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Model output discussion - mid January


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In days of old, When nights were cold, And models weren't invented, We might have hoped, we might have prayed, But we didn't drive ourselves demented.   The MJO the QBO,

netweather members celebrate when the long-awaited easterly finally arrives...

00z EC showing interesting battleground snow event for the north and west next Tuesday, as Atlantic frontal system moves in from the west and bumps into the cold air If only my wife could u

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I’m more inclined to see this evolution as more plausible in the context of the ec suite. However, take away some of that amplification to reach middle ground solution and not sure where that leaves us before the latter part of week 2 when hopefully the Scandi ridge establishes 

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3 minutes ago, tight isobar said:

All hopes pinned on at-amping...

We need the waa inroads to become solid in format...then its truely game on ..and the freezer door gets yanked a-jar.

See where the ens sit!!??

Just about to say the same thing  TI Ensembles could be very interesting on this run.

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5 minutes ago, Draig Goch said:

GFS 6z gives some relief from the floods, swollen rivers etc for SW UK with the weekly forecast rainfall totals being much less than last week giving an indication of the rain not being as heavy, persistent or indeed as frequent as the last 7 days. 

image.jpeg

So am I right in saying the coast of south Pembrokeshire can expect about 10-20mm in the next week? If so that's a big improvement after 27mm fell last Sunday alone! 

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27 minutes ago, Snowmadsam said:

North of the M4: Image result for snow scape

South of the M4: Image result for desert

The intrigue continues on todays runs with more interesting options on the table....

Bobbydog may have something to say on this post...thief..??

Edited by tight isobar
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2 hours ago, jvenge said:

Hmm. Where you take those charts from actually show T2 temperatures, so not much point to speculate. Even though at T312 it's already a speculation.

 

gfs-9-312.png

I based that on the synoptic didn’t bother looking at the above, and it would be very cold while it is indeed speculation, I think we all should know by now the models are [email protected] with T2 temps especially GFS too warm. In summer it has contrasting issue of being too cool during heatwaves for instance.  Most models aren’t great with local temps especially I think there are 1km grid at most there can be a lot of variation even within a very short distance. 

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1 minute ago, Ed Stone said:

Whatever eventually transpires, if that were to verify (what do you think!:D) parts of Eastern England could experience so pretty cold mornings...?:cold:

IMG_0466.thumb.PNG.e0019747f3e2bc9cb0f27

Severely cold barely a drop of wind, -10C fairly widely in the E if there’s snow cover and clear skies a localised -13C / -14C around Norfolk I’d say. Mere speculation but shiver my timbers. Consistency there now for very cold air to be either nearby or hopefully over us Eastern England most at risk to exposure of coldest uppers....

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43 minutes ago, Nick F said:

Day 8 seems to be a pivotal point on GFS's recent runs to where we go thereafter. 

Lobe of the TPV centred over Hudson (Canada) pushes E then NE over eastern N America towards NW Atlantic pumping WAA towards S Greenland and Iceland, building an upper ridge north, while the TPV over Canada tightens and deepens in response to being squeezed south by cross-polar ridging further north from the -EPO ridge being pumped up from Siberian intense cold vortex upstream, this cross polar ridging helping weaken the height field over Svalbard and Greenland too - which will aid in cold air advecting S towards the UK.

GFSOPNH06_192_1.thumb.png.7643b75ad1f4175cc9472a6684ec4936.pngGFSOPNH06_216_1.thumb.png.5fa1cbbe00cad47693429b17a2eb6bf5.png

This appears to be initiated largely by a stratospheric wave 1 reflection event, this chart from 5 days ago -

5a6b1335c3088_wave130300_1318012100.thumb.png.ccb1b134a7404d1c0d2dcf4822ab33d4.png

Creates the Arctic geopotential dipole and encourages a positive NAO.

https://www.netweather.tv/forum/topic/88772-stratosphere-temperature-watch-201718/?do=findComment&comment=3725140

 

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Morning all :)

Another day but the same distance away from the future it seems...

Some interesting model output in far FI yesterday taking us well into February but like eggs, we'll kept it medium range so looking up to and including February 5th:

ECM 00Z at T+240:

ECM1-240.GIF?26-12

Not perhaps the stellar output of previous days but not without some interest. Anticyclonic and probably cloudy and fairly mild despite a broadly NW'ly flow. A weak and very cold HP over Scandinavia but you'd think the northern arm of the jet too strong but the T+264 chart would be interesting.

