Quincy

Relatively messy storm mode so far. Keeping an eye on an arc of semi-discrete cells around the Sioux City area. Those may have the least disrupted inflow environment to work with. Storms farther north appear to be clustering and interacting with cooler outflow, while storms to the west near the MCV center are likely elevated. 

Localized supercell potential evident today in the front right quadrant of an MCV, which is moving into Nebraska late this morning. 

The threat should maximize between far northeastern Nebraska and southwestern Minnesota, where supercell wind profiles impinge on large/locally extreme instability late this afternoon. 

The main limiting factor I see is that there may be some subtle veer-back signatures in the wind profiles, due to the MCV moving NNE (southerly component to 500mb flow). Wind fields should improve toward 00z and especially with northward extent, with a lifting warm front, moving north across southern Minnesota. 

I’d expect an arc of semi-discrete supercells to intensify and tend to cluster, as they track across the NE/IA/SD border area. There is certainly a window for a few tornadoes, but storm mode may limit this from being a higher end localized event. If any isolated cells form ahead of the main arc of storms, they could pose a somewhat greater tornado risk across southern Minnesota.

We hit 92F in Oklahoma City today. Wichita Falls, TX hit 103F. Believe it or not, that only tied the record for May 8th. 

Sunday the 8th looks like it will mostly remain capped, but maybe there will be isolated severe storms.

Monday appears to have the most apparent potential through this period. Most likely in or near Iowa.

The 10-13th is forecast to be an odd pattern for early/mid May. Pronounced ridging across the central U.S. and a cutoff low across the Southeast. I’m not sure there will be much overlap between appreciable forcing, shear and instability. Still, I could see a few severe storms, somewhere between the central High Plains and Upper Midwest. 

What a mess for chasing. I doubt anyone saw tornadoes unless they were right up close. And many chasers (and tourists) were way too close. Witnessed many chasers, including tour vans, fragrantly breaking traffic laws on the roads.

21z FWD sounding still shows a cap holding on. Warm front is basically stalled just north of the Red River. Thinking OKC is going to be spared the worst, but we’ll see how it continues to evolve. 

Relatively quiet this far. Panhandle storms appear to be overrunning the warm front and ingesting cooler air. Low level lapse rates are still unfavorable across most of Oklahoma. A cell tried to go up near Abilene, but weak forcing seems to be the issue there. 

Focus moves toward a dryline bulge, just east of Lubbock. It looks like we may have convective initiation now after a failed attempt earlier. 

18