Quincy

It’s a convectively contaminated sounding at 23z that’s near a squall line associated with a cold front. The NAM shows multiple rounds and areas of warm sector storms, to the east and several hours earlier. I don’t think low-level lapse rates are a big issue here. The models show a relatively uncontaminated warm sector around 18-21z. You can get QLCS tornadoes even with the surging cold front, but I’d be more focused on the warm sector and any pre-frontal trough.

CIPS analogs show a relatively high correlation with tornadic events based on the 00z GFS. 4/27/11 is #2 and yes, some other analogs are much more tame. Percent of analogs with at least one long-track tornado:

I think it’s more about placement. To be clear, I’m not seeing any significant trends with respect to speed and orientation of trough amplification. It’s more about a gradual westward tick. Hopefully that makes sense. I’m trying to make sure I don’t get too hung up on specifics either.

Want to try to not get too specific on details this far out, but the synoptic signal is there for a potentially higher-end event. There are some key differences, but 4/27/11 is ranking as a relatively close analog at this stage. Speaking of details/trends, the GFS/Euro have been trending a bit slower and to the west. That’ll be something to keep an eye on, which may put AR/LA more into the action, as opposed to AL and areas farther east. If the system slows a bit and remains more neutrally tilted as opposed to negatively tilted, that’s setting off more alarm bells. The shortwave is looking somewhat more progressive and compact than some historical major events. 4/27/11 and 4/28/14, for example, were more amplified with upper level lows cutting off. If the progs are correct, a northwesterly 100kt 500mb jet will spell trouble. Remember your MS vicinity climo. Mean MLCAPE for tornadoes is only ~500 to 1000 J/kg and 1000 to 2000 for significant tornadoes. Global models and longer range NAM get you into the latter camp. Wind profiles speak for themselves, very impressive at face value. Global models showing a string-of-pearls QPF signal ahead of the cold front is alarming, especially if there is a pre-frontal trough. I try to not look at forecast soundings too much, but a warm nose/cap around 850-750mb during the first half of the day would suppress precipitation and with cooler temperatures aloft penetrating, that’s why you’re seeing seasonably large instability profiles. Summary: Don’t get hung up on details. The synoptic signal is alarming. Watch for a slower/westward trend.

The overall pattern looks unseasonably quiet across the Plains through at least the next 5-7 days. This is reflected well by the CFS severe weather guidance dashboard, which has blue boxes in the coming days, something that is very unusual for early to mid-June. The Northern Plains area into the Upper Midwest may see some severe thunderstorm activity this weekend, as a trough ejects eastward. What happens with that trough next week is the glaring issue. Medium-range guidance and ensembles are fairly consistent with broad troughing across the Missouri Valley/Midwest/Great Lakes vicinity through much of next week. In uncharacteristic form for mid-June, instability appears limited through at least the middle of next week and possibly the end of the week as well. Northwest flow events tend to become more common into July and sometimes even mid to late June, but with modest instability, at best, that does not bode well for severe thunderstorm prospects via NW flow next week. As we approach next weekend, there have been signs that the pattern shuffles and there could be a return to at least near average severe thunderstorm activity for the third week of June. European ensemble data and the weeklies, to a lesser degree, show a more zonal flow-type pattern across the northern tier of states by next weekend or early in week 3. (roughly the June 15-18 window) The potential may exist for one or perhaps a few shortwaves to impinge on the northern High Plains/Northern Plains vicinity with an uptick in severe potential there. This is also highlighted by the CFS dashboard, although it does not take much in the way of wind shear to throw blanket regions of elevated SCP values in June when there is seasonably-typical instability in place. (The CFS dashboard is based on supercell composite parameter / SCP values, either over a broad area or elevated in any area) On the other hand, the latest Euro weekly data seems to imply that any pattern shift is short-lived and that more Upper Midwest/Great Lakes troughing could set up by the middle or end of June week 3. As we go deeper into June, the Great Lakes/Midwest vicinity could experience northwest flow severe threats, but that type of pattern needs instability in place. The trends suggest that moisture is going to be scoured south and east (quite a feat for June), even when there is appreciable upper level flow in the northern states. Who knows, maybe that could result in an unusual late season threat across the Mid-South, but that's speculation on an already conditional scenario. Any way you slice it, the prospects for severe thunderstorm activity in the Plains in the near future are very slim. Sure, you can get some High Plains magic here or there, but that's to be expected, even in the quietest months of June. I'd be cautiously optimistic about prospects for June week 3. On the bright side, that period (June 16-22) has featured some significant events over the past decade. Almost each year seems to have at least one noteworthy event in that window, but we'll see.

