bjc0303

Pretty impressive agreement between ECMWF, CMC, and GFS. Differ on amplitude and timing, but the general consensus shows a severe weather event over the same general area for Sunday. Impressive for a week out. Not sure who is more potent: the GFS or the ECMWF. GFS more unstable, ECMWF by far the stronger between the two wrt shear profiles. 70 knot deep layer shear and 35-45 knot 0-1km shear on the ECMWF. Definitely one to watch, and one that has some synoptic backing for sure. Would think the dry line sets up along I-35 if things hold, but with how strong the synoptics are it could push near Tulsa. Seems to me that this is a pattern offering higher predictability. It doesn't seem like there is much to offer in terms of downstream/eastern amplification. The GEFS 6-8 day analogue forecast: At least 10 Svr reports At least 1 tornado At least 1 sig tor. Seems to me that models should have a good handle on this one.

GFS certainly coming in more potent. It slows down the progression of the pattern and amplifies the upper level trough as it ejects, which is leading to these really strong low systems. Interesting development.

GFS continues to advertise big time pattern shift, with significant shortwave traversing plains in the 8-10 day range. This coincides with some teleconnection/GWO phase space forecasts. With several days of return flow (even though prior cold front pretty significant), we could see a bit of an active stretch coming up.

Operational GFS and CFS ensemble appear to suggest a looming pattern change in the 7-14 day window coinciding with the latest ERTAF week 3 forecast of AA tornado activity. Could be plains first decent period.

Agreed. It's a shame this Atlantic system had to blast a cold front into the Gulf. The second that happened, this one was pretty much dead. Strong moisture return on the heels of a frontal intrusion will always throw us under thick cloud cover, and that concerned me from the start. Given I live in OK, this one is still probably worth watching, especially morning of.. But I wouldn't exactly say I'm holding my breath on it.

Warmest temps are always behind the dry line.. The thermal axis should lie along and behind the dry line during max heating.

I don't see the moisture being the problem as much as cloud cover inhibiting insolation (on the GFS at least). And this isn't overturning, either. With recent frontal intrusions comes airmass modification, and with isentropic upglide happening we can probably expect tons of cloud cover, at least early on. Guessing that's why the GFS isn't getting surface temps too high. ECMWF on the other hand puts out low 70s over a broader region. Find a sounding (on the GFS) with low 70s temperature and the inhibition is nearly gone even with upper 50s dewpoints. Not really time to get caught up in EML temperatures. The strength of the wave itself will provide some pretty impressive ascent. We'll see how much of that glances the southern portion of the dry line however.

I would agree but I wouldn't say it was that way because there weren't a bunch of EF-3+ tornadoes roaming around. It was just a mix of badly timed or placed events, and mesoscale features ruining otherwise good looking setups. Pretty boring season. On the large scale, we had a bigly amplified pattern that didn't allow for good moisture return for basically all of M-A-M until the latter half of May. I mean, you could say that the pattern sucked and that we didn't get any prominent events, but to me it's still weird to judge chase season quality on numbers of EF-3+ tornadoes.

My birthday Just a note.. Tornado ratings don't mean anything when evaluating the quality of events. You're basically equating the quality of the season with the number of damaging tornadoes...doesn't make sense. The Wyoming event was pretty wild even if most of the tornadoes were 'weak' in the sense that they didn't have much to hit out there. Just an odd comment.. If we wanna harp on chaseability that's a different story. 2017 did suck in that regard. Guesses (or predictions?): Another 1300+ tornado year. Somewhat more active is my guess - at least from a chaseability standpoint. If we can stay out of the high-amplitude pattern we were in for a large chunk of spring last year, then I think we're a lock for 1300+. First high risk: April 28th - May 5th timeframe. Oh, you want an exact day? Okay. May 2nd. Plains high. Let us all take a moment of silence for that one late April system that held so much promise - yeah, the one that had I-35 outbreak written all over it by not only the GFS but the Euro as well? - yeah that one. Days before, both models said "HAHA NOPE" and it became total garbage.

Looks as if the 12z ECMWF has taken a step towards GFS with wave amplification, leading to a stronger anticyclone..at least by Sun 12z. Still loading in. And none of this will really change how much snow is seen..the broader large scale pattern will keep heavier snowfall from being a thing. We need some deep system out of the southwest, at least for those of us in OK/TX/KS..

