Model Output Discussion October 2012

[Liam J]

Well I can't quite believe how good the pub run is tbh (for the coldies), Rather than post charts have a mess around with the Netweather GFS chart viewer using the link below, I'm just off to place bets on a 1962 re-run

http://www.netweather.tv/index.cgi?action=nwdc;sess=

[AWD]

The PV gets cut in half on the 18z

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=240&code=0&mode=0&carte=1

[peterf]

all the coldies have fainted lol.

[lorenzo]

GFS 18z been in the pub since the 06z

Looks like it took the PV with it..

[Mark Neal.]

Amzing GFS 18z for lovers of cold lol. Its the pub run and out in FI, so a huge pinch of salt needed

[londonsnow]

Haven't posted for ages but that 18z has interested me. Just one run from the gfs so I'm holding fire for the moment. Greenland heights are encouraging for the coldies. a very early cool down in scandinavia and further south looks on the cards, but all the veterans on here know its still way off. Let's see what the 0z throws our way!

[Met4Cast]

Haven't posted for ages but that 18z has interested me. Just one run from the gfs so I'm holding fire for the moment. Greenland heights are encouraging for the coldies. a very early cool down in scandinavia and further south looks on the cards, but all the veterans on here know its still way off. Let's see what the 0z throws our way!

The 18z has followed on from other very similar runs from the last couple of days, the trend is for exactly what the 18z is showing, I'm awaiting the ensembles!

Edited October 17, 2012 by Daniel AKA WMD

[londonsnow]

I haven't been on the ball with recent charts Daniel (moving from London so a bit harassed!) but I'll be watching closely over the winter! Bit off topic but then it is late. Cheers, Ls

[Met4Cast]

Ensemble members are slowly but surely coming around to the idea of colder end to the month, operation of course still on the cooler side

[Lettucing Gutted]

GFS 18z been in the pub since the 06z

Looks like it took the PV with it..

Indeed. I know this is FI and only for the end of October but the beauty with this Polar Vortex setup is that unlike the recent "Warm Arctic-Cold Continents" pattern which brought very cold winter weather to many mid-latitude areas (including the UK) in the winters of 2009-2010 and 2010/2011 but also exceptionally warm conditions to the Arctic which then resulted though modification in the Arctic of the Arctic airmass dramatic flips from very cold to very warm conditions throughout the Northern Hemisphere in the late winter/early spring. This Polar Vortex setup from the GFS 18z on the other hand if sustained allows the constant regeneration and maintenance of Arctic air over the Arctic aswell as its sustained and unmodified advection into the mid-latitudes so its a "Cold Arctic-Cold Continents" pattern like the classic setup from the winter of 1962-1963. http://www.meteociel...12&map=0&mode=0 Edited October 18, 2012 by Craig Evans

[Met4Cast]

EPIC 00z for cold lovers.

You can see where this is going from the below chart alone

Full blown Northerly, Arctic air dives Southwards

High Pressure looks like it's going to topple South-Eastwards over the UK

But then, we see a semi-decent reload, at least, enough to send another pulse of cold air South across the country

FI of course and the Ensembles haven't come out yet, but the cold trend continues, the start of it not too far out of the reliable timeframe, either

[Snowmad79]

EPIC 00z for cold lovers.

You can see where this is going from the below chart alone

Full blown Northerly, Arctic air dives Southwards

High Pressure looks like it's going to topple South-Eastwards over the UK

But then, we see a semi-decent reload, at least, enough to send another pulse of cold air South across the country

FI of course and the Ensembles haven't come out yet, but the cold trend continues, the start of it not too far out of the reliable timeframe, either

Yes another VERY cold blast on the GFS 00z, that model is definitely sticking to its guns. As for the UKMO, it looks a right mess at 144hrs with the multiple shortwaves it is forming all over the place.

Over the last few years, the GFS was always the first model to pick up on the (early?) cold blasts even if the other models were not having it. Something like the GFS is forcasting is usually a protracted and drawn out event that seems to stay in FI for a while sometimes being dropped in line with other output, only to then delevop and come into play later on down the line.

Nice teasing runs from the GFS...

[chionomaniac]

Dr No (ECM) says no to a northerly.

