When is it going to snow? Models Indicating Cold Spell In Mid-November

Overall, November is looking like it will be colder than average following a colder than average September and October. For those wondering “when is it going to snow?” it currently looks like it will be mid-November at the earliest before we see any "extensive" snow away from the highest summits.

There are tentative signs that we could see a blast of very cold air around the middle of November. Both the ECM and GFS models are suggesting that ridging to our west in the Atlantic and northwest over Greenland will bring an end to the Jetstream-influenced weather that we will be experiencing over the coming 7-10 days. This type set-up can potentially open the door to colder air from the north or northeast (GFS for mid Nov - http://images.meteociel.fr/im/5910/gensnh-0-0-384_wyo1.png).

Blocking certainly showing up on the CFS charts for November - https://pbs.twimg.com/media/A6dWfglCUAA3dMR.jpg:large

Upper air (1500 m or so) temps on 15 Nov. Image meteociel.fr

It’s all ifs, buts and maybes looking at the models at the moment. The first real wintry blast of 2010 did not occur until the last week of November. The signs were there about 10-14 days in advance. In the situation described above, the building blocks are moving into place for a wintry blast but they can easily come tumbling back down again over the next day or two. There is nothing in the models to suggest an extended cold period. In fact, this post refers to outliers being presented in the models for November only. It's not a forecast, but instead an interpretation of what the models are suggesting at this early stage.

It is also also worth nothing that a cold spell in mid-November may not bring widespread low temperatures and/or snowfall as seen during the late Nov freeze of 2010, as it is quite early in the season. Entrenched cold over the Continent/Scandinavia will not have been established by mid-November so any cold airmass that reaches Ireland and the UK will not be as extreme as witnessed in 2010.

Finally, it is worth remembering that the meteorological winter* does not begin until Dec 5, so enjoy the last few weeks of autumn!

Mark Dunphy
*The Meteorological winter is a three month period that runs from Dec 5th to March 5th. It is the coldest three month period of the year in the northern hemisphere. Astronomical winter is what we all refer to when we talk about the winter season and this is based on when the sun reaches the most southern point on the globe, the Tropic of Capricorn.