Model Output Discussion - Winter arrives

[Cold Winter Night]

34 minutes ago, minus10 said:

Hi Cold Winter Night,

Thanks for the update, more positive than the general feeling on here this morning. Still learning with some of these diagrams. Can you explain "in simple terms if possible" what the regime projection chart is actually relating to , particulary EOF2 and EOF1. Is it ensemble based with a similar pattern to the MJO. ? Many thanks

Ps sorry forgot to quote you...

Yes, no problem.

The Regime chart indeed shows the ECMWF-EPS ensemble up to 192h.

The set up of this chart is indeed similar to the MJO ones, trying to show the strength and spatial distribution of weather patterns.
Only MJO has to do with pressure and precipitation along the equator.
The Regime chart is about pressure pattterns in the North-Atlantic-European space.

EOF stands for "Empirical Orthogonal Function" and comes from spatial statistics. It is also known as Principal Component Analysis.
To put it in a simple way, the idea is to reduce the complexity of weather patterns to some basic large scale circulation patterns or "regimes".

EOF-1 is in fact the NAO (North Atlantic Oscillation).
With positive height anomalies near Greenland and negative anomalies near the Azores and Europe, NAO (and EOF-1) is negative.
With negative height anomalies near Greenland, and positive anomalies near the Azores and Europe, NAO/EOF-1 is positive.

EOF-2 describes blocking height anomalies, not North-South, but more East-West.
Positive height anomalies near Scandinavia and the Northern part of Europe means positive blocking (BLO+/EOF-2 positive).
Negative height anomalies over Scandinavia/Europe with positive height anomalies in the Atlantic or near the British isles means negative blocking (BLO- or EOF-2 negative). Atlantic Ridging (AR) is a special case of this regime.

Here you see these four options, on top EOF-1 positive and negative, at the bottom EOF-2 positive and negative.

The model output assigns each calculated pattern in the Atlantic-European area to one of the four regimes. In the cluster charts this is visualised with the coloured borders, just like the figure above.

In the regime chart you get an at-a-glance overview of what direction we are heading. Closer to the circle means that the pattern is not very pronounced, at the edges it would be the extreme versions of the patterns.

Below is the same chart I show, but with NAO and BLO on it and today's chart.
It shows that we are currently in a weak NAO+, neutral BLO situation, but towards 192h moving into the BLO+ territory.

I don't know why ECMWF put EOF-1/2 on the chart and not NAO/BLO, as they do in their own explanations.

You can read more here:

Extended Range Predictability - Forecast User Guide - ECMWF Confluence Wiki

CONFLUENCE.ECMWF.INT

 

[Midlands Ice Age]

22 minutes ago, Ali1977 said:

Not sure but those with met knowledge are monitoring 

Looks to me like at least someone is following my Ozone reports on the snow and ice thread!!!

The latest one  -

 

 

MIA

[northwestsnow]

  I'm remaining optimistic of a cooling trend Christmas week - of course with a blocking high across Western Europe where it sets up matters surface temps wise.

following a chap on twitter ( won't mention names, he's an American) who has been suggesting a - NAO later in December and a SSW for the New year for some time,he's made some good calls ,hoping for a continuation of his good form )

Fingers crossed, latest mjo update has us in phase 7 I think , 10 day lag ....

 

[minus10]

21 minutes ago, Cold Winter Night said:

Yes, no problem.

The Regime chart indeed shows the ECMWF-EPS ensemble up to 192h.

The set up of this chart is indeed similar to the MJO ones, trying to show the strength and spatial distribution of weather patterns.
Only MJO has to do with pressure and precipitation along the equator.
The Regime chart is about pressure pattterns in the North-Atlantic-European space.

EOF stands for "Empirical Orthogonal Function" and comes from spatial statistics. It is also known as Principal Component Analysis.
To put it in a simple way, the idea is to reduce the complexity of weather patterns to some basic large scale circulation patterns or "regimes".

EOF-1 is in fact the NAO (North Atlantic Oscillation).
With positive height anomalies near Greenland and negative anomalies near the Azores and Europe, NAO (and EOF-1) is negative.
With negative height anomalies near Greenland, and positive anomalies near the Azores and Europe, NAO/EOF-1 is positive.

EOF-2 describes blocking height anomalies, not North-South, but more East-West.
Positive height anomalies near Scandinavia and the Northern part of Europe means positive blocking (BLO+/EOF-2 positive).
Negative height anomalies over Scandinavia/Europe with positive height anomalies in the Atlantic or near the British isles means negative blocking (BLO- or EOF-2 negative). Atlantic Ridging (AR) is a special case of this regime.

Here you see these four options, on top EOF-1 positive and negative, at the bottom EOF-2 positive and negative.

The model output assigns each calculated pattern in the Atlantic-European area to one of the four regimes. In the cluster charts this is visualised with the coloured borders, just like the figure above.

In the regime chart you get an at-a-glance overview of what direction we are heading. Closer to the circle means that the pattern is not very pronounced, at the edges it would be the extreme versions of the patterns.

Below is the same chart I show, but with NAO and BLO on it and today's chart.
It shows that we are currently in a weak NAO+, neutral BLO situation, but towards 192h moving into the BLO+ territory.

I don't know why ECMWF put EOF-1/2 on the chart and not NAO/BLO, as they do in their own explanations.

You can read more here:

Extended Range Predictability - Forecast User Guide - ECMWF Confluence Wiki

CONFLUENCE.ECMWF.INT

 

Thanks so much cwn. Very informative. I'm learning slowly...bit by bit. .

[phil nw.]

Ok folks whilst it's quiet i will lock this now and will open a new thread ready for the 12z charts.

New thread here

 

Edited December 11, 2021 by phil nw.