The latest weather buzz

Weather updates from site founder Brian Gaze that keep you in the know.


Ice bears a duck

Posted  21st October 16:12

In the short to medium term the weather is looking quite unsettled. How are things shaping up as we head into and through November?

Cold signal fading

The recent upgrade to the GEFS model means charts and data going out to 35 days ahead are now available. This and the extended range ECM model are increasingly useful tools when trying to identify longer range weather trends. Needless to say they are not intended to provide day to day details!

One thing of note is there was a suggestion of cold spells being more frequent during the late part of the meteorological autumn. That could still turn out to be the case but recent model runs have been backing away from the idea.

The chart below from the GEFS model shows forecast 850hPa temperature anomalies for the week beginning November 3rd. Over the UK things are looking pretty close to the 1981 - 2010 average. There's more hint of a negative (colder) anomaly in the north west. It suggests the likelihood of colder incursions from the west or northwest being more frequent than in the south and east.

850hPa temp anomaly, week beginning 3rd November 2020

By the week beginning November 10th a positive (milder) anomaly is present over most of the UK as can be seen on the chart below. It doesn't suggest VERY mild conditions and also remember it is averaging the values over the entire week. Therefore, a mix of warmer and colder days is possible. Nonetheless, it doesn't support the idea of an early winter. 

850hPa temp anomaly, week beginning 10th November 2020

The chart below for the week beginning November 17th is very similar. Again it leans towards milder than average conditions. 

850hPa temp anomaly, week beginning 17th November 2020

Taking the above into account the present suggestion is that November temperatures are looking quite close to the norm. There earlier colder signal has faded.  

High pressure in the south

The GEFS 35 day pressure plot for London is below. The green shading indicates the standard deviation which is a measure of the forecast spread. The trend currently appears to be towards somewhat higher pressure.

My interpretation is it is pointing towards pressure increasingly building to the south of the UK. That often suggests mild weather, although if the high pressure area builds far enough northwards it can begin to turn colder as the Atlantic flow is cut off and calm conditions allow it to cool quickly at the surface.    

London MSLP 35 day plot, init Tuesday 20th October

TL;DR

To summarise the signal for colder conditions in November which I spoke about a while ago has faded if computer models are to be believed. There are caveats, for example, La Nina conditions are believed to increase the likelihood of early wintry outbreaks.

Therefore, the old saying "Ice in November to bear a duck, rest of the winter be slush and muck" may not be put to the test this year. However, there is still plenty of time for things to change.  

Latest charts


Your comments

Open from 7am to 11pm. Off topic comments may result in your account being blocked.

brian gaze 4 years ago
November turned into a very mild month with the CET finishing about 2C above the 30 year average.

1 

For terms and conditions see Readers Comments on the Cookie and privacy policy page.

RECENT UPDATES

Back to top


COMPUTER MODELS

INFO

Short range
Short to medium range
Medium to long range
Deterministic
Ensemble

See the Model inventory for the full list of model charts and data