Model Output Discussions 18z 31/01/2016

[phil nw.]

Latest GFS and UKMO runs continues to show a colder and very unsettled week to come as the jet gradually eases further south.The main headlines will again be the frequent bands of rain and wind as low after low heads our way.

GFS does increase wintry interest towards the end of the coming week as the lows track across the south with cold air over more of the UK,rain turning to snow looking more likely for lower ground further north as freezing levels drop.

Images for Friday next

Just for interest at this stage of course but it wouldn't take much for this wintry scene to extend further south. 

Next week in the ens has consistently shown a colder period to dig in so good reason to keep monitoring the models in the coming days for cold/snow lovers.

This Winter ain't over yet.

[Liam J]

Now this would feel bitter! Sadly all in FI but it would feel like proper winter.

[nick sussex]

Just looking at the UKMO and it looks like an area of colder 850's runs eastwards and engages a shortwave running along the Channel between T60 and T72hrs.

 

Even at this range these shortwaves can be difficult to forecast and so it might change. Possibly some marginal snow depending on other factors.

 

 

 

 

[Mucka]

GFS ensembles sniffing a shock Easterly? 

 

Might not last too long even if it came off but it would be a big turnaround in the output!

[nick sussex]

Only 3 days ago the GEFS wasn't going anywhere fast with the MJO signal now its in a hurry to get to phase 7.

Overall both the GEFS and ECM have increased the amplitude of the signal since yesterday. For those that saw Ian F's post in relation to my musings on the MJO yesterday he commented that the UKMO didn't expect much amplitude in the MJO once it moved towards the more favourable colder phases for the UK and hence they didn't expect it to be much of a factor.

The MJO movement in Dec/Jan was also originally expected to not figure much by the UKMO because of that lower amplitude but it seems to be doing something similar in terms of being under estimated. We'll need to wait a few more days to see whether this increase can continue.

 

Edited February 6, 2016 by nick sussex

[Chris K]

15 minutes ago, snowice said:

The problem with the models everything is in FI and every day it gets pushed out further the snow on the 06z on the 12th is gone at this rate it will be over before its started lack of post says it all I'm afraid us poor coldies are suffering this winter! 

The lack of posts is inevitable to be honest - It can't be that much of a surprise. A majority on here during winter are seeking cold and snow and I would assume that most are just fed up now of this generally poor winter (to put it lightly) with the unrelenting wind and rain.

We are entering mid-Feb in terms of model output and for now, a cool, unsettled outlook still looks most likely for the foreseeable. Anything remotely snowy would be a bonus and may at least bring a smile to people's faces, but I doubt there will be the commotion on here in comparison to what we would see in Dec/Jan. 

In terms of the current outputs, we cannot rule out completely some back-edge snowfall with these LP systems trundling further South, particularly for those further North and on elevated ground.

However for now, I feel the primary concern should be the amount of rainfall to add on top the already saturated/flooded ground in many areas, along with some strong winds at times.

[mountain shadow]

Agreed Nick.  Similar to last month.

Obtaining favourable MJOs during El Ninos are meant to be difficult, I wonder if this is where the confusion is?

If we could get to a high amplification in phase 8 whilst the vortex is disrupted then a A1 northerly is not out the question. 

[nick sussex]

8 minutes ago, mountain shadow said:

Agreed Nick.  Similar to last month.

Obtaining favourable MJOs during El Ninos are meant to be difficult, I wonder if this is where the confusion is?

If we could get to a high amplification in phase 8 whilst the vortex is disrupted then a A1 northerly is not out the question.

Yes last month the MJO although suffering from El Nino interference did help to develop that colder spell with those more positive anomalies to the west/nw of the UK.

Its for this reason that I didn't throw the towel in although I was close to it a few times during the last week. I think the MJO is now our best and last chance  of seeing something more wintry before winter finishes.

There are of course no guarantees especially with that rampant PV and El Nino but we'll just have to see what happens.

 

Edited February 6, 2016 by nick sussex

[Daniel*]

GFS is also showing that 'wave' feature Nick, accompanied by a small low ahead of it.  

