comet
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Posts posted by comet
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We need to see the heights pushing up from Alaska force their way into the Arctic to support the ridge and allow heights to build over north western Russia rather than retreat back into Canada.
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Nice round of applause for the gfs please.
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May have been a little slow on the uptake here regarding the struggle the models are having with longer term outlook. There has been a reasonable warming and more importantly strong geopotential height rises from 10mb down across northern and north eastern Canada. Below are the geopotential heights at 30b on11/12
70mb I presume the ridging we are seeing in the PNA /EPO locale is the models interpretation of how this warming and heights will play out as they filter down into the troposphere. If we see a slow propagation then the impacts will probably be far less dramatic than if we see a faster propagation. Scandinavian height rises make sense rather like a counterbalance wave 2 effect. Then as the heights move clockwise we will see a cross polar flow setting up with wave 1 heights in the Pacific and wave 2 ridging north so perhaps a transition from east /north easterly into northerly.
The stratosphere gfs instant weather maps give an indication which way the heights are expected to travel. It is only towards the end of the run that I think we see the possible forcing (warming) from MJO related wave breaking.
Feel free to add/correct if my analysis is off.
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21 minutes ago, nick sussex said:
Great detail from New Hampshire state forecast talking about the overall NH pattern into late December:
Overview...
Interpreting through late December. Considerable forecast warming in
the stratosphere, polar low / night-time jet displaced to the other
side of the N hemisphere subsequent of noteworthy anomalous ridging
across Northern N America. Beneath which warm air continues to surge
into the Arctic from the NW Pacific (with perhaps MJO contributions)
and the NW Atlantic displacing colder air S where it becomes bowled
up across NE Asia / NE N America. Ensemble means continue to signal
an active weather pattern with an amplified H5 ridge-trof pattern
over the CONUS, anomalous H85 T warming over the N Pacific with cold
anomalies continually reloaded over Central/E N America, however a
trend towards higher heights / surface mean sea level pressure with
stratospheric cross-polar flow shifting into NW Europe.
Sounds great for NW Europe and the UK but is this not just an interpretation of what the gfs op run is showing rather than a detailed view of what the mets in this area are expecting to see happen. Not saying it will not happen though.
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2 hours ago, bluearmy said:
Whilst the ecm trop run looks poor for coldies, the upper strat is excellent - if only we could get a coupling and see that imprint further down
Anyway, will be in Berlin in a few hours
They are coupled and have been for a while.
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8 hours ago, bluearmy said:
GEFS continues with the trend to take the vortex closer to the pole on a trip back to Canada from Siberia end week 2.
given the strength of the wave 1 on berlin at day 10, its a surprise that the displacement signal wains thereafter
the 12z Geopotential heights do not agree with this. See instant weather maps.
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First signs on ecm 12z operational at t240 throwing up a ridge towards the Arctic from the pacific side. FI will be especially volatile with its output until the models grasp how strong a ridge we are likely to see. Also how significant a strat warming to coincide with MJO ridge will determine length and severity of possible oncoming cold spell end of Dec onwards.
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Obviously the greater the Alaskan ridging into the Arctic the greater the impact on the AO and northern hemisphere blocking. At the moment the amount of ridging is changing run to run but if the northerly modelled by the 12z was to be followed by a very strong Alaskan ridge similar to the one modelled in the 06z run then we could really be in business.
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Without a doubt the strong MJO and subsequent warming early November in the strat has pre-conditioned the atmosphere making it much more susceptible to MJO forcings etc. Great run this from the 12z gfs.
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Lets hope we see more charts like this from 06z run this morning.
This would probably lead to a very long and protracted bitterly cold and wintry spell for Europe and the UK. Now that is what I would call the start of a big freeze. Here's hoping.
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No surprise to see the 12z gefs showing a better prospect for cold with stronger northern blocking are the ones showing greater warming in the strat. This I Imagine ties in with the strength of the MJO signal with one leading the other. Not sure which leads which though as we have seen strong MJO action before in past winters with only weak strat response. What ever now that the strat and trop are properly coupled it is important to get a strong strat response I think.
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56 minutes ago, TEITS said:
In my opinion we haven't been seeing wild swings in the output in recent days. Actually the models have been consistent in bringing us a return to milder SW,lys.
Personally I think members should forget about the predicted Scandi HP and focus on just what the models are currently predicting. The reason I say this is because even towards the latter stages of the GFS we couldn't be further away from an E,ly via a Scandi HP if we tried. If anything any future cold spells in distant F.I are more likely to come from a NW/N,ly.
Agreed. Nothing what so ever to suggest any sort of cold spell developing from the east northeast in the next 10 days at least. in fact I could not think of a worse winter chart than the one offered up by the 06z at t192.
