Model output discussions pm 31/12/15

[bobbydog]

i'm not seeing a very cold easterly yet.....

 

 

large swathe of scotland battered

 

Edited January 1, 2016 by bobbydog

[mulzy]

Happy new year All!!

A very brave call from Steve M yesterday - his scenario seems rather unlikely now but I have a lot of respect for him for placing his cards on the table in an excellent and easy to read post.

Meanwhile unsettled and stormy sums it up as epitomised by the day 7 ECM ensemble mean chart.

 

[Nouska]

38 minutes ago, Iceberg said:

Only got time to look at the first 10 gef members out to t168 but 7-8 out of the 10 have winds somewhere between 100-140km for the uk between t120 and t168. Might well be an odds on event now....

Quite a strong signal for something noteworthy - a quick way of checking individual members and comparing with last three runs.

http://www.meteociel.com/modeles/gefs_table.php?x=258&y=3&run=6&ext=com&mode=10&sort=2

Example is 10 metre wind and direction set on descending. Location is mid Borders.

 

Edited January 1, 2016 by Nouska

[phil nw.]

2 minutes ago, mulzy said:

Happy new year All!!

A very brave call from Steve M yesterday - his scenario seems rather unlikely now but I have a lot of respect for him for placing his cards on the table in an excellent and easy to read post.

Meanwhile unsettled and stormy sums it up as epitomised by the day 7 ECM ensemble mean chart.

 

Yes it was always against the odds type scenario but it was a very informative analysis showing what to look for.

Todays ens against yesterdays show the swing against the cold with a reduction in the number of cold members and indeed the severity.

The period around day 5 and 6 was where things could have swung our way as the following lows tracked into the continent.

Looks likely now this window of opportunity has gone this time with the deep cold remaining tantilisingly out of reach to the east.

 

[nick sussex]

The GFS 06hrs run in the earlier timeframe has amplified the Azores ridge and its output has moved towards the Euros with low pressure heading more se and centred near the se of the UK at T120hrs.

The NAVGEM( hope giver) ! has now backtracked from its earlier 00hrs run and the 06hrs has the angle of the Atlantic low favourable to deliver some snow at T144hrs as that moves into colder air, the surface flow off that being se.

The Norwegian shortwave which in effect harpooned the WAA to the north wants to add insult to injury as BA alluded to by phasing with the incoming Atlantic low. The hope giver has a less developed shortwave which is more quickly incorporated into the Atlantic low circulation and hence the angle of this more condusive to some snow.

Looking at the GEFS still a variety of solutions within T144hrs, the medium term is probably easier to forecast than the shorter term detail for the UK because the shortwave may behave differently and the models to a degree are not sure how much that Azores ridge will amplify.

 

[Day 10]

The hunt for winter goes on, charts like this are so sickening for coldies, cold everywhere except the bloody UK! Here's hoping the New Year brings a change of luck for us wanting snow, but also drier weather would be nice especially for the poor flood hit areas who are totally sick of this endless rain.

 

[BLAST FROM THE PAST]

HNY Team.

 

Wow the 00z is a very interestingly active run.  Southerly tracking LP after LP.

7th

10th

 

11th

 

and to finish off,,,,deja vu

 

 

BFTP

 

 

[nick sussex]

As everyone who follows this thread during the last few weeks has seen my latest weather obsession is centred around the MJO.

I've been reading some interesting research into the MJO and ENSO inter -relationship. A quite brilliant study suggests we should view the MJO not just between cold and warm ENSO's but more thoroughly between what the trend is at that time.

They summised that we need to separate this out into different categories because the tropospheric response is different. Their categories where:

Cold ENSO and the MJO

Declining ENSO and the MJO

Advancing ENSO and the MJO

Warm ENSO and the MJO

Generally the composite charts we see deal with cold or warm ENSO , La Nina and El Nino however its the declining/advancing aspects that are perhaps more interesting.

I'll link to the study here:

http://journals.ametsoc.org/doi/full/10.1175/2010JCLI3446.1

Now as many of you who follow the strat thread theres often a lot of debate regarding SSW's sudden stratospheric warming.

So how about the relationship between the MJO and SSW's?

Well the research suggests those MJO phases are linked in terms of being viewed as a signal or correlation between certain phases and SSW's that follow.