In all honesty, the moderate seemed a bit overdone. It's a very complex setup and it doesn't take much to throw a wrench in higher-end potential, especially with a seasonally anomalous setup so far south. On the bright side, drought areas have and should continue to get drenched with much needed rainfall.

You do realize tomorrow was upgraded to a moderate risk? Granted it's not looking like an outbreak of discrete storms, but significant severe seems likely given the degree of shear and instability expected.

The low-level jet signal is pretty intense given the latitude this late in the season. Yes, there's some convective feedback, but LLJ is progged to reach 50 knots by 03z (near the solstice, that's only an hour after sunset around here) all the way down into Oklahoma with 50-60+ kts in Kansas. Have to imagine a big wind producing convective system evolves late, but earlier day is more of a question mark. It may be a convective mess with the degree of instability with storms just firing all over the place. Who knows. I can't say I've chased long enough to see a similar setup south of I-70 in late June. It will be interesting, but this year especially has taught me to not get too excited about a forecast two or more days out. The fact alone that we're seeing noteworthy upper level flow this far south for 2-3 days is intriguing. Beyond this weekend, such flow (probably even stronger) looks to return for much of next week from the northern Plains to Upper Midwest/Great Lakes. The severe season is not entirely over... yet...

The season is cooked for anywhere near/south of I-70. Mega death ridge reigns for the next 7-10 days, but the pattern could favor some AOA severe activity from Idaho/Montana/Wyoming into the Dakotas. The week two period favors more Great Lakes troughing, so that would tend to suggest an MCS/derecho pattern from the Upper Midwest into the Lakes vicinity.

There's pretty solid reliability in the end of May. Even in a bad year, odds favor that more than half (sometimes all) of the days should feature at least something worth chasing. This year has been abysmal for tornadoes, but there was the Wyoming event yesterday and several other days have featured supercells and "interesting" storm structure. The window during which one chooses to go on a chasecation does seem a bit risky. If you go before the final week of May, odds increase that there will be several down days and possibly a busted period. Go before May 15th and you're doomed, unless you get really lucky. Wait until June and while the ceiling may be higher for at least one or two higher-end days, there's also increased odds that there will be down time. I guess if tornadoes are all that you're after, it's a bit risky. At least it has been this year and last year as well. Unless we're really moving into a new pattern (I doubt it), late May is king and produces well in the vast majority of years.

Today's northeastern Colorado is a fairly typical 10% day in late May. (Could be big or could be slop) Shear is there and so is moisture, but lingering clouds and concerns about storm mode/mergers suggest this could just as easily flop as perform. With that said, climatologically favored upslope trajectories with ample moisture suggest that there probably will be at least a few tornadoes. Will they be seen or last longer than a couple of minutes? We'll see.

Also for next week, the Euro is really ugly. The 500mb maps suggest virtually ZERO 500mb flow of 30+ knots in the Plains. A major failure of the calendar if it verifies.

Friday looks to have the best potential (over favorable terrain) in the coming days, particularly over Kansas. Tomorrow looks like a mess up north (northern Plains), while the southern Plains may struggle a bit with storm longevity. Not to mention that outside of the Dakotas, deep layer shear appears marginal (only around 30kts in the 0-6km layer). You'll probably get some locally enhancement in climo-favored northeastern Colorado, but that's about it. (A conditional threat may exist along a warm front in the eastern Dakotas, but that seems fairly conditional) Saturday looks to be just a little too late/east. A closer look at a consensus of guidance (which I will lean more toward the Euro) favors increasingly unidirectional mid/upper level flow and capping issues. An area that may have the best potential will probably fall near the lower Missouri Valley (northern Missouri and surrounding areas). I'm not sure that the eastern Kansas dryline setup will work. Sure, if the system slows a bit and we see a stronger signal for backing of low-level flow, then maybe, but we've seen similar setups fumble this year in such a scenario. With respect to the CFS, that might be a hiccup, but when it shows such low "values" for SCP during peak season, that's a major red flag. Taken verbatim, the latest CFS would be pretty dull next week, although you'd probably still have at least a day or two thread the needle somewhere, either along remnant outflow or terrain-aided.