Wet snowfall a distinct possibility for southern counties particularly on back edge as colder air is dragged in possibly turning initial rain into sleet/snow for S/E.  

[karyo]

10 minutes ago, nick sussex said:

Yes last month the MJO although suffering from El Nino interference did help to develop that colder spell with those more positive anomalies to the west/nw of the UK.

Its for this reason that I didn't throw the towel in although I was close to it a few times during the last week. I think the MJO is now our best and last chance  of seeing something more wintry before winter finishes.

There are of course no guarantees especially with that rampant PV and El Nino but we'll just have to see what happens.

 

hi Nick, do you think that the el nino may become a bit more helpful for cold prospects now that it is much more centrally based?

[Singularity]

The big deal this year is that this is no ordinary El Nino!

The Met Office seem to be having a hard time comprehending the ramifications but to be fair, I also can't go around being massively confident in the MJO doing what we'd like. That's experimental science for you 

 

 

Spotted this from NMM for Monday, which ties in with the UKMO shortwave that Nick spotted. Indeed the pressure/500 mb chart shows a neat little feature. A possible consequence of having cold, deeply unstable air moving across relatively warm lands following notably warmer seas.

The track, though, is circumstantial. Shame as I wouldn't mind seeing a bit of properly visible (daylight hours) snowfall for the first time in over three years!

Only a faint hint of snow from GFS so it is a very marginal situation (as usual).

Snow or no snow, it's another significant batch of precipitation for the south, in what looks to be a very wet week due to all those small lows swinging across southern UK. I'm not convinced by UKMO's decision to merge all the smaller lows into one deep system but it's certainly a possibility which could shift the focus for heavy rain further north again for a time Wed-Thu (but perhaps only to the middle third) before coming back south on Friday. 

 

Looking at ECM for +72 hours, just a hint of shortwave development so similar to GFS.

 

[nick sussex]

11 minutes ago, karyo said:

hi Nick, do you think that the el nino may become a bit more helpful for cold prospects now that it is much more centrally based?

Its still very strong even in the eastern region although its on its way down now. There has been research into the NH impact in strong El Nino years and the MJO.

The biggest positive anomaly impact is to the west/nw of the UK and that was done using the 3.4 ENSO area so it seems that this area is the more important one. That colder spell in January did show that positive anomaly, ironically the problem when we initially saw that stronger ridging into Greenland was the strat warming which caused the PV initial reaction to increase the westerlies.

Indeed I'm getting less interested in the strat as there are so many caveats to its impact and often we come off worse as that often displaces the PV to give the eastern USA the deep cold!

[karyo]

1 minute ago, nick sussex said:

Its still very strong even in the eastern region although its on its way down now. There has been research into the NH impact in strong El Nino years and the MJO.

The biggest positive anomaly impact is to the west/nw of the UK and that was done using the 3.4 ENSO area so it seems that this area is the more important one. That colder spell in January did show that positive anomaly, ironically the problem when we initially saw that stronger ridging into Greenland was the strat warming which caused the PV initial reaction to increase the westerlies.

Indeed I'm getting less interested in the strat as there are so many caveats to its impact and often we come off worse as that often displaces the PV to give the eastern USA the deep cold!

Totally agree!

[Singularity]

49 minutes ago, nick sussex said:

Only 3 days ago the GEFS wasn't going anywhere fast with the MJO signal now its in a hurry to get to phase 7.

Overall both the GEFS and ECM have increased the amplitude of the signal since yesterday. For those that saw Ian F's post in relation to my musings on the MJO yesterday he commented that the UKMO didn't expect much amplitude in the MJO once it moved towards the more favourable colder phases for the UK and hence they didn't expect it to be much of a factor.

The MJO movement in Dec/Jan was also originally expected to not figure much by the UKMO because of that lower amplitude but it seems to be doing something similar in terms of being under estimated. We'll need to wait a few more days to see whether this increase can continue.

 

Comical how GEFS have gone from one extreme to the other in the space of a week 

Yet actually the speed of propagation looks very reasonable now. Especially given the jump to the 4/5 border that the observations show for yesterday. I wonder if it will pause for breath today or just keep on going through to 5 already?

