Model output discussion - 1st December onwards

[tinybill]

21 minutes ago, lorenzo said:

That's a helluva stormy approach to New Years on tonight's 12z !

Then, this extreme evolution

Unsurprisingly the clustering highlights the uncertainty in evolution.

Fingers crossed this one bombs in the atlantic and gets stuck there.

what the next  name after  eve

[Jason M]

At 102 the GFS looks like GEM IMHO. Just saying 

Doubt it will end the same way but its interesting nonetheless.

[Eskimo]

Is it doing what we want it to do? 

Edited December 23, 2015 by PerfectStorm

[Allseasons-Si]

4 minutes ago, tinybill said:

what the next  name after  eve

Frank i believe tiny,some mothers do have em

the heights on this run are alot further north @ 120hrs

18z12z

so the battle still  geos on.

[Allseasons-Si]

25 minutes ago, chrisbell-nottheweatherman said:

Is a central pressure of 925mB even possible in the UK?  What sort of windspeeds might we expect with something that powerful?

Here you go Chris,that would be worrying

Cat	Hurricane Scale			Pressure(Millibars)
	Mph	Kph	Knots
1	74-95	119-153	64-82	980+
2	96-110	154-177	83-95	979-965
3	111-130	178-209	96-113	964-945
4	131-155	210-249	114-135	944-920
5	156+	250+	136+	below 920

Edited December 23, 2015 by Allseasons-si

[chrisbell-nottheweatherman]

2 minutes ago, Allseasons-si said:

Here you go Chris

Cat	Hurricane Scale			Pressure(Millibars)
	Mph	Kph	Knots
1	74-95	119-153	64-82	980+
2	96-110	154-177	83-95	979-965
3	111-130	178-209	96-113	964-945
4	131-155	210-249	114-135	944-920
5	156+	250+	136+	below 920

Thanks, though, based on that, I wish I hadn't asked!

[SnOwFeSt]

Last minute upgrades?! Heights much further north, vortex still looking fierce but pushed further west. Hopefully a trend that will continue. Yes please!!!

[damianslaw]

Focusing on the short term - another bout of heavy rain quite likely for many Christmas Day and Boxing Day - worryingly so for Cumbria.. however, what is interesting is how the colder air to the north is now being projected to dig in slightly longer during the same period, locking Scotland into quite chilly uppers - so at least something more seasonal there, mild/very mild further south.

The theme thereafter is looking a very unsettled stormy one with lots of uncertainty - BBC long range forecast only went to Tuesday emphasising just how volatile the set up looks. Late December is notoriously a stormy topsy turvy period, Christmas and New Year storms are very common place - so nothing too unusual, although some of the output is showing exceptionally low heights - we saw similar charts in winter 2013/2014.

What I am gleaning is for a slight shift in the Jetstream, and a propensity for the trough to push further eastwards which should kick the euro high in to touch and introduce a more westerly flow generally with every chance of some polar maritime air for the north especially as we enter the New Year - meaning a return to more near normal temperatures and wintry precipitation in the north. Yes still very zonal, but more normal for the time of year..

With that I'll not be looking at the models until at least Sunday - good to have a break over Christmas more generally from the internet etc...

I'm concerned though for Cumbria come Boxing Day - we simply can't take any more rain..

[Allseasons-Si]

GEM @ 180hrsgfs @ 180hrs

both have the cold pool head west toward italy.

 

Edited December 23, 2015 by Allseasons-si

[Geordiesnow]

6 minutes ago, Allseasons-si said:

Here you go Chris,that would be worrying

Cat	Hurricane Scale			Pressure(Millibars)
	Mph	Kph	Knots
1	74-95	119-153	64-82	980+
2	96-110	154-177	83-95	979-965
3	111-130	178-209	96-113	964-945
4	131-155	210-249	114-135	944-920
5	156+	250+	136+	below 920

But thats not neccessary full on accurate as it a lot of it will depend on the tightness of the isobars so you could have a 960MB low producing less strong winds than a very tight gradient 980MB low. 

That said, some of the runs do show the potential of the low being very tightly packed and with quite a low pressure centre which would no doubt produce storm force winds. Its far too early to think about the details of it but the models do show the potential of potentially storm force winds, its certainly more potential of coming off than anything sustained in terms of cold weather. 

That rainfall for Boxing day still looks concerning but models are still not in full agreement on the strength of the low with the GFS reverting back to a more shallow feature and no doubt will result in any rainfall being more persistent in one area. 

[TomDav]

Nice (almost) cross-polar flow at 204hrs

Edited December 23, 2015 by TomDav

[Allseasons-Si]

Crikey,and out to 240hrs,we still have a battle on,the pub run is on a high tonight,not the liquor

 

[nick sussex]

The GFS 18hrs run in the higher resolution continues to head toward a positive PNA so that's good to see. The Azores high now displacing further west.

This should rid us of that odious Euro high as the jet angles in from the nw/se direction. Interesting that it also wants to develop high pressure out of Russia.

Its hard to make a longer term call because we don't know what the exact response will be to the MJO, when you have this background change going on you can find sudden swings in the outputs as they react to that.

 

[SnOwFeSt]

Nice split vortex toward the end of the run. Despite the despondency and some people writing off most of January, this run shows that there is still plenty to play for. I hope it is the start of a trend of more resilient blocking. Perhaps the GEM called this right afterall?!

[Cheshire Freeze]

3 minutes ago, nick sussex said:

The GFS 18hrs run in the higher resolution continues to head toward a positive PNA so that's good to see. The Azores high now displacing further west.

This should rid us of that odious Euro high as the jet angles in from the nw/se direction. Interesting that it also wants to develop high pressure out of Russia.