Assuming we're near 320 right now and we finish May with only 323 (3 more tornadoes!), following 1991-2010 climo for the rest of the year would put us right at 1000. However, it doesn't quite work that well, as I mentioned earlier in the year, more than 50% of years and months finish with below "average" tornado counts. It's the big events/outbreaks/seasons that skew the average a bit higher. At some point, you do have to consider persistence and I do think if there was a year to finish with less than 1000, it was this year. We managed to pull off the feat in 2016, but peak season was fairly active that year. We also did it in 2013, but the second half of May was fairly active. I guess that speaks volumes, as if we stay slow, it's going to be that much harder to dig out of the hole. If things don't turn around in the next few weeks, this might be an even worse version of 2013. Imagine if 2013 was slow in May and didn't have November 17th, that's about as bad as it can possibly get...

Last week, May 6-12, was a staggering 91% below climatology (based on preliminary reports) in terms of tornadoes with only six. The only such period that saw fewer since 1950 was four in 1987.

This reminds me a bit of my days back in New England... When there was whispering of a "great" winter pattern setting up. The talk started in October, growing louder and louder into November. The conversation suddenly grew quiet, so much so that by the time March came and the ground was still brown, not a word was uttered about the winter that never came. While the season is not over, we're at the all-star break, but our team had a painful first half. Batter after batter kept striking out. Prospects in the bullpen couldn't throw a solid inning, let alone a complete game, and the number of home runs hit, let's just say, were nearly a record low. Sure, not all games were lost and even a play or two made the highlight reel, assuming you were in the stands with a good view on that isolated day. However, we're most likely out of contention for the pennant and we're well below .500 for the year. Sure, there could be a historic late season comeback, but barring something like that, this will be a year that simply wasn't ours for the winning. Yes, things could change, but the trends are becoming increasingly less favorable. The silver lining (I feel like I've been saying this all year) is that even the worst years seem to have a masterful performance between late May and mid-June. Think back to 2014, when an epically bad Plains season was rescued in the 9th inning with two outs by hitters such as Pilger and Coleridge, seemingly out of nowhere. Recall 2017, a year that saw several highly anticipated games only fall short, sometimes painstakingly short, of expectations. Another 9th inning wonder came to bat when a rare Moderate Risk on the Front Range, of all places, actually performed and featured a few photogenic tornadoes. Another year that comes to mind is 2015. That year, overall, wasn't great and it was the first and only time that I strayed west of the Rockies during a late May trip to the Plains. I had a friend with me and after two abysmal chases in marginal setups, I did not want to disappoint her with a week of sunburn. It resulted in missing out on the Canadian day. The drive back was perhaps even harder, as I was not paying close attention on my way back east, ending up in Albuquerque one day, when I should have been in Dora... We can all learn from seasons like this. My advice is don't live and die by the models with every breath. Forecasts change. Speaking again about my New England roots...some of the most memorable, major snowfalls were not anticipated more than a couple of days in advance. Sometimes a narrow band of snow, drawing parallels to a residual outflow boundary, waiting to be lit up, brought rush hour to a standstill as bystanders could only get out of their cars and look in awe. Likewise, magical tornadoes can spin out of seemingly marginal-looking environments. It is true that like snowstorms, some historic severe weather outbreaks can be well predicted, even as far as a week in advance. However, objective data tells us that beyond day 7, the skill of computer models becomes increasingly erratic, as extended model forecasts can and will change, sometimes drastically. In a way, I'm actually glad it's working out like this. I would rather have tempered expectations going into a below average stretch, than have hopes of fields of wedges obliterated morning convection and mammoth cap busts. The beauty of low expectations is that if the pattern does change, or if there is an unforeseen magical storm chase day, then it feels that much more special. The bottom line... peak season is just about here and the models look pretty bad for the next week and as far as we can see with at least modest confidence, the signs are not encouraging. As a chaser, you have a few ways to look at this. Are you going to wait and hope that the pattern does change, allowing for a stellar finish to the season, or do you dial back to reality? Be ready, but flexible. Expect the unexpected. Prepare for the worst, but hope for the best. Stay optimistic, but don't be naive. You never know when the next MRGL or SLGT day could feature the storm chase of a lifetime.

