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Model output discussion - here comes the beast!


Message added by Paul

Please only post model discussion in this thread 

For more general chat and banter, or moans and ramps loosely around the models, please head to the banter thread:
https://www.netweather.tv/forum/topic/86721-model-moans-ramps-and-banter/

For general weather chat including about the snow/cold chances around the country, please go to the regional threads:
https://www.netweather.tv/forum/forum/142-regional-discussions/

We also have a special post SSW cold spell discussion open here:
https://www.netweather.tv/forum/topic/89358-ssw-related-cold-spell-will-it-wont-it/

Thank you!

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19 minutes ago, Fergie said:

One word. Thundersnow.

I never even knew such a thing existed before 2010.

Main outing was 2006 or 2007 iirc

the trend is most definitely towards the high risk = high reward category 

@Steve Murr has already pointed out the variances re the cold pool and @Man With Beard has Illustrated this on the five eps clusters 

We can debate how the back end of the week will pan out but there is no strong evidence either way so all viewpoints have merit. Experience may not be much use here as this is not a scenario played out on the Eastern side of the Atlantic many times in the past couple hundred years ! 

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Early guidance forewarning of next weeks weather was issued earlier on, and this has been further enhanced with extended outlooks in bulletins. AFAIK (comms not being my area) public agencies and majo

Come on those looking for the breadown before the major cold and snow has begun You will be very lucky if that is the correct word to see this in ANY winter in the rest of your lives I would sugg

Microscale detail absorbing an awful lot of attention on here, when in reality it is a waste of emotion. The macroscale pattern is now fixed - it will not change significantly now for the start of nex

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10 minutes ago, chionomaniac said:

Just to say that anyone is welcome to discuss any port of the model output that they choose to, whether it is a breakdown, the mammoth cold prior to this, or solely T+384 charts.

If someone is discussing something that you don't want to discuss, then move on until you find someone who is.

Personally, I will keep an eye on Friday's low and will be happy to discuss it, but my concentration from tomorrow evening will be in the regionals and shorter term synoptics.

I also don't buy into those who say cold air is hard to dislodge once in place. That's nonsense, it is the blocking pattern that may be difficult to displace, not the cold air. If that was the case then this cold spell would never get off the ground because the WAA into the Arctic is needed to help with the block and no-one seems to suggest that this warm surge won't occur because the Arctic cold air is difficult to displace!

GFSOPEU18_0_2.thumb.png.f2207b72baf33e1d1615954ec5f73118.png

 

I get your reasoning but it took an SSW to displace that air. In our case on Friday it's a small low pressure pushing into -20 uppers as if they are not even there.

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IMO the gfs has modelled snow events for us in Ireland quite well this winter season, although from a NW flow, I watch it with optimism for this up and coming spell and based on the attached......i’m am preparing for Tuesday. :yahoo:

If you run on through the frames come Friday some of the systems seem to stall over Ireland giving massive totals.

Hopefully Net Weather servers are ready for this week coming......and possibly into the week after 

8050927D-6ECD-44D3-8198-C520B81C21FE.png

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So, before the 12z's roll, what's the state of play re the low at the end of the week.  Time is Friday morning, here's GFS:

gfs-0-138.png?6

Here's UKMO:

UW144-21.GIF?24-06

Here's ECM:

ECM1-144.GIF?24-12

Two things occur to me, first, the GFS is a very round low, the other two are more oval shaped, second the GFS has 1065 over Greenland and the others have slightly lower pressure.  I'm suggesting the GFS is overdoing things here, and would expect it to backtrack to the UKMO or ECM solution over upcoming runs.  We'll see starting with the 12s.

Edited by Mike Poole
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17 minutes ago, chionomaniac said:

 

I also don't buy into those who say cold air is hard to dislodge once in place. That's nonsense, it is the blocking pattern that may be difficult to displace, not the cold air. If that was the case then this cold spell would never get off the ground because the WAA into the Arctic is needed to help with the block and no-one seems to suggest that this warm surge won't occur because the Arctic cold air is difficult to displace!

 

That’s a really interesting point. Earlier I wrote about fridays low hitting the block, and then opted to change the text to “cold air.” I would value a physicists input in this. In the same way as cold air over the arctic can be blown aside by WAA we have also seen occasions where blocks are quickly flattened by Atlantic energy. When, on observed occasions, this doesn’t happen, and there is an overly progressive model pattern on th table, is the resistance we see the result of pressure or temperature? Obviously there is often a correlation, and in winter a block often brings in cold air... but not always, and uppers within a block will depend on it’s origin.

