Model output discussion - 7th January onwards

[Chris.R]

 Here is an interesting question I’ve been thinking about.  

I recently read that due to the US federal government shutdown the GFS was affected when it was given a bad data format. Has this been rectified or could The shutdown  still be having an affect on it’s performance?  Apologies if this has already been discussed. 

Edited January 14, 2019 by Chris.R

[Catacol]

We will start to feel the chill at the end of this week - but ensemble guidance firming up on the beginning of the main event which looks like Tuesday/Wednesday. Overnight EPS guidance provides a very easy guide to the track of a low diving NW/SE into Europe to establish the trough we need down there.

Using the same 00z start point for a GFS take on things we see the same trough angle, but much less in the way of heights to the east and up over the arctic to help deflect/disrupt....and this is why we have a more easterly solution and a low pressure looking rather well formed on the op runs

There was a lot of talk last night about whether GFS models the exit of systems from US/Canada better than others....perhaps a red herring in this case? Of more importance is the modelling of the block in front of it, downstream of the US, and we know GFS is not good at gripping atlantic blocking. EPS favoured I think. However if upstream is examined for a moment, a good image ripped from Twitter of the problems facing US forecasters as that Canadian lobe decides what it is going to do - and you can see quite clearly that we have all kinds of different solutions in there!

Once the major diving low comes the angle of attack may still end up too far east to be a snow scenario for most - though the MetO wording of "rain could turn to snow almost anywhere" has ensured that they have covered all bases neatly. This is a high risk scenario that could deliver some substantial snow for parts IF (and the capitals are deliberate) we get the angle and the disruption just right. We will see.

Anything beyond that is worth discussing later in the week - I'm focused at the moment on Tuesday/Wednesday, extent of arctic/scandy heights to disrupt and deflect that incoming trough and extent to which the incoming air carries very cold or just cold air with it. Right now it looks pretty darn frigid as an airmass, and as a result will be a fabulous trigger to what follows afterwards, regardless of whether we can get everything backed west enough to turn it into a major snow event midweek or we have to wait a little bit longer.....

 

Edited January 14, 2019 by Catacol

[Team Jo]

And quoting the original post just makes it reappear.....

Please report posts that you feel shouldn’t be here rather than commenting on them. Then one of us will get a notification.

Edited January 14, 2019 by Team Jo
Probably a bit snippy from me...?

[feb1991blizzard]

I have to say i am not impressed with the outputs at all this morning from a snow perspective, big uptick in GEFS, small uptick in EPS, lowering of the GEFS members supporting a potential greenland high.

[weirpig]

Para all over the place in the mid term compared to its previous run.  nothing to be gleaned i dont think this morning. 

[Tim Bland]

GFSp much better than old GFS with plenty of snow events for everyone 

[Timmytour]

15 minutes ago, Chris.R said:

 Here is an interesting question I’ve been thinking about.  

I recently read that due to the US federal government shutdown the GFS was affected when it was given a bad data format. Has this been rectified or could The shutdown  still be having an affect on it’s performance?  Apologies if this has already been discussed. 

The general rule of thumb is the less cold and less snowy  GFS charts are, the more likely it is likely to have been effected by bad data/ lack of data in a certain sector of at a certain time / the US government shutdown

[Kentspur]

29 minutes ago, Mr Frost said:

So because he posted charts relating to a chance of a snow event in the North he should not bother? 

Should you not be posting this in whatever regional thread you belong to then as I am certain this is a thread that relates to ALL members from the UK and Ireland.

I'm not sure what you're talking about the main point I was getting at is that the chart posted does NOT show snow for most as it says it doesn't mean other models such as the Para don't show this.

This is a model output discussion and I feel I was making a perfectly valid point. I deliberately added in not to be IMBY and genuinely wish the northern members every flake they wish for. Not sure why you're trying to make out Im dividing this forum 

Edited January 14, 2019 by Kentspur

[Derecho]

10 hours ago, Catacol said:

I'll jump in here and say no. The Beast was primarily a strat driven event - it was visible up to 2 weeks away and was caused by the speed and extremity of the downwell. The vortex shard that could be seen tracking east to west pulled the trop with it - and it was all about cyclonic energy running the wrong way. The lesson of Feb/Mar 18 was that, when in full bloom, an effective warming bosses the pattern.

People have got very hung up on the route rather than the destination here this evening. Whether we get a full blown slider scenario or a more defined low tracking SE the trend is for a deep Euro trough to establish with a signal for heights to spike to the north once it is in place. This is where we are going - but will it be 3+2 or 4+1 in getting there? The models are really going to struggle with resolving the amount of energy in the Canadian lobe with a slow SSW downwell and a pacific pattern that still wants to work a meridional solution. 