Its hard to make a longer term call because we don't know what the exact response will be to the MJO, when you have this background change going on you can find sudden swings in the outputs as they react to that.

 

The best thing about recent gfs modelling is the suggestion the AO is to tank into the new year. The 18z shows this once again. Although this isn't shown to affect the uk too positively at the moment, it's the first step towards a potential eventual -NAO as we progress further into the new year.

[nick sussex]

Just now, CreweCold said:

The best thing about recent gfs modelling is the suggestion the AO is to tank into the new year. The 18z shows this once again. Although this isn't shown to affect the uk too positively at the moment, it's the first step towards a potential eventual -NAO as we progress further into the new year.

Yes the  MJO expert at NCEP thinks that the response could see the AO drop. He was talking of down initially to neutral though which is a whole lot better than the current hugely positive reading.

I'm optimistic that we will at least see the end of the Euro high but after that I don't want to raise expectations too much. We'll see over the next few days, nothing would surprise me because the MJO is not an exact science in terms of the tropospheric response. We might be underwhelmed or nicely surprised!

[JeffC]

1 hour ago, tinybill said:

what the next  name after  eve

Fffffind somewhere else to go storm?

[damianslaw]

36 minutes ago, nick sussex said:

The GFS 18hrs run in the higher resolution continues to head toward a positive PNA so that's good to see. The Azores high now displacing further west.

This should rid us of that odious Euro high as the jet angles in from the nw/se direction. Interesting that it also wants to develop high pressure out of Russia.

Its hard to make a longer term call because we don't know what the exact response will be to the MJO, when you have this background change going on you can find sudden swings in the outputs as they react to that.

 

I said the other post would be the last before Christmas -but there is much logic in a longer term pattern change the trough driving eastwards pushing the euro high out westwards anchoring heights out of N Russia NW - to produce a more negative AO, the jet forced on a more NW-SE trajectory, wave breaking into the strat - a weakened PV and then bingo a much better background synoptic state for colder weather second half of the winter - easy really...

[Cheshire Freeze]

Very few GEFS members now have a tropospheric vortex as strong as it is now at the end of the first week of Jan. In fact it looks to be on the ropes somewhat. Is the big fella about to fall? I'd expect some eye candy charts to start popping up in FI over the next week or so.

[nick sussex]

Swilliam in terms of the positive PNA, yes of course I'd love a Russian high and an easterly but at the moment the displaced Azores high looks more favoured with the jet running nw/se in towards western Europe.

The best type of block for the UK is though a smaller Scandi high rather than a large Russian high because its incredibly difficult to get that to ridge far enough west.

The GEFS does have some solutions with a battle between high pressure to the east and the troughing and that might well happen with the positive PNA.

I tend to keep an open mind when theres background changes going on like the MJO. The response with displaced Azores high looks like a plausible first step, after that I think we'll need a while longer to see what the definitive trend is.

[DAVID SNOW]

7 minutes ago, CreweCold said:

Very few GEFS members now have a tropospheric vortex as strong as it is now at the end of the first week of Jan. In fact it looks to be on the ropes somewhat. Is the big fella about to fall? I'd expect some eye candy charts to start popping up in FI over the next week or so.

There is always hope CC and you may be correct, but the end of the first week in jan is FI, no matter which model we look at.

[bobbydog]

27 minutes ago, CreweCold said:

Very few GEFS members now have a tropospheric vortex as strong as it is now at the end of the first week of Jan. In fact it looks to be on the ropes somewhat. Is the big fella about to fall? I'd expect some eye candy charts to start popping up in FI over the next week or so.

unless of course we have no FI 'n internet because the FI 'n storms which keep popping up in FI have blown down all the FI 'n powerlines....

[Chris K]

1 hour ago, CreweCold said:

Very few GEFS members now have a tropospheric vortex as strong as it is now at the end of the first week of Jan. In fact it looks to be on the ropes somewhat. Is the big fella about to fall? I'd expect some eye candy charts to start popping up in FI over the next week or so.

Is there really any significance to seeing cold charts appear more often in FI...? (If they do of course)

We've seen great charts get blown away in the more supposed reliable time frames... so as exciting as it is, I don't like getting my hopes up when in the short-medium term it continues to look like alternating cool/mild phases, wet and at times very stormy. 

After a drab, mild, damp December the upcoming cyclonic phase is like an extra kick in the teeth, particular those affected by floods...now wind damage could be an added concern.

Edited December 24, 2015 by Chris K

[Cheshire Freeze]

1 minute ago, Chris K said:

Is there really any significance to seeing cold charts appear more often in FI...?

We've seen great charts get blown away in the more supposed reliable time frames... so as exciting as it is, I don't like getting my hopes up when in the short-medium term it continues to look like alternating cool/mild phases, wet and at times very stormy. 

After a drab, mild, damp December the upcoming cyclonic phase is like an extra kick in the teeth, particular those affected by floods...now wind damage could be an added concern.

It fits with the common consensus of a peak vortex intensity in December, with that intensity easing off through Jan. So from that perspective, together with some hits on the tropospheric vortex, we can have reasonable confidence that the GEFS may actually be foreshadowing a net hemispheric change in Jan. Watch this space.

[Duane S.]

Does appear the models are finally starting to play about a displaced to the west Azores High, this will likely be a response of the MJO likely to head into phase 6 at a decent amplitude in about a week or so. I expect to see more of this in coming days. Whether in reality we get that connect and even if we do, what sort of mid Atlantic ridging is achievable  with the vortex aligned where it is, we will have to wait and see but it can only be good news for the the most important initial stepping stone to something cold, the removal of the Euro heights.