Model Output Discussion - 7th-13th November

[kold weather]

As we seem to be ramping up for the winter season in terms of activity this is a new thread for the week. Looks like the models are starting to latch onto at least a more seasonal feel to the weather.

[ITSY]

ECM is rather interesting to say the least - didn't see that coming! a few days ago it was cold GFS FI v warmish ECM - they've switched!! love to see ECM take off - and the Meto outlook seems to follow suit given their model last night! 12Z's will be interesting, as GFS Operational not buying ECM evolution at all at the moment

[Liam J]

The 32day ECM output (not available for public viewing) was hinting at a colder outlook towards the end of November, perhaps we are seeing this evolution move closer to the reliable? I would like to see the GFS latch onto this idea on future runs, as we can't just dismiss a major forecasting model. Thats if the ECM doesn't drop it on the 12z. Still a long way off, worth watching but it's far to early to be getting excited over.

Edited November 7, 2011 by Liam J

[kold weather]

To be fair the GFS is a fair bit cooler as well then of late, daytime temps still not that low but night-time temps would certainly fall away if cloud levels aren't to great...indeed temps probably very similar on both the ECM and the 06z GFS.

[bluearmy]

i have noted that a few of you seem to be relying on gfs op post T192 for your feed on what is likely. i would caution against this unless we are seeing good continuity run to run and agreement with its ensembles. much better to look at the ens mean, spreads on both ecm, gefs and naefs to get a feel for what is likely. the possible retrogression of heights across to our north to link up with the developing block west of greenland would not be a surprise to anyone doing this over the past few days. all this info is out there if you have the time to look at it. infact, much better to look at the naefs output post T192 than the gfs op run if you have to make a choice.

[beng]

i have noted that a few of you seem to be relying on gfs op post T192 for your feed on what is likely. i would caution against this...

Yes agreed and especially if that operational happens to be the 06z run - which often seems to be out of step with the other GFS runs.

GFS at 90h on the 6z is much more progressive with the low over Eastern Canada - so all eyes on that in the 12z.

[nick sussex]

NOAA still not that happy with GFS operational runs as they seem to be too quick in eastward movement of shortwaves so this might explain its inconsistency with that eastern USA troughing.

For the timebeing the UKMO further outlook doesn't see a big retrogression of the pattern and they don't expect a westwards push of colder air out of Scandi. They do however give support to the overall pattern shown by the ECM upto 240hrs.

I think it's a case of waiting to see what happens initially with the disagreements regarding the first increase in pressure over Greenland, I still think we need the pattern upstream to amplify again otherwise the best we could expect is some faux cold.

Edited November 7, 2011 by nick sussex

[kold weather]

i have noted that a few of you seem to be relying on gfs op post T192 for your feed on what is likely. i would caution against this unless we are seeing good continuity run to run and agreement with its ensembles. much better to look at the ens mean, spreads on both ecm, gefs and naefs to get a feel for what is likely. the possible retrogression of heights across to our north to link up with the developing block west of greenland would not be a surprise to anyone doing this over the past few days. all this info is out there if you have the time to look at it. infact, much better to look at the naefs output post T192 than the gfs op run if you have to make a choice.

Indeed that is a real option BUT i think the ECM is WAY too progressive. Most models tend to pick up the right signals but typically are rather too keen. i think as GP said any retrograding high is still a solid 10-15 days away.

whats does raise the eyebrows however is the ECM ens, which also solidly go with a -ve NAO. I've been onboard for some sort of cold spell towards the back end of November, it nearly always happens with La nina's for some reason, but we'll see. I wouldn't be all that surprised if the end outcome was HP nearby the UK and a cooler maybe frosty spell.

[shedhead]

Indeed that is a real option BUT i think the ECM is WAY too progressive. Most models tend to pick up the right signals but typically are rather too keen. i think as GP said any retrograding high is still a solid 10-15 days away.

whats does raise the eyebrows however is the ECM ens, which also solidly go with a -ve NAO. I've been onboard for some sort of cold spell towards the back end of November, it nearly always happens with La nina's for some reason, but we'll see. I wouldn't be all that surprised if the end outcome was HP nearby the UK and a cooler maybe frosty spell.