GEM 00Z OP at the same time:

gem-0-240.png?00

The OP GEM runs have never favoured amplification this week though it's worth noting how far west the Azores HP has moved. There's a residual ridge back over NW Europe but a second ridge NW and you just wonder if, assuming we can catch a break, there could be some amplification north. Otherwise, it's a mild and fairly benign outlook but with frontal rain moving in with strengthening winds as the LP centres approach.

GFS 00Z OP at T+240:

gfs-0-240.png

GFS delivers the chart of the morning for cold weather fans with a NNE'ly flow and an HP ridging south from Greenland. Uppers are -4 to -8 so snow to high ground and in any heavier outbreaks and cold for all. Into further FI and after a notable five day spell, the cold set up collapses as the Atlantic returns leaving residual heights over Scandinavia by T+384.

GFS 00Z Control at the same time:

gens-0-1-240.png

Another cold chart though with a more NW'ly component. The amplification to Greenland hasn't worked and this would be more a 2-3 day cold snap for most before the Atlantic returns.

GFS 06Z at T+234:

gfs-0-234.png?6

The trough is much closer than on the 00Z OP and the amplification less marked. Still cold and unsettled and probably wintry to higher ground. Further into FI and battle is joined between the Atlantic and a developing Scandinavian HP. The former looks to prevail but it's a very long way off.

Finally, GFS 06Z Control at T+240 (there being no T+234):

gens-0-1-240.png

A cold N'ly airflow for the British Isles with plenty of rain or snow.

To conclude then, GFS has picked up the cold baton with gusto into medium range this morning though any colder spell looks to be brief before the Atlantic returns. That's something often modelled at the initial stages by GFS which loves to "reset" things but the reality is the colder air and block is harder to shift. The problem for cold fans at the moment is all this remains tantalisingly out of reach at this time and until we start seeing in high-res it's wise to be cautious.

GEM goes out to T+240 but has offered nothing all week for cold weather fans. ECM has pitched around like a boat in a storm offering all sorts of fantasy charts at T+240. GFS has been resolutely anticyclonic but has offered more consistent "cold" output this week so far. Is "something" happening or are we all being led up a garden path strewn with red herrings ?

More runs are needed..

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17 minutes ago, Ed Stone said:

Whatever eventually transpires, if that were to verify (what do you think!:D) parts of Eastern England could experience so pretty cold mornings...?:cold:

IMG_0466.thumb.PNG.e0019747f3e2bc9cb0f27

ALLLL!!! Be careful Ed you don't wanna speculate about cold low mins .  Jvenge will tell you off and slap your bum ?

Edited by ICE COLD
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5 minutes ago, frosty ground said:

The Control run has a little bit of potential :cold:

gens-0-1-240.png

Oddly enough, it's the least anticyclonic run I've seen for a while and has echoes of an OP from earlier in the week. Heights from the Pole pushing the jet and associated troughs further south. -4 to -8 uppers so you'd think there might be some wintry possibilities but the southerly tracking jet the big change (but it's all low-res).

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2 minutes ago, Ed Stone said:

For this type of weather to materialise: gens-0-1-240.png

I'm guessing that we don't want the ECM on board? As we all know what that means!:shok:

Garden path initiation? :D

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huge differences at day 10 between the ECM and the GFS

ECH1-240-14.thumb.gif.f584e824c82614b69092e40a580a47ba.gif

gfsnh-0-240-3.thumb.png.9cf994b9d3adb3192da8920ab2e40bea.png

one thing is for certain- that there is huge uncertainty in the output. but i can't be sure...

i'd say the chances are 50/50. though there's only a 10% chance of that....

Edited by bobbydog
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3 minutes ago, bobbydog said:

huge differences at day 10 between the ECM and the GFS

ECH1-240-14.thumb.gif.f584e824c82614b69092e40a580a47ba.gif

gfsnh-0-240-3.thumb.png.9cf994b9d3adb3192da8920ab2e40bea.png

one thing is for certain- that there is huge uncertainty in the output. but i can't be sure...

i'd say the chances are 50/50. though there's only a 10% chance of that....

Day 10 ensemble means are very similar 

Screenshot_20180126-130439.png

Screenshot_20180126-130425.png

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