Interesting  , I was at a meteorological conference earlier this year and someone was giving a presentation about European winters and ENSO. They concluded that La Nina winters see more blocking in the earlier weeks and El Nino winters later on. I then raised my hand and asked about SSW events and their impacts (given we had a weak to moderate La Nina last winter during the beast from the east). A discussion then followed where the meteorologists sounded like they were giving more credit to the marked MJO phase that occurred in early-mid February. For referene the MJO phase for last February is shown on the left with the current GFS forecast on the right. The forecast at the moment is for the MJO to remain subdued.

 

Anyhow back to the more immediate concerns and the updated 06z swingometers for January 20th have now switched to a briefly anticyclonic picture in the wake of the slider. The coldest uppers would come from something in the form of P15. The PV looks as though it could ramp up to our NW which would blow the cobwebs away and make the slider irrelevent. If the PV did organise like it did in last nights 18z it would take some stopping.

 

Thankfully there are still some colder options in the ens although less so then the 06z yesterday. A lot of runs are cold cyclonic but not cold enough for snow which would make for some pretty miserable weather. P13 gets a good block going to the NW.

 

The ramp up of the PV is a bit of a concern for the moment, the global temperature anomaly chart for T168 shows some of the deep American cold filtering out in the NW Atlantic so I reckon a period of average to rather cold westerly flows may be a good bet. So we need a Scandi high or a high to the north to fend that off.

Finally with regards to the SSW I'm not too concerned yet, however if we are staring down the barrel of a rampant Polar Vortex around the turn of February I will be more worried.

[Paul]

I'm just about to the end of my rope in terms of the way some members are behaving on here.

• The moderation team do their best to make the best decisions for the forum - we are all human though and may miss things/get things wrong at times. 
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• Those who enjoy those benefits of moderation but take exception the instant their own posts are subject to any form of moderation are being entirely unfair the team and in the case of public rants, to everyone else on the community too, by allowing their own issues to disrupt threads. 
• The same applies to those who rant publicly about posts being off topic or whatever else. (Particularly, as in the case of earlier, when no time at all has passed since the post was made)
• It is everyone's responsibility to look after this community, whether that be in considering what to post, using the report function, communicating ideas and thoughts and feedback with the team (in appropriate places - eg pm's, feedback forum, private team forum etc). 

 

[Jason M]

43 minutes ago, feb1991blizzard said:

I have to say i am not impressed with the outputs at all this morning from a snow perspective, big uptick in GEFS, small uptick in EPS, lowering of the GEFS members supporting a potential greenland high.

Just looked through myself and I agree with you. I was really surprised at how zonal the GFSP was. Still some hope within the GEFS but I just get the sense that the trend has not been good since yesterday morning. 

 

[Man With Beard]

A bit of a hiccup on the ECM ensembles this morning, then. Not exactly a catastrophe though.

On my ensembles watch last week, for the most favourable set for cold, i think I judged 32 out of 51 clearly cold runs by 24th January.

I did the same this morning, and now it is 27 out of 51 runs by 24th January. So 5 runs out of 51 have jumped ship. Not loads. 

Looking at the clusters for the 24th:

You can see four of the clusters still have euro troughing where we would want it for cold/snow (2, 4, 5 and 6), but the op run clusters sees low heights getting stuck over the UK (or still en-route to our east?) so snow prospects depends on how cold it was in the days before - and the control cluster has found an extra burst of ridging from the Azores. This is actually a common development that can get missed at long range, so would need taking seriously. But on the whole, the weighting is still in the "cold" camp.

Now looking slightly further ahead (T300), what strikes me is a developing 50/50 call on whether a Euro trough sets up more on our longitude, or whether a little further east:

To keep the cold going, it would be best to keep it a little to our east. If it is over us, or to the south, there would be a danger of mild air eventually being drawn up from the south. Also, it looks a 50/50 call this morning if NW ridging will strengthen enough by this time to stop too much Atlantic influence (a little would be nice to maintain the moisture, but not too much, unless it dives to our south). 

All in all, it's slightly out-of-kilter with the output of the past 5 days (ECM output that is), so will need to see tonight and tomorrow if this is a trend, or if it is just the natural fluctuation of the models around a general destination.

[Yarmy]

52 minutes ago, Chris.R said:

 Here is an interesting question I’ve been thinking about.  

I recently read that due to the US federal government shutdown the GFS was affected when it was given a bad data format. Has this been rectified or could The shutdown  still be having an affect on it’s performance?  Apologies if this has already been discussed. 

This prompted me to have a look around to see what's been affected. It looks like the National Weather Service has "excepted status" which means they have to go on working even if they don't get paid, it seems. It's obviously important that things like the radiosonde network are kept running, not just for the GFS but for all the other models which use the data.

