Quincy

Several factors seem to point toward higher-end potential today across the region. Many have been discussed above. Lapse rates: 15z mesoanalysis shows mid-level lapse rates of 7-7.5 C/km across much of Louisiana and western Mississippi. A broad area of >8 C/km exists over East Texas. Typically these events “underperform” in terms of hail production in the Mississippi Valley, but you could see quite a bit of hail, especially across LA/AR/E TX. Instability: Thanks in part to steep lapse rates aloft, instability profiles also appear to become uncharacteristically large for such a cool season event. Also, rich low-level moisture is rapidly being transported north and east. Note lower 70s dew points already in place from SE TX into S LA. This is supporting enlarged low-level CAPE, which is a key variable with respect to significant tornado events. Shear: Both deep layer and low-level shear will easily be supportive of severe/sig severe. Also note a more westerly component to the upper level flow than we tend to have in place. WSW/SW, as opposed to the SSW flow we often see when big troughs trigger moderate risk events in the region. More thoughts on the upper level support… We see a broad trough impinging on the area. This is allowing the steeper lapse rate plume to overspread moist low levels. Too often we see a barreling trough with a messy QLCS mode. While convective evolution could still get messy, the shear vectors do favor discrete or at least semi discrete modes for several hours. A few limiting factors: Despite a more westerly than southerly component to the upper level flow, deep shear vectors are still fairly parallel to the initiating warm conveyor belt (SW to NE). This could result in bands and clusters of supercells, full of mergers and other storm interactions. Still, backing of wind fields is creating sickle-shaped low-level hodographs, in addition to elongated deep layer hodographs. Finally, low-level lapse rates will probably remain fairly marginal for a while. This may cap the ceiling a bit, particularly early in the event. The threat should really ramp up late this afternoon and, unfortunately, continue into the evening hours with eastward extent across Mississippi. Hopefully awareness is there and impact to life and property is minimized.

The slight, enhanced and moderate risk areas were essentially unchanged. The marginal risk was expanded slightly farther west across East Texas.

Wildfires in NW Oklahoma today. I don’t think I’ve had any rain here in Moore in a month. There were a few days in July with scattered storms west and north of here, but that’s about it. Either 7-10 split or they fizzled before making it here. Barely any rain since the start of June.

Witnessed a tornado in central Kansas a short time ago:

Another derecho could be forming across northeastern Kansas. Pressure falls are noted ahead of the convective system. Topeka’s 00z sounding sampled 1432 J/kg of DCAPE.

Been chasing the storm cluster in southwestern Nebraska. Keeping a distance to get some structure photos, but there may have been a brief tornado or two underneath there. (Via other storm chasers)

To echo @Chinook, forecast hodographs look rather lengthy, thanks to the substantial shear mentioned above. If storms don’t get too clustered, you could see at least a couple long-track, intense supercells. Severe hail would be the most likely hazard. Low-level SRH is forecast to modestly improve after 00z, but I’m not sure the tornado threat will be fully realized. This is thanks to storms tending to merge and grow upscale, but a tornado or two could form. Other supercells seem probable across the Colorado Front Range and possibly northeastern New Mexico as well. Tuesday could be a rather active day across the region…

It’s nice to see rain and storms across the southern High Plains. Hopefully the pattern continues so we can keep chipping away at the drought.

Chased down in he Permian Basin today, because June decided to start off with another crashing cold front. Going to take a break from chasing for a while. The pattern looks below average anyway.

Several semi-discrete supercells formed from the Texas panhandle into northern/western Oklahoma and southern Kansas on Tuesday. I had pretty low expectations going into the day, so I’d say the storms outperformed, despite being HP beasts.

Started the day in Sioux City and made the decision to go south. It was a race against the clock, but I opted to target eastern Kansas. I chased (or attempted to) a couple of semi-discrete supercells in the Flint Hills, but with trees and lack of roads, I bailed south for isolated cells closer to the Oklahoma border. Those storms started to fade rather quickly, but I was able to get a couple of photos of the southernmost cell, before calling the chase off.

Well, shear/instability are there. The parameter space in Minnesota is high-end with some anomalous values, but that doesn’t mean the setup was going to produce a bunch of discrete supercells. I suspect we see some QLCS tornado reports. Kansas is still iffy, but maybe they squeak out a tornado or two around sunset. Even there, storm modes have been mixed.

Not really a big surprise. Also doubts down in Kansas, but the event is still young.

