Eagle Eye

Another helpful part of the website for working out where best will be to get clear view of storms and what to expect from them from Cameron Nixon. Would be helpful to bookmark it for storm days. Parameters – Cameron J. Nixon CAMERONJNIXON.WORDPRESS.COM This is a comprehensive "cheat sheet" of severe convective weather parameters. Definitions of parameters can be found here. Composite parameters and...

Chesil View To be fair to Tamara she's not infallible, even the professionals did seem to think the cold could well occur. It's just been one of those Winters hasnt it.

Despite the Greenland high regime not being favourable for we did get one and we did get a win for the teleconnections. This was from my post back on January 12th. "So we get another seperate jet situation w/favourably kinematics for the high just south of the Caribbean to be forced up again eventually as the momentum forces itself from jet to poleward forcing and so a mid-Atlantic block and/or a Greenland high is very possible" "The CFS weekly is showing the southern disconnected jet and the slow southern descent of - VE zonal wind anomalies into the 2nd week of February ish, hence the Greenland high support increases. " Yes I used the CFS but only to get the timing right and it worked. It's a shame it wasn't helpful for us but predicting if it'll be helpful is a whole other ball park because then that relies on predicting the strength of it, working out support for a Euro high etc. The momentum to poleward forcing wasn't really enough to gain a strong Greenland high, it was just more of a weakened Greenland vortex area. However, if you think you can dismiss teleconnections then you're wrong, in fact, whilst it wasn't what we wanted it did become slightly favourable for us as we got some snow for the north. If you're expecting teleconnections to get it within 100s of miles months away you're wrong. With that said, we continue to run out of time on the chase for Winter, the MJO is going back into it's shell as it re enters a surpressed phase w/the drier air distributed by the changing IOD pattern into the phase 8 area. Along w/that AAM is doing what it's supposed to but it's just not being forced poleward, so we're stuck w/out much momentum and so we're relying on transient events which could well happen and have been shown on the models but they can easily be thrown out of kilter.

Well this Winter certainly happened, if you can call it that.

WeatherArc A Reed Timmer classic to me, the ones that start off just shooting vertically and then showing the strong shear show the potential for tornado's "in the air" for that storm chase.

Renegade Supercells early season in Texas, classic setup of sorts. Could be very interesting to say the least.

Paper from one of Reed's tornado measurements has been written up. Will be an interesting read. https://amt.copernicus.org/articles/17/943/2024/

12Z GFS has helped set the trend towards a split semi in stone, much better than all the displements runs earlier. Hopefully the trend continues and better. Still quite far out.

Singularity Problem with the major SSW is that if it does happen, most of the runs appear to be wave-1 displacement driven with most of the vortex over Europe so favourable surface responses at the moment are looking a bit meh. So I'm not really thinking those March's are likely at the moment but we'll see. I really would warn people here getting excited over the modelled SSW, no matter the strength it's really not looking the best, arguably the worst scenario considering some runs saying about - 15ms zonal mean zonal winds. Most of the deterministic runs have been displacement type for a while. I'm still hanging onto hope but this feels like it's not going to end up well.

Secondary AAM rebound appears to be well underway, momentum being added to the atmosphere, significant jet shift surely likely for the NPJ, perhaps displacing the Pacific trough as has been expected for a while. This appears to be helpful in Greenland high forcing still. Interested to see how accurate the response forecasts tend to be in this scenario. Original post: https://community.netweather.tv/topic/99814-model-output-discussion-22nd-jan-2024-onwards/?do=findComment&comment=5031468

Secondary AAM rebound appears to be well underway, momentum being added to the atmosphere, significant jet shift surely likely for the NPJ, perhaps displacing the Pacific trough as has been expected for a while. This appears to be helpful in Greenland high forcing still. Interested to see how accurate the response forecasts tend to be in this scenario.

