http://modeles.meteociel.fr/modeles/gfs/runs/2013121818/gfsnh-0-324.png?18

Another deep area of LP to start the New Year

Hi.  It's not a matter of the pressure reading, it's about the nature of the pressure system.  For example you can have a low pressure cell with pressure of 1,020 mb, for example in an area of predominantly high pressure.  Similarly you can have a weak high pressure of 1,015 mb in an area of predominantly low pressure. 

High pressure means only that the air is sinking, which pushes up the pressure at the surface.  Low pressure means that the air is rising, lowering the pressure at the surface.

There's a perfect example here: http://modeles.meteociel.fr/modeles/gfs/runs/2013121818/gfsnh-0-168.png?18

Look at the area over western Kazakstan (just east of Turkey) - there's a shallow low pressure with central pressure a little below 1,025mb

Here: http://modeles.meteociel.fr/modeles/gfs/runs/2013121818/gfsnh-0-60.png?18

there are two surface highs of around 1,020mb over Canada

OK?

Hi.  It's not a matter of the pressure reading, it's about the nature of the pressure system.  For example you can have a low pressure cell with pressure of 1,020 mb, for example in an area of predominantly high pressure.  Similarly you can have a weak high pressure of 1,015 mb in an area of predominantly low pressure. 

High pressure means only that the air is sinking, which pushes up the pressure at the surface.  Low pressure means that the air is rising, lowering the pressure at the surface.

There's a perfect example here: http://modeles.meteociel.fr/modeles/gfs/runs/2013121818/gfsnh-0-168.png?18

Look at the area over western Kazakstan (just east of Turkey) - there's a shallow low pressure with central pressure a little below 1,025mb

Here: http://modeles.meteociel.fr/modeles/gfs/runs/2013121818/gfsnh-0-60.png?18

there are two surface highs of around 1,020mb over Canada

OK?

A colder run as you say

Xmas Eve showing 4c  Xmas Day 3c  Boxing Day 2c

http://expert-images.weatheronline.co.uk/daten/proficharts/en/2013/12/19/basis00/ukuk/rart/13122406_2_1900.gif

JFF JFF

Xmas Eve could have a wintry taste for some

http://modeles.meteociel.fr/modeles/gfs/runs/2013121900/gfsnh-0-126.png?0

Interesting GFS and UKMO, but ECM remains poor sending it too far north

GEM loaded with potential

http://modeles.meteociel.fr/modeles/gem/runs/2013121900/gem-0-240.png?00

The latest run continues the FI theme of a massive Siberian High pushing into the deep Artic and displacing the PV.

If this comes to pass (and it is in deep FI), it will herald a change from zonality, to cold zonality at the very least.

Not sure if this link has been posted before, but a very useful way of checking the current wind speeds not only locally but globally

http://earth.nullschool.net/#current/wind/isobaric/850hPa/orthographic=-8.91,31.71,795 

If you click Earth in the bottom left corner it opens a settings menu where you can change the heights.

Good morning. Here is the report on the NWP output for today's midnight outputs for today Thursday December 19th 2013.

All models show the run up to Christmas as unsettled and potentially quite stormy at times as deep depressions continue to run East over or just to the North of the UK. Spells of heavy rain will be commonplace especially later tomorrow and Saturday in the South. Christmas Eve also looks like it could be very wet and windy too. All other times will see a mix of sunshine and showers with wintry showers over the hills at times as air turns briefly colder under these events.

GFS shows Christmas Eve as a very unsettled day with deep Low pressure straddling the UK with each centre providing the risk of prolonged and heavy rain and it looks like it would be cold enough for snow on Northern hills. Christmas Day and boxing Day remain very similar with unstable and sometimes strong Westerly winds providing plenty of opportunity for heavy rain and wintry showers. This weather type continues up to and over the New Year with temperatures near to or a little below average.

UKMO shows an intense depression just to the North of Scotland on Christmas Eve with strong Westerly winds and rain clearing to brighter or clearer spells and wintry showers with some snow on Northern hills.

GEM maintains deep Low pressure over the UK throughout the Christmas week and in the days thereafter with heavy rain and strong winds never far away and with temperatures borderline for snow on hills at times.

