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Captain Shortwave

Model Output Discussion - The final stretch to Christmas

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Cannot believe the uncertainty of that low pressure system at such short range too. Tomorrow is when I'm going to start playing 'pin the tail on the donkey!' 

I think the centre of the low will cross through the Central belt of Scotland and then move down the East coast bringing the risk of snow on the wrap around of the system. 

This really is anybody's guess though! Never seen such a huge disagreement and confusion of the models like this ever before!

 

I have, 2010 was one of those times... There was a battle with every model at how and when the cold spell would end! Some even showed us such events the uk would've been buried under many feet of snow (South East)

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Gfs op and gfsp going for cold N/E with snow in places on 27, 28th,later in gfs p it develops an easterly flow, the alantic has-8uppers interesting times ahead for coldies! Ukmo doesn't agree as per usual??

Edited by snowice

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UKMO is again epic for snow this weekend! Other models eg GEM or JMA have similar routes for the low. Also bare in mind that for snow it's not just about the upper temps. WBFL / DP / Theta e all come into play. I expect these are very low if the low arrived as per UKMO.

Nice route for the weekend low from ECM!! There is going to be some happy snow lovers on here this morning!!

http://www.meteociel.fr/modeles/ecmwf.php?ech=72&mode=1&map=0&type=0&archive=0

Edited by Tim Bland

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UKMO is again epic for snow this weekend! Other models eg GEM or JMA have similar routes for the low. Also bare in mind that for snow it's not just about the upper temps. WBFL / DP / Theta e all come into play. I expect these are very low if the low arrived as per UKMO

Ecm at 120 has the low on a different track?

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Ecm at 120 has the low on a different track?

Most importantly both ECM and UKMO have the system traveling from NW to SE. Snow will fall on the northern and eastern side of the low. Ideally we want the track through Ireland and exit South east England for most of us to see the white stuff.

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Hows our chances looking guys for the weekend any agreement in the models having issues with the charts loading on my phone.

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UKMO is again epic for snow this weekend! Other models eg GEM or JMA have similar routes for the low. Also bare in mind that for snow it's not just about the upper temps. WBFL / DP / Theta e all come into play. I expect these are very low if the low arrived as per UKMO.

Nice route for the weekend low from ECM!! There is going to be some happy snow lovers on here this morning!!

http://www.meteociel.fr/modeles/ecmwf.php?ech=72&mode=1&map=0&type=0&archive=0

 

Epic ? Its a blip with a large warm sector on the UKMO. The ECM drags alot of milder air into the mix.. so more of the same. Cold wet and windy Imo before drying out and thats before the SWerlies kick in as the incoming high sinks into europe...

 

Dire model viewing if its a lengthy cold spell your after.. Nevermind wanting to get a smidging of snow!

Edited by Snowmad79

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Most importantly both ECM and UKMO have the system traveling from NW to SE. Snow will fall on the northern and eastern side of the low. Ideally we want the track through Ireland and exit South east England for most of us to see the white stuff.

Yes, this is the second option that John Hammond outlined last night in his forecast for the week...

Charts to show the differences after 5 days...

ECM: http://www.wetterzentrale.de/pics/Recm1201.gif

UKMO: http://www.wetterzentrale.de/pics/Rukm1201.gif

GFS: http://www.wetterzentrale.de/pics/Rtavn1201.gif

It's all about how that low pressure moves!

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Epic ? Its a blip with a large warm sector on the UKMO. The ECM drags alot of milder air into the mix.. so more of the same. Cold wet and windy Imo before drying out and thats before the SWerlies kick in as the incoming high sinks into europe...

 

Dire model viewing if its a lengthy cold spell your after.. Nevermind wanting to get a smidging of snow!

Its a pity there Azores high is angled that way, might have got an undercut and scandi high after 240h.

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Its only a model! No one knows for sure yet how it's going to pan out but one thing is for sure the charts aren't looking mild no matter how some people on here are desperately wanting them to be. Good charts for us coldies.

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Confused.com we seem to have two polar views this morning...

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Yes, this is the second option that John Hammond outlined last night in his forecast for the week...

Charts to show the differences after 5 days...

ECM: http://www.wetterzentrale.de/pics/Recm1201.gif

UKMO: http://www.wetterzentrale.de/pics/Rukm1201.gif

GFS: http://www.wetterzentrale.de/pics/Rtavn1201.gif

It's all about how that low pressure moves!

It's early and I'm looking at the models on my phone, which isn't always easy. It looks like the GFS(P) 0Z has the low moving on a more southerly track too now. On the 18Z the core of the low was moving to the NE with a trough extending south, similar to how the GPS 0Z still has it, leaving it kind of on its own in that respect? Edited by Ravelin

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ECM and UKMO both bring in a brief easterly.

UW120-21.GIF?23-06UW120-7.GIF

 

UKMO 120 is snowy for some in S England.  bg_snow.gifbg_snow.gif

 

One to watch.

bg_snow.gifmsp_thumbup.gif

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I noticed yesterday that the trend had been to build HP further N than had previously been forecasted.

This may continue, and if you take the ECM 144 (which is in FI, the boundary of which stands this morning at t96),

then a northward adjustment of a mere 200 miles would usher in a Polar continental for the South.