Let's talk SSW potential. What we don't want is the GFS 06Z to be repeated, it's an example of a wave becoming baratropic-ally stable before a wave-2 can occur and that leads to when the EHF disconnects (which is the switch from a baroclinic wave to a baratropic one) it's a wave-1 diffusion into the polar vortex. What that'll do is disconnect and stretch it but clearly Eurasia-ward. It's then both easier for the vortex to recover and become baratropic (vortex like) even when displaced right over Europe. Easily leading to a state where we're relying on a strong Greenland high surface response for any luck here as the SSW would be another negative for us and even that that's not looking good on the 06Z. This appears to be a trend with the GFS and has been the outcome of many recent SSW's over the last few years so I'm sort of inclined to believe it, the timeframe for a wave-2 being fairly short. It's another multiple rounds of wave-1 due to timing on the 06Z GFS, could well end up in a major SSW but later and still displaced based most likely. As once the EHF pushes polewards, it won't recover on the wave it just disconnected on. Timing as ever is important and it's currently an uphill struggle. Just a warning. Hopefully the 12Z is better. Away from the Strat, GLAAM on the rise soon/potentially now if it can maintain and w/the already +VE GLAAM and MJO 7-8 phase during a late Winter El Nino and enhanced Western Pacific-western Hemisphere (slightly) convective envelope then we have good support background signals wise. Greenland high easily supported at the moment later into February, how much that is helpful will depend on basing and actual strength of response. Good tropospheric signs but we're running out of time for them to produce.

johncam Yeah, Greenland is the easiest to get cold from unless you get certain angles of Scandi high really but I don't think Winter is over yet, still got the possible SSW and about a month left.

johncam Greenland isn't the only high available that's good for us.

johncam Greenland high quite possibly there which is also supported long term by the GFS unless I haven't got the updated EC46.

AAM tendency definitely down over next few days but the actual total momentum ignoring the tendency is still +VE easily compared to recent and long term averages, any +VE EAMT event soon would lead to probably the largest AAM response of the Winter.

Mike Poole Yes very interesting to say the least. Good thing is that it's - VE NAM drive so should reflect back a Greenland high so could reinforce an MJO-GLAAM driving Greenland high if that were to occur. Looks to be driven around this time.

Major SSW on the GFS 00Z run on Stratobserve, the trend has been going towards this for a while. Good wavebreaking for a QTR if it did occur. Just something to keep an eye on.

Can we pretend this isn't at like day 15. Its a CAD episode if it did come off.

Mike Poole Great post. Yes models have been under modeling the MJO for a while now, suspected it was possible as we got close to these phases as well, happy to be right, good to know I understand something well I guess. It's a classic of undermodelling both suppressed and active phases during outside influence. "the GFS slightly above but as we go further towards the future, they move very close together and phase 5-7 are more responding to a quickly falling -VE IOD (a fairly strong wave strength response but it's not the only variable, just 1 of the MJO spread inputs) so potentially may be underdoing the strength of the active western Pacific response further away from the western Maritime region slightly infiltrated w/dry air occluded into the far western Maritime region likely in response to the trend away from a +VE IOD, not a full on dry response but not as +VE wet as the normal composite and that dry air into parts of the Maritime region. Whereas a wetter than normal eastern Maritime and western Pacific that has been characterised poorly by the GFS so far. Theoretically leading to a larger response in phase 7. " The MJO forecast strength during times of extreme IOD change especially but also other outside influences definetely needs to be taken w/many pinches of salt.

Mike Poole I'm never entirely sure of the MJO, it's not my best subject but appears to be a new cycle sort of forming but not far behind the last one?

The GFS 12Z is a very familiar scenario for the south In all seriousness, good set of runs. Perhaps a trend in the right direction.

MJO phase 8 and built-up momentum response likely late February or into March. There appears to be a good chance of a phase 8 w/the w'ly moving w'ly burst as the slow Nino-neutral/Nina transition occurs and the phase 7-8 is also typical of that transitioning time. However because of the w'ly burst, perhaps the response would be more neutral/Nina esque. The MJO low pass appears to suggest neutral with slightly more amplification with the momentum. As we get into March we really need more amplification though. Given the potential before this in mid-Feb isn't looking as good as it was before though there's some decent colder solutions in the spread.

Second high-rise GLAAM by mid Feb possible, stronger than this one. Would have a response into March depending on the MJO. However, not sure of it yet as its kept being delayed by the CFS.

I mean it's a trend I quite like.