Model Output Discussion 18th Nov.2013-12z onwards.

[BlueHedgehog074]

Drizzle and cloudy Easterlies for me along with either a new pair of eyes or a pair of spectacles that resemble mini telescopes.

Think I will pass on being able to see again until this GFS run is over. 

Mwhe he he he hee...

 

Probably should have made the writing a little bit bigger though, to be fair, as it is somewhat hard to read.

 

(As for the GFS 18Z, would certainly agree that the Low for Friday does seem to have been modeled a little bit further West, with that North-Westerly flow looking a tiny bit more potent. Comparison between both the 12Z and 18Z GFS runs underneath for 6pm, Friday)

 

 

(No doubt some adjustments to the Low's positioning and exact track still likely).

Edited November 25, 2013 by DiagonalRedLine

[Cheshire Freeze]

Happy with that at 192 hrs

 

 

Pacific ridging making decent inroads there. May not amount to much on this run but at least we're seeing a little vortex distortion at an earlier timeframe.

Edited November 24, 2013 by CreweCold

[Snowman.]

 

That's a big old block getting up in the Arctic.

Edited November 24, 2013 by SN0WM4N

[Snowman.]

For the 6th of December not much of the PV there tbh.

 

[bluearmy]

Looking at the latter stages of ecm ens (T300+), it is in pretty good agreement with naefs. The siberian vortex equalling out with the deepening canadian chunk. As i've harped on several times, that transfer of energy will keep the atlantic mobile so any amplification will keep on heading east. Those of you who expect something amplified to our west to settle in during the first ten days of dec - the extended ens from ecm and naefs dont see it and are agreed in the pattern. Of course they could be wrong. I expect a two day northerly around the 5/7th to be followed by another mlb from our west. Probably chilly to follow cold.

[Snowman.]

FI of 18z is amazing but progress has been made in the shorter time frame.

[Cheshire Freeze]

Looking at the latter stages of ecm ens (T300+), it is in pretty good agreement with naefs. The siberian vortex equalling out with the deepening canadian chunk. As i've harped on several times, that transfer of energy will keep the atlantic mobile so any amplification will keep on heading east. Those of you who expect something amplified to our west to settle in during the first ten days of dec - the extended ens from ecm and naefs dont see it and are agreed in the pattern. Of course they could be wrong. I expect a two day northerly around the 5/7th to be followed by another mlb from our west. Probably chilly to follow cold.

 

Hi Nick, I don't think anyone has been advocating the formation of a HLB over the next 2 weeks. However, it's possible that the polar profile will continue to provide some interest, and as Mucka noted yesterday I'm in it for the long game so I shall continue to sit back and watch how this all unfolds as we progress through December (which, as I suggested in the winter thread yesterday, will be a very mixed month- but with a couple of cold periods).

 

I had an exchange over PM with BFTP recently and we're both intrigued to see how December pans out given the below average strat temperatures.

Edited November 24, 2013 by CreweCold

[Mucka]

Looking at the latter stages of ecm ens (T300+), it is in pretty good agreement with naefs. The siberian vortex equalling out with the deepening canadian chunk. As i've harped on several times, that transfer of energy will keep the atlantic mobile so any amplification will keep on heading east. Those of you who expect something amplified to our west to settle in during the first ten days of dec - the extended ens from ecm and naefs dont see it and are agreed in the pattern. Of course they could be wrong. I expect a two day northerly around the 5/7th to be followed by another mlb from our west. Probably chilly to follow cold.

 

Well that seems reasonable and there hasn't really been anything in the output (the odd ensemble member perhaps) that has brought a cold spell to the UK in that period just the odd transient waft of Arctic air. If there is to be anything more substantial it will need to show up early next week(coming week) I think as the window of opportunity then comes into the high res part of the run.

That is why I made a comment on Saturday about the GFS operational's likely looking quite different on Monday than they did then (that and a gut feeling/hopecasting)

Edited November 24, 2013 by Mucka

[Catacol]

Wow - the aleutian ridge has really come to the party this November. Big and strong again in the extended GFS.

 

This fits the pattern of the last half dozen years or so... and the same pattern has HP to our north and LP to our south on average across the winter season so I hope it stays where it is as a building block. 