Heres another great study into that:

http://onlinelibrary.wiley.com/doi/10.1029/2012GL053144/full

 

 

 

 

[tinybill]

all i say  lets hope this don't happen   920  mb  over scotland

[fergieweather]

3 hours ago, Summer Sun said:

Looking at the precipitation totals the flooding risk could transfer down to the south and south west as we progress through next week

Eastern Scotland remains the *key* concern over weekend into start of next week - some worrying totals there across upslopes in a strong SE'ly flow, beneath a large-scale gravity wave - with a currently 50% PROB of this area seeing around 180mm across a 2-3 day period.

Elsewhere, certainly some potential in areas such as parts of the SW and S Wales for cumulative issues combining either fluvial or surface water localised flooding. However, the key difference looking ahead is how possible impacts shift from the SSW/SW-facing upslopes hammered in the recent repetitive events (notably SW Scotland; Cumbria; parts of Wales and NI), more to SE'ly-facing ones.  

Further into January, whilst we see no sign of the Dec-style Tm-sourced, very high Theta-w conveyors and exceptional mildness returning, there is nonetheless continued +ve anomalies for PPN in longer-range suites, albeit with rather mixed signals by/after mid-month (around bias of cyclonicity nationwide, versus spells of greater anticylonicity at least in the south). However, even without the high moisture-loading that characterised December's scary events, the ongoing antecedent situation (sodden ground) means further flooding issues remain very likely, with heightened sensitivities even to otherwise modest rainfall amounts.  Add to that a greater chance in January (versus Dec) for some passing/temporary spells of wintry hazards (mostly in N/NE), and it may become a month where yet again, forecasts are festooned with all-too-frequent NSWWS and EA warnings of varying scope and severity. Not great.

[chrisbell-nottheweatherman]

3 minutes ago, fergieweather said:

Eastern Scotland remains the *key* concern over weekend into start of next week - some worrying totals there across upslopes in a strong SE'ly flow, beneath a large-scale gravity wave - with a currently 50% PROB of this area seeing around 180mm across a 2-3 day period.

Elsewhere, certainly some potential in areas such as parts of the SW and S Wales for cumulative issues combining either fluvial or surface water localised flooding. However, the key difference looking ahead is how possible impacts shift from the SSW/SW-facing upslopes hammered in the recent repetitive events (notably SW Scotland; Cumbria; parts of Wales and NI), more to SE'ly-facing ones.  

Further into January, whilst we see no sign of the Dec-style Tm-sourced, very high Theta-w conveyors and exceptional mildness returning, there is nonetheless continued +ve anomalies for PPN in longer-range suites, albeit with rather mixed signals by/after mid-month (around bias of cyclonicity nationwide, versus spells of greater anticylonicity at least in the south). However, even without the high moisture-loading that characterised December's scary events, the ongoing antecedent situation (sodden ground) means further flooding issues remain very likely, with heightened sensitivities even to otherwise modest rainfall amounts.  Add to that a greater chance in January (versus Dec) for some passing/temporary spells of wintry hazards (mostly in N/NE), and it may become a month where yet again, forecasts are festooned with all-too-frequent NSWWS and EA warnings of varying scope and severity. Not great.

Thanks for the warning Ian, and Happy New Year.  I evidently misunderstood your earlier post, in which you said:

Quote

...whilst new EC Monthly joins ongoing GloSea5 idea now, i.e. of +ve temp anomalies re-asserting through mid-late Jan to establish widely across the UK, with broadly W/SW flow courtesy +ve MSLP focused to SW

I think a few of us thought that meant a return to the Euro high in much the same manner as December.

[fergieweather]

3 minutes ago, chrisbell-nottheweatherman said:

Thanks for the warning Ian, and Happy New Year.  I evidently misunderstood your earlier post, in which you said:

I think a few of us thought that meant a return to the Euro high in much the same manner as December.

No - different set-up to December. Yes, there's the obvious parallel in how +ve temp anomaly remains dominant, but not as per the exceptional mildness of December and thus more likely to be slightly above average in cumulative sense (or average for some regions). The mixed GloSea signals concern degree of anticylonic bias to quieten-things down at times in the south, versus otherwise zonal/cyclonic dominance. Equally, as noted by UKMO in assessment last night discussing fortunes across all of January "... (ENS) postage stamps show that the wavelength may well be long enough to allow occasional meridional extensions, and therefore colder outbreaks. There are however, no signs of any prolonged cold, nor (prolonged) settled conditions." Although on face value the +ve (or nearer-neutral) PPN anomalies across Jan don't look anywhere near as pronounced as December's, this can't be taken literally: as the UKMO also stress, "....it is likely to be the case that local large totals, as seen recently, would not be captured by these products (EC Monthly/GloSea)."