NAVGEM looks a lot like UKMO for Christmas Eve with the following two days of Christmas following suit with deep Low pressure over or close to the UK maintaining strong winds and heavy rain for many with some wintry type showers in between.

ECM shows very unsettled weather over Christmas with rain at times and snow on the hills though it has removed the damaging winds scenario over Christmas on previous output. Nevertheless there is still plenty of wind and rain shown to wash down the Christmas festivities.

The GFS Ensembles maintain a very average setup temperature wise made up of an oscillating sine wave pattern by all members with fast changing air types bringing rain areas across from the West followed by showers, wintry on hills. Christmas itself continues to be modelled as a very wet period especially in the South.

The Jet Stream continues to be programmed to be crossing the UK strongly from the West for the next week, slipping South of the UK at times over Christmas. It then resets slightly further North across the UK in the run up to the New Year, still very strong.

In Summary there is nothing new to report this morning with all models continuing to predict very volatile conditions with spells of rain and gales alternating with brighter and more showery conditions with some snow on the hills. The risk of severe gales over Christmas remains though the operational runs have backed off a little from this today. For those hoping for a pattern change as we look towards the New Year may find that they may have to wait rather longer from this morning's extended model outputs.

Thanks Martin, glad you dropped the word mini T

Another day and zonal all the way as far as the models can see. Although there is a suggestion that the jet will push slightly further south after Christmas and then we might be in the cooler, if not very cold air, for longer with each passing wave. If you want to experience some lying snow then hiking or skiing in the northern hills is an option.

Not so sure about that gfs longer term shows sighns of change quite a bit different this morning at 500

http://www.meteo.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

gfs control looks very intresting later on

http://www.meteociel.fr/modeles/gefs_cartes.php?ech=180&code=0&mode=0&carte=1

ECM ens very poor

no sign of any cold weather

http://www.knmi.nl/exp/pluim/vijftiendaagse/index.php

Yes good to see the pressure at the pole increasing, inline with Gavin P's video the other day. Hopefully this is a trend that will increase. Perhaps the first tentative sign of a change as we go into the new year.

GFS has come up with a different phasing of energy that sees the PV spread out all over the place; some of it deposited over the UK, some of it heading across Siberia and so on.

This allows a blocking high to become sustained across the Pole, driving high latitude blocking which makes for interesting snow potential for the UK that seems to gradually increase as the run progresses.

Shame that ECM isn't sniffing that idea at the moment - it has the energy from the U.S. tracking across more slowly than GFS and phasing far more effectively for bombogenesis to occur i.e. very intense low pressure systems developing very rapidly. The day 5 offering is a 932mb low centred not far NW of the UK!

UKMO seems to have produced the usual halfway house scenario in terms of LP intensity and energy phasing. It even has that secondary low coming off the U.S. on day 6 as a stronger feature than GFS but weaker than ECM has it... in fact quite a bit weaker, such that it is leaning far more towards GFS on that. I reckon that's a positive in terms of how the pattern could develop from there in terms of the high latitude blocking 

...but most positive of all is what UKMO models for the Polar region:

http://www.meteociel.fr/ukmo/archives/2013121900/UN144-21.GIF

That ridge of high pressure from Asia is far more impressive than GFS and ECM have it, and to my eyes offers a quicker route to establishing some high latitude blocking... if it verifies.

06z so far similar to the 00z

GFS joining the <935mb party for Xmas Eve. http://www.wetterzentrale.de/pics/Rtavn1141.png

ECM has it too: http://www.wetterzentrale.de/pics/Recm1201.gif

Whereas UKMO is 30mb less deep: http://www.wetterzentrale.de/pics/Rukm1201.gif

But the upper pattern and shading is almost identical, so is it just a case of the UKMO charts missing a lot of isobars? There's a suspicious-looking "hole" in the middle of the low.

Edit: also you can see the rsik of a secondary low racing across the UK: http://www.wetterzentrale.de/pics/Rtavn1261.png

GFS doesn't really develop it on this run but it is something to watch out for...

A milder run than the 00z , not much to start jumping about at