knocker

Brilliant output from the gfs this evening. The cut off upper low over southern Europe facilitates Azores/eastern Europe HP linkage which effectively cuts off the colder air. Oh my...........

This has already been answered but just to reiterate the key factors are the height and size of the ice sheet. For example surface pressure from the Geosummit sounding at midday was 656mb with a temp of -52C Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4785997

This has already been answered but just to reiterate the key factors are the height and size of the ice sheet. For example surface pressure from the Geosummit sounding at midday was 656mb with a temp of -52C

A presentation by C.K.M. Douglas to the Geographic Sociery, 17 April 1939 polar front and its place in modern meteorology.pdf

A lot of weeping and wailing doing the rounds at the moment...........I feel their pain.

I know I remember going to school and it was up to my chin. Of course I wasn't very tall

Is it my imagination or is there a whiff of desparation in the air?

Evolution of Warming During the prewarming stage an intense polar night jet stream with strong vertical wind shear will appear. At this time a blocking situation develops in the troposphere. There is amplification of wave numbers 1 and 2 occuring in the upper troposphere and lower stratosphere. There are two types (Type A and Type B) of wave amplification which takes place during the prewarming period. In Type A, intensification of wave number 2 occurs about 2 weeks prior to the onset of the major warming. This is closely followed by an increase in the amplitude of wave number 1 with a subsequent weakening of wave number 2. During this time, wave number 1 reaches a peak about 1 week prior to the warming. In Type B warming, wave number 1 maintains a large amplitude for a long period. Type A is the most frequently occurring type of stratospheric warming. An important character of sudden warming is its downward propagation from 45 km into the lower stratosphere. This feature is not zonal in character, but hasnonzonal structure, with a planetary wave tilting westward with height. In the middle latitudes, warming in the stratosphere (40 km) is followed by cooling in the mesosphere (65 km). Simultaneously, the opposite occurs in low latitudes, with stratospheric cooling and mesospheric warming, but the magnitude of the changes in the lower latitudes is one order less compared to that noted in higher latitudes. Source _ Stratosphere Troposphere Interactions. K. Mohanakumar Further to this The numbers are the "wavenumber". This means that in a given belt of latitude, a wave with wavenumber 1 will have one peak and one trough around the entire world. This is called wave 1. Likewise, a wave with wavenumber 2 ("Wave 2") has two peaks and two troughs as you go around the globe within this latitude belt. And so on. As you can probably see, as you increase the wavenumber, you are cramming more waves in as you go around the world. So the distance between each peak and each trough gets less. This is another way of expressing the relationship between wavenumber and wavelength. Wavenumber is essentially the inverse of wavelength. Original post: https://community.netweather.tv/topic/98196-model-output-discussion-new-year-and-beyond/?do=findComment&comment=4781731

Evolution of Warming During the prewarming stage an intense polar night jet stream with strong vertical wind shear will appear. At this time a blocking situation develops in the troposphere. There is amplification of wave numbers 1 and 2 occuring in the upper troposphere and lower stratosphere. There are two types (Type A and Type B) of wave amplification which takes place during the prewarming period. In Type A, intensification of wave number 2 occurs about 2 weeks prior to the onset of the major warming. This is closely followed by an increase in the amplitude of wave number 1 with a subsequent weakening of wave number 2. During this time, wave number 1 reaches a peak about 1 week prior to the warming. In Type B warming, wave number 1 maintains a large amplitude for a long period. Type A is the most frequently occurring type of stratospheric warming. An important character of sudden warming is its downward propagation from 45 km into the lower stratosphere. This feature is not zonal in character, but hasnonzonal structure, with a planetary wave tilting westward with height. In the middle latitudes, warming in the stratosphere (40 km) is followed by cooling in the mesosphere (65 km). Simultaneously, the opposite occurs in low latitudes, with stratospheric cooling and mesospheric warming, but the magnitude of the changes in the lower latitudes is one order less compared to that noted in higher latitudes. Source _ Stratosphere Troposphere Interactions. K. Mohanakumar Further to this The numbers are the "wavenumber". This means that in a given belt of latitude, a wave with wavenumber 1 will have one peak and one trough around the entire world. This is called wave 1. Likewise, a wave with wavenumber 2 ("Wave 2") has two peaks and two troughs as you go around the globe within this latitude belt. And so on. As you can probably see, as you increase the wavenumber, you are cramming more waves in as you go around the world. So the distance between each peak and each trough gets less. This is another way of expressing the relationship between wavenumber and wavelength. Wavenumber is essentially the inverse of wavelength.

I don't know, for this maybe? http://www.theweatherprediction.com/habyhints/127/

I am not surprised after your earlier inflammatory comment

Your efforts are admirable Eagle Eye, thank you for that, and you might find the attached of interest as it combines the facts and theoretical Mohanakumar 2.docx

Probably too short a time span but this may be of interest https://www.ecmwf.int/en/about/media-centre/news/2020/drop-aircraft-observations-could-have-impact-weather-forecasts

I hear on the grapevine that a suicide watch is under consideration.

Looks like the air con will be on over Xmas.

They said winter is all over.........................it is now

That is still a tad iffy but could well be some snow over Dartmoor

The little feature to the SW is an upper warm front

Goddammit I cannot now unread that

It is losing amplification and indicating more Atlantic influence which of course would support the temps forecast previously posted.

Not so good over the Xmas week

Temps back to average by Xmas week

Is that correct? https://confluence.ecmwf.int/display/FCST/Known+IFS+forecasting+issues

waugh-etal-BAMS-2017 polar vortex.pdf

People are fixating on the 850mb temps once again instead of looking at the boundary layer