready for a dumping and then BANG snow everywhere!!!!

[Tim Bland]

Snizzle alert!!!

[jules216]

Sit rep from central Europe. EPS this morning look a lot different to last night EC 12Z which for some reason took a strange route with that low around Baltics. Now models seem to bring it to the west across me in Slovakia resulting in further cooling of central Europe. As we speak the inversion cold under current Euro high is rather impressive as lakes are starting to freeze and ice days appearing left right and center. Stable frost below -5C since the weekend cool NW arrived. Despite me not being a fan of inversion cold I understand it would be the second best scenario in winter in UK after snow  In that case I am "lucky" to be living in a valley that will still generate mean temperature well below 1981/2010 mean even under constant Euro high. Providing no sudden changes happen in models that would bring a stiff westerly in to central Europe I will be skating on deep frozen lakes as early as next week, snow though would be a big bonus for sure.  

[swfc]

1 minute ago, Tim Bland said:

Snizzle alert!!!

Pity the high isn't a 1ooo miles nw. Still it's a big change from the oz even at 144 hrs 

[Jeremy Shockey]

GFS 6z for 4th Dec 850s

I think we ( cold lovers ) would take this for 4th Dec if it transpired.

[Methuselah]

Dependent on DPs, some Eastern parts might see some snow...  as T850s get closer to -8C?

    

[Jamie M]

PV under attack in these charts.

Interest for some cold does seem to be growing. Good eye on these in the next week or so. MJO needs to be on board too.

Very dry/chilly at 252h

[Methuselah]

Nice patch of 20C uppers approaching the Med:

    

[TSNWK]

Where do you get those charts from? Abd how would I share within this thread 

Edited November 25, 2020 by TSNWK

[swfc]

1 minute ago, General Cluster said:

Nice patch of 20C uppers approaching the Med:

    

Yep t-shirt and wellies

[That ECM]

@nick sussex something to prop up the high?

[nick sussex]

The GFS and ECM now look on the same page re evolution .

Unfortunately the same issue remains from last night . The lack of low pressure in the northern Med and instead this being projected towards Iberia.

Sometimes too much amplification upstream can be a bad thing as this takes the energy not sufficiently se but south .

Putting that aside as there’s still time for changes it’s now a case of chasing the cold pool which develops to the east . As opposed to late winter easterlies cold pools at this time of year can develop in situ which you can see happening on the GFS 06 hrs run .

Overall an interesting period of model watching coming up.

So can that cold pool develop more in terms of depth of cold and can we squeeze out more energy disrupting se to help low pressure to set up further east over Southern Europe .

[Kentspur]

14 minutes ago, General Cluster said:

Dependent on DPs, some Eastern parts might see some snow...  as T850s get closer to -8C?

    

I noticed fellow yido I've been keeping a beady eye on those GFS precip charts! Night of 3rd-4th December shows many Eastern areas under wintry showers with 850s of -6 to -8c

[mushymanrob]

1 hour ago, LRD said:

This is why I don't like anomaly charts:

The ECM one on the left makes it appear that a nailed on long-lasting cold spell is on the way. But we're not (yet) facing that. Because pressure is so low, normally, over Greenland, that anomaly has to be huge to represent true northern blocking

I dont use them, they are inconsistent imho, so dont offer me much of a guide, ill stick to the noaa charts.

[IDO]

Chilly, seasonal period incoming:

Feeling colder from D8 onwards on this run with that brisk easterly/SE breeze.

After this it seems to want to repeat the dropping trough but with less upstream amplification on this run it is too far east and a transient toppler (cold uppers for the east). Again out in the far reaches of no one cares, it repeats the pattern again. Not a bad signal as it could develop into something wintry:

[Eagle Eye]

Good luck bet you'll never find a chart as good as this. 

[mushymanrob]

1 hour ago, LRD said:

I can't really read those charts but I can't see an awful lot of difference in the shape of the green contour lines (a more curved pattern in the Atlantic but that's about it as far as I can see) between this chart from 2010:

...and this one from today:

There are some differences in the red and blue areas of course which I presume is signifying lower and higher pressure systems but what do those green lines actually show?

Honest question not a pop at that particular model

 

Its the slight differences that make all the difference. the 2010 chart has the pressure anomaly in the mid north Atlantic further North, and a negative pressure anomaly over the UK.  So the 2010 chart will have more of a Northerly component. The current one has a flatter upper flow, and a shallow high pressure anomaly over the Uk . So the conditions we get will be markedly different despite a seemingly minor difference.

As i see them, today NOAAs are in a bit of a stalemate, with high pressure anomalies both to the west over the Atlantic, and to the East over Eatern Europe/Siberia. They are apparently holding the shallow troughing (seen in the 8-14 day chart more) in place. So theres not likely to be much change.. But IF the block to our East gives way, then the trough over us/just north of us could track Eastwards to sit over Scandinavia. Hey presto... a repeat of 2010 or 1981 is on the cards!.

[Paul_1978]

29 minutes ago, XanderP007 said:

Good luck bet you'll never find a chart as good as this. 

No chart attached to your post

[Nailed-on Nigel]

3 minutes ago, Paul_1978 said:

No chart attached to your post

That's why you'll never find it.