Keep in mind, these really cold patterns are usually the result of highly amplified ridges with a NE trough.. While the pattern is great for repeated shots of cold air masses, it is not-so-good for moisture return nor is it going to result in a storm track conducive for widespread plains snowfall. Until we get out of this N/NW flow aloft we will stay cold (sometimes bitterly cold, like is being hinted at next week) but relatively dry.

Should note that shear values (specifically, low level shear (strong SRW and SRH) abs deep layer (effective bulk shear) are far more important than the 500 mb flow values. Hence why OFBs are important in late season tornado events. They don't alter the flow aloft, but alter low level flow increasing low- and deep-layer shear... while also providing a rich source of low level horizontal, streamwise vorticity owing to barpclinic zone (often leading to accelerated low level mesocyclogenesis). You can have 55 knot 500 westerly flow, but it won't mean much with 45 knot surface westerlies... odd example, unrealistic even, but the point remains. Shear, and SRW, dominate over the pure mid level flow. Would be interested though in examining borderline cases where low level shear is high (ESRH greater than, say, 250?) But deep layer (effective BWD) fails to meet 35 knots.

Yeah, I'm really hoping for some KS/NE/IA action. I really don't want to have to drive way up to the Dakotas.

It's been brutal, this pattern. Making it worse is the persistence. They say persistence pays off..... Hopefully that applies to meteorology!

Yeah, just gonna have to make due (Fri/Sat) with what we have. Still not buying Friday staying completely capped, and will eagerly await coming home with a burn/tan if it does fail to convect. I agree though, what a waste of TWO pretty severe-favorable looking longwave troughs. One in late April and the other last week. Unbelievable that neither quite panned out.. Both had outbreak potential, relatively speaking (as happens with pronounced, favorably-positioned longwave patterns). I wouldn't give up on June quite yet (although, if you're stuck with southern plains chasing, perhaps).. Central and northern plains through June could be rocking.

Agreed. Synoptically driven patterns don't look completely dead however. FWIW (very, very little) the 06z GFS shows an active pattern into June.. Which would likely bring a string of active days over KS, NE, perhaps even OK (pending EML strength). Jet certainly looks to remain active for at least another 2-3 weeks; this is reflected in the recent ERTAF forecast.

Pretty good signal, tho think GFS probably a hair too east as usual putting OKC/Norman in risk area. Think we will get a quality two days of storms, 2013 style with a dry line/sagging cold/stationary front.

Looking more and more like tornado activity will pick back up again late this week into the weekend. Models now converging on what I would call a typical late may tornado setup with rich gulf moisture, strong-extreme instability, and a well developed evening LLJ. More fine-scale details cannot be resolved right now, such as strength of the EML/base temps, boundary placement, etc.. but looking increasingly conducive for tornadic supercells. Unlike recent setups this one may have more densely populated areas in the mix. Not worth going over much more at this point. GFS forecasts have quite the hot EML, but no real consistency. While some parts may get shut out due to capping, someone is going to see CI. Even now the GFS convects, and I imagine smaller scale perturbations provide glancing influence to erode capping. Saturday may be an outflow boundary day.

Disagree on capping. If anything, 1) morning convection and 2) high LCL heights may be an issue, but given we are five days out, it is hard to put much stock into analyzing anything more than the large scale pattern. 12z ECMWF edit: early precip looks to be less of an issue Tues this run. Again - kind of pointless analyzing details like this, but the ECMWF lights up a large portion of the OK/TX/KS dry line with QPF 18-06z Tues. Does so again Thursday... Will have to watch.

While details get washed out in the mean, I really can't complain about this sequence throughout the week. impressive. Considering various deterministic and ensemble solutions... Tues, Weds, and Fri look interesting to me. Weds is conditional on timing, where Tuesday looks more certain. Friday looks solid on the large scale. we'll see how things pan out but I really like the prospects of next week.

Gotta say that ensemble mean forecasts for next week look pretty impressive, with promising events possible Tues, Weds, and Friday it looks.

EPS mean shows a pretty prolonged period of western troughing

Latest deterministic and ensemble models show.... next to nothing for the entirety of the cycle. EPS offers a *glimmer* of hope at the 330-360 hour range... But it's looking pretty meh across the board.

That and trough activity over NE

I think there's some huge differences between this Friday's trough and next week's. The two manifest themselves in different ways. This one more progressive, meaning less room for error. Next week's trough is a large-scale trough with shortwaves moving with the mean flow. These are where your outbreaks come from. Not to say next week will be an outbreak - so much can go wrong with severe. However, I don't think the two are very comparable.