bluearmy

Lukesluckybunch Shannon is back big time !

Singularity there have been a couple of gfs ops recently that downwelled within a couple days on the cross sectionals - tended to be those that developed a large split vortex later on with the Arctic ridge dropping into the Atlantic ridge pushing north. I suppose that the weak strat vortex this season makes it prone to that. Of course that’s not a standard NH strat winter profile for developments next week, still uncertainty around how the ssw will manifest itself. Currently backing off a split solution (of any note). The eps clusters look better in the extended.

Singularity. It is open to interpretation. This winter is quite strange high up and perhaps difficult to make judgments upon. If you look at the 00z gfs op, you will see a neg AO in the trop which is nothing to do with the reversal high up that occurs at the same time. The positive flow sitting between in the mid to lower strat in the past, we have seen reversals take place with a positive AO in place and within a few days a big ridge is thrown up on the pacific side which punches across the Arctic and affects our side of the NH. That would be visible as the blue negative flow in the cross sectional chart working down top to bottom. That’s what a QTR is. This winter with the trop and strat generally in tandem it’s probably not so relevant. It’s been tough to see whether the impetus for neg flow has come from a downwelling wave or is instigated from the trop and then quickly upwelled. Mike has posted on this a fair bit. fwiw, next weeks reversal is currently uncertain in how it plays out. I think that until we get a handle on that we can’t set much store in the modelling for week 2.

Daniel* yep - it was over retrogression in 2018 until we get a handle on what reversal we are likely to see then can’t really speculate

feb1991blizzard fair re week 2

Daniel* are you confident that the split on that run is sufficient to stop the Canadian segment hurtling back across the Atlantic after a very short period ? blizzard81 not really true - we’ve had at least three periods where week 2 modelling looked v wintry

This won’t be exactly how it plays out The 12z runs have begun to sniff out the way forward but they can’t have stumbled across the correct route first time. At least it makes the next few runs worth watching ….. note that the mid/upper strat was more split on the 00z run at day 10 than the 12z. Another run which doesn’t stack up as you might have expected Original post: https://community.netweather.tv/topic/99814-model-output-discussion-22nd-jan-2024-onwards/?do=findComment&comment=5034508

Complications from the impending reversal around mid month makes analysis of week 2 modelling pretty worthless imo.

blizzard81 you won’t like the direction the control goes btw imo, it’s Implausible that the ops are now going to verify at days 7/9

This won’t be exactly how it plays out The 12z runs have begun to sniff out the way forward but they can’t have stumbled across the correct route first time. At least it makes the next few runs worth watching ….. note that the mid/upper strat was more split on the 00z run at day 10 than the 12z. Another run which doesn’t stack up as you might have expected

Gowon if only there was some cold air ahead of the trough

Lukesluckybunch not sustained

Jacob but where do the pieces fall ?? Not well for us and the 06z looks similar thus far recovers late on to make a better split than the 00z and the trop profile reflects that with a building Atlantic upper ridge

Frustrating to see the trough in op runs showing a propensity to stick a southern runner into the mix next week - if we’d managed to keep hold of reasonably cold air aloft then who knows hey ho

Ice Day the eps at day 12 show plenty of very disrupted and split vortex’s but few have rolled a double six as yet

Dennis do you have the same chart for 100hpa??

Weatherbell is down this morning. Looks like the geps are late on meteociel too the gefs were a curates egg mean not far from something exceptional but at two weeks range the eps clusters don’t look too good I guess pre ssw modelling unreliability should be our hope here. there are some more than interesting gefs members so hopefully we can roll the ssw dice and get a qtr like those show Dennis I appreciate this is your area dennis but if we have a strongly coupled atmosphere then we would likely see a trop response within days (as 18z showed yesterday) but also more affects in March as you post

IDO the gfs has a poor vortex split with an atlantic segment left to our west. This is the risk of the split ssw solution. We’ve had three decent results from the last five and the gefs mean is better than the op. I think the displacement solution won’t bring the scandi trough far enough south (for the majority of the populated U.K.) . So we are probably at the mercy of the ssw dice roll for winter's last hurrah ……

feb1991blizzard some consistency from gfs op with the split solution. And three of the past four runs have created a strong reversal coupled top to bottom and still we would worry that southern parts may be that bit too far south …..

If anything, the strat split slightly greater on the pub run

Gefs end week 2 are further south on the lw Atlantic trough trying to get in that’s a plus

sebastiaan1973 yes Sebastian- finally a gfs op which splits through the strat and trop. Recent runs that have split high up but not low down and in the trop didn’t make much sense. We take our chances with a split and hope it’s a big reversal or we play safe with an Asian displacement and hope that an Atlantic ridge can fill the space left rather than an atlantic trough (extended from the Canadian tpv) which has been shown on recent gfs ops Penguin16 if you are actually a penguin then I understand

Don but high anoms to nw sadly the anomoly charts are a mean so will contain clusters To say there are no high anoms to our nw isn’t correct the problem (as ever) is to our south

I did say last week jan that I had concerns that feb could be a v frustrating month with patterns that bit too far north for the U.K. to benefit it is panning out that way atm but with a notable reversal of upper flow likely just beyond mid month we can expect the modelling to struggle and flap around a bit now as it looks beyond day 10 as @feb1991blizzard has noted, the gfs op modelling of the strat looks somewhat strange over the past few runs.

Week 2 eps …….torquay hotel window ???.