Would it be safe to say that both pressure and temperature can cause deflection of systems? Or is my basic physics way off here?

Either way I still suspect GFS 06 is rather quick to send that low on Friday up north, whether the resistance to that pattern is pressure or temperature related. 

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12 minutes ago, Daniel Smith said:

I don’t see where this breakdown talk is coming from

What I see is the possibilty of low pressure pushing into the UK & introducing less cold air into the mix, before colder air returns as it clears away, bringing widespread heavy snow (perhaps rain in the far S)

I also see the possibility of this low pressure elongating and being further South as per UKMO/ECM and bringing widespread heavy snow. 

I don’t see anything in the models to suggest Fridays event is a “breakdown”. 

Agreed! It’s like some sort of mass hysteria initiated from GFS. :p 

It is quite assured the first half of March is very likely to remain cold / very cold with the chance of snow remaining omnipresent across all areas. And I disagree it’s simple physics, colder air is denser.

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i think the only thing goign into meltdown is thie forum once we get fully underway with the Cold air.....nowcasting is getting closer and closer and will be the most accurate forecast model!!

 

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2 minutes ago, ajpoolshark said:

 

Sorry for pulling you both up and no malice or points scoring on the agenda, but whether you think the GFS 06z will verify or not (and the general concensus is that it won't) the said model run does show a breakdown in the current pattern from T192 onwards with low pressure taking control and spinwheeling to the west of the UK bring much milder and damper air from the south/SW/SE with double digit temps in the southern half of the UK widely.........So whilst again the concensus says that the GFS is a rogue model and it's outputs should be dismissed, please don't say the models don't show  breakdown when one clearly does........now with that 'mild rebuke' out of the way, Iets move on to the 12z outputs which no doubt be a snowfest! :snowman-emoji:

...and let's not forget the GEM who also has a similar low spoiler next week and the GEM brings in a breakdown:

gem-1-240.thumb.png.2e4fb2484b12142b801d7447b4b664c1.png

My opinion is that the low moving north will drag a milder flow in the UK quadrant and could scupper chances of cold further down the line. I suspect if we are to get a long-term significant cold spell we need ECM to verify. 

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13 minutes ago, Daniel* said:

Agreed! It’s like some sort of mass hysteria initiated from GFS. :p 

It is quite assured the first half of March is very likely to remain cold / very cold with the chance of snow remaining omnipresent across all areas. And I disagree it’s simple physics, colder air is denser.

That was not my point. I know colder air is denser but what I said is that I don't buy the theory that cold air is hard to dislodge once in place. It may be slightly harder to displace than warmer air but if the block isn't strong enough then the mild air will come marching through. Anyway I am hoping that the low pressure is further south on the next runs.

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51 minutes ago, Frosty. said:

Here's a sample of the GEFS 6z which supports prolonging the upcoming severe wintry spell through next weekend and beyond which also goes along with the latest view from Exeter!:):cold-emoji:

1_174_850tmp.png

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6_174_850tmp.png

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7_174_850tmp.png

7_174_2mtmpmax.png

13_174_850tmp.png

16_174_850tmp.png

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17_174_850tmp.png

17_174_2mtmpmax.png

19_174_850tmp.png

19_174_2mtmpmax.png

20_174_850tmp.png

20_174_2mtmpmax.png

Really quite staggering at any stage in Winter, let alone early Spring!!

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5 minutes ago, chionomaniac said:

That was not my point. I know colder air is denser but what I said is that I don't buy the theory that cold air is hard to dislodge once in place. It may be slightly harder to displace than warmer air but if the block isn't strong enough then the mild air will come marching through. Anyway I am hoping that the low pressure is further south on the next runs.

It's only because it rarely reaches here, that it can't be moved! But when it does, it can last for weeks. I remember 2013 when it just seemed to stick around well into April, so much so that people were getting fed up with it! Look at that persistent vortex that's been over NE Canada since December, it's taken a massive and much welcomed SSW to displace it. It was not easy to move. The difference is, it so often ends up there as it is in prime position under a default westerly pattern. Now it's in reversal, we are temporarily going to be like Kamchatsky or Vladivostok! 

