Model Output Discussion 01/09/17

[Man With Beard]

13 minutes ago, Heekster said:

Isn't it normal though for the model that shows mlld to be right even if all the others are different, that's what I found last year.

Hi Heekster, yes seems like it has been this way for a few years, but during cold seasons it works the other way round - events such as Jan 2013 popped up on the UKMO first at D5 while others were going mild, and Jan 2010, the one where the whole country turned white, only appeared at T48!!

So if we get snow out of this pattern maybe it will be a good sign for the season as a whole! (very unscientific though!!)

[geordiekev]

14 minutes ago, CreweCold said:

Looking at the ECM tonight and I get a sense of de ja vu. All looks very very similar to how mid-late November panned out last year

I was thinking the exact same thing a few days back worried about how last year panned out.  It's a good thing we get a new shuffled deck each year to play with though.

[Allseasons-Si]

Another chart is that of the 8-14 day 5oomb anomly chart from the NOAA with a nice Greeny high there with winds of a NE variety,and the mean NAO,AO graphs still show a neg phase with uncertainty at the end

day ten geopotential height anomoly's,gfs and ecm,show that we still have heights into Greenland/arctic regions

@nick sussex,this is what i think of the ukmo

so still some good chart viewing today,and may it continue

[A Frayed Knot]

Please delete if not allowed ' But can someone explain this and would it help with the UK getting in on the act .

[bluearmy]

4 minutes ago, A Frayed Knot said:

Please delete if not allowed ' But can someone explain this and would it help with the UK getting in on the act .

It's tomorrows output - whilst a genoa low is often good news for nw European cold, the block isn't well positioned  

[knocker]

21 minutes ago, Allseasons-si said:

Another chart is that of the 8-14 day 5oomb anomly chart from the NOAA with a nice Greeny high there with winds of a NE variety,and the mean NAO,AO graphs still show a neg phase with uncertainty at the end

day ten geopotential height anomoly's,gfs and ecm,show that we still have heights into Greenland/arctic regions

@nick sussex,this is what i think of the ukmo

so still some good chart viewing today,and may it continue

Sorry Allseasons I'm not following where you get a Greeny high from the NOAA chart and winds of a NE variety

Edited November 12, 2017 by knocker

[Snowy L]

I think a west based NAO is on the way again on the 18z. Sorry Nick.

 

Edit: Does that Atlantic low at t144 look tilted better?

Edited November 12, 2017 by Snowy L

[Allseasons-Si]

1 minute ago, Snowy L said:

I think a west based NAO is on the way again on the 18z. Sorry Nick.

Lets see what the outcome will be Snowy L

better heights to the north of that trough in the Atlantic should send it SE.

[northwestsnow]

Pressure looks higher across Europe on the 18z- not a good sign in my book but lets see how it progresses..

edit that low in the Atlantic is really throwing a spanner in the works here-

Edited November 12, 2017 by northwestsnow

[Allseasons-Si]

8 minutes ago, knocker said:

Sorry Allseasons I'm not following where you get a Greeny high from the NOAA chart and winds of a NE variety

Correct me if i'm wrong but doesn't the red dotted lines represent +ve height's(high preasure) and purple/blue dotted lines represent -ve heights(low preasure)?

[Snowy L]

Much better looking Greenland High on this run, exploding to over 1065hpa. Faroe Islands should have some fun.

[tight isobar]

3 minutes ago, northwestsnow said:

Pressure looks higher across Europe on the 18z- not a good sign in my book but lets see how it progresses..

edit that low in the Atlantic is really throwing a spanner in the works here-

Agree...

That little feature is a complete pain in the ####!..

Has on this run scuppered' the flow.

[Had Worse]

3 minutes ago, northwestsnow said:

Pressure looks higher across Europe on the 18z- not a good sign in my book but lets see how it progresses..

edit that low in the Atlantic is really throwing a spanner in the works here-

I see there' a potential tropical disturbance heading towards the Azores.  Could that upset the apple cart?

[tight isobar]

Greenland heights' increasingly becoming canadian'...

If persists through output....then its a longer route to cold...

Although the pacific ridge is still the gas burner into the pole!!!

[johnholmes]

NOAA with a nice Greeny high there with winds of a NE variety,

There are no such winds, I suspect you are mixing up +ve heights markers, the dotted red lines, with contour heights, not surface winds. If you would like to chat please pm me and I will try to explain

John

[knocker]

11 minutes ago, Allseasons-si said:

Correct me if i'm wrong but doesn't the red dotted lines represent +ve height's(high preasure) and purple/blue dotted lines represent -ve heights(low preasure)?

Yes they represent plus and negative anomalies, that is pressure higher or lower than climatology but they do not represent physical lines on a chart. Thus you have weakish positive anomalies over Greenland but the actual 500mb chart is represented by the thick green contour lines that show a ridge pushing north into southern Greenland. The same contour lines also show a very weak north westerly flow over the UK.

EDIT

I see John has replied at the same time

Edited November 12, 2017 by knocker

[Nick F]

9 minutes ago, Allseasons-si said:

Another chart is that of the 8-14 day 5oomb anomly chart from the NOAA with a nice Greeny high there with winds of a NE variety,and the mean NAO,AO graphs still show a neg phase with uncertainty at the end

The 8-14 day 500mb anomalies doesn’t show a NEly though, the coloured lines are anomalies or the deviation (+/-) in heights to the average. Then green lines are more representative of the mean flow in 8-14 day range.

