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Model output discussion-mid Autumn and beyond


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Thanks knocker. Useful to come over to this thread for a dose of reality rather than seeing P14 of the 18z GFS run which shows cold weather at 300 hours, when we all know that it's standard wet, windy

Hi Malcolm, I just saw your post after doing mine above. Yes this thread seems under used which is a shame.The idea of this one as you probably know is for any members to post what hopefully

Finally getting time to check how the 500 mb anomaly charts have been over the past week. They have not consistently but generally gone from suggesting trough domination to one that now has ridging as

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20 minutes ago, northwestsnow said:

Judging by Matt Hugos tweet the EC det was a mild outlier.

Who knows what tomorrow will bring..

It is dude trust me the gfs 18z is going to be a frigid run!!get ready for major upgrades u going to wet yourself!!cant wait!its going to be slider galore with plenty of snowfall!!

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Sticking to the reliable - i.e. out to about Monday, the models today are strengthening the signal of blocked conditions holding greater sway than yesterday, fending off the atlantic, and allowing a cold pool of air to develop to the NE. GFS then shows an undercut situation, with low pressure tracking on a more southerly track, and likely trough disruption - battleline territory between cold to the north and mild to the south, and the cold winning. UKMO seems to be heading that way as well. ECM whilst it too shows a stronger block holding off the atlantic it then sees ridge development over Iberia surging North and kicking it quickly into turn, with an airstream from the SW then invading the UK by months end. What the ECM may be underestimating is the depth and extent of cold pooling to our NE, and it is this feature which I believe will determine whether we see low pressure anchoring in towards the UK and turning milder, or instead we see the cold air win out, with low pressure forced on a southerly track, or indeed not making any inroads at all, or conversely disrupting allowing winds to come down from the NE.

Which will be the winner the ridge over Iberia - or the cold pool to our NE driven by arctic heights - which are forecast to intensify over the coming days.

 

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After a relatively quiet Autumn that could be about to change as GFS begins to line up the lows heading towards the UK at t144 I've circled 3 of them below 2 will certainly hit based on tonights run the 3rd (furthest away) is just a possibility for now

gfsnh-0-144.thumb.png.fa1732a5bbbd8a868631cbb3f1fbd58d.png

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On 20/11/2018 at 22:06, knocker said:

looks like this thread is turning into another search for cold. There will be nowhere to post soon

I'll try to help! 

What with the new kind on the block, the FV3 (aka GFS Parallel), I thought it would be interesting to test how it has handled the current synoptic pattern in comparison to the existing "big 3".

I've chosen this Sunday, which seemed like would a real pickle to forecast days ago - and for which there now seems to be good agreement.

Starting with the latest T72 charts and then taking the 00Z charts back to T216.

ECM (T72), then FV3 (T66), then GFS (T66), then UKMO (T72)

ECM1-72.GIF?22-12  gfs-0-66.png?6  gfs-0-66.png?6  UW72-21.GIF?22-06

T96

ECM1-96.GIF?00  gfs-0-96.png  gfs-0-96.png  UW96-21.GIF?21-00

T120

ECM1-120.GIF?00  gfs-0-120.png  gfs-0-120.png  UW120-21.GIF?20-00

T144

ECM1-144.GIF?00  gfs-0-144.png  gfs-0-144.png  UW144-21.GIF?19-00

So far, not bad on all models. The old GFS is a little at sea with the small low near the UK, and the UKMO made large errors with low pressure north of Norway. That leaves ECM vs FV3. I'm going to give it to the ECM - just - as it has been slightly more consistent with the size and tilt of the Atlantic low, and probably shades it for most accuracy with Icelandic heights. But having said that, the FV3 a touch ahead on trough disruption? (still not totally resolved of course!)

T168 - we're down to three as the UKMO drops out

ECM1-168.GIF?00  gfs-0-168.png  gfs-0-168.png

Still pretty good from all models; the ECM didn't quite get W Greenland right (but is already onto trough disruption in the Atlantic), the FV3 was a little too keen on the front sweeping down Scandinavia, and the GFS didn't push heights through Greenland sufficiently, and didn't get the intensity of the Atlantic. 

I'm going to give this one to the FV3 - very good forecast for Greenland, and already has the small low near the UK in the right place.

T192

ECM1-192.GIF?00  gfs-0-192.png  gfs-0-192.png

Now the errors creep in more. The ECM wins this one for me. The FV3 is second, as it has overdone the Greenland High, and the GFS was miles out with a Scandi High and heights almost gone from Iceland.

T216

ECM1-216.GIF?00  gfs-0-216.png  gfs-0-216.png

The ECM is a long way ahead here - though it has tilted northern heights the wrong way, the GFS and FV3 have both pushed heights way too far north. However - it is worth pointing out that the FV3 was the only model to stick the centre of heights on Iceland on every single run. Not bad!!

VERDICT:
Based on this very small sample of one timeframe (!), the ECM still emerges as the top model. However, the FV3 gives it much closer competition than the older GFS did, and edged second place ahead of the UKMO even at shorter ranges.

CONCLUSION:
In the FV3 (GFS Parallel) we have another model to take seriously in the future and - possibly - in the same category as the ECM.

 

 

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Nothing wrong with using all the models available, not least in a thread dedicated to what they are showing... cold. That said though, I wouldn't normally bring out the CFS because more often than not it shows mild!

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Okay folks ..looks like after the cold slack easterly  around about early to mid week we are getting a dose of Atlantic weather  Some stormy weather and high seas to the west of the uk in picticular. ...the Jet stream is on a roll...?

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25 minutes ago, ANYWEATHER said:

Okay folks ..looks like after the cold slack easterly  around about early to mid week we are getting a dose of Atlantic weather  Some stormy weather and high seas to the west of the uk in picticular. ...the Jet stream is on a roll...?

And about time too. ? 

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The theme of the year has been short bursts of atlantic energy quickly running out of steam, with the predominant feature - high pressure ruling the roost..

Will we see this repeat in the coming month, quite probably. Despite the models churning out a deep low next week, there are signals a ridge will develop behind nosing north through mid atlantic turning winds into the NW, hence an amplified flow develops, a twin pronged attack could surface as we move into the middle of the month - the attack being from high pressure to the west and also high pressure to the north east - the trough squeezed dry through the middle, and the two joining hands.

I'll be surprised if the atlantic steam rolls through into mid December - could be wrong..

I'll be returning to model watching from 4th December, and suspect we will see the models churning out an anticyclonic outlook as we approach mid December.

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It's looking like a change to a more westerly regime by day 5 as a deep mid Atlantic low phases with the main vortex over Greenland as it approaches the UK with wet and windy conditions moving in.

The UKMO fax at T120hrs

fax120s.gif?2

This certainly appears to introduce a period of Atlantic weather for a little while,at least to day 10. based on the 12z mean charts from the ECM/GFS.

EDH1-240.GIF?23-0gensnh-21-1-240.png

Showing 2 main sectors of the vortex ie.over Canada and Siberia with signs of mean ridging towards the west coast of N.America and another around E,Europe/Scandinavia at this time.

Generally speaking although some rise in temperatures are expected the pattern at this stage is not looking particularly mild with readings around average most days.

C.England

graphe3_1000_266_92___.gif

so a move towards more typical late November conditions next week after the next 3 or 4 days of this rather cold spell.

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