nick sussex

A word about the ECM. NOAA commented on the differences, the discussion doesn't include tonights ECM but the flat versus more amplified is still in evidence. The NOAA state forecasts will cover the ECM later on: MODELS ARE STILL STRUGGLING WITH SOME OF THE DETAILS SURROUNDING WHETHER A LOBE OF ENERGY ORIGINATING IN THE GULF OF AK OVER THE WEEKEND BECOMES QUICKLY ABSORBED IN THE NORTHERN STREAM FLOW/AMPLIFYING TROUGH, OR SEPARATES INTO A CUTOFF UPPER LOW ACROSS THE SOUTHWESTERN U.S. OR EVEN ACROSS THE EASTERN PACIFIC. THE ECMWF MADE A SUBSTANTIAL CHANGE WITH THE 12Z THU RUN FROM A MORE CONSOLIDATED TROUGH TO A DEEP CUTOFF LOW PERSISTING ACROSS THE E PAC/SOUTHWEST/NORTHERN MEXICO THROUGH DAY 7, AND THE MODEL PERSISTED WITH THIS SOLUTION IN THE 00Z RUN. THE GFS HAS BEEN A BIT MORE CONSISTENT FOR SEVERAL RUNS, SHOWING AN ELONGATED AREA OF VORTICITY EXTENDING WESTWARD INTO THE SOUTHWESTERN STATES FROM THE LARGER TROUGH. ENSEMBLE TRENDS HAVE MOVED IN A DIRECTION OPPOSITE OF THE DETERMINISTIC ECMWF, WITH MORE ECENS/NAEFS MEMBERS SHIFTING TO A MORE GFS-LIKE SOLUTION. GIVEN THAT THE ECMWF HAS BEEN PERSISTENT IN THIS NEW SOLUTION FOR TWO CONSECUTIVE RUNS, HOWEVER, CANNOT JUSTIFY THROWING IT OUT ENTIRELY. THIS HAS IMPLICATIONS FOR THE EASTERN U.S. TROUGH, WITH LESS/NO CUTOFF LIKELY MEANING A MORE AMPLIFIED LARGE SCALE EASTERN TROUGH AND THUS COLDER TEMPERATURES BY THE MIDDLE OF NEXT WEEK IN A GFS SCENARIO RELATIVE TO THE ECMWF.

Even with the ECM being more progressive a good sign is the Azores high shows no signs of ridging east. So it threw everything east and still didn't manage that. So I'd take that as a positive.

We're seeing a bit of a reversal here. Normally its the GFS which is flatter upstream but in recent runs its been the ECM.

The overblown low is a typical GFS bias. It did the same thing a few weeks back, if we remember the GFS and UKMO were more interested in developing a shortwave to the sw. The ECM didn't want to know, eventually we settled on a weak low which ran ene. NOAA have often commented on this bias and so the odds of that low verifying are very small.

Yes it’s a case of one better for the initial snow and one for a better northerly . It’s great to be discussing these options.

The GFS is better for backedge snow as it doesn’t develop a shortwave in the flow from the north . The UKMO because of that has a slower push south of the cold.

Wow even more upgrades with the pattern edged further south and the trigger low further south. I think the GFS has overblown the low but apart from that what a great start to the evening. And will the Svandi block appear?

You’re such a tease! Can we have a pseudo Scandi block , so not a typical one but the Svalbard to towards Norway one! I’ll call it the Svandi Block.

Well yes but the reason I’ve referred to it as displaced is because we often see the Azores high ridging east into southern Europe in response to the more common winter jet stream pattern. Its not allowed to do that here because the jet is curving se into the Continent. So you’re right it’s over the Azores but has been blocked from extending eastwards and displaced from where it’s normally located especially during recent winters.

Just caught up with the GFS 06hrs run which upgrades the cold potential by keeping the PV further to the nw which is in line with what you'd expect from a neg AO and positive PNA pattern. I think whats particularly interesting is the high developing to the ne which will act as a break on where low pressure can track from upstream. High pressure there will force the jet to divert more se, if you're a coldie then this could help keep the UK on the cold side , then you look to the nw the upstream PV will reinvigorate the jet with a large temp difference as that cold hits the Atlantic. Now we often think of mobility as a west east flow with not much on offer but in this instance the jet will track further south than normal and be diverted se close to the UK. In these situations if you keep the cold low pressure can deliver snow on the east/ne flank of that. I've done a crayon job to show what to keep an eye on in future runs. The area to keep an eye on is that circled red, as long as you maintain decent heights there this will keep your snow options open, you can also see the displaced Azores high as long as that remains displaced and you keep lowish heights over central Europe you're in the game. In terms of what type of low might drop se, preferably you want a weakish feature, as that's more likely to slide se favourably and not remove any embedded cold ahead of it. It might be if we get lucky that high pressure to the ne will develop further. Before we get too excited though we need to get over the initial hurdle of clearing a low se of the UK with ridge building in from the nw. That's within the T168hrs timeframe.

I’m regionless . Unless I want to set one up with just one member! In terms of that snow in Spain that is quite high up so don’t feel too hard done by. We did get some here at 1100 feet which is the first snow for two years.