[Mucka]

Happy New Year everybody

 

GFS 12z has toned down the Scandi shortwave that helped make short work of any blocking to our North and as a consequence we at least maintain some faint Northern blocking post 120 forcing the pattern South which would at least make the ensuing zonal conditions cold zonal. So we aren't going to get a cold spell but there are still prospects for some places to at least see snow falling in early January which is far removed from December patterns.

 

 

UKMO likewise re maintaining some weak Northern blocking. Definitely a trend we want to see develop.

 

Edited January 1, 2016 by Mucka

[booferking]

Cold zonal pattern seems to be the form horse now i don,t mind as N.Ireland always does well in these conditions it also seems that we all might get some from it.

[TSNWK]

10 minutes ago, Mucka said:

Happy New Year everybody

 

GFS 12z has toned down the Scandi shortwave that helped make short work of any blocking to our North and as a consequence we at least maintain some faint Northern blocking post 120 forcing the pattern South which would at least make the ensuing zonal conditions cold zonal. So we aren't going to get a cold spell but there are still prospects for some places to at least see snow falling in early January which is far removed from December patterns.

 

 

UKMO likewise re maintaining some weak Northern blocking. Definitely a trend we want to see develop.

 

Is that 156 suggesting snow for the south east.... Where did that come from?

[booferking]

Cold zonal then a northerly is the best chance for us all to see snow looks like we might get this going by the last runs.

[Cloud 10]

I appreciated it PS,and at least it didn't end up in the moaning thread.

 

Meanwhile,the GFS is pouring heights towards Greeland on the 12z.

 

Edited January 1, 2016 by Polar Maritime
To move discussion on..

[Mucka]

 

1 minute ago, TSNWK said:

Is that 156 suggesting snow for the south east.... Where did that come from?

Yes it suggests a band of snow pushing North but not to be taken too literally.

Better to look for how well we maintain any semblance of blocking through 96h to 144h and how the trough reacts in general terms for now IMO.

Any snow away from high ground would be transient and unlikely to settle anyway, then again I think many of us would give our right hand to see some snow falling right now.

[TSNWK]

Some substantial changes in this evenings UKMO and GFS 12z and of a positive nature for coldies.. But just one set of runs against what we read from fergie... Nobody say trends

[TSNWK]

4 minutes ago, Mucka said:

 

Yes it suggests a band of snow pushing North but not to be taken too literally.

Better to look for how well we maintain any semblance of blocking through 96h to 144h and how the trough reacts in general terms for now IMO.

Any snow away from high ground would be transient and unlikely to settle anyway, then again I think many of us would give our right hand to see some snow falling right now.

Many thanks Mucka! Here is a thought folks.. How many times have we been disappointed when a short wave has popped up.. Is it askng too much this time for the ironic cold short wave towards Norway to disappear.... Close your eyes and wish and as if by magic...

Edited January 1, 2016 by TSNWK

[booferking]

Was Glazier point not saying what we are starting to see now on the carts  a couple of days ago height rises around Greenland??

[That ECM]

3 minutes ago, Cloud 10 said:

 

I appreciated it PS,and at least it didn't end up in the moaning thread.

 

Meanwhile,the GFS is pouring heights towards Greeland on the 12z.

 

Right or wrong, it does show,imo, that a few subtle changes and what we would get would be very different to the current thinking. The meto would change if they see a change. They only comment on what they currently see from the output. No bias either way. I think a block to our NW is our route to cold and as such I am liking this run but I am as likely to be wrong as the next person.

[West is Best]

That's a very interesting 12z GFS run. I continue to like the look of the height rises over Greenland: hitting 1045mb at various points. And whilst the northerly is both in FI and short-lived, the setup in the medium term (almost at T168) looks intriguing. These are fun charts, and certainly a vast improvement for cold lovers than the Atlantic muck during December. Fair old bit of polar vortex going on here even:

 

 

[Mucka]

GFS ensembles, Scandi shortwave, Northern blocking.

The shortwave is toned down in over 80% of ensemble members out to 78h which should give us slightly stronger Northern blocking through the period out to 168.

Look for this in the ECM output because as a generalisation it should help snow chances down the line.

[minus 9]

No model after 10 days is that reliable, maybe 30-40% accurate if that. The ecm 10 day charts change nearly every run.  So things can and will change.