By cutting 4-5 days out of the time taken to get going, the impacts would be significant. Already GFS is toying around with those impacts manifesting as a decent northerly sometime in the 10-14 day range. The 12z has considerable height rises across the Arctic by day 16 but that's something to think about in a week or so's time perhaps, when we have a better idea as to how soon and with what amplitude the MJO will reach phase 7. If it followed today's GEFS update we'd have plenty to keep the forum buzzing!

[nick sussex]

Just now, karyo said:

Totally agree!

I'll use that wonderful and quite funny analogy that I saw on the strat thread. Its like waiting for an elephant to give birth!

The strat has done us no favours at all this season, indeed at times the warmings have been a hindrance as they have moved the PV into worse locations. They're like England football teams at major tournaments! A lot of hype and media attention and normally deliver nothing but disappointment!

[Singularity]

ECM v. UKMO for +144:

 

ECM has a better -EPO ridge across the U.S., with the deep cold pulled further south across the eastern U.S. and less engagement with the western N. Atlantic trough as a result. If there's any development associated with the cold pool, it might help pull the Atlantic trough west for +168 hours?

[nick sussex]

5 minutes ago, Singularity said:

ECM v. UKMO for +144:

 

ECM has a better -EPO ridge across the U.S., with the deep cold pulled further south across the eastern U.S. and less engagement with the western N. Atlantic trough as a result. If there's any development associated with the cold pool, it might help pull the Atlantic trough west for +168 hours?

Yes these differences are something NCEP mentioned especially in relation to the amplitude of the troughing in the eastern USA.

[Singularity]

Okay... might take until +192 with the W. Atlantic feature.

Interesting how the individual disturbances within messy trough at +144 again refuse to merge into a single storm system. The southern arm of the jet is just too enticing... so we end up with another angry looking low heading for southern UK. Thanks, ECM *sarcasm alert*.

Edit:

I saw it first!

Edited February 6, 2016 by Singularity
fun game, this.

[wishingforsnow]

11 minutes ago, Singularity said:

Okay... might take until +192 with the W. Atlantic feature.

Interesting how the individual disturbances within messy trough at +144 again refuse to merge into a single storm system. The southern arm of the jet is just too enticing... so we end up with another angry looking low heading for southern UK. Thanks, ECM *sarcasm alert*.

Edit:

I saw it first!

That looks like a lot of blue

[snowray]

Mildest Northerly I have ever seen in February, Just about sums up this Winter!

[wishingforsnow]

3 minutes ago, snowray said:

Mildest Northerly I have ever seen in February, Just about sums up this Winter!

That's a really confusing chart. There seems to be cold air over the UK though?

[snowray]

Followed by the mildest Easterly ever!

[Singularity]

7 minutes ago, snowray said:

Mildest Northerly I have ever seen in February, Just about sums up this Winter!

True, I expected at least a bit more of a draw from Iceland but never mind. We'd be losing our minds over marginality under that scenario, relying on evaporative cooling as the winds fell lighter. 

This would feel raw, but snowfall would be hard to come by given the lack of decent surface cold to draw across from the continent. 

If we could get a better reach N of the ridge from the Atlantic +168 to +192... yep, here we go again! 

 

Edit: I should add - I'm not saying ECM is following the right path as opposed to GFS with respect to which troughs drop south and when. It's the overall theme than I'm very much behind.

ECM actually gets rather ugly in the Canada/Greenland area days 9-10. Probably a transitional event but I prefer the GFS route which keeps the storms exiting the Pacific on a more southerly track through N. America, so preventing such a coming together of low heights around Greenland.

Edited February 6, 2016 by Singularity

[wishingforsnow]

Wasn't GFS 06z hinting at possible high pressure next week?

It would be nice if the models and forecasters could firm up on an outcome after next week on this and hopefully a true end to the incessant wind and rain of the past 4 months as opposed to a few dry days only. Its really feeling like early 2014 right now where we were looking for absolutely any signs of a dry out after being pelted with storms day in and day out for months on end.

Edited February 6, 2016 by wishingforsnow

[Daniel*]

Comparing to yesterday 192 it seems increasingly looking that the big old block of HP is going to exert some influence on Western Europe retrogressing westwards....