Winter 2023-24 third update

There hasn't been a really cold winter in the UK for a long time. The last one to be slightly colder than the average, when measured by Central England Temperature (CET), was 2020-21. Last year brought a very cold spell in December, but the milder conditions for much of the rest of the winter more than offset it. Could this year be the one?

For context and background information please read:

Winter 2023-24 weather, Is a cold winter on the way? issued on 16th September, 2023.

Is a cold winter likely issued on 24th October, 2023.

Autumn

Both September and October were very mild months. In fact, the Central England Temperature (CET) for September was 17C which was a new record. 

Although November is just past the half way mark at the time of publication, the CET is provisionally 1.9C above the 1961-90 norm.

Our view is that weather patterns this autumn are more closely correlated to mild winters than cold ones.

Seasonal models

Publicly available data from most of the seasonal models covers the entire period of the meteorological winter.

D/J/F = December, January, February

The Climate Forecast System v2 is available on TWO. View the latest CFS v2 charts.

Since the second review, issued on 24th October 2023, the seasonal models have firmed up in suggesting:

1) Above average temperatures

2) Above average amounts of rain, so potentially a wet winter

It is important to appreciate that the skill level of seasonal models for the UK and north western Europe is low, in other words they are not very accurate.

North Atlantic Sea Surface Temperatures (SST)

SSTs around the UK remain above the norm. This will increase the likelihood of above average temperatures and help to make northerly air streams less cold than would otherwise be the case.

El Niño Southern Oscillation (ENSO)

A "strong" El Niño event is forecast to persist through the Northern Hemisphere winter.

Our view is a strong El Niño reduces the chance of a cold winter in western Europe, although it possibly leads to an increased chance of cold snaps towards the end of the season.

Other teleconnections

No change from previous update. 

Solar Activity

No change from previous update.

Analogue years

The Winter Analogue Index (WAI) 30 day tracker at the time of publication has the 10 best Northern Hemisphere matches as follows: 

1) 2009 (Very cold)

2) 1952 (Rather cold)

3) 2022 (Slightly milder than average)

4) 1984 (Very cold)

5) 1976 (Rather cold)

6) 1951 (Slightly colder than average)

7) 2003 (Quite mild)

8) 1988 (Very mild)

9) 2021 (Mild) 

10) 1989 (Very mild)

At this stage the WAI is very mixed. It is notable that 4 of the top 5 matches are with colder than average winters. Nonetheless, 1988 and 1989 both appear in the top 10 and they were fifth and tenth mildest going back all the way to 1659!  

Milder and wetter than average favoured?

Since the second update the seasonal models have not changed a great deal in terms of temperature. In terms of precipitation the signal for a wetter than average season has strengthened.

The WAI is mixed, with very cold and very mild winters appearing.

Recent climatology favours milder conditions. All months so far this year (as was the case at this time last year) have produced positive temperature anomalies and winter 2021-22 was mild. November has been notably mild despite cooler conditions after mid-month.

Other factors are consistent with the previous update.

On balance, a lot of the model data points towards a milder and wetter than average winter, but there are other factors to consider. The winter forecast is released at the end of November.

News and information

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