[kold weather]

Same basic page as yesterday with several varying options down the line, the ECM still quite keen to shove a strong LP southwards towards Spain which probably ruins otherwise decent synoptics. Only way to cold from that evolution is a near complete reshift in the pattern which obviously holds real risks as well.

The GFS has less risk of that but in itself isn't all that interesting. I think there is merit in the idea of some form of ridging trying to establish in the Atlantic which we are seeing in the GFS and to a lesser (and more westerly extent) on the ECM.

However, it does seem like we are in for a reasonably cool period, some days will probably be outright cold at the surface. How frosty it is probably depends on cloud cover, I suspect for the SE quarter there will be less chance of that than further NW.

So cool, maybe cold for some. Very little hope of snow other than maybe the odd bit of snizzle perhaps. Going forward little sign of mild, but also not much of a signal for anything too cold or snowy either. 

[johnholmes]

Hi

I said I would come back with the EC-GFS 500 mb anomaly charts when they came out. Below is their issue dated today.

First I will try after this post to give an answer to the questions posed about them, LRD and ktom. Probably in the form of an enclosed answer so it does not clutter up the thread. They do take a lot of experience in looking at them to understand but they are also, usually, very good, at predicting major wavelength changes in the 6-14 day period, or indeed predicting no major change. But I'll do my best to explain them. Back to the latest EC-GFS output.

They are subtly different from previous runs, see below:

What has happened with this output is that instead of the emphasis being on the ridge-trough set up with an open trough extending into Europe, coupled with relatively high heights (ridging) in the Atlantic, is they have made much more of the bottom of that trough, indeed into a cut off upper low, noted by some in the synoptic outputs. This has the effect of stopping the deeper cold air flowing directly into Europe . Both are not that similar either compared to the past 2-3 days. Thus my suggestion, I think, a couple of days ago, that we needed NOAA to show a similar chart and EC-GFS to remain with that previous pattern, preferrably all 3 for a couple of days to give any major belief in the pattern occurring. So I would suggest that is now looking like it not occurring in the 6-14 day time scale,  although the air is going to be relatively colder than average at 500 mb. Maybe if I suggest that we spend more time in Pm type air rather than Tm air, so at the surface rather cold most of the next 6-14 days. No major snowfall events, ,more like fog/frost but with some wintry showers possible from, say, the Pennines/Welsh mounains north. Remember these are 'mean' or average predictions of the flow at 500 mb so from one day to another some variation in the flow is likely. This MIGHT change the 24-36 hour weather to a more wintry showers type from fog and frost.

Sorry if this does not make too much sense to some of you. I am rapidly losing the art of explaining charts and forecasts.

 

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

[johnholmes]

Just now, johnholmes said:

Hi

I said I would come back with the EC-GFS 500 mb anomaly charts when they came out. Below is their issue dated today.

First I will try after this post to give an answer to the questions posed about them, LRD and ktom. Probably in the form of an enclosed answer so it does not clutter up the thread. They do take a lot of experience in looking at them to understand but they are also, usually, very good, at predicting major wavelength changes in the 6-14 day period, or indeed predicting no major change. But I'll do my best to explain them. Back to the latest EC-GFS output.

They are subtly different from previous runs, see below:

What has happened with this output is that instead of the emphasis being on the ridge-trough set up with an open trough extending into Europe, coupled with relatively high heights (ridging) in the Atlantic, is they have made much more of the bottom of that trough, indeed into a cut off upper low, noted by some in the synoptic outputs. This has the effect of stopping the deeper cold air flowing directly into Europe . Both are not that similar either compared to the past 2-3 days. Thus my suggestion, I think, a couple of days ago, that we needed NOAA to show a similar chart and EC-GFS to remain with that previous pattern, preferrably all 3 for a couple of days to give any major belief in the pattern occurring. So I would suggest that is now looking like it not occurring in the 6-14 day time scale,  although the air is going to be relatively colder than average at 500 mb. Maybe if I suggest that we spend more time in Pm type air rather than Tm air, so at the surface rather cold most of the next 6-14 days. No major snowfall events, ,more like fog/frost but with some wintry showers possible from, say, the Pennines/Welsh mounains north. Remember these are 'mean' or average predictions of the flow at 500 mb so from one day to another some variation in the flow is likely. This MIGHT change the 24-36 hour weather to a more wintry showers type from fog and frost.

Sorry if this does not make too much sense to some of you. I am rapidly losing the art of explaining charts and forecasts.

In fact the post from KW is a clearer idea of what to expect than mine!

 

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

 

[johnholmes]

8 minutes ago, johnholmes said:

 

Add this as my forecast for the UK

So rather cold with Pm air much of the time, a reasonable 500 flow on noaa again, and off the atlantic with heights never especially low 546-552 DM for the south. Weather dependent on low level flow day to day. Cloud cover governing frost or not and ppn mainly cold rain where it occurs away from northern hills. This for the 6-14 day period; no idea beyond, not my patch.

[Daniel*]

The last mild day for perhaps a long time. 12.6°C here atm. It’s turned cooler for most.

[Eagle Eye]

47 minutes ago, Paul_1978 said:

No chart attached to your post

Sorry will be soon

Can't edit the post

Edited November 25, 2020 by XanderP007