Model output discussion - 1st December onwards

[warrenb]

In an easterly anything in blue on the chart would deliver snow. Remember far less humidity in a continental flow.

[bobbydog]

4 minutes ago, nick sussex said:

You mean it actually started? lol As for the GEFS ensembles yes theres some interest shown in the darkest reaches of FI but I'd ignore these until there are concrete signs of change within max T240hrs.  The only variable I can see at present that might bring about some changes is the MJO, although this is subject to much debate in terms of whether its a faux signal or a real one and whether it can survive the El Nino onslaught. The update comes out later this afternoon, perhaps that might offer some good news.

positive thoughts Nick, positive thoughts....

[karlos1983]

6 minutes ago, warrenb said:

In an easterly anything in blue on the chart would deliver snow. Remember far less humidity in a continental flow.

Well maybe to coastal regions of the East/ south east, certainly wouldn't penetrate to far inland. I think if we tapped into an easterly, for it to give a widespread outbreak of cold, we want to be seeing some decent pooling on the continent of -15 uppers. 0 or -5 aint gonna cut it.

imo anyway 

Edited December 21, 2015 by karlos1983

[feb1991blizzard]

6 minutes ago, warrenb said:

In an easterly anything in blue on the chart would deliver snow. Remember far less humidity in a continental flow.

Surely you mean a fairly deep shade of blue, -4c from an Easterly wouldn't produce any PPN anyway, if it did it would be light rain.

[warrenb]

In an easterly down here in Kent we have had snow from from -2 uppers. Maybe it won't penetrate far, but just because it doesn't snow in your backyard doesn't mean it isn't cold.

 

If people are looking for Dec 2010 every time they think of cold then they will be very disappointed 99.9% of the time.

Edited December 21, 2015 by warrenb

[feb1991blizzard]

1 minute ago, warrenb said:

In an easterly down here in Kent we have had snow from from -2 uppers. Maybe it won't penetrate far, but just because it doesn't snow in your backyard doesn't mean it isn't cold.

What type of Easterly though, we are talking about an Easterly with blocking here, not a Lee Easterly or a slider.

[Hocus Pocus]

For me when viewing the output any potential easterly looks to be short lived with the jet rolling over the to with  strong euro heights underneath there is only one solution. I suppose it's the building blocks down the line that are important when viewing the NH profile but if this potential isn't realised soon then we'll be back to square one and waiting for the next opportunity.

Edited December 21, 2015 by Hocus Pocus

[karlos1983]

10 minutes ago, warrenb said:

In an easterly down here in Kent we have had snow from from -2 uppers. Maybe it won't penetrate far, but just because it doesn't snow in your backyard doesn't mean it isn't cold.

I'm not talking about my backyard. I want a cold spell that benefits many, even if I miss out, which as a rule of thumb, when you live on the coast in central southern England, you miss out 99 times out of 100. I'm just saying that if we see uppers of 0 or -5 hitting the east, then it really isnt going to cut it. It would be like getting an invite from the landlord of your local pub, saying you don't need to bring your wallet tonight I am paying for all drinks, only to get to the party and finding out that only soft drinks are free. It's nice, but I'd probably give it a miss.

Edited December 21, 2015 by karlos1983

[MPG]

There is no easterly for UK on the GFS 0z or 6z effecting the UK. Why are people talking about it?

[nick sussex]

1 minute ago, karlos1983 said:

I'm not talking about my backyard. I want a cold spell that benefits many, even if I miss out, which as a rule of thumb, when you live on the coast in central southern England, you miss out 99 times out of 100. I'm just saying that if we see uppers or 0 or -5 hitting the east, then it really isnt going to cut it. It would be like getting an invite from the landlord of your local pub, saying you don't need to bring your wallet tonight I am paying for all drinks, only to get to the party and finding out that only soft drinks are free. It's nice, but I'd probably give it a miss.

