Winter Model Discussion - Cold Hunting -12Z 06/01/13

[egret]

I am still an anomaly junkie - all this op run analysis just makes my brain sweat.

8 day anomaly is still very good:

Way off topic but that chart would make great set of place mats for the dinner table! LoL!

[latitude]

Im thinking back to Ian Browns comments yesterday. We are still not seeing a model consistancy with regards to any spoiler. All we are seeing is varations of a cold theme which I think is encouraging.

[ChartViewer]

Indian model NCMRWF at T144

T168

T192

T216

Edited January 7, 2013 by ChartViewer

[Snowman.]

I'd like to bank the CMA please

http://www.meteociel...cmae_cartes.php

It showed that LAST night.

I said it stops the initial easterly then fires it up later down the line.

Just lets the Atlantic plough through a bit.

[Thundery wintry showers]

After the weekend, If we didn't see that pesky high building up from the Azores, ahead of that deepening trough off New Foundland, then I would be more confident on deeper cold setting in from the E or NE, But it gets rather messy after the end of this week, with a ridge building over Scandi and a ridge building NE from the Azores along with a strong equatorward jet edging east on the eastern flank of the Azores ridge - which will bring further shortwave energy down from the NW across the UK.

Good points about the Azores High- I was thinking more in terms of a persistent east-Atlantic trough but you are right, the high building from the Azores has become more of a substantial feature on recent runs with the jet rather too far north across the Atlantic to give the UK easy shots at significant easterly outbreaks (they can still happen but it is harder to get the low pressure undercutting to the S and SE).

I remember that high pressure over the Azores ridging at times into the mid-Atlantic was a recurring feature that scuppered many "nearly easterlies" in February 2005 although of course we got there in the end (albeit not off a particularly cold continent).

Edited January 7, 2013 by Thundery wintry showers

[tonbridgemole]

GFS Ensemble Mean Temps....looking at this chart it would seem most of the northern land mass will be in the freezer in 8 to 10 days.....?

[johnholmes]

Thanks John but did you have the same problems in the days of pen and paper, we have Archives of the synoptic patterns going way back but the ones pre computer look rather smoothed out, so you wonder whether you have a clear picture of the days preceding an easterly setting in, if we look at 62/63 for instance there is a pretty smooth transition in the lead up to boxing day no major shortwave drama in the Atlantic that I can see.

we were only able to 'look' 24 hours ahead so nothing like we see today; as I've commented blocks, setting them up and breaking them down have always been very difficult. Living where we do then the mobile westerly is usually easier to track, follow and predict be it human 24-48 hours ahead or models now way out ahead.

[WhiteFox]

Im thinking back to Ian Browns comments yesterday. We are still not seeing a model consistancy with regards to any spoiler. All we are seeing is varations of a cold theme which I think is encouraging.

Yes this is very true. The key difference on GFS 6z v ECM 0z is that the ECM shows the AH ridging further north and stronger with a system initially over Iceland at 144 strengthening and moving SE eventually allowing a rather flabby looking Scandi High to ridge west.

The GFS 6z has less northward ridging of the AH, and shows the Scandi High ridging further west initially which blocks the Iceland short wave and allows the second system over Ireland to head SSE which drags in the Easterly on its norther flank.

So, clarity needed on what happens to the Azores High and the fledgeling Scnandi high before we have any idea what happens next. What does seem to be starting to become consistent is the emergence of the Scandi High at 96 hours on both GFS and ECM. So, I would agree with those who say that FI looks to begin around 96 hours right now, because the modelling of the Azores and Scandi High are crucial to what comes next IMHO.

[Weathizard]

Most of the ENS show this cold spell to be a transient one, 4 days ish of cold uppers before Atlantic is brung back into play but not in the form of zonal mostly in the form of highs not being orientated right and flattening, lots of potential though, undercutting high on most ens with high in the mid Atlantic.

Getting quite frustrating though, models not really giving us a clue at the moment so many complexities to the outcome, thought we'd have some idea by now but its never easy for us! Unless we are really lucky!

PS: I've always rated the CFS

Reverse zonality.

Edited January 7, 2013 by Weathizard

[Snowmaggedon]

The experts don't seem to expect anything significant in terms of cold until the latter parts of January, so I wouldn't be suprised to see the charts produce some absolute corkers in a couple of days time. Anything we get before then in terms of snow and cold should really be counted as a bonus.

