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Model Output Discussion 01/09/17

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Purely out of academic interest and nothing more this chart is not a million miles away this morning's ecm for the same time

gfs_z500a_natl_29.thumb.png.99af370cd3ba14819a85c814db20754e.png

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The UKMO 12Z run has a stronger jet running through the UK as we head into the medium range than the GFS does but both models do have a similar overall pattern but they are probably not all that far off from what the ECM is sho really but as been mentioned before, the ECM models has an over amplification bias which gets more noticetable as it goes further on in the output.

For now, I would rather take the UKMO output because of the season we are in, an easterly does not appeal to me at the moment especially as any cold air looks quite weak and the Arctic is not forecast to have a particularly strong PV developing anytime soon.

Looking forward to a chilly weekend, hopefully that ripple in the weather front clears quickly on Saturday so everyone is in that clean fresh polar air with frost and perhaps fog more of a potential going into Sunday night.

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The ecm develops a strong block to our east with some quite serious cold pooling over western Russia. Will we be able to tap into this in a few weeks time I wonder. Nice to see it building. It means we have a ticket at least. 

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7 hours ago, Man With Beard said:

LOL! Don't you know your Icelandic ;) ??

It means "Classification period".

More importantly, "klasa sviosmyndir" means "cluster scenarios"

Thanks for that MWB!  Amazing what you can learn on this fantastic forum!

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The ecm det showing the expected cooling down next week. Good to see the colder air sneaking down to the Middle East

ecm_t850a_5d_eur_11.thumb.png.4afbb7c6bfc779b954eda6c210403ecf.png

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45 minutes ago, knocker said:

The ecm det showing the expected cooling down next week. Good to see the colder air sneaking down to the Middle East

ecm_t850a_5d_eur_11.thumb.png.4afbb7c6bfc779b954eda6c210403ecf.png

That trend to send colder air and lower pressure into S Europe is gaining speed. Doesn't mean anything at the moment but it is a potential building block towards High Pressure to its north. 

I'm tempted to trust the models more on this - I feel verification of this type of scenario is better than the N Atlantic heights one.

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The anomalies this evening are not without interest.  Upstream perhaps some intensification of the vortex N. Canada and slight realignment of the associated trough SE to the UK which is also equated with the renewed amplification in NW Europe and the eastern Atlantic. Thus we have stronger Scandinavian ridging and the trough digging further south to the low pressure in the Mediterranean region. This emphasises the weakening and split flow in the eastern Atlantic particularly if the Azores pushes north in mid Atlantic.

This portends some interesting surface detail for the det runs to sort with any west-east movement restricted and a slack low pressure area to the south of the UK Not forgetting that energy is still winging east just to the north.

ecm_eps_z500a_5d_nh_11.thumb.png.2d69f5b1804e3431a94ea96a29c25694.pnggefs_z500a_5d_nh_41.thumb.png.5c78df84e1b73ac176c6f311fd4a7f3b.png610day_03.thumb.gif.474be2e521fdd33f532d7b0bcd6d5391.gif

There would appear to be no significant change to this pattern in the 10-14 day period so we could quite possibly be looking at a period of fairly benign dry weather with temps a little below average, certainly in the southern half of the UK

gefs_z500a_5d_nh_61.thumb.png.c434a0cd135377fe1dc105da5e9fa4f4.png814day_03.thumb.gif.44e9f0a244986ce5fa143d5d075a11fc.gif

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Quite a few ecm ensembles go cold in the 10 day plus range, especially the control run. 

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Taking cursory glances at the models over the past week or so.. but now able to comment more..

Both ECM and GFS quite similiar in their output for the foreseeable future -  a generally weak meridional mobile flow, with the jet taking a more NW-SE alignment, sending troughs on a NW-SE trajectory and locking most of the UK on the colder side of the jet more than on the milder side - so quite a change to conditions in October when we were firmly locked on the milder side.

What this means is a rather seasonal feel to things, drier than normal, with frost and fog on the cards, and plenty of sunshine especially in the south - very pleasant overall despite temps probably coming in average at best in the south, a bit colder than normal in the north, Friday night may bring some heavy rain to central parts, but other than that frontal activity looks fairly weak away from the NW. Northern high ground likely to receive first dustings of snow of the season.

Longer term - ECM suggesting heights building to the NE, and lower pressure over southern Europe. Much will depend on how far the trough digs into Europe, but there are signs it wants to head SE as opposed to east towards scandi, which would help aid the ridging and building of heights west out of Russia.

From a personal perspective, its a very pleasing outlook, November can be a grim wet damp dark month, but this year at least it looks like starting on a much drier sunnier and crisper note..

 

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1 minute ago, booferking said:

Interesting end to the gfs coming up.:shok:

gfsnh-0-222.png

Early in the season for a pub run special ! 

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4 minutes ago, bluearmy said:

Early in the season for a pub run special ! 

Never to early:rofl:

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North Europe heights is the most favourable ECM cluster for D10-D15 tonight - potential for an easterly on that:

ec-ens_nat_z500scenarios_2017110112_324.

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Today will see a ridge of high pressure slide over the UK so generally a rather benign day but with some regional variations. Early morning for in many places in the south will slowly clear during the morning leaving a pleasant day. But a slow moving,weakening front, will mean cloud will linger in Wales and the Midlands with perhaps the odd spot of drizzle. Further north, and including N. Ireland and Scotland, a bright day but much cooler than in the south where it will be pleasant in the light winds.