Got to says that's the form horse for me too, rather than the retrogressive evolution currently being signalled, moreover I expect that set up to predomiate this Winter. Any genuine cold looks set to crash south across E Europe into the E Med, but still plenty of faux cold here under generally high pressure, with some Easterly stuff thrown in at times as heights occasionally builds farther north towards Scandi.

Edited November 7, 2011 by shedhead

[kold weather]

We'll have to wait and see, the pattern isn't a bad one to get into becuase if the PV does weaken we'd be in a favourable position for any high to retrograde down the line. i just think its abit of a stretch for us to go from where we are now to the ECM solution.

Ah well we'll see what the 12z GFS suggests!

[Frosty.]

Thankfully there is light at the end of the tunnel but how bright will that light be? a dim glow from the latest gfs or full on headlight bright from the ecm. For this week it's more of the same mild muck with temps around 15-16c for most days this week and a lot of cloud with some drizzly showers scattered around along with mist on hills, tending to brighten up later this week, especially to the north of high ground and temps could respond and reach 17 or possibly 18c around fri/sat. Next week could see the current pattern disolving with something colder replacing it and hopefully the trend to colder weather will continue for the rest of the month with a chance of snow later and with widespread frosts.

[Cheshire Freeze]

Got to says that's the form horse for me too, rather than the retrogressive evolution currently being signalled, moreover I expect that set up to predomiate this Winter. Any genuine cold looks set to crash south across E Europe into the E Med, but still plenty of faux cold here under generally high pressure, with some Easterly stuff thrown in at times as heights occasionally builds farther north towards Scandi.

To be perfectly honest I'm completely happy with the synoptic evolution, though it may be a touch progressive timescale wise. High pressure to the east retrogressing to Greenland is what I was advocating for mid-late November a good 3 weeks ago and I still stand by this.

[Robbie Garrett]

Thanks to those who posted the ECM screens in the last topic.

[johnholmes]

i have noted that a few of you seem to be relying on gfs op post T192 for your feed on what is likely. i would caution against this unless we are seeing good continuity run to run and agreement with its ensembles. much better to look at the ens mean, spreads on both ecm, gefs and naefs to get a feel for what is likely. the possible retrogression of heights across to our north to link up with the developing block west of greenland would not be a surprise to anyone doing this over the past few days. all this info is out there if you have the time to look at it. infact, much better to look at the naefs output post T192 than the gfs op run if you have to make a choice.

very true blue

[No Balls Like Snow Balls]

I think that we have a 75% chance of having a much colder period of weather from the 14th November onwards, when i say much colder I don't mean freezing temperatures and blizzards!!, what i mean is slightly below average temperatures for November thus bringing a chance of snow for the North of Scotland and I don't mean the top of Cairngorm either.

The NAO and AO are due to go negative soon , both the NAO and AO being negative increase the chances of colder weather over Northern Europe.

The 500mb height anomolies also point to height increases to our North and East which also greatly increases the chances of colder air moving into Northern Europe.

all 3 of the major models GFS,ECMWF and UKMO also show height rises in there latest outputs, albeit the GFS shows it's height rises to be in a different place to the ECM and UKMO we would still see much colder temperatures than of late.

The only thing I can't quite figure out is that in 7 days time the MJO is forecast to move into phase 8 which the MJO composite for phase 8 doesn't quite mirror the current model trend of height rises to our North , Phase 6 most closely mirrors the current UKMO and ECMWF output , the MJO forecast has it's FI like the models though I guess so the phase could quite easily stay in phase 6 i guess.

Edited November 7, 2011 by No balls like Snow Balls

[kold weather]

The forecasts are intersting but with regards to those MJO forecasts I wouldn't exactly take them as a certainty as I've seen make terrible calls before, models don't seem to handle those sorts of features very well for some reason.

12z GFS about to come out anyway so we'll see if anything interesting emerges from it.

[wimblettben]

I think that we have a 75% chance of having a much colder period of weather from the 14th November onwards, when i say much colder I don't mean freezing temperatures and blizzards!!, what i mean is slightly below average temperatures for November thus bringing a chance of snow for the North of Scotland and I don't mean the top of Cairngorm either.