This year has been comical. April was one of the coldest on record for parts of the country and now we're almost literally jumping right ahead to summer. #2018ing Quote from the latest SPC day 1 outlook:

The long range ensemble guidance isn't very impressive either. Just because there's some subtle troughing over the West Cosst doesn't mean much. That's late May climo. The difference this go around is that almost all guidance shows positive height anomalies over the Plains in late May, or in other words, shades of death ridge himself. Even though the overall pattern looks less-than-optimal, the fact that some troughing is modeled in the West suggests at least some shortwaves should be able to impinge on the High Plains. Maybe we don't get a big trough or an otherwise intense sequence, but with time, some of the key ingredients (particularly boundary layer moisture) will almost undoubtedly be there. As Andy mentioned, upper level flow looks weak, at least for the next 7-10 days. Troughing continues over Hudson Bay with plenty of robust jet streaks targeting the Great Lakes. Since the northeastern portion of the U.S. generally sees most of their higher-end severe weather events under a northwest flow regime, maybe they'll squeak out a big event or two? One can live and die by each model run, but it's healthy to take a step back. I've actually cut back how much I look at long range data, knowing that it will change a lot and late May to early June climo says that even the worst years see at least some noteworthy activity in the period. Still, it would be ignoring the data to refute the fact that trends are becoming less encouraging for the next 7-10 days, at least...

The 18z NAM and to some degree, the 12z Euro, show relatively large T/Td spreads throughout the boundary layer. This coincides with both models failing to initiate any convection in vicinity of the strongest bouyancy around 00z Saturday. The GFS, on the other hand, with large CAPE and somewhat less anemic low level moisture, shows precipitation blowing up in north-central Kansas. Another note is that the NAM, which I would lean toward, shows relatively high LCLs (around 2km), which makes sense given the relative lack of quality boundary layer moisture. With that said, the environment between eastern Colorado and the Kansas vicinity should feature at least some severe threat, given favorable CAPE/shear overlays, glancing effects of upper level energy and convergence along a frontal boundary. It will take some time to resolve mesoscale details, but I think one can justify the SPC slight risk. Otherwise, anything more substantial or widespread seems conditional, if not unlikely, at this point.

I haven't really looked into Thursday that much, but Wednesday has my attention, especially for areas closer to the Mississippi River. Still waiting on the 12z Euro to come into range, but I did notice that the last few runs of the Euro flip-flopped around with positioning and strengths of the wind fields. The overall sign is there for at least a marginal severe setup, given flow aloft and boundary layer moisture. It's still a few days out, so details are cloudy, but it is May and May is starting to look more interesting, especially in the longer range...

It looks like we may be, gradually, moving toward a more active pattern for the central states. With that said, even with some activity in the coming week, I'd be willing to bet that the week finishes at least slightly below average with respect to climatology for severe. That could change if the pattern late this week, that @jojo762 eluded to, looks more significant. Shortwave energy pivots from the northern/central Plains into the Midwest/Great Lakes around the middle of this week. I don't think Tuesday winds up producing much of anything, but you can't rule out isolated severe in the Kansas/Oklahoma vicinity, especially if boundary layer moisture trends improve. Wednesday is already highlighted in SPC's latest day 4-8 convective outlook, but that targets more of the Ohio Valley sub-forum. Thursday is progged to be a transition day, but details are tough at this point. Maybe it features isolated severe in the High Plains or even along a warm front farther east, but only time will tell. Friday-Saturday has the potential to feature at least one, if not two noteworthy severe weather setups in the Plains. Details will certainly change, but a positively tilted trough is modeled to swing from the Four Corners region into the High Plains through the period. The setup is not all that different from last week, although the speed of the system looks faster and troughing not as vigorous. Longer-range trends for the following week (especially mid to late next week) are increasingly encouraging. Perhaps the Lower 48 will finally be moving into a pattern with more consistent/substantial troughing across the western half of the U.S. It's been a long time coming, but in a way, it's better to see this pattern during the second half of May, rather than earlier in the season. Although it's tough to have much of a detailed look into late May, climatology and ensemble data suggest the signs are encouraging.

While I agree that the next 7-10 days (beyond Thursday) should be relatively quiet, the pattern isn't exactly bleak. Climo suggests that there's very often downtime in early May anyway, after the atmosphere reloads from late April (or in this case very early May) activity. Based on the OP/ENS Euro, a few weak impulses are able to impact the southern/central Plains in the northwest flow regime highlighted above. While upper level flow may be marginal, don't discount mesoscale features and robust boundary layer heating in areas like Oklahoma and Texas. Guidance in the longer range, i.e. days 10-14+, is even more encouraging, as that western ridge may shift eastward. We'll see!

Their discussion is a bit odd. They talk about a pattern change around weeks 2-3, but say that confidence is "extremely low." They then put out moderate confidence for average conditions in week 2 and low for week 3. Maybe it's nitpicking, but it seems to leave them open for just about anything during the period. Posting that map for early May isn't really anything astonishing at all, it's right where the climatological tornado probabilities peak: Pessimism aside, there is support from both the operational EC and EPS that suggests a shortwave trough may cross the central U.S. around the 4/30 to 5/1 time-frame. The GFS/GEFS is much more bullish in a deeper trough out west around the same time. The bottom line is that once we get through another week or so of an unseasonably lousy pattern for severe weather across the CONUS, there is at least some reason to believe that we return to near-seasonable levels around the start of May, meaning we have legit opportunities at severe weather events, outside of the Gulf Coast and Texas. I'm not very excited yet, but at least we're stepping in the right direction, if you are a fan of severe thunderstorms.