This ECM article from 2015 shows how important it is:

https://www.ecmwf.int/en/newsletter/149/meteorology/global-radiosonde-network-under-pressure

When the Russian met reduced their radiosonde readings from twice a day to once a day, it had a significant effect on the forecast skill.

[Mr Frost]

I hope the GFS has sniffed out the snow potential for next Tuesday - this would be fantastic! 

Mon the snow!!!!! 

 

[Frosty.]

The GEFS mean is still trending much, much colder through late January with widespread moderate / severe frosts, ice days and an increasing risk of snow..no downgrade that I can see from the 6z !

[feb1991blizzard]

We really need at least a steadying hand on the 12z's but preferably an upgrade, or i can see this thing starting to unravel before its even got going.

[shaky]

2 minutes ago, feb1991blizzard said:

We really need at least a steadying hand on the 12z's but preferably an upgrade, or i can see this thing starting to unravel before its even got going.ng

It already has buddy!!!i cant see it changing much now!!compared to the snowfest charts we were seeing friday and saturday it just seems to have been delayed more and more!story of the winter really!!nice charts at 240 hours only for it to be flattened  closer to the time!!

[northwestsnow]

4 minutes ago, feb1991blizzard said:

We really need at least a steadying hand on the 12z's but preferably an upgrade, or i can see this thing starting to unravel before its even got going.

Well, my opinion FWIW   is that the azores high has complicated things short term, an unwelcome complication i might add..

The mid term is looking like Exeter have signposted previously with colder air from the NW, we ought to be looking to heights moving into the north Atlantic as the trough(s) head SE into Europe..

I totally understand the frustration to be fair - we have been in this long game for what seems like an age...

Northern areas with altitude could well be very snowy as we head to the last week of Jan..i appreciate that does not please many..

EC46 again will be important, im confident the signal will maintain.

[feb1991blizzard]

Just now, shaky said:

It already has buddy!!!i cant see it changing much now!!compared to the snowfest charts we were seeing friday and saturday it just seems to have been delayed more and more!story of the winter really!!nice charts at 240 hours only for it to be flattened  closer to the time!!

I agree snowfest chart operationals have gone, but there is such a big window of opportunity, the potential is still there for some sliders to give dumpings 25th - 30th and blocking to get going in feb, BUT, its got to start a shift back soon, its not  a hopeless situation, there are still a heck of a lot of ens members across suites that are still showing either cold or very cold, or the potential to become either of those two things, all i am saying is this - yes we always get downgrades in the run up to a cold spell, but they usually are replaced with upgrades pretty quickly, my experience tells me if we get another day or 2 of negatives then its time to worry, at the moment though, we still have a shot.

[knocker]

2 hours ago, winterof79 said:

Hi Knocks can you post the ECM  50 mb geo chart please.

Cheers

I'm afraid I can't winter, sorry

[Lloyds32]

9 minutes ago, feb1991blizzard said:

We really need at least a steadying hand on the 12z's but preferably an upgrade, or i can see this thing starting to unravel before its even got going.

Can you explain what needs a steadying hand, and what might unravel? The models show a system dropping SE bringing wet and windy conditions with the potential of snow over high ground in the north etc?

 

[Spikey M]

My Weather App is calling for sleet in Central Suffolk next Tuesday. I can't see much more than that in the near future and the Models look like they may be about to bottle even that.

Edited January 14, 2019 by Spikey M

[feb1991blizzard]

1 minute ago, Lloyds32 said:

Can you explain what needs a steadying hand, and what might unravel? The models show a system dropping SE bringing wet and windy conditions with the potential of snow over high ground in the north etc?

 

The chances of a widespread snow event and decent cold spell between now and around the 5th - 10th feb.

[markw2680]

5 minutes ago, feb1991blizzard said:

I agree snowfest chart operationals have gone, but there is such a big window of opportunity, the potential is still there for some sliders to give dumpings 25th - 30th and blocking to get going in feb, BUT, its got to start a shift back soon, its not  a hopeless situation, there are still a heck of a lot of ens members across suites that are still showing either cold or very cold, or the potential to become either of those two things, all i am saying is this - yes we always get downgrades in the run up to a cold spell, but they usually are replaced with upgrades pretty quickly, my experience tells me if we get another day or 2 of negatives then its time to worry, at the moment though, we still have a shot.

Completely agree with this, very often you get a few runs that don’t look as good but then they start to improve again getting closer to the event etc

[Penicuikblizzard]

12 minutes ago, shaky said:

It already has buddy!!!i cant see it changing much now!!compared to the snowfest charts we were seeing friday and saturday it just seems to have been delayed more and more!story of the winter really!!nice charts at 240 hours only for it to be flattened  closer to the time!!

It’s been the same since the start of December with the models, the cold is always 10 days away,,,I keep getting shot down for saying this but it’s true and we are now mid way through January. A little cold blip coming this week though.