nick sussex

Quite bizarre . The ECM ensembles for London seem on a different planet to the GEFS. Not a single ECM ensemble for London gets below -5 upto day 10. Yet on the GEFS there’s quite a few . One model and its ensembles are going to be eating a large piece of humble pie over the next days.

Well that was deflating! I viewed the GFS first and thought great , UK coldies might yet get a decent festive period and then both the ECM and UKMO turnout some poor runs. The ECM does have another jam tomorrow scenario developing by day 10 but really not sure coldies need another tease ! Can the Euros be wrong again as they were yesterday .

Tonight’s ECM is fast turning into Obe Wan Kenobi ! With coldies in here channeling their angst through Princess Leia who desperately seeks his help ! The first Star Wars film for me will always be the best.

Not sure any of the models have covered themselves in glory over the last few days . I know the GFS is turning into the modela non grata of this thread but the Euros also deserve some derision .

The GFS and UKMO handle upstream low pressure differently and until that’s resolved still no resolution to the Christmas Boxing Day weather . We certainly want rid of that bowling ball low on the GFS !

For what it’s worth the JMA 06 hrs run backs the Euros upto T132 hrs .

The GFS handles the shortwave near Norway differently as it has a weaker block already at day 4 . So you get the double whammy of less forcing on the Atlantic low and the shortwave doesn’t clear sufficiently se . The ECM and UKMO have to both be wrong at day 4 into 5. Which would be a very unusual outcome . Perhaps a blended solution might be the outcome which then of course brings the potential for some snow for favoured areas. Anyway we’ll see this evening what happens but generally you’d much rather the GFS was the outlier than say one of the Euros at this stage .

The GEFS are solidly behind the cold hanging on for northern parts so at the moment it’s just variations between how far north south the jet tracks through the UK . This is why small shifts in that make a big difference in the ensembles for southern parts. This is quite different to the ensembles ditching any blocking and a return to bog standard westerlies . Lets see where we are by tonight’s runs , there’s a lot going on !

The problem with the ECM and GFS outputs is everything is on a knife edge with the block transferring west and so how much forcing remains on low pressure to slide under the UK remains highly uncertain . So a real mixed bag today . Christmas Day/Boxing Day still looks uncertain with the models differing on how far north low pressure gets . Still time for changes re the block , we saw this the other day with one run a west based neg NAO and then switching on the next .

Of course . I do realize that but the UKMO has been getting on my nerves so I gave it both barrels ! I’ll repeat what I said though coldies should want rid of its output as it’s throwing up complications as in the slow clearing shortwave day 4 into 5 and its remnants being fired into the upstream low and then another shortwave to the north day 6 . The ECM shows less drama which is very nice to see !

Oh no the 63 comparisons have surfaced . This is always a bad sign ! Time to get the Coldie Helpline on speed dial !

Everyone knows I’m very picky when it comes to the models . So always like to see less complications . Regardless if an output looks good later if there’s an earlier area of concern that gets my attention . I know everyone is in happy mood after the GFS so I will muzzle it till the ECM comes out !

The UKMO also develops another shortwave to the ne by day 6 . Overall I think we need rid of its output which seems to be obsessed with complications. So goodbye and good riddance to it , come back when you’re in a festive mood!

Still don’t like what the UKMO does with that shortwave . Regardless of its okay day 6 , you never want to see energy phasing with an incoming low when you’re trying to get the negative tilt and some trough disruption .

The government is fully behind the GFS 06 hrs run as it could stop households mixing ! Snow induced lockdown !

Cold wise there’s more margin for error the further north you are . We’ve seen in the past lows end up doing what you mentioned . It wouldn’t be a big shock.

I think it’s too early to say in all honesty . The morning trends have been encouraging though.

It might be an idea if you’re going to family on the big day to get one of those bung in the oven Xmas dinners just in case ! Of course not forgetting your bobble hat, ear muffs and gloves and sledge just in case your in the higher risk areas !

I’d say 10 members vary from passable to very good . So it could have been worse . The GFS 06 hrs run manages to spread the fun around because of its evolution . It’s all very stressful for coldies in here as the stakes are quite high given the rarity of snow on Christmas /Boxing Day . One thing to bear in mind if this lands getting to friends and family could be an issue depending on where you live .

Thanks for posting those. A real mix of solutions on offer . Some very good and some ugly looking ones .

An excellent GFS 06 hrs run which has a lot of moving parts ! It blocks the high in so it can’t move too far west and then amplifies the upstream flow to help build more heights into Greenland . Its pretty clear now that we have two key areas the Norway shortwave to clear and not do a UKMO op , and troughing developing over west Greenland. Timing of the re-amplification is key so shortwave energy has moved through so any amplification upstream doesn’t try to drive low pressure ne before that’s cleared . So pretty simple then !

GFS 06 hrs run has a different troughing set up over west Greenland and this helps to block in the high and stop a seepage of heights too far west . And because of this more forcing on the pattern . The splitting of energy with now two lows moving east rather than one system also helps .

The one with the coldest outlook ! Lol Seriously though at that range I’d favour the Euros over the GFS which doesn’t help much at the moment because the ECM and UKMO disagree with that shortwave . Tonight should at least resolve the shortwave . Finally !

As a neutral observer currently in Cyprus and not Eastbourne I’ll try and deliver the unvarnished truth over the next few days . The set up shown over Christmas /Boxing Day can’t deliver for everyone so something to bear in mind. Generally the models struggle with blocking . Especially when low pressure is trying to move in from the west/sw. The alignment of the block is key to aid trough disruption, you want the block to be aligned ne sw and facing head on to any Atlantic attack . The complication with the current set up is how far east and south the block is not so much the alignment at the point of the first attack from low pressure. The initial start point re cold air is determined by the strength of the block , how far east se it is and the clearance of the Norway shortwave as that’s the marker for the colder air coming s sw. You’ll see from the ECM why it has the colder air further sw , the shortwave has cleared south towards Denmark . The models in the current set up not only have to deal with their normal bias at long range of pushing too much energy ne but also the movement of the block which wants to go further west nw . The weak point is where low pressure wants to track ne which is over the UK , and where all the drama is going to unfold !

Who would be a weather forecaster ! Good luck on the Xmas Day forecast ! The better ECM stems from our old favorite what the shortwave does which is the marker for the cold air . The UKMO doesn’t clear this , it weakens and then gets absorbed by the upstream low . Day 7 into 8 shows a front likely straddling the south with colder undercut from the east . The term that drives southern coldies mad is likely to be wheeled out by forecasters .......... north of the M4 ! However given the timeframes no one should be either celebrating or ringing the helpline ! The cold/milder boundary is likely to keep shifting .