I don't think anyone's calling the entire season over, at least not without some sarcasm. We all realize that even in the worst storm chasing seasons, there are usually at least a couple of events/stretches that perform between mid-May and mid-June. What we have here is increasing confidence that the next 1-2 weeks will probably be unseasonably quiet. That says a few things: Since the ensembles and CFS dashboard have pretty good verification stats inside of 2 weeks, there is near-certainty that the next 1-2 weeks will be relatively quiet. It's pretty unusual to go through the last two weeks of April without a higher end outbreak and/or several active severe weather events. 4/29, 4/30 in 2017 4/26 in 2016 (with several other active days in late April) 4/26 in 2015 was a small moderate risk with a localized outbreak, but there were several events over the Plains from 4/16 through 4/26. 4/27, 4/28 in 2014. Yes, most of that was east of the Plains, but 4/28 was a high-end tornado outbreak in Dixie. 2013 was pretty blah, although there were modest events in Oklahoma on 4/17 and 4/26, a widespread wind event across the East Coast on 4/19 and fairly widespread large hail (with some significant) in Iowa on 4/30. 4/30 in 2012 was a decent event in the Plains and other days that come to mind are 4/21 with a several tornadoes in the Upper Midwest and 4/26 through the end of the month was a relatively active period in the Plains/Midwest. Recall that 2012 had a historic severe weather sequence earlier in the month... I don't think I really need to go into detail about 2011... 4/22 in 2010 featured a High Plains severe weather outbreak with modest events on 4/23, 4/24, 4/29 and 4/30. If you want to count an event in the mid-Atlantic, include 4/25. 2009 had several small to medium sized events all throughout the last two weeks of April. 2008 had tornadoes in 9 out of the last 14 days of April and while no single event sticks out as a "big one," 4/23 featured severe weather over a broad portion of the Plains with a localized outbreak in Texas, while 4/24 was a moderate risk/localized outbreak in the central Plains. This is just the past ten years and if you want to be a purist and say that tornado chasing in the Plains isn't always great in late April, you'd be correct, but this sub-forum includes areas farther east and the general discussion is severe weather in the central U.S. It's not "this is a thread that's only for tornado chasing west of I-35." Since tornado probabilities are rapidly increasing through late April, the quieter it is now, the more below average the year-to-date tornado count will fall. It is possible that a few days around the end of April could heat up, but confidence is very high that the next 7-10 days will be unusually quiet on the broad scale. The record for the longest start to a year ever with no tornadoes in Oklahoma is in jeopardy. After finishing today with no tornadoes, that places 2018 into a tie with 1970 with no Oklahoma tornadoes through April 18th of a year, dating back to 1950. There are still 8 more days to go to tie the record of April 26th, 1962, but one could argue that the odds of breaking that record are better than not breaking it, based on the synoptic pattern expected through the 26th. If you want to be a storm chasing purist or look at this from a chasecationing angle, then yes, the heart of the season is still out of range of most modeling and for all we know, could end up being very active. With that said, we've seen a trend this year for a lousy pattern and just about everything has gone wrong. Since 2012, 4 out of the last 6 years have been fairly dull, overall, in May and June. 2016 was fairly active in May, but then the pattern basically shut down for June. 2013 was pretty much garbage the entire year, aside from the second half of May and then two single days in the fall. Climate goes through ups and downs. Overall, the Plains has been on the bottom end of a roller coaster ride for several years now. I think seasons like 2008 and 2011 may skew some of our thinking. High-end events are relatively rare, but sway the mean. The result is that more than half of years will have "below average" tornado counts, but the years that are above average can be way above average, skewed by high-end outbreaks. On a personal note, this may be the first month of April that I don't have any storm chases since I started spring chasing in 2014. That says a lot, considering I live in Oklahoma now and in 2014-2016, I lived on the East Coast. I basically played climatology those years and did not even open up my schedule to storm chase during the first half of April. The bright side is that I haven't had too many highly successful chases in April yet, so from a storm chasing perspective, the season still has a long way to go.

The 12z EPS is pretty awful, with Great Lakes troughing right through day 15.