The NAO and AO are due to go negative soon , both the NAO and AO being negative increase the chances of colder weather over Northern Europe.

The 500mb height anomolies also point to height increases to our North and East which also greatly increases the chances of colder air moving into Northern Europe.

all 3 of the major models GFS,ECMWF and UKMO also show height rises in there latest outputs, albeit the GFS shows it's height rises to be in a different place to the ECM and UKMO we would still see much colder temperatures than of late.

The only thing I can't quite figure out is that in 7 days time the MJO is forecast to move into phase 8 which the MJO composite for phase 8 doesn't quite mirror the current model trend of height rises to our North , Phase 6 most closely mirrors the current UKMO and ECMWF output , the MJO forecast has it's FI like the models though I guess so the phase could quite easily stay in phase 6 i guess.

It's a shame though that the snow won't be able to make it's way further South and effect most of the United Kingdom.

Must admit that it is quite odd seeing possible temperatures of 18C for end of this week when you think that that figure was rarely hit in Northern parts of the UK during the Summer.

[phil nw.]

Before the 12z output just a look at the Ens. graphs for Holland.

ECM

GFS

The 2m temps.do show cooling a trend from next week, the ECM more so.

However nothing dramatically so to suggest any cold air from the East yet.

You could argue that some of the lower temps. are in line with the advancing season.

Edited November 7, 2011 by phil n.warks.

[Cheshire Freeze]

Before the 12z output just a look at the Ens. graphs for Holland.

ECM

GFS

The 2m temps.do show cooling a trend from next week, the ECM more so.

However nothing dramatically so to suggest any cold air from the East yet.

You could argue that some of the lower temps. are in line with the advancing season.

Yeah but equally there is some jolly cold runs in there too.

[kold weather]

Also showsthe ECM op run was on the cold side of the ensembles, probably further backing up the idea that the HP may not get as far NW as the 00z op run suggests.

At least we maybe seeing signs of shiftin g away from the constant very mild southerlies we've had for the last 2 months or so.

In 2 months time the 144hrs chart could become quite a cold looking set-up...just too early yet!

[Isolated Frost]

It's a shame though that the snow won't be able to make it's way further South and effect most of the United Kingdom.

Must admit that it is quite odd seeing possible temperatures of 18C for end of this week when you think that that figure was rarely hit in Northern parts of the UK during the Summer.

Wha?! Maybe not on Ben Nevis- but thats a gross generalisation. Most places passed 22-23c. Many got past 25c.

12z GFS not as progressive but very similar at +144 (compared to 06z)

[wimblettben]

Wha?! Maybe not on Ben Nevis- but thats a gross generalisation. Most places passed 22-23c. Many got past 25c.

12z GFS not as progressive but very similar at +144 (compared to 06z)

It rarely hit those figures though.

Thats what I meant. And most of the time when the temperature did get above the 20s it was only around for a few days.

Obviously the temperature was higher in more Southern areas.

[kold weather]

12z GFS shoots a cold pool into SE Europe so probably snow for those places. The UK starts to feed in air from Europe which helps in turn to bring in cooler nights again.S

lowly changing the pattern from the looks of the 12z to a HP dominated pattern.

[No Balls Like Snow Balls]

It's a shame though that the snow won't be able to make it's way further South and effect most of the United Kingdom.

Must admit that it is quite odd seeing possible temperatures of 18C for end of this week when you think that that figure was rarely hit in Northern parts of the UK during the Summer.

I don't think anywhere will see 18c this week not even the centre of London, just using the GFS 2m temps, i only see 15c being reached maybe a 16c squeezed somewhere before a cool down again on Sunday and much noticeably cooler temps following on Monday.

[Cheshire Freeze]

12z GFS shoots a cold pool into SE Europe so probably snow for those places. The UK starts to feed in air from Europe which helps in turn to bring in cooler nights again.S

lowly changing the pattern from the looks of the 12z to a HP dominated pattern.

Although usually ignored, FI around 240-300 hours is the time to watch for trends in how the high pressure behaves.