Yes for a convective easterly you generally need 850 values much colder. Frontal snow however is a different scenario, values just below freezing can produce that with an east/se flow set up.

Its been a long time since we saw a 5 star convective easterly, we have seen some cold easterlies however its been the infamous snow grains set up or ones with little convection.

For this reason the perfect easterly set up is a rarity.

[karlos1983]

5 minutes ago, MPG said:

There is no easterly for UK on the GFS 0z or 6z effecting the UK. Why are people talking about it?

Because there is a Purb showing it #3 I believe. Not against the rules, if a chart is shown in the Models, then it can be discussed right?

Tongue very much in cheek..

Edited December 21, 2015 by karlos1983

[warrenb]

4 minutes ago, nick sussex said:

Yes for a convective easterly you generally need 850 values much colder. Frontal snow however is a different scenario, values just below freezing can produce that with an east/se flow set up.

Its been a long time since we saw a 5 star convective easterly, we have seen some cold easterlies however its been the infamous snow grains set up or ones with little convection.

For this reason the perfect easterly set up is a rarity.

This is correct. In the early 80's when you would see the sky darken in the East and the temperature rise slightly as the sun went in are very rare. One shower giving a couple of inches of snow only really come from uppers below -6/-7. But as pointed out frontal snow from for example a channel low can deliver copious amounts of snow at -1/-2 uppers.

[Liam J]

Pinch of salt needed but the 00z EPS control into January still looks interesting with the UK bathed in -5c or below 850's from PM W/NW winds and the 522 thickness into NW Europe, temps for many around 3c or lower with snow accumulations... Just for fun it's showing over 12'' for parts of Scotland but the snow isn't restricted to Scotland... 

Edited December 21, 2015 by *Sub*Zero*

[Polar Maritime]

8 minutes ago, *Sub*Zero* said:

Pinch of salt needed but the 00z ECM control into January still looks interesting with the UK bathed in -5c or below 850's from PM W/NW winds and the 522 thickness into NW Europe, temps for many around 3c or lower with snow accumulations... Just for fun it's showing over 12'' for parts of Scotland but the snow isn't restricted to Scotland... 

Yes Liam, A W/NW flow looks very realistic given today's outputs, At least that's where all the cold is bottled up. As i said early'r these type of set-ups can deliver some big surprise snowfalls, A pattern certainly not to be sniffed at, And one GP alluded to other day with an air of confidence...

Edited December 21, 2015 by Polar Maritime

[Hocus Pocus]

11 minutes ago, Polar Maritime said:

Yes Liam, A W/NW flow looks very realistic given today's outputs, At least that's where all the cold is bottled up. As i said early'r these type of set-ups can deliver some big surprise snowfalls, A pattern certainly not to be sniffed at, And one GP alluded to other day with an air of confidence...

I remember January 84 had a similar set up if my memory serves me right, NW parts would certainly do well out of such a set up although those further South and East would wonder what all the fuss was about.

Edited December 21, 2015 by Hocus Pocus

[Frosty.]

48 minutes ago, nick sussex said:

You mean it actually started? lol 

LOL I thought it was already spring, there are daffodils everywhere and blossom on some trees...when does winter start again?

at least these three can see the funny side of how awful the models are still looking for coldies!

[Liam J]

9 minutes ago, Polar Maritime said:

Yes Liam, A W/NW flow looks very realistic given today's outputs, At least that's where all the cold is bottled up. As i said early'r these type of set-ups can deliver some big surprise snowfalls, A pattern certainly not to be sniffed at, And one GP alluded to other day with an air of confidence...

Not at all, and a pattern i'd welcome with open arms after recent weeks! At least a PM W/NW flow would resemble something like winter with some frosts and snow for some... I know not everyone benefits from that type of set up but at least it wouldn't be ridiculously mild! Also the last ECM monthly update was hinting at similar pattern change into January, we can hope! 

[Mucka]

ECM ensembles have completely dropped any idea of cold making it to our shores any time soon but for one solitary member and is firmly showing more mild but with temps getting back near average in January. 