I'm pleased to announce the recipient of the first winter season Epic Fail award goes to yesterday evenings ECM which was incorrect at just T96hrs! Anyway moving on from a woeful performance by the ECM good agreement this morning for the pattern with the big 3 splitting low pressure to the sw with a low tracking east with a chance of snow on the northern flank and then a briefish n/nw flow. After that the Azores high displaces allowing a lowering of heights across central Europe. Because of that low pressure will try and track more se in towards the UK. At this time the depth of any low and exact track will determine whether the UK remains on the cold side of the jet which if that is the case a chance of some further snowfall as that engages that colder air. The current evolution isn't one that shouts deep cold or non-stop cold for the timebeing but has the scope to deliver some cold and snow. Overall though interest for coldies. It could be worse and certainly given recent winters the fact we're even talking about some possibilities is a refreshing change.

Anyway moving on from BambiGate ! a good sign to see our common winter foe the Azores high displaced . And as long as you keep low heights over central Europe that keeps the door open for some wintry weather.

I wonder if this is a data coverage issue in a key area which is causing this big difference between the ECM and GFS. You can look at this two ways there’s a very strong signal to displace the Azores high so even with different starts both outputs want to converge eventually to that .

Quite astonishing to see the differences between the ECM and GFS at T144hrs hrs. One would hope with an extra 6 hours of new data and the fact the chasm begins at just T96 hrs the GFS might hopefully be correct! Regardless the ECM did manage to get to a decent end point and so let’s hope even with different evolutions at the start we get there eventually in terms of something wintry popping up.

The GFS gets to T90 hrs and hasn’t moved towards the ECM shortwave calamity . Very bizarre goings on with the ECM handling things so differently in the early stages of its 12 hrs output .

Blame me its my melodramatic posting style! Talking of which as you know my heritage is Greek Cypriot so it comes naturally!

I'm not promising a big freeze but the upstream pattern and neg AO suggest a low track se'wards into the UK which always gives opportunities for some snow and cold. MS re the neg NAO that has been difficult to achieve in recent years. We'll have to see over coming days whether the outputs deliver that.

The updated NOAA monthly forecast has just been issued. http://www.cpc.ncep.noaa.gov/products/predictions/long_range/fxus07.html If the UK can't get some snow and cold from what I've read then theres a curse! It might be wintry in the east USA with energy firing east into the Atlantic but with a negative AO and the MJO on the move towards the west Pacific low track into the UK should be forced further south. So to be frank it would be tragic beyond belief if coldies here don't get something to enjoy during December.

I'm still waiting for the NOAA updated monthly forecast but in the meantime the New York state forecast calls into question the outputs which remove the Greenland block too quickly. It's a long read but well worth it. Looking farther ahead, the major pattern change that starts to take shape Wednesday will mature by the end of next week. Long range ensemble guidance is an excellent agreement with this pattern change, and has only grown stronger with forecast blocking over the past few days. The anomalously strong and eastward extending East Asian Jet is in the process of weakening, and this will allow for a strong amplification of the Pacific wave train. This will force the downstream pattern across North America to strongly amplify, with a strengthening ridge along the west coast and a deep longwave trough carving out over central and eastern North America. At the same time, blocking over Greenland will strengthen. The increasing high latitude blocking will project on an increasingly strong negative AO (Arctic Oscillation), with the Greenland Block forcing a negative NAO (North Atlantic Oscillation). The western ridge/eastern trough and amplification farther west in the Pacific will force an increasingly positive PNA (Pacific North American) pattern. The coupling of a negative NAO and positive PNA pattern will result in an extended period of below normal temperatures and active winter weather for the Great Lakes starting late next week, and lasting for an extended period of time. The first few days of the pattern change late next week will be routine cold, but after about December 10th there are increasing signals in long range ensemble guidance that several blasts of true arctic air may be in play for the Great Lakes and Northeast. Obviously details are impossible to predict at this time range, but the large scale pattern suggests the possibility of numerous high impact lake effect snow events starting late next week or next weekend, and continuing through the middle of December. Stay tuned. The upstream pattern is really one that should help downstream for UK coldies, the fact they mention an extended period of time is good. Of course energy being thrown east into the Atlantic will run towards the UK but it should be angled more favourably. The displaced Azores high would be as a result of that upstream amplitude in the east USA with that troughing.

I tend to think of the north as anywhere from the Peak District northwards.

Here you go, hope this link helps: http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/

Frustratingly the MJO forecasts haven’t updated for two days . Very bad timing for that to happen . We might be seeing some conflicting messages in the outputs and more volatility than normal . This displaced Azores high in the ECM has me wondering.

This thread is a mix of analysis and the occasional toys out of prams. We’re not the BBC giving a forecast . And the ups and downs and some of the melodrama and humour in here are part and parcel of the success of these forums . Coldies in here are not your average members of the public , the majority are snow lovers who are passionate and so no I don’t want a dry humourless emotionless thread just discussing the track of a low. Yes of course you want to see some analysis and there’s lots of that in here, but at times it’s going to happen that we might lose it and and have the occasional moan.

Well after a tragic start , one which nearly ended up with my laptop meeting a grisly end the ECM performs a miracle of sorts! The displaced Azores high and low heights over Europe saved my mood however once again we’re chasing rainbows and it’s hard to have faith in any outputs till there’s agreement in the early stages . My mood is now in a holding pattern waiting for the next move from the outputs!