Still on track for some blocking over N Atlantic and Greenland area in the medium range as per ensemble and operational guidance. Longer term, the AO shows hints of recovery towards neutral indices on the chart Allseasons posted and the EPS AO and NAO forecasts likewise return to neutral indices towards the end of the month after a dip in neutral over coming 7-10 days. However, these forecasts have been chopping and changing, though there is potential for the trop PV to strengthen as we head towards late month and early Dec, the reason this could well happen is a continued forecast for an upward spike in zonal winds at 10hPa which indicates a strengthening of the stratospheric PV toward the top which would ultimately work down towards the troposphere.

http://www.geo.fu-berlin.de/en/met/ag/strat/produkte/winterdiagnostics/index.html

but in the meantime, northern hemispheric flow over N Pacific, N America, N Atlantic and Europe looks like becoming rather convoluted and blocky ... so some interesting Synoptics evolving in the days ahead. Whether they produce what many are looking for, i.e. deep cold and snow, seems elusive for now, so not seeing another late Dec 2010 for now.

 

[northwestsnow]

Yes 18z is a bit of a mare - that low in the Atlantic just hangs around like a very unwelcome guest and really prevents much retrogression.

Time to wheel out the 1st of the season

 

Edited November 12, 2017 by northwestsnow

[nick sussex]

The shortwave you see running towards the UK needs to separate more quickly from the parent low upstream.

The longer it keeps a train of energy back to that the worse the outcome because you need it get a move on to allow ridging to the north to force the pattern further south .

The next low moving in needs to disrupt if you’re to salvage the situation but another problem is the main height rise to the north is towards west Greenland.

Positively this doesn’t support the UKMO but you can see here how this run could easily have gone completely pear shaped given the issues with shortwave energy to the west .

[tight isobar]

1 minute ago, nick sussex said:

The shortwave you see running towards the UK needs to separate more quickly from the parent low upstream.

The longer it keeps a train of energy back to that the worse the outcome because you need it get a move on to allow ridging to the north to force the pattern further south .

The next low moving in needs to disrupt if you’re to salvage the situation but another problem is the main height rise to the north is towards west Greenland.

Positively this doesn’t support the UKMO but you can see here how this run could easily have gone completely pear shaped given the issues with shortwave energy to the west .

Ye-ole short wave drama stricks AGAIN!

being a maritime/island sucks big time in such set-ups....

Lets see where we end up...18z...

[Allseasons-Si]

2 minutes ago, Nick F said:

The 8-14 day 500mb anomalies doesn’t show a NEly though, the coloured lines are anomalies or the deviation (+/-) in heights to the average. Then green lines are more representative of the mean flow in 8-14 day range.

Still on track for some blocking over N Atlantic and Greenland area in the medium range as per ensemble and operational guidance. Longer term, the AO shows hints of recovery towards neutral indices on the chart Allseasons posted and the EPS AO and NAO forecasts likewise return to neutral indices towards the end of the month after a dip in neutral over coming 7-10 days. However, these forecasts have been chopping and changing, though there is potential for the trop PV to strengthen as we head towards late month and early Dec, the reason this could well happen is a continued forecast for an upward spike in zonal winds at 10hPa which indicates a strengthening of the stratospheric PV toward the top which would ultimately work down towards the troposphere.

http://www.geo.fu-berlin.de/en/met/ag/strat/produkte/winterdiagnostics/index.html

but in the meantime, northern hemispheric flow over N Pacific, N America, N Atlantic and Europe looks like becoming rather convoluted and blocky ... so some interesting Synoptics evolving in the days ahead. Whether they produce what many are looking for, i.e. deep cold and snow, seems elusive for now, so not seeing another late Dec 2010 for now.

 

 

3 minutes ago, knocker said:

Yes they represent plus and negative anomalies, that is pressure higher or lower than climatology but they do not represent physical lines on a chart. Thus you have weakish positive anomalies over Greenland but the actual 500mb chart is represented by the thick green contour lines that show a ridge pushing north into southern Greenland. The same contour lines also show a very weak north westerly flow over the UK.

EDIT

I see John has replied at the same time

 

5 minutes ago, johnholmes said:

NOAA with a nice Greeny high there with winds of a NE variety,

There are no such winds, I suspect you are mixing up +ve heights markers, the dotted red lines, with contour heights, not surface winds. If you would like to chat please pm me and I will try to explain

John

Thanks guys

just didn't know what the green line represented

[feb1991blizzard]

1 minute ago, nick sussex said:

The shortwave you see running towards the UK needs to separate more quickly from the parent low upstream.

The longer it keeps a train of energy back to that the worse the outcome because you need it get a move on to allow ridging to the north to force the pattern further south .

The next low moving in needs to disrupt if you’re to salvage the situation but another problem is the main height rise to the north is towards west Greenland.

Positively this doesn’t support the UKMO but you can see here how this run could easily have gone completely pear shaped given the issues with shortwave energy to the west .

Yes, this always seems to happen over the last few years, we seem to need a bigger and bigger ridge between the low's / shortwaves to get a clean separation of energy, its like we just have less and less margin to play with as the years go by, its easy to predict what the next run will do based on the last, it all started in 2012, when I was first on this forum at the turn of the last decade, it seemed much easier to get blocking.

[northwestsnow]

LOL 18z is a horror show-  and wet, very wet.

All that blocking to our North west and we get soaked.

 

 

[nick sussex]

No PV over east Canada or Greenland and the weather Gods managed to dish up this tripe on the GFS 18 hrs run.

This is more disappointing than my last look at the weighing scales ! 

 

[tight isobar]

18z looking a dogs dinner in regards to blocking...

And looks' then finds every angle to shut down any forming block....

This could be a real headache to watch over next couple days.

A saviour could come in the from of russian peninsula waa....

If it can get in a cause a partial split in pv!

In coming runs....

Edited November 12, 2017 by tight isobar