nick sussex

The ECM day 5 certainly looks better than the GFS. A cleaner evolution with the shortwave further se and the block a bit further east se .

These sorts of really annoying charts aren’t that uncommon with this set up. The troughing over Scandi acts as the magnet to low pressure which runs east and then wants to head ne at the weak part of the block . There’s not enough forcing on low pressure to the sw . Eventually you’ll end up with the jet forcing ne through the UK and the deeper cold running off into the sunset freezing the fish to the nw of the UK. Its a horrible ghastly irritating waste of a block !

The issue is still the block is too far west so there’s always going to be pressure on the jet to switch more ne into the UK . The block needs to be adjusted se ASAP !

Quite a difference between the UKMO and GFS by day 6 regarding the timing of low pressure moving east into the sw of the UK. Ironically it’s role reversal now with the UKMO improving and the GFS hitting the buffers from their 00hrs runs.

Could be very wet or very white come Christmas. You can make a reasonable case for both outcomes especially further north . The more west based negative NAO is always a nerve shredder for coldies , low pressure tries to move ne at the weakest part of the blocking . This then phases with the Scandi troughing , what you don’t want is overly deep lows trying to move in .

Did something happen whilst I was having my breakfast ! The ECM avoids a shortwave drama near Norway and delivers some nice charts over Christmas . So now the wait begins to tonight’s outputs .

Jeez ! The typhoon popped up to stall the MJO and now sunspots ! What did coldies do in a previous life to deserve this !

An underwhelming start with the UKMO now deciding to leave the shortwave over west Norway . This reduces the forcing on the upstream troughing and the day 7 has the cold air stuck to the north with the core of heights to the north too far west . The GFS takes the shortwave se but then spills too much energy east . It does seem like pulling teeth for coldies at the moment . The ECM needs to step up and stop the rot !

High risk high reward. Do coldies feel lucky ! If the high or a wedge is to win out then you want the Atlantic to try and move in and then energy to slip se wards . Along the frontal boundary you could get some significant snow . If of course the high proves more resolute then the models will start correcting west and sw but often this happens more in the reliable timeframe . Theres generally a model bias especially with the GFS to direct more energy east and ne rather than se at longer range . The ECM output has a better foundation early on as the upstream trough set up is elongated and aligned more nw se . The rounded trough of the GFS signifies less trough disruption , regardless of the later fireworks it really looks on dodgy ground.

Something to bear in mind with low pressure moving in from the sw against high pressure . The isobars you see on the slp charts will give a slightly misleading picture . So if they look se the flow will be more ese to east. This is relevant when you’re trying to import drier air with lower dew points to meet Atlantic fronts .

The GFS does provide some fireworks for coldies over Christmas . However the shape of the upstream troughing doesn’t look favourable day 8 and it performs a high wire act after that to get some energy running se . Really not convinced by its evolution as it relies on so many things going right at the same time and could easily unravel . You really need a more elongated troughing running nw se and more energy going in that direction from day 8 . Anyway let’s hope the ECM can plot a route forward that has a lot more margin for error .

The ECM saves itself by day 9 as the shortwave over ne Canada phases at the base of the troughing . This causes an anti clockwise effect on that which pulls the energy nw . You’d still rather see a sharper trough at day 8 for more margin for error .

Day 8 ECM looks a bit ropey . I’m not liking that upstream troughing set up .

The ECM is close to the GEM UKMO solutions day 6 . The splitting energy as you can see the GFS has one low upstream and flatter and no shortwave running ne out of Canada . The others have the split energy with two lows and that shortwave . The ECM does though have that little shortwave attached on the eastern flank west of Iceland . The UKMO and GEM have the cleanest solutions upstream by day 6 .

The GFS and UKMO handle the area west of Greenland quite differently by day 6 so until that’s resolved uncertainty remains regarding where the high sets up . The GEM and the UKMO are on the same page upstream re the main features so the deciding vote goes to the ECM ! Day 5 ECM looks like it’s saying no to the GFS solution .

Flat upstream and different over the east Pacific sums up tonight’s ECM op. After the models seemed to be moving in the right direction for coldies tonight’s outputs bar the GEM have been very underwhelming .

It’s likely go for a second attempt , if you see that shortwave energy ne of Iceland , that’s likely to run se towards Scandi . Upstream looks okay with that amplified wave moving east across Canada this helps to pull back too much energy spilling east into Greenland .

It’s been a case of chasing the high for the last few days . More solid support now for it heading further north . This mornings GFS attempts two rounds It doesn’t quite manage the relevant jet cut back sw to draw the coldest air into the UK but it will still turn colder . So the jet cut back is now key both for the much colder uppers and drawing more instability into the flow .

Interesting trends from the GFS and ECM. The key thing though isn’t just the high edging nw but where any troughing sets up to the east . Cold and frosty is of course nice for Christmas but getting any troughing further west will help on the snow front .

I remember the 1988/1989 horror show . The November was quite cold and then the winter sank without trace . The Bartlett High does get wheeled out a lot in here any time people see high pressure to the sw . Anyway let’s talk no more about it as I’m sure coldies old enough to remember the winter in name only don’t need to be further traumatized !

The ECM when you want it to be wrong it’s right and the reverse . The Scandi block of cold air gets blown away and unless there’s some Hollywood scriptwriters in town then hard to make a case for anything interesting in the next ten days unless you like your roof tiles being blown off. What happens post day ten looks like it will rely on some shuffling in the upstream pattern by way of the MJO although over recent winters it has promised much but delivered little. It’s early days though so no reason to get too downbeat if you’re a coldie . Some hideous looking charts from a cold perspective do appear at times and are par for the course even in decent UK winters .

A similar GFS run to the earlier 00hrs but with a bit more trough disruption . The cold pool to the east does make some progress westwards , at this range still likely to be some more changes so coldies should certainly turn up for the 12hrs runs later .

At that range there’s still likely to be some changes and that cold pool to the ne isn’t far away . Could go either way at this stage .

Looking at the outputs of the big 3 . Some uncertainty remains as to how much trough disruption occurs and the boundary between more continental sourced air v the Atlantic upto day 6. Any westwards corrections especially on the ECM might provide some interest .

Pretty uninspiring ECM op unless you like wind and rain . The GFS op is now the only model which detaches the low from the mothership . Given the Euros aren’t interested in a battleground scenario and the differences are close range the GFS seems to be on a sticky wicket . Having said this the ECM has been pretty woeful in recent weeks. Later on the ECM does have the PV in bits but the upstream pattern is as flat as a pancake at that point , hopefully the MJO might start feeding through although in recent years the MJO has promised much but rarely delivered . Anyway it’s only December so no need to panic . And I haven’t wheeled out any film analogies which is normally a sign to book a trip to Lapland . I just realized I mentioned mothership!