[swfc]

The experts don't seem to expect anything significant in terms of cold until the latter parts of January, so I wouldn't be suprised to see the charts produce some absolute corkers in a couple of days time. Anything we get before then in terms of snow and cold should really be counted as a bonus.

Bonus?A bonus would be seeing a snowflake before mid jan! .The problem is that the so called cold and snowy weather keeps getting pushed that far away that wel be discussing a fi cold spell mid feb before we no it.This process started at the end of november when the call was for a freezing december?Ok it had a cold feel but nothing out of the ordinary.Now were talking latter end of jan and to be honest getting past 90 hrs is hard enough.We need a break here because otherwise the uk could be surrounded with great winter weather whilst we sit and admire.heres hoping

[Timmytour]

The experts don't seem to expect anything significant in terms of cold until the latter parts of January, so I wouldn't be suprised to see the charts produce some absolute corkers in a couple of days time. Anything we get before then in terms of snow and cold should really be counted as a bonus.

Which experts? The few I've seen all stress the uncertainty of things and rule neither anything out from this weekend, nor anything in for the latter stages of January

[Tim Bland]

I can't see anything getting pushed back. Mid Jan was always touted as being the turning point. Its only in the last few days that we have staterd looking at the potential for ccold and snow from 12th (Sat) Ensembles are rock solid for uppers in to go below -5 for most parts between 12th and 15th (Sat to Weds) and during this period many areas could see wintry showers or more persitent wintry percipitation via troughs etc. Lots of possiblities after mid next week but 10 days is always FI anyway.

PS Great Update from Meto for weekend and next week.... http://www.metoffice.gov.uk/weather/uk/ee/ee_forecast_weather.html

Edited January 7, 2013 by Tim Bland

[Troubleatmill]

06z Ensemble stamps at t144 show just how much variation in output there is, i know people say "dont say the models are struggling" but they really do when we are in a set up out of the norm such as we are.

Edited January 7, 2013 by Nick JB

[Summer Sun]

Today's met office update pretty much sums up the charts at the moment great uncertainty

UK Outlook for Tuesday 22 Jan 2013 to Tuesday 5 Feb 2013:

There is greater than average uncertainty through this period, with no strong signal for any one weather type to dominate. However, on balance colder, drier conditions are more favoured rather than the milder, wetter weather experienced so far this winter.

Updated: 1135 on Mon 7 Jan

If thats the case I'd expect a few more charts like this to appear in FI with the Atlantic getting blocked off

06z ensembles

Edited January 7, 2013 by Gavin.

[bobbydog]

looking at the ensembles, i don't think we're any the wiser really. i couldn't tell you where FI starts but it's no later than +144. we have a shortwave minefield to get through first and after that..... who knows....

[ITSY]

Like has already been said, the real event so to speak may not happen for some time yet, with many predicting that changes wont start propagating down to our level (from the strat) for a couple more weeks yet. So everything cold before then, is to be welcomed IMO.

On that note, I'm leaving low res alone for the moment because the models are so unpredictable right now that it changes from run to run. In the short term, 14 or 15 of the ens members (out of 20 for the observers) give me (cambridge) some form of snow event this weekend into Monday. In terms of high res potential, that is the best yet from an IMBYish perspective. Indeed, some of the options would make my trip to Arsenal v City on sunday afternoon a rather interesting affair...

(Don't know why this has gone blue).

The ens give a 70% snow risk for some come the 13th, and many sustain that sort of level for several days.

A potentially quite potent Easterly (lasting for a few days at least) is increasingly possible at the back end of this week, in my view.

What happens after that is anyone's guess, but that is a scenario that I think most would take given the winter so far.

Edited January 7, 2013 by ITSY

[latitude]

Today's met office update pretty much sums up the charts at the moment great uncertainty

UK Outlook for Tuesday 22 Jan 2013 to Tuesday 5 Feb 2013:

There is greater than average uncertainty through this period, with no strong signal for any one weather type to dominate. However, on balance colder, drier conditions are more favoured rather than the milder, wetter weather experienced so far this winter.

Updated: 1135 on Mon 7 Jan

If thats the case I'd expect a few more charts like this to appear in FI with the Atlantic getting blocked off

06z ensembles

I wouldn't. That sounds exactly what they said when the December failure was picked up, with a more westerly pattern shown in the METO output.

Edited January 7, 2013 by latitude

[snowking]

06z Ensemble stamps at t144 show just how much variation in output there is, i know people say "dont say the models are struggling" but they really do when we are in a set up out of the norm such as we are.