 

[Mucka]

18z ensembles mixed of course but some quite cold runs showing up in FI

 

http://www.meteociel.fr/cartes_obs/gens_display.php?x=247&y=58&run=18&runpara=0&type=0&ext=1

[Captain Shortwave]

18z ensembles mixed of course but some quite cold runs showing up in FI

 

http://www.meteociel.fr/cartes_obs/gens_display.php?x=247&y=58&run=18&runpara=0&type=0&ext=1

Perturbation number 8 please

[Panayiotis]

GFS 18z ensembles show the northerly toppler perfectly at day 5 (so far uppers for my area are around -3C but this could drop further as we approach the date). And as others above have said, the cold members are still there for around the second week of December (which is where my thoughts are for the next cool/cold snap)....

For my area:

http://modeles.meteociel.fr/modeles/gens/graphe_ens3.php?x=203&ext=1&y=142&run=18&runpara=0

[TSNWK]

00:00 northerly still on for the weekend. Then our high migrates back over us, but check out the back of FI, is that the part of the polar vortex sitting over the UK

[Radiating Dendrite]

00:00 northerly still on for the weekend. Then our high migrates back over us, but check out the back of FI, is that the part of the polar vortex sitting over the UK

Typical GFS..... runs out of ideas so decides to unleash a day after tomorrow style low.

[Ali1977]

Not a great ECM for cold lovers, interesting GFS but nothing to get excited about.

[IDO]

I think what some of us have been anticipating for a while, a spell of zonal weather, is beginning to trend ominously. The GFS 0z op shows all the signs, with the Pacific ridge failing (relocating to N.America) and the PV regrouping:

T384:

Not a good NH profile.

The mean from T240 has the sinking high:

The pressure ensemble chart beginning to take on some continuity between members:

Lets hope GFS is on the wrong track.

A quiet dry week. The toppler for the end of the week barely shows up now on both GFS and ECM:

An Eastern UK slider with the core of the precipitation in the North Sea:

The following five days (next week) are dry to the south but becoming more unsettled to the north as the high sinks (GFS), and by late FI the whole UK is wet.

Edited November 25, 2013 by i'm dreaming of...

[Great Plum]

Looking at the GFS 0Z ensembles, it is clear that the op is 'off on one' after day 5...

http://www.wetterzentrale.de/pics/MT8_London_ens.png

Notice the trend after the 5th December - ensemble mean is down to -3/-4 at some points... Baby steps!

[Frosty.]

I really think something more wintry is brewing for the first half of December, high pressure across eastern canada transferring into greenland, the alignment of the jet which gradually tilts nw-se and a huge amount of cold air bottled up to the northwest and north and ready for the champagne cork to pop, the Gem and Ecm 00z are showing a weaker anticyclonic signal than last night's 12z and something much more unsettled and progressively colder & windier is evolving, there is even a brief blast of cold air from the north late friday into the weekend but that would be nothing compared to what comes during the following weeks.

[shedhead]

The lack of interest in here speaks volumns for the overnight outputs and the lack of cold prospects in general.  ECM is a real shocker, showing a slow, inexorable sinking of the high and eventual development of 'Bartlett like' pattern, whilst GFS is already steering the weekend 'plunge' well east of us and then rebuilding pressure across the south in particular. So once again this morning a switch to colder weather seems a long way off, with even the latest 'cold zonality' call for early Dec already looking on rather shaky ground.  

Edited November 25, 2013 by shedhead

[fat chad]

With reference to shedheads last post. Did some posters say last week that the models will fluctuate and probably show zonal until the vortex has relocated over siberia /Russia? Just asking

[Captain Shortwave]

As per the metoffice update we got from Ian yesterday, the models are trending to a westerly scenario. What is not clear is the source of air we will get from this set-up. If the block over Canada stays solid we might get a westerly sourced from the pole (if rather modified), which gives a cold zonal scenario. Unfortunately if the high splits as per ECM op, then simply it allows low pressure to move north east from the states and then we end end with a bog standard westerly set-up.

One thing for sure, for all the beauty of that developing Alaska high, it's not really making much of an impression over our side of the pole based on current output.

Edited November 25, 2013 by Captain shortwave

[syed2878]

i'm really confused on 1hand frosty banging his drum about a cold blast at the start of winter and yet others r talking about zonality. It's confusing for some of who cant read charts properly also for new comers too.