I did notice one very cold GFS 00Z ensemble member.

Now that would be fun.

[bluearmy]

ECM and ukmo have the direction of travel of energy in the arctic sw towards greenland and then Newfoundland. ECM then transfers this east whilst we sit with a mid lat block. I wonder if the neg AO split at the end of ECM would be a better sustained solution than the gfs northerly short blasts

[Gibby]

Good morning folks. Here's the morning review of the outputs of GFS, UKMO and ECM.

All models show a weakening Low pressure area close to the UK with a slow moving trough just to the SE of the UK. Sunshine and showers are the order of events for most with most showers near Southern and Western coasts. The front to the SE will plague the SE of England for several more days with cloud cover and occasional rain at times. By Sunday another weakish Low drifts North in the upper air flow pulling the front to the SE North and bringing rain and drizzle to most areas with time and leading us into a rather warm South or southeast airflow to start next week.

GFS then keeps the UK in an area of slack winds early next week with mostly dry and rather cloudy conditions with temperatures above normal generally. Later in the week a deep Low pressure high up in the Norwegian Sea drives very cold Arctic winds South which eventually engage in the ridge from a Greenland High over Eastern Britain by then and start to infiltrate SW across Britain. By the weekend temperatures would of plummeted many degrees with rain in the South in a strong and cold East wind. The North at this stage would be mainly dry but cold. In FI the trend is for even colder conditions for all in strong Northerly flow with wintry showers in many Northern and Eastern areas giving appreciable falls on the mountains of Scotland. Frost would become widespread at night. A couple of slightly warmer incursions could occur at times but the overall theme right out to the end of FI is High pressure to the West and a cold Northerly feed over Britain.

The GFS Ensembles show the operational as a massively cold outlier again from later next week. the preferred option is for the milder phase to be followed by more average 850's in continuing changeable conditions in normal temperatures with overall less rainfall than of late. There is a huge spread in options though from the end of the mild phase from the middle of next week.

The Jet Stream Ensembles average suggests the current diving South of the flow west of Ireland and the returning North over the UK continues for a few more days before the flow disrupts and splits with a weaker arm moving East to the South while a Northern arm moves Eastwards to the North then dives SE over the North Sea later next week.

UKMO at midnight on Wednesday shows high pressure over the Baltic with Low pressure off NW Spain with a light and warm SE flow over the UK. Temperatures will be well above normal in dry and bright conditions with no more than a shower risk in the far SW.

ECM follows the UKMO route with a warm and dry spell early and midweek with High pressure gently resting over the UK diverting any cold plunge GFS shows way to the East towards Russia, Winds will blow gently from the East for many and with time fog problems would likely develop,taking it's time to clear each morning and subsequently lowering daytime temperature values nearer to normal by the end of the week.

In Summary this morning it's the American Model vs the Euros in where we go with the weather next week. The GFS operational is insistent on putting the weather on course for an early winter cold plunge by late next week though once more it is not well supported in it's ensembles. The Euro's on the other hand take things on a much more gentle track with High pressure in control and a gentle fall off in temperature values later next week after a rather warm few days early on. The fall off due to the overnight formation of fog lasting well into the days. IMO the most likely scenario will be a Euro style option and I think the GFS model will drop it's Northerly plunge option soon if it doesn't get increased support from it's ensemble partners. Time will tell.

[johnholmes]

As you say Gibby which will be nearer the mark in 6-10 days time.

The link below shaws the differences clearly using the ECMWF-GFS 500mb anomaly charts. GFS has kept this for a couple of days now as has ECMWF kept its version, generally supported by NOAA outputs.

http://www.meteo.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

Edited October 18, 2012 by johnholmes

[BLAST FROM THE PAST]

Big difference between GFS and ECM with UKMO which looks to me looks muddled. The jetstream is way way from its default position BUT IMO its been doing this for 5 years now increasingly so are we in the new default position?

I have using my method touted cold end to October with the cold blast coming from N/NE so on that basis I don't favour the ECM output. However, I also expected cold for time of year, so is GFS too extreme? Possibly, so we meet in the middle?