I would disagree to a certain extent with this my friend

I actually think we have some fairly good agreement in principal from the 6z ensembles there of weak scandinavian high and low to our south bringing an easterly flow. This is reflected in the ensemble mean between 132 and 144:

The divergence really begins from 144, and by 240 we have a split between solutions which manage to build the azores ridge slightly closer towards Greenland, giving us further cold with a temporary northerly/easterly, and others which send too much energy over the top of the ridge. What the FI ensembles all have in common at 6z is a flattening of the pattern by 384 - and actually if you take a look at what GP has posted over in the stratosphere thread, this would tend to reflect why NWP is currently flattening the pattern beyond day 10 (before this starts a panic this doesn't mean this pattern is either permanent nor does it mean its correct!)

SK

[ITSY]

Agreed with SK there. But all should remember that even at T+384, we are still in a SSW event, with lag time to be considered and 5-6 weeks of winter left. Plenty of time for further developments. In the meanwhile, don't be downbeat, look to the East for this coming weekend (and hope it doesn't change!)

[nick sussex]

Yes, tricky for any model to predict this far off with any accuracy the low progged to drop southeast this weekend, needs close watching though, as there's potential for snow on its northern flank based on current parameters for snow to fall.

After the weekend, If we didn't see that pesky high building up from the Azores, ahead of that deepening trough off New Foundland, then I would be more confident on deeper cold setting in from the E or NE, But it gets rather messy after the end of this week, with a ridge building over Scandi and a ridge building NE from the Azores along with a strong equatorward jet edging east on the eastern flank of the Azores ridge - which will bring further shortwave energy down from the NW across the UK.

All getting rather complicated, why can't we have a straightforward easterly!

Yes I certainly agree with you regarding anything straightforward with an easterly.

Its the same old story with the ECM dangling the carrot , that could go one of two ways, we see a correction westwards and joy in here or it gets shunted east and carnage ensues in this thread.

Lets hope the Chinese are suddenly leading the way in NWP because that output is great!!! if only!

[Timmytour]

A lot cause for optimism is being shown in the models recently, but, as ever, expectation should be tempered. Many remember "that ECM" run and it's interesting going back to read that thread again.....so much unbridled joy tempered just very occasionally with posts such as

Posted 05 December 2012 - 18:56

Edited by RAIN RAIN RAIN, 05 December 2012 - 18:58

in which he shows how a stonker of a chart at T168 back in Feb 12 failed to materialise.

But it's worth noting as well, in what seems to be a very fluid situation at present, that the models can flip from showing the not so good to showing the excellent again.

Personally I think the 12z gfs will turn out to be a very good run..... delaying the start of the cold spell compared to the 6z but providing it with additional severeness and the ability to sustain at the same time. But that's more of a gut feel than anything in particular i can point out.....and even if that bears out to be the case, I've no doubt further runs will not look as good.

In the meantime.......please do not give this woman a microphone!

.

[bluearmy]

What the FI ensembles all have in common at 6z is a flattening of the pattern by 384 -

SK

do they SK? what about 50% of them that dont ??

[TAFKAP]

A lot cause for optimism is being shown in the models recently, but, as ever, expectation should be tempered. Many remember "that ECM" run and it's interesting going back to read that thread again.....so much unbridled joy tempered just very occasionally with posts such as

in which he shows how a stonker of a chart at T168 back in Feb 12 failed to materialise.

But it's worth noting as well, in what seems to be a very fluid situation at present, that the models can flip from showing the not so good to showing the excellent again.

Personally I think the 12z gfs will turn out to be a very good run..... delaying the start of the cold spell compared to the 6z but providing it with additional severeness and the ability to sustain at the same time. But that's more of a gut feel than anything in particular i can point out.....and even if that bears out to be the case, I've no doubt further runs will not look as good.

In the meantime.......please do not give this woman a microphone!

.

LOL but a bit harsh on Miss Gaga. More an unfortunate out fit than being genuinely fat. Now THIS lady is the one microphones should be kept from.

[Weathizard]

I still think we are on course for a good cold spell, the ens are actually still very decent for most parts of the uk, London shows a mean from the 13th of lower than -3 throughout the rest of the run. I'm much more positive after I've seen the changes on the 06z anyway, much better within 120. I really hope this doesn't end up going wrong otherwise this forum will go into complete meltdown!