Late morning weather map:

Higher-end wind profiles for sure…

Here’s your giant hail:

Challenging storm chasing today and tomorrow, despite higher than average tornado probabilities. Today looks to be a close call with convective initiation prior to sunset in Nebraska. Do you drift west and hope for storms coming off the High Plains? Wander north into eastern South Dakota and hope storms can mature, despite weaknesses in the wind fields? Or hang in northeastern Nebraska until time runs out? Definitely reminds me of 6/17/14 in terms of timing. I don’t think storms became established until after 00z. First tornado reports were shortly after 01z. Tomorrow appears to have three plays: 1. Chase the SPC/parameter space bullseye near the MN/Dakotas border. Race east across MN with tornadic supercells likely, but storm motions will be fast and storms may ultimately form an MCS. 2. Play farther south, near the NE/IA border. Storm motion will be more W to E. Question will be how many sustained cells will persist into Iowa? IA has a bad rap for storm chasing. Seems to bust most of the time, but goes bonkers once in a while. 3. Kansas. The not-so-classic Kansas chase setup. Does a storm or two become established? Could play up near I-70 or even go for a Hail Mary down by the Oklahoma border. Good luck to all chasers!

An interesting setup tomorrow with several nuances that make for a difficult forecast. I doubt we will have high confidence on details until at least mid to late morning. The synoptic setup shares some DISTANT similarities to the 6/16 - 6/17/2014 sequence. I am not calling for the same evolution, but I do recall the Pilger day and similar surface features. The difference here is that we're a few weeks earlier in the season and the moisture field may be somewhat fragmented, resulting in more capping and delayed initiation. Interestingly enough, 6/17/2014 was a late initiation day in the same general area (northeastern Nebraska), with storms not firing until only a couple of hours before sunset. Anyway, I attempted to roughly illustrate the current mean HREF surface map features, effective 21z/4 PM Sunday. The area to watch is likely the triple point, somewhere in central/south-central Nebraska. I wouldn't say it's a true front, but it appears as if a surface trough will drape south from an area of low pressure over eastern North Dakota, toward a low near the Kansas/Nebraska border. A dryline will probably intersect the low at an effective triple point. Low-level moisture fields appear to be fragmented, as a moisture gradient may exist, displaced slightly to the east, over Iowa. There, strong capping will likely preclude convective initiation prior to loss of daytime heating. Storms could fire along the trough (both across eastern Nebraska and farther west toward the High Plains), but it seems as if the best shot an initiation, perhaps only 1-3 hours prior to sunset, would be near the triple point. We could see early day storms also bring a hail risk to the Upper Midwest and might there be some warm front action across Minnesota/Wisconsin as well? Maybe even attempts at convective initiation along the trough over the eastern Dakotas? Definitely an odd, complex setup. Some models struggle to convect prior to 00z. If initiation is too soon, there may not be adequate boundary layer moisture recovery across Nebraska. The sweet spot seems to be somewhere over the eastern half of Nebraska, around 6-9 PM, assuming that the cap is breached and storms can form near/ahead of the triple point. If storms were to fire on the northwest side of the trough/low, they will be displaced from better moisture/wind fields in the lower levels.

@MNstormsready to add to the wealth?

Large hail = 1” or larger in diameter Very large hail = 2” or larger Giant hail = 4” or larger

Chased western South Dakota today. Convergence on the north side of the Black Hills helped a high based supercell form, but storms very quickly became outflow dominant and clustered. Had a neat sunset, at least. Convective initiation may be more widespread tomorrow with stronger forcing and somewhat better moisture. Still, most CAMs snow linear segments and bowing structures, despite seemingly (supercell) favorable wind profiles. It seems like another day to hang around the Black Hills, OR head south and hope for something to stay somewhat more discrete and tap into better moisture down in Nebraska.

Looks like Sunday-Monday have noteworthy severe potential, somewhere between the Central Plains and Upper Midwest. We could see the threat linger into Tuesday, before troughing ejects toward the Ohio Valley. Just in time to close out May.

Meanwhile here in Oklahoma City our temperature during daylight hours didn’t get above 56F today. Pretty absurd. Average low is 61F. (We did have a midnight high of 59, to get technical)

Did not see the tornado, but was able to photograph the supercell from the south, long after the tornado dissipated. Lots of dust.

An upper level trough, slowly moving across the Central U.S., should bring a threat of severe thunderstorms across the Southern Plains through tomorrow. The Texas Gulf Coast and parts of Arkansas/Louisiana could be affected on Wednesday, before the pattern becomes unfavorable for severe thunderstorm activity for a couple of days. A more traditionally favored severe pattern should then setup for the weekend, through the final days of May. Ensemble guidance is in good agreement with broad troughing across the West and some ridging across the eastern half of the U.S.. While some limitations will likely prevent this stretch from being higher-end on a broad scale, isolated to scattered severe thunderstorms seem probable between about May 28-31. From a storm chasing perspective, sometimes broad troughing is preferred as you get later into spring, as storm motion can be a bit slower and mesoscale features dictate the precise placements of threats.