BBC SE weather showed rain for SE on Sunday with 17c and 16c on Monday......less warm than may have been hoped

JH, how would you call it going ahead? This is the type of split where experience like yours sees through the muddied waters?

BFTP

Edited October 18, 2012 by BLAST FROM THE PAST

[Frosty.]

The latest models show a ridge on saturday so it should be a fine day in most of the uk with temps of 13-16c across southern britain but a bit cooler further north, sunday also looks fine in the southeast, east and north but a developing low heading towards the southwest with rain spreading north but mainly heading up the western side of the uk and then into northern england before continuing north through scotland on monday, the first half of next week looks warm in the south of britain with temps of 17-19c up to and including wednesday but cooler further north, almost indian summer conditions and very pleasant for late october. The second half of next week remains uncertain but the gfs 00z op run continues to be very bullish about an arctic plunge making heavy weather of spreading south and as the mild and cold airmasses clash, there is a risk of torrential rain with flooding, eventually the rain pushing away south but as the cold air digs in behind, the rain could turn to sleet or even wet snow before it clears, we are then left with a direct northerly from the north pole with showers draped around the coast in a wishbone formation, the showers turning increasingly to hail, sleet and snow and with widespread moderate to sharp frosts. The 528 dam line even reaches the south coast, would be quite impressive for october 27th.

Edited October 18, 2012 by Frosty039

[johnholmes]

Big difference between GFS and ECM with UKMO which looks to me looks muddled. The jetstream is way way from its default position BUT IMO its been doing this for 5 years now increasingly so are we in the new default position?

I have using my method touted cold end to October with the cold blast coming from N/NE so on that basis I don't favour the ECM output. However, I also expected cold for time of year, so is GFS too extreme? Possibly, so we meet in the middle?

BBC SE weather showed rain for SE on Sunday with 17c and 16c on Monday......less warm than may have been hoped

JH, how would you call it going ahead? This is the type of split where experience like yours sees through the muddied waters?

BFTP

Its hard to see, I suspect some kind of half way house between the 500mb pattern showing on the link I posted. I never feel confident when only two of these models agree and the third has a different view, so I'm on the fence for 2-3 days!

The sit on the fence refers to end of October into early November NOT any further; for that I do not pretend to have enough knowledge.

Edited October 18, 2012 by johnholmes

[SMU]

hi John- ' generally supported by the NOAA' can you comment who or what that means-

thanks

steve

[johnholmes]

yes Steve, I'm not referring to their forecast comments, simply to the NOAA 6-10 and 8-14 day 500mb anomaly outlooks.

[BLAST FROM THE PAST]

Its hard to see, I suspect some kind of half way house between the 500mb pattern showing on the link I posted. I never feel confident when only two of these models agree and the third has a different view, so I'm on the fence for 2-3 days!

The sit on the fence refers to end of October into early November NOT any further; for that I do not pretend to have enough knowledge.

Cheers John, that says it all in just a few words.....a lot more model watching for folk then. Yes that is the period I'm querying as the difference is fairly neartime

BFTP

[johnholmes]

If I was backed into a corner I do think the GFS idea is OTT, about 35% possibility of a flow from N-NW but nothing like as extreme as it is suggesting. Very often in these situations the end result is a half way house between the two versions, GFS-ECMWF. No idea if there is any science in it or why models showing such differences do quite often end with the half way house. To me the ECMWF does seem rather more feasible but again don't ask for the science, just my overall feelings about how things look?

[SMU]

So another day another set of runs- the stalemate continues..

Now I can add attachments-

Original 228 Chart from the 12z GFS on the 16th-

Now 36 hours down the 186/192 chart should have moved forward-

GFS 00z 186 chart-

z

& the ECM

Summary we are still 7 days from this outcome so some variability is to be expected...-

Going back to what I was saying about seemless transitions & what feels right & for the fact how the GFS has handled polar shortwaves before ( a al 2010) then the form horse is still the GFS-

However because the ECM is the top model we cannot discard it-

GFS > ECM & UKMO in this scenario...

S

Cheers John

Edited October 18, 2012 by Steve Murr

[Summer Sun]

These are a week or more away but perhaps the first low level snow of the new season for some

Day time HIGHS!

The further south it moves it turns to sleet

Into the weekend