 

 

On the face of it  this mornings output has been poor with much less made of any amplification and a dominant PV but closer inspection of the ensembles shows that there is still a pattern change afoot though it may not be immediately obvious to us in weather terms as any blocking may be just out of reach initially.

Signals for a Scandi high are always very fickle, getting one at high enough latitude, well oriented and with enough low heights in Europe to pull in a decent and cold upper air Easterly flow is probably the rarest winter pattern of all for us. Greenland highs tend to be better signaled and with more wiggle room for getting cold and snow to our shores.

My gut feeling is this evenings output will be much better received re any blocking chances to our NE early January but I can also see potential if the models eventually drop the idea completely as I think they will switch the point of the attack with a strong Atlantic ridge and WAA toward Greenland being modeled first week of January in that case.

So although the op runs this morning and ensembles to a degree are disappointing I am feeling quite optimistic the output will improve again soon.

Edited December 21, 2015 by Mucka

[Daniel*]

It is a known fault to drop the idea and eventually go back to it in the subsequent run(s). Shannon Entropy must be very high where the models are at there most unpredictable with a lot going on.

[karlos1983]

15 minutes ago, Daniel* said:

It is a known fault to drop the idea and eventually go back to it in the subsequent run(s). Shannon Entropy must be very high where the models are at there most unpredictable with a lot going on.

There's the words that brings both hope and caution depending what the models are showing, it must be winter, I hate those words 

Edited December 21, 2015 by karlos1983

[bobbydog]

20 minutes ago, Daniel* said:

It is a known fault to drop the idea and eventually go back to it in the subsequent run(s). Shannon Entropy must be very high where the models are at there most unpredictable with a lot going on.

its a known myth daniel

[Daniel*]

2 minutes ago, bobbydog said:

its a known myth daniel

No,

Ian F has used the term multiple times over the years, some of his insight would be welcome.

[nick sussex]

23 minutes ago, karlos1983 said:

There's the words that brings both hope and caution depending what the models are showing, it must be winter, I hate those words 

Yes what normally happens is the models play around with colder solutions and then think oops its the UK and revert to the milder outcome! At the moment there doesn't look like much Shannon Entropy because basically they're all crxp bar some GEFS ensembles. Even when the Euro high was shown to ridge north we didn't have a single operational solution within T240hrs delivering proper cold to the UK.

On a happier note the GEFS and GFS MJO forecasts have updated and at least get this to a decent amplitude phase 6. Still waiting for the ECM/UKMO to update. The Euros according to NCEP have better verification than the GFS/GEFS so are probably the ones to watch though.

Edited December 21, 2015 by nick sussex

[karlos1983]

Just now, nick sussex said:

Yes what normally happens is the models play around with colder solutions and then think oops its the UK and revert to the milder outcome! At the moment there doesn't look like much Shannon Entropy because basically they're all crxp bar some GEFS ensembles. Even when the Euro high was shown to ridge north we didn't have a single operational solution delivering proper cold to the UK.

On a happier note the GEFS and GFS MJO forecasts have updated and at least get this to a decent amplitude phase 6. Still waiting for the ECM/UKMO to update. The Euros according to NCEP have better verification than the GFS/GEFS so are probably the ones to watch though.

How quickly does it zoom through phase 6/7 though Nick? Are the MJO charts freely available?

Cheers

Karl

[nick sussex]

5 minutes ago, karlos1983 said:

How quickly does it zoom through phase 6/7 though Nick? Are the MJO charts freely available?

Cheers

Karl

Hi Karl

You can see the MJO model forecasts here:

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/clivar_wh.shtml

NCEP also do a full MJO update including overview and forecast and that should be out by tomorrow. In terms of phase 7 that's the big uncertainty at the moment, the signal for that is less clear.

The GEFS/GFS haven't yet updated on the main page but you can see them here.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjo.shtml

Edited December 21, 2015 by nick sussex