Later to day and overnight winds will pick up from the south west over Scotland as fronts and rain approach from the WNW

PPVA89.thumb.gif.e4675875247560ef01dd66f0b150388b.gifPPVE89.thumb.gif.05ebeadf05ece6f1807b683004678eb3.gifPPVG89.thumb.gif.491d73b406b9547867ebdc3c64680792.gif

This theme continues to some extent over the next couple of days as the aforementioned fronts weaken and by 12 Friday the south is still in a slack gradient (a col) with the HP away to the SE and a low to the south west with the north still in a westerly flow from the trough to the north. Over the next 48 hours the low intensifies and tracks north east into the North Sea and then into southern Norway bringing rain to England and Wales through Saturday and (oh my god) blizzards to Norway.

gfs_ptype_slp_eur3_7.thumb.png.be6b9c5b39f239772b285f6965ab6b0b.pnggfs_ptype_slp_eur3_11.thumb.png.b64525f12f65c4d72307d9841a5d216b.pnggfs_ptype_slp_eur3_15.thumb.png.8002977bb0dbc8032754c5e64b050f30.png

In the wake of this the Azores HP ridges NE Sunday/Monday bringing quieter conditions once again but much cooler with a widespread air frost Monday morning. But elsewhere all is not quiet and a deep depression east of Greenland has tracked east and filled on the strong jet running south of Greenland and by 12 Tuesday it is south of Iceland with the associated fronts, and rain, traversing the UK to the south east. The fronts quickly clear and from this point the battle ensues between the energy/troughs tracking east from the NW and the Azores HP to the south west (not a million miles from the anomalies here) and to get an idea where the gfs is going with this keep an eye on the depression south of Greenland

gfs_ptype_slp_eur3_23.thumb.png.a056bb6cbcc449e55c84d064d22e9c52.pnggfs_uv500_natl_23.thumb.png.e793ddf25c5a6dd9bb418b43390f43d9.pnggfs_ptype_slp_eur3_32.thumb.png.8bcaee2954dd3b86c3da68b65ba99e44.png

Spot on. Explosive cyclogenesis on the 170kt jet which would bring heavy rain and severe gales to the UK. Fortunately this scenario is very unlikely to unfold but that does not exclude a watching brief of course.

gfs_ptype_slp_eur3_35.thumb.png.7bff999eefe41eeeff760a26867276f6.pnggfs_uv250_natl_35.thumb.png.6bb36715fbff3a3cc0709313a9e9a09f.pnggfs_ptype_slp_eur3_37.thumb.png.63d558e028056f17a2f4a57a3146b7ed.png

Leaving the cylogenesis aside a glance at this morning's GEFS anomalies indicates where the det run is coming from. A couple of the lower Strat charts for good measure.

gefs_z500a_5d_nh_43.thumb.png.348fec857d5f3948c5931e8cdcd9aa46.png2017110200_f192_200.nonenonehghtnonenone_nhem.gfs003.thumb.gif.2d0351175caf5484d4ad443f05c55342.gif2017110200_f192_100.nonenonehghtnonenone_nhem.gfs003.thumb.gif.5be6b7307d191783497e6bd47d045fd5.gif

 

Edited by knocker
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Yes saw that cyclonegenesis espisode on the GFS 0z chart this morning. Given conditions in the atlantic I find it hard to believe it will happen. Last year or year before yes. Whats interesting is the creeping of colder NWly and Nly polar maritime air closer to our shores and into a more reliable timeframe.     

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The ecm predictable is okay up to the middle of next week vis the gfs but thereafter ignores the Armageddon route thanks to the cut off upper low ti the south supporting the Azores ridging north east. Having said that energy/trough does eventually break down resistance.

ecm_t850a_5d_natl_11.thumb.png.ca05c69ba280d4b0d510ee716f7eee83.png

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General dropping of the AO in week 2 to negative/neutral on recent ens runs now reflected in gefs going markedly negative. wonder if the eps and gems will follow this trend? 

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I’ve seen worse November outputs!

Azores high mainly displaced to the west and the PV not setting up shop to the north.

Both the ECM and GFS are in good agreement on the overall pattern upto day ten which isn’t often the case so perhaps a bit more confidence that this will verify .

The more uncertain aspect is whether we see enough upstream amplification and increase in heights towards the nw to deliver a bit more interest.

 

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23 minutes ago, Iceaxecrampon said:

00Z

Decent Scandy Low just over a week off.

h500slp.thumb.png.5701eb71d169a995601ade3cf10b5719.png

 

Yes with what looks like a genuine  GH

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Morning all :)

One of the problems with the set up consistently modelled by GFS is, as we've seen in previous winters, the Azores HP is displaced NE toward the SW approaches. The trough is aligned NW-SE but to the east of the British Isles so we get occasional incursions of PM sourced air but, to be fair, Europe and especially Eastern Europe gets colder.

The HP is being pushed north by small ex-tropical shortwaves which move north toward the Azores.

Occasionally, the HP tries to retrograde WNW but the strength of the jet prevents that and the HP quickly returns to its "home".

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