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9 minutes ago, IDO said:

...and let's not forget the GEM who also has a similar low spoiler next week and the GEM brings in a breakdown:

gem-1-240.thumb.png.2e4fb2484b12142b801d7447b4b664c1.png

My opinion is that the low moving north will drag a milder flow in the UK quadrant and could scupper chances of cold further down the line. I suspect if we are to get a long-term significant cold spell we need ECM to verify. 

Even so there would be mass snow potential (mass disruption) especially for those up north. Not bad even if it's just for one day. People are never happy even tho we would have sold our grandmother for a cold spell like this in November.

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37 minutes ago, Catacol said:

That’s a really interesting point. Earlier I wrote about fridays low hitting the block, and then opted to change the text to “cold air.” I would value a physicists input in this. In the same way as cold air over the arctic can be blown aside by WAA we have also seen occasions where blocks are quickly flattened by Atlantic energy. When, on observed occasions, this doesn’t happen, and there is an overly progressive model pattern on th table, is the resistance we see the result of pressure or temperature? Obviously there is often a correlation, and in winter a block often brings in cold air... but not always, and uppers within a block will depend on it’s origin.

Would it be safe to say that both pressure and temperature can cause deflection of systems? Or is my basic physics way off here?

Either way I still suspect GFS 06 is rather quick to send that low on Friday up north, whether the resistance to that pattern is pressure or temperature related. 

Could it be more simple that most models are programmed to favour warm air advancing??? So when a cold block in real time seem more reluctant to budge it’s the models programming that doesn’t show the lead up correctly?? Hence why the term occurs of the cold is difficult to budge from the models getting it wrong in the short range of warm air meeting cold?

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13 minutes ago, ajpoolshark said:

 

Sorry for pulling you both up and no malice or points scoring on the agenda, but whether you think the GFS 06z will verify or not (and the general concensus is that it won't) the said model run does show a breakdown in the current pattern from T192 onwards with low pressure taking control and spinwheeling to the west of the UK bring much milder and damper air from the south/SW/SE with double digit temps in the southern half of the UK widely.........So whilst again the concensus says that the GFS is a rogue model and it's outputs should be dismissed, please don't say the models don't infer a breakdown (or that no 'breakdown' talk is relevant) when one clearly does........now with that 'mild rebuke' out of the way, Iets move on to the 12z outputs which no doubt be a snowfest! :snowman-emoji:

 Pigs may fly :snowman-emoji:

I’m not disagreeing with that, however too much emphasis is being out on it, when things are from resolved. Even next week there is still much uncertainty surrounding shower distribution, snow amounts it’s likely there will be significant falls. Met Office text forecast no mention at all, of a breakdown till following week after next weekend at the earliest. As far as I’m concerned talking about a breakdown is very premature, not quite appropriate probably defeats purpose of this thread, but I sense it will be a pointless task for now. We have some fantastic looking charts, we go into the freezer within the next 48 hours the best charts, I have ever seen modelled imminent, expect unexpected.

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1 minute ago, ajpoolshark said:

This is the model output discussion thread, and if any model output shows a breakdown, snowmageddon, spanish plumes, the day after tomorrow or hurricances whether it's T0 or T384 then this is the valid place to discuss it surely?.....IMHO if anyone's mind is boggled then it's best to go to another  thread so one doesn't have to see any 'breakdown' talk :)

I get your point but surely talking about a breakdown when the cold spell hasn't even started is like talking about what the lottery numbers will be next Saturday. Why can't we just talk about the here and now. This is an amazing spell of weather coming up, especially for our tiny island it's so rare to get such amazing synoptics. By the time it's here people will be so busy worrying about a breakdown they won't actually enjoy it.

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2 minutes ago, Daniel* said:

 Pigs may fly :snowman-emoji:

I’m not disagreeing with that, however too much emphasis is being out on it, when things are from resolved. Even next week there is still much uncertainty surrounding shower distribution, snow amounts it’s likely there will be significant falls. Met Office text forecast no mention at all, of a breakdown till following week after next weekend at the earliest. As far as I’m concerned talking about a breakdown is very premature, not quite appropriate probably defeats purpose of this thread, but I sense it will be a pointless task for now. We have some fantastic looking charts, we go into the freezer within the next 48 hours the best charts, I have ever seen modelled imminent, expect unexpected.

Totally agree! GFS being over progressive (as usual). I think it will correct south over the next few runs. 

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