Model Output Discussion - mid Autumn

[TSNWK]

Just now, northwestsnow said:

 NWP is carnage.. 

I don't even think we can have much confidence beyond Saturday right now..

good.. far better that, than locked in vortex / azores high and sine wave zonal pattern..

[northwestsnow]

6z day 9

0z day 9

Actually,are they that different

[MattStoke]

I'll take the GFS 6z, please.

[sheikhy]

1 minute ago, MattStoke said:

I'll take the GFS 6z, please.

Yum!!!front bumping into cold continental air!!!

[bluearmy]

Short lived scandi ridge is feasible at that timescale 

it is all rather messy atm 

[northwestsnow]

6z looks very cold next week..

 

[nick sussex]

There is an opportunity to develop the Scandinavian high as the upstream flow amplifies .

This carves more energy se to the west , the jet then bounces ne and then tries to cut back sw .

Alot depends on events in Canada here , you can see that wave moves east , this helps to amplify  the down stream pattern .

The UKMO is flatter and this then pushes low heights into Greenland .

GFS 06 hrs run to T138 hrs 

 

Associated jet forecast .

Now the UKMO 00 hrs to T144 hrs .

[northwestsnow]

It's important to remember we can see some very cold minima with High Pressure in charge late Nov early Dec..

While the holy grail of a Greenland high is obviously preferred, an anticyclone can produce ..

Just look at how quickly the surface temps drops as soon as the sun sets 

6pm

9pm

Edited November 21, 2023 by northwestsnow

[blizzard81]

Well one things for sure - this isn't a boring start to the season. 

[Snowman.]

Not surpised by the 6z Scandi high, worth noting that while early days in the ensembles there is definite uptick in pushing heights NE already..

[nick sussex]

The flattest upstream is the UKMO . All the other models have varying waves , the GFS being the most amplified .

I’m pretty certain the UKMO is wrong here . It looks much too flat against the others .

[TSNWK]

I might regret saying this.. but I just have gut feeling that this Scandinavia high option will gain traction...

1st mooted with surprise yesterday ecm seems to be firming up   and Scandinavia highs are notoriously difficult to model..

[blizzard81]

3 minutes ago, nick sussex said:

The flattest upstream is the UKMO . All the other models have varying waves , the GFS being the most amplified .

I’m pretty certain the UKMO is wrong here . It looks much too flat against the others .

This often happens with the ukmo doesn't it? Trouble is it can get things right quite often, especially when it's going against wintry heaven

[Anthony Burden]

Morning all,ECM GFS UKMO all have one think in common high pressure it’s positioning and orientation key to every door regarding mild cold effecting our shores.GFS keen on transferring the high from Atlantic to Scandinavian based bringing a possible very cold N/easterly to the UK.All to play for at present great watching nothing boring about the weather pattern at present.

[Met4Cast]

First indications of the long standing easterly wave triggered by the -IOD in the Indian Ocean is coming to an end. This should help with the next MJO cycle & indeed help switch the AAM into +ve territory more concretely. Late Dec/early Jan continues to look interesting.

Tropical forcing whilst not currently supportive of blocked patterns looks to switch around somewhat through December.

[Dennis]

december CFS

 

 

Edited November 21, 2023 by Dennis

[northwestsnow]

3 minutes ago, Met4Cast said:

First indications of the long standing easterly wave triggered by the -IOD in the Indian Ocean is coming to an end. This should help with the next MJO cycle & indeed help switch the AAM into +ve territory more concretely. Late Dec/early Jan continues to look interesting.

Tropical forcing whilst not currently supportive of blocked patterns looks to switch around somewhat through December.

Interesting thanks.

If we could squeeze a week or so of anticylonic ascendancy in the meantime that would be great.

[Dennis]

5 minutes ago, Met4Cast said:

First indications of the long standing easterly wave triggered by the -IOD in the Indian Ocean is coming to an end. This should help with the next MJO cycle & indeed help switch the AAM into +ve territory more concretely. Late Dec/early Jan continues to look interesting.

Tropical forcing whilst not currently supportive of blocked patterns looks to switch around somewhat through December.

fun there we go mate 

[blizzard81]

5 minutes ago, Dennis said:

december CFS

 

 

That looks very good indeed

[Downburst]

1 hour ago, winterof79 said:

In early winter, North Atlantic Oscillation (NAO) forces a North Atlantic sea surface temperature (SST) tripole, which persists and tends to induce a nearly reversed NAO pattern in February.

 

Plain Language Summary

The North Atlantic Oscillation (NAO) is a crucial atmospheric system that significantly impacts the weather and climate of the surrounding regions during winter. However, it often reverses between early and late winter, and the reasons for its mid-winter reversal remain unclear. The NAO behavior can be influenced by multiple factors, such as atmospheric internal processes, underlying surface, and remote climate system, which makes the issue more complex. This study highlights the role of underlying sea surface temperature anomalies (SSTAs) in the mid-winter reversal of NAO. The North Atlantic SSTAs are closely associated with the NAO and exhibit a tripole pattern. For strong sea surface temperature (SST) tripole events, the NAO primarily induces the early winter North Atlantic SST tripole. The SSTAs develop in early winter, peak in January, and feedback on the atmospheric circulation in late winter. The atmospheric circulation anomalies exhibit an almost reversed NAO pattern in February, forming a wavetrain that propagates above the Gulf Stream to the Middle East. As a result, during the warm phase of the SST tripole, Europe experiences colder temperatures, and the Caspian Sea experiences warmer temperatures in February than usual, as opposed to the positive NAO’s control over warm Europe and cold Caspian Sea in December.

Courtesy of AGU

I'll be looking at a glut on Mediterranean/mid east area early crops for Spring now. Thanks for the tip 

GFS 06z and it's high pressure near or over the top nearly all the way. Great news for farmers who in many cases can't get into fields etc. Rainfall accumulation looks great

 

Interesting that the charts at the beginning and the end of the run seem very similar indeed, at least in north atlantic and it was the same on the 00z run, given the total lack of confidence in the end of course, but isn't this suggesting not much forcing is happening. 

Beginning and End side by side

[January Snowstorm]

Quite often over the years we regularly say the long term models look better after Christmas, February will be the month etc that everything swings in our favour! The reality that transpires is usually a bust. I guess the point I'm making is let's hope for a Scandi high now, a Greenland high now. In weather slow moving highs can repeat over a Winter cycle so what's being shown now for next week is not bad. In fact a Scandi high so early in season would be great news!

[Rain All Night]

Here's a gallery of all the T+168h frames from the last four sets of model runs, for anyone else who like me has been struggling to keep up...

This morning's UKMO sticks out like a sore thumb!

[Sweatyman]

1 hour ago, northwestsnow said:

6z looks very cold next week..

 

9pm isnt that?

[Rain All Night]

Plenty of good stuff to look at on the ECM ensemble forecast for my south coast location this morning:

Edited November 21, 2023 by RainAllNight

[minus10]

Well as others have said i think its clear whatever else happens the set up with higher than average pressure over the Atlantic and lower than average pressure to the east will provide colder than average conditions with frosts...dependent on cloud cover caught up in the pattern....until beginning of December at least.

Gefs 6z/ec 0z 500 means / anoms..

Gefs 6z/ Ec 0z 850 anoms..

..this can also be seen with the NOAA anoms...(yesterday)

...it will be nice to have some more seasonal drier weather..spoiler i suspect being the cloud drifting down from the north on the eastern side...hopefully this wont be too much of a problem...looking forward to doing those autumn gardening jobs now..