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55 minutes ago, Broadmayne blizzard said:
Because as Tamara and GP pointed out the other day there will be a transition period from the end of the current Atlantic ridge driven cold spell to another cold spell come xmas/new year driven by hieght rises to our north and northeast. This was always on the cards and it is no surprise to see it in the modelling.
Posters putting to much faith in what Tamara and GP have to say will lead to tears time and again. Some posters have very short memories. Having said that they may be right and they may be wrong. Events happening in the strat now that it is properly coupled with the trop will dictate where the weather will be heading in the next couple of weeks. This reminds me very much of 12/13 so I would not be surprised to see a more mobile pattern unfortunately over the next couple of weeks similar to Dec 12 when the strat was undergoing a warming. It may not be till late Dec or early Jan before we see a switch back to a much colder and blocked pattern setting up again. I really hope I am wrong though.
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The last couple of days I had been pondering why the models were showing a slider when all models were showing pressure falling to the north. It did not make sense and either the models were wrong and we would see deeper lows moving in a more West to East direction or pressure to the north was being modelled wrong and pressure would remain higher to the north and thus the slider. It now looks as though it was the latter. The question I am now asking is if the models were wrong with heights to the north at just 3to4 days out then there is a high chance they are wrong at 6and 7 days out etc.
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16 minutes ago, abbie123 said:
BBC saying staying cold in to next week with further snow ..
I hope he is right but unfortunately that does not mean a great deal. I am quite sure you yourself may have seen a snowy picture at the start of a bbc weather bulletin with the wording snow on the way tomorrow and yet when he gets into the forecast the only places likely to see snow were the Scottish highlands. Talk about misleading.
Anyway still holding out a slim hope of the slider Sunday into Monday may take a more favourable path for those of us down south and also the possibility of seeing a few flakes during Friday into Saturday. If the GFS is to be believed then it shows it is still possible to get potent northerlies even so early into the season.
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39 minutes ago, bluearmy said:
You actually force me to check the archive charts for the past week. Not surprisingly ukmo has done best with the northerly as ecm and gfs had it before day 6 although gfs got the trigger low badly wrong for quite a few runs. As far as the diving trough thereafter, gfs and ecm have both been trailing it with ecm actually making a decent fist if it at day 10 (though it went arwy in its days 8/10 output for a coiled, runs thereafter). Gfs has made a poor call on the diving trough the past couple, days although we can't be sure that the 12z are right on this just yet. Ecm was right to call the accelerated demise of the Atlantic ridging.
No model is right but to say that gfs is the model to follow is just plain wrong !
In your opinion. Meanwhile lets hope the ecm gets its act together and manages to deliver an output that is somewhere near accurate tomorrow, Fingers crossed eh.
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Regardless of what the stats say for our tiny little portion of the globe the ecm has been less than impressive lately. Having said that all this talk about sliders and possible snow amounts is all academic at this range ( almost a week away) heck even three days out a bit of a lottery. One thing I am sure of is whatever the models are showing today will have changed by tomorrow. UKMO has moved towards GFS this evening and I am fairly sure the ECM will follow suite.
The GFS seems to be the model to follow at the moment the other two models were showing a quite tepid northerly while the GFS stuck to its guns and now the other two have followed suite, Regarding the extended outlook and FI it would be the icing on the cake but to far away to take much notice of at the moment. Certainly something to keep track of though.
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Excellent output so far great to finally see the ukmo on board. The ecm must surly follow to round off a superb afternoons model watching.
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15 minutes ago, Allseasons-si said:
Yes i see that but it's 15 days away,my thinking is that the trough sinking further into europe and the subsequent block building to our NE putting the brakes on fron the Atlantic,battleground scenario?
Would not mind seeing the synoptics trending that way myself.
Hopefully we are in for a pub run special and not go down the euro route.
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Apart from a fairly potent 2 day northerly the Ecm 12z was nothing to write home about, quite disappointing to honest. Same can really be said for the UKMO run as well.
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It is conceivable that we could see a channel low if we get the slider running down the western side of the UK and then heads east. Long shot at this stage but something to watch perhaps.
Just seen pert 13 and it shows this scenario playing out so you never know.
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Loving this run. What a difference a slight easterly push and orientation of the low in the north sea to the precipitation across the country with many areas back in the firing line for some significant snow perhaps.
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Must admit to feeling a little deflated now that snowmaggedon is off the table although it all looked a little to good to be true. Mind you if the models correct east a couple of hundred miles over the coming week then many areas could be in line for a decent snow event.
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Would be nice to see a correction souh with the low and pull away slightly futher east to allow coldest uppers down across the country.
What we dont want to see is any back tracks at this stage in the game.
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70mb 
Model output discussion - winter proper underway
in Forecast Model Discussion
Posted · Edited by comet
While the gefs show charts like the one's below then there is still plenty to play for plus the gfs 0z op run is not to shabby at all.