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Paul

Hunt For Cold: Model Discussion - Heading Into Christmas

Paul

If you're hunting for cold potential in the model output, this thread is for you. But if you'd like to look more widely at the models, please head over to the general model discussion thread.

This is a model related thread, so a general, frequent theme of the model output is a given, but it will not be strictly enforced:

  • Some topic drift, humorous responses etc are fine
  • Posts likely to lead the thread off on an entirely off topic tangent are not ok. For example (but not solely limited to): Posts entirely or mainly about Met Office, BBC or media forecasts with little or no model context, and posts solely asking for a weather forecast in a specific location.
  • Posts which start with something like 'I know this is off topic but ...' are not ok.
  • Posts which break the forum guidelines are not ok (eg trolling, troll-hunting, weather guilt tripping, overly defensive/aggressive, abusive, disrespectful to others)

Message added by Paul

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1 minute ago, bluearmy said:

Bang in line with ec 46 from yesterday's run...... tbh, the way this extended forecast from the eps  is counting down is becoming a little worrying ..... all too consistent ......soemthing will scupper it surely ......... my own thoughts were that a scandi ridge would pop up from our block but the eps are having little to do with that (transitory feature always feasible of course)

the next step is for the Azores trough to edge east into the lower heights you described in your post and our upper ridge edges west into mid Atlantic ..... be interesting to see if the gefs catch onto this ....there have been some signs they might last couple runs 

Haha!

Yes, there will be a hump in the road somewhere soon Blue, you know that!!

Nice to hear things sound OK in the background, hopefully EC strat forecast will be consistent as GFS and para are not showing much consistency whatsoever..

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gefs strat warming against the jma warming is extremely different in magnitude

 image.thumb.png.1348b97879fdbae670980378bffc8a48.png gefs

 

 

image.thumb.png.7cd4453c78cd0bbbb3fa6cde3c15ae44.pngjma

Edited by MR EXTREMES

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So this is where the FV3 00Z takes us; the apparent build-up of cold air, away to our NW, N, NE and E, is hopefully significant, though could be another end-of-run mood swing?

Netweather GFS Image

The GEFS ensembles, however, show this:

One member really goes for it, with -15C uppers!GEFS Ensembles Chart

 SLP graph indicating the eventual departure of HP.GEFS Ensembles Chart

The VSTR is perhaps starting to register? In the interim - plenty of snore!:lazy:😁

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7 hours ago, ZK099 said:

What exactly are you basing the Atlantic returning with a positive AO on?? Complete conjecture based upon background signals as the experts here have been explaining all evening. The pieces of the jigsaw may not fall in our favour, but there is absolutely no way of knowing that yet, until the SSW actually happens. Your saying that is almost as unfounded as someone telling us we're guaranteed the coldest winter spell we've ever had in January. Bottom line is be patient and wait to see how the pieces fall into place. 

I just think it's better to stay realistic until we see some concrete signs of wintry weather returning. At the moment models are showing the same pattern, run after run, with the odd exception like one of yesterday's GFS runs. But the runs that show any type of cold are about 1 out of 10. 

ao.sprd2.gif

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I am still plumping for the Aleutian low and High somewhere in our vicinity.

I really do feel the GEFS will sort this out after a while here is the mean and a couple of others from the panel

I am of the opinion that Greenland may be the preferred resting place.

 

 

 

 

gensnh-21-1-240.png

gensnh-8-1-240.png

gensnh-11-1-240.png

gensnh-18-1-240.png

Edited by winterof79

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9 minutes ago, edinburgh_1992 said:

I just think it's better to stay realistic until we see some concrete signs of wintry weather returning. At the moment models are showing the same pattern, run after run, with the odd exception like one of yesterday's GFS runs. But the runs that show any type of cold are about 1 out of 10. 

ao.sprd2.gif

Well perhaps the -NAO will will be the precursor of an -AO

CF9D9760-71D4-4343-96D6-79DFFF9A98E4.thumb.gif.c52089dd36cbd9f5b92e80dde7e1a0d2.gif

Also, that 1 very -AO on the chart you’ve posted is not without foundation? if we were sitting here stuck in a pattern without a logical way of changing said pattern, by way of example a SSW let’s say...then that one straggler that goes very negative on the AO graph could be dismissed completely..... but... it’s not without foundation is it. 😉

 

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50 minutes ago, MR EXTREMES said:

as i tried to explain about the strat the other day there's another warming showing if we dont get a split this time then the next one will do the trick.

image.thumb.png.202630f54702207dc91bdb4ea86805ca.png

Or more likely knowing our luck, Armageddon charts will appear following the first warming, then just before the epic cold spell arrives, the second warming will screw it up! 😂

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23 hours ago, Mike Poole said:

Here's the GEFS zonal wind chart, 4th day running every single member shows technical SSW - none of them even marginal. 

u_60N_10hpa_gefs.thumb.png.885d8ed882702cb5ab33d701b5ffac17.png

So it does make me wonder what it is that is causing such inconsistency from the op runs over the same sort of timescale.  Just have to wait and see, I guess.

Today's GEFS chart.

u_60N_10hpa_gefs.thumb.png.39966463502348ea8742e93b035803fa.png

I said yesterday I thought GEFS was wrong.  It has been, and hoped we wouldn't notice!  Yes, all members still show an SSW.  But compare the time of the wind reversal on today's chart v yesterdays.  It is a day later and today's runs don't really fit within the uncertainty range of yesterdays.  I predict it will be another day later tomorrow, until it agrees with ECM about a reversal ~30th Dec.