Recm1441.gif

Fine margins.  The unusual bout of RaCy is causing huge uncertainty in model land and I

think the GEFS are making an error in the modelling of the storm,

therefore I am dismissing the entire suite this morning.  

The GFS P is less wrong.  All IMHO of course!  Have a good day!

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I think (and anybody can only think at the moment) that the depression dropping s at the w/end (assuming it does) mustn't be viewed in the way we would normally do. Ie. system dropping to our west will bring snow to the east of it as the less cold air is held to the west. The warm uppers that head north and engage the depression dropping se out of the arctic will bring a warm sector in ahead of the deepening system. hence, the cold will remain to the north and nw of the low. hugely complicated and not really worth analysing where the warm/cold uppers are in relation to any wraparound until we get the track agreed upon. Yes, the threat of some snowfall but perhaps not as threatening as ECM might appear. next week does look chilly though for the most part.

Btw, the latest ec32 looks cool zonal weeks 3 and 4 on the mean/anomolys with not too much sign of any blocking though there could be some clusters

Edited by bluearmy

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Well it still looks that whatever the track of the LP system we end in FI in a zonal flow with a N/S split an option and a UK high from ECM (expected more amplified solution):

 

GEM at D10: post-14819-0-17953200-1419320050_thumb.p ECMpost-14819-0-30426700-1419320077_thumb.g

 

The GFS P & OP are very similar at D10: post-14819-0-76363400-1419320175_thumb.ppost-14819-0-09644700-1419320176_thumb.p

 

As is the op and mean: post-14819-0-52486100-1419320214_thumb.p It remains zonal out to D16: post-14819-0-39565900-1419320245_thumb.p

 

The clustering at D10: the common theme is a SW to NE jet with heights close to the south driving NE as the Azores pushes up, due to the US trough and the Canadian PV lobe reorganising:

 

post-14819-0-09653600-1419320526_thumb.p

 

By D12 the pattern has flattened and only 1/2 members show any attempt to send higher pressure to Scandi, the jet has realighned west-east on nearly all members with a very flat upstream. 

 

By D16 although still zonal the NH is showing signs of heights building again with polar heights and Pacific/Alaskan Ridges in about 50% of members. 

So very consistent output from the GEFS with a possible change being muted at around D16 (strat?) In the interim we have a storm over the weekend that looks borderline for snow followed by the heights to our west slowly migrating to  our NE and then a zonal flow from the pumped up Canadian PV.

Edited by i'm dreaming of...

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Oddest thing I've seen this morning is the Ukmo 6/15 (issued 04:39 ) still stating a northerly flow for next week with snow showers in the north possibly spreading south at times - puzzling unless MOGREPS is strong on the jet splitting off the eastern seaboard and supporting a mid Atlantic high.

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Very interesting output this morning with Euros in agreement on the low dropping S/SE while GFS and GFS(p) split energy to differing degrees sending some S/SE and the rest E.

 

Euros dropping the low S/SE.

 

UN120-21.GIF?23-06ECH1-120.GIF?23-12

 

GFS/GFS (p) splitting energy S/E.

 

gfsnh-0-132.png?0gfsnh-0-132.png

 

 

 

The Euros are the better scenario for cold lovers as not only would it improve snow chances for many parts of England it would also help prop the ridge up and keep the pattern more amplified behind. 

 

UKMO/ GFS amplification 144.

 

UN144-21.GIFgfsnh-0-144.png?0

 

I mentioned the possibility that the models may not be sniffing a possibility of some undercut behind the ridge and though this mornings output does not actually model this it  does go another step toward that possibility which is intriguing as it enhances the prospect of MLB being maintained and a cold blocking pattern setting up. At this point that would most likely be a Scandinavian high.

You can see the UKMO above is not that far from some undercut on the Western flank of the ridge. The GFS with its flatter pattern has relatively low prospects for some undercut but this is why I stated last night that if it was a possibility the Euros would latch onto it before GFS.

Let's not get too carried away though, it still is not being modelled - yet. 

 

Yet again it is battle between the Euros and GFS but I would side with the Euros being more likely correct and hopefully GFS will come on board sooner rather than later.

If the Euros are correct then there could still be some wintry surprises (upgrades to the cold) in the charts before Dec is out.

 

After many runs of the cold potential being eroded by the output we have at last started to push back the other way this morning.

Will it continue into this evening and tomorrow or disappear like a Spring snowfall?

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Once the low pulls out the way ECM shows the final few days of 2014 and the start of 2015 looking fairly settled with high pressure dominating surface temperatures are likely to remain chilly with some frosty mornings

 

ECM1-144.GIF?23-12ECM1-192.GIF?23-12ECM1-240.GIF?23-12

ECU0-144.GIF?23-12ECU0-192.GIF?23-12ECU0-240.GIF?23-12

Edited by Summer Sun

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Oddest thing I've seen this morning is the Ukmo 6/15 (issued 04:39 ) still stating a northerly flow for next week with snow showers in the north possibly spreading south at times - puzzling unless MOGREPS is strong on the jet splitting off the eastern seaboard and supporting a mid Atlantic high.

Noticed that too BA strange.

IDO:Zonal in FI....there's a turn up for the books.

The modelling of the exit of the depression is keenly anticipated and could mean plenty of snow for the Pennines but is a way off being nailed.I will be travelling to the Dales Saturday so of particular interest.

Edited by winterof79

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