brettjrob

The current 7-10 day period is looking pretty grim to me. This week's string of southwest flow days is highly flawed, with Saturday at least offering some legitimate potential given CI. Then the pattern goes back to pure ugliness for at least 4-5 days heading through Memorial Day weekend into mid next week. Hurts, coming on the heels of perhaps the biggest waste of a late May longwave western trough I've seen (last week).

Although we've seen most of the Plains drought-free by late spring the last two years, what's most striking on those DM maps is that the most significant drought nationwide is in the Southeast. I can't recall seeing that since 2007.

The crappy closed low next Tue-Wed reminds me in a really vague sense of 15 May 2013. Mind you, there wasn't a massive east coast trough then. But it is evidence of how these barotropic-ish closed lows whose shear profiles leave something to be desired can still get the job done in May.

00z 4 km CAMs unanimous on an intense but slightly elevated supercell streaking across south central OK tomorrow evening. I can recall an event around this time last year with some similarities and a similar consensus (over NW OK and S KS) where the CAMs said "just kidding" by late morning the day of, so nothing's assured. The SBCINH is awfully formidable even right at 00z, and I have little doubt it will require a mesolow with localized enhanced convergence to pop off a storm at all. Fingers crossed for a nice mothership at sunset dumping some baseballs and putting on a highly visible light show for awhile after dusk.

Unfortunately, the 12z NAM and ECMWF both now support the idea of wave timing ~6 h too early, resulting in veered and anemic flow around H85 along the dryline. Leaning more and more toward a primary large hail threat for now.

Not my intention at all. Would note the GFS and Canadian have been relatively steadfast in depicting veered H85 as an issue, though. Euro has been more encouraging on several recent runs.

dProg/dt on the GFS for 00z Mon shows a tendency toward a less negative tilt with the trough axis, and associated more zonal flow at H5. I already don't like low-amplitude waves this early in the season on the Plains, and this is only raising my concerns. In my experience, H85 flow as veered as what the 06/00z GFS shows verbatim along the dryline in OK is nearly a dealbreaker for meaningful tornado potential in this part of the country. For the most part, when you have low-amplitude waves traversing a Plains dryline in the early season, the shortwave timing has to be absolutely impeccable - where you get your LLJ to back and intensify right around 21-00z. If that isn't the case, as is currently modeled Sunday, you either get (1) a cap bust, or (2) if you're fortunate enough to get CI, tornado potential is limited, even if other factors (e.g., good moisture return) are in place. Still time for 6-12 h timing shifts, so not throwing in the towel by any means - just commenting.

Tuesday is looking more and more like the best shot to start pulling real moisture up more than 2 hours before showtime - something Sunday is sorely lacking on most of today's runs.

The 500 mb pattern progged over the next two weeks right now is nothing short of insane, especially by the standard of recent years. Nonstop intense shortwaves dropping into the Rockies and carving across the central CONUS, one after another, with no end in sight. It's been at least since 2011 since we saw a similar pattern in the springtime, and maybe 2008 for the Plains. Really, the first half of May 2003 is what comes to mind, looking at this morning's GFS. It's just happening 30-45 days too early to take full advantage with these short wavelengths, from a severe perspective. But we'll probably get our first headline-making tornado event of the year (outside the Gulf coast) out of this period somehow, regardless.

I don't think I've ever seen one of these quick hitting, compact shortwaves pan out in the Plains early in the spring, but that doesn't mean it can't happen. Last night's GFS and Euro both raise an eyebrow for Sunday. I will say that, as currently progged, I wouldn't be especially worried about mixing as a main failure mode. Rapid cyclogenesis and strong moist advection in the final 12-24 h should minimize the impact there. I think it's more an issue of shortwave timing and whether we can actually pull the preexisting juice to our south up in time.

Bleh. Everything out through D+10 looks like the wavelengths are too short for anything big. Nothing unusual this early, but it sure has been awhile since we saw a half decent March setup in the southern Plains (3/18/12, perhaps?). At least there are some indications of a continued favorable base state heading into the beginning of April.

As Tyler mentioned, we have clickable soundings available on pivotalweather.com. To my knowledge, we're the only site offering this for the HRRR or the 4-km NAM CONUS nest. The load times for GFS and NAM soundings should also be as fast or faster than comparable sites (under 4 sec. in most cases). On our Skew-T Log-P panel, you can find dew point (heavy green line) and wet bulb temp (light blue line). We use SHARPpy for the sounding graphics, which features numerous panels that can be swapped out in the code. Note that while there is a lot of information pertinent to severe weather, we have a simple algorithm that determines whether a sounding profile is "wintry" and will automatically swap out some of that in favor of info like Precip Type, snow growth efficiency, etc. That information is found at the bottom right of the sounding image. If you have any questions or comments/requests, feel free to PM me here!

No doubt. Once again, as with every year after 2010 so far, a significantly flawed Plains chase season with a few nice bright spots. The good, well-rounded year with a few obvious big days and several more localized gems still eludes us. I will say, thanks to late May, that it was at least a decent chase season (for everyone who made it out that week). That's more than can be said for the overall severe weather season across the country.

lol and right on cue, our last hope for the season S of I-80 has taken a dive since I last posted. Wave mistimed for good Plains action, and also flattening out more on recent guidance. Tomorrow is pretty marginal, and this morning's CAMs are not optimistic at all, but I'm still considering giving it a shot along the CO/KS border (if not farther W... sigh). Otherwise, my first chaseless June will be quite possible. Tuesday is similarly lukewarm for IA/MO. On the plus side, at least the medium range progs have stopped giving us false hope? That's about the best that can be said for the past 2 weeks.

Last night's Euro looked awfully impressive for KS on Tuesday. Nice surprise that's popped up over the last couple days after it had become easy to assume we were done S of I-80 for the year. Given how well the late May setups performed aided by excellent ET/near surface moisture on the High Plains, I'm already excited about the possibilities for this one, even if some details are less than optimal.