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The 06z Op shows a small improvement  at T72 with better ridging to the NW and a defined contour bringing the aforesaid Easterly draw across southern areas on Xmas Eve. That should dry the ground out a bit following days of rain.

With the projected wind reversal still showing around 25th , i would ‘take a punt’ on future runs showing an increased number of colder scenarios around 3rd Jan as the downwelling progresses. 

 

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In the short term, A frosty Christmas Day morning looking less likely now away from more North Eastern parts of the UK 

08F87F19-E0C7-487D-9B45-D143F5B7A201.thumb.png.3c6bc7c5a5ecb2c796a7ffe77c0043b5.png

Edited by karlos1983

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1 minute ago, karlos1983 said:

 

In the short term, A frosty Christmas Day morning looking less likely now away from more North Eastern parr’s of the UK 

08F87F19-E0C7-487D-9B45-D143F5B7A201.thumb.png.3c6bc7c5a5ecb2c796a7ffe77c0043b5.png

The position of the high allows to much Tm air in the mix so probably would be largely cloudy and has looked that way for the last day or so...

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6 minutes ago, Froze were the Days said:

The position of the high allows to much Tm air in the mix so probably would be largely cloudy and has looked that way for the last day or so...

Away from the SW half of the country a frost is very much on the cards..

5332359E-CD42-4922-988F-D3C737B3D3F0.thumb.gif.9c45532046abcc7613d2156d232e360d.gif

for other parts of the uk the last 24 hours or so, yes that signal has been dropped somewhat, now that it’s been consistently shown in more than 1 or 2 runs, I think it’s fair to say it won’t happen.... which is what I said in my previous post... 🤔

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22 minutes ago, Mike Poole said:

Today's GEFS chart.

u_60N_10hpa_gefs.thumb.png.39966463502348ea8742e93b035803fa.png

I said yesterday I thought GEFS was wrong.  It has been, and hoped we wouldn't notice!  Yes, all members still show an SSW.  But compare the time of the wind reversal on today's chart v yesterdays.  It is a day later and today's runs don't really fit within the uncertainty range of yesterdays.  I predict it will be another day later tomorrow, until it agrees with ECM about a reversal ~30th Dec.

Tbf to the gefs, ec op was showing 28th then 29th and now 30th ..... the strat evolution is nailed down yet and at 10jpa and above, it should be much clearer at this range 

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7 minutes ago, bluearmy said:

Tbf to the gefs, ec op was showing 28th then 29th and now 30th ..... the strat evolution is nailed down yet and at 10jpa and above, it should be much clearer at this range 

Fair comment!  To be honest, it's getting a bit difficult to remember which model was showing what when...

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3 minutes ago, Mike Poole said:

Fair comment!  To be honest, it's getting a bit difficult to remember which model was showing what when...

I think it’s fair to say non are showing SSW impact - it’s just going to be a week of charts picking a pretend outcome out of a hat till we get through the actual SSW.

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Icelandic site hasn’t updated since yesterday am ..... that’s going to mean we lose sight of the ec clusters which is a bit of a bummer when we are looking for any signs of a qtr on the extended eps 

the 10 day spreads would just about show on Monday - more likely by Boxing Day 

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06z GFS doesn’t end well at 10hpa.. hopefully the damage is already done by then?

28A2CAC1-AD18-4650-BBC1-09EFEC13B06B.thumb.png.5aff861b1115ba9cd69f6766c44b4330.png

Edited by karlos1983

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npsh500.png

At least the dog's sniffing in the right areas now.

We do often see SSW peak timing delayed from the initial model projections. Probably a case of being too 'clean' with the transferal of energy through the layers of the atmosphere - and in this case exacerbated for GFS by a positive bias that it seems to have with wave-1 height-building on the Pacific side (it was achieving peak reversals using this instead of the wave-2 configuration).

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The end of the 06z GFS run allowing for more HLB than the 00Z

Let us hope that continues. Sometimes the NH profile shows a better representation on Wetter.

GFSOPNH06_360_1.png

GFSOPNH00_360_1.png

Edited by winterof79

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4 minutes ago, karlos1983 said:

06z GFS doesn’t end well at 10hpa.. hopefully the damage is already done by then?

 

Yes, the strato vortex looks like re-organising after a not great split. The last gfs run that showed a good split was the 12z yesterday.

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It can be all too easy to only focus on IMBY model output. Here are the 00z ensembles for my location. As you can see, tightly clustered until 27 December and then divergence thereafter with both the Op and the Control at the mildest end of the suite. So the High Pressure over and near the UK has potential to set up rather differently with different conditions on the ground in Europe, as I've illustrated with the postage stamps for 240h too.

 

gefsens850Warsaw_Poland0 (4).png

Screen Shot 2018-12-21 at 11.57.22 AM.png

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We can't except anything at all until the slug leaves. Seen absolutely nothing to show that may be soon! 

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Based on a large amount of reading into this across multiple forums, I strongly advise paying little attention to GFS strat-wise beyond about 6 days until further notice - it just can't cut the mustard at the moment.

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Just now, Leo97t said:

We can't except anything at all until the slug leaves. Seen absolutely nothing to show that may be soon! 

Depends in your definition of soon ......

 

re the upper strat - the temps on Meteociel don’t seem to well reflect what’s happening with the heights - vortex is split but not necessarily split enough - and it isn’t too far from ecm op now at day 10. (Temps look pretty different )

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Bottom line is we not getting snow any time soon but are we gona get any cold and frostty nights and days under that high!!anybody confirm that the high next week is going to bring cold crisp days and frosty nights!!maybe some temperature maps for day and night if possible please🤔

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