[gottolovethisweather]

The lack of interest in here speaks volumns for the overnight outputs and the lack of cold prospects in general.  ECM is a real shocker, showing a slow, inexorable sinking of the high and eventual development of 'Bartlett like' pattern, whilst GFS is already steering the weekend 'plunge' well east of us and then rebuilding pressure across the south in particular. So once again this morning a switch to colder weather seems a long way off, with even the latest 'cold zonality' call for early Dec already looking on rather shaky ground.  

 

Is there a lack of interest?    I'm still popping in on a daily basis, sometimes too many times for my own sanity  , but I see no reason for those folk whom wish to chase down the FI charts, to not continue to do so.  Yes, this working week is much a case of "Play it again, Sam" but there is a change a coming and that's what folk will be watching. I suggest this change in weather type, wherever it comes from might not occur until the 3rd December.

 

see my regional based post from yesterday.

 

So definitely a case of, patience grasshopper. Whatever, the EPIC charts may well not be delivering until we head deeper in Winter proper.

Edited November 25, 2013 by gottolovethisweather

[gottolovethisweather]

With reference to shedheads last post. Did some posters say last week that the models will fluctuate and probably show zonal until the vortex has relocated over siberia /Russia? Just asking

 

I don't possess the knowledge to be able to answer that exactly, but what is happening up in the Jet, the Troposhere and the Stratosphere ultimately dictates what we see down at the surface. For now, I don't anticipate much change, bar local effects until December.

[Summer Sun]

Here's the latest on the 00z models from Gibby

 

All models currently show High pressure across NW Britain with light and slack winds across the UK. Trapped under this High pressure as expected large amounts of cloud has formed and spread out to give many areas rather cloudy weather which looks like lasting through much of this working week. However, as always some breaks will appear in the cloud and allow frost and fog to form overnight which will continue to occur over the coming nights too. Through the middle of the week Northern areas will become milder for a time before a cold front moving SE at the end of the week starts the weekend off with a chilly NW wind and some bright spells and the odd shower following a band of rain SE on the front through Friday.

 

GFS then shows High pressure reasserting it's influence across Southern Britain at least for a time early next week with bright and dry conditions while the North quickly become more changeable again with Westerly winds and some rain. This changeable theme then spreads further South and East later next week with a marked wind increase by the second weekend as an unusually deep depression lies to the North, giving severe gales, heavy rain followed by wintry showers to all areas to close the run.

 

UKMO shows a cold and breezy start to next weekend with wintry showers possible in the East and frost at night. Conditions then moderate through Sunday as a ridge builds from our Atlantic High while the North sees milder Westerly winds returning on Sunday.

 

GEM today also shows a NW flow to start the weekend, rather cold with some showers for a time, wintry on hills. As we move into next week it's trend is for more unsettled weather to extend to all areas by the middle of the week with wind and rain for all as the High finally collapses and dissolves to the SW.

 

NAVGEM keeps High pressure across the South to start next week with a milder Atlantic Westerly flow developing across the North. The South would likely see frost and fog patches night and morning while the North is less cold and rather cloudy but mostly dry.

 

ECM also shows High pressure across the South to start next week although it pulls slowly South and weakens as more instability in the atmosphere pushes down from the North by midweek with the threat of rain increasing for all, first in the North. Temperatures would be close to average through the period.

 

The GFS Ensembles show a slightly colder domination this morning as the benign conditions of this week slowly give way to more unsettled weather with rain at times and temperatures likely to be close to or rather below normal later in the run which would allow for some snowfall to occur on Northern hills at times.

 

The Jet Stream driving the weather at the moment is well to the North of the UK and remains there for some time to come. There is signs then of a tilt in the flow to run it SE across the UK at least for a time as pressure falls to the North next week.

 

In Summary the weather this week will see only slow changes and variations day to day. Anticyclonic gloom will be prevalent but some clearer slots could give rise to frost and freezing fog patches at times before midweek. Then later it looks like most models support an injection of colder clearer air from the NW at the weekend. In Week 2 the trend seems to be for things to slowly turn more unsettled and windy with rain at times as our High finally becomes slowly eroded from the North. Though no prospect of marked cold is shown again this morning some change of air mass to Polar maritime later could bring some wintriness to showers over higher ground especially in the North.

 

http://www.norton-radstockweather.co.uk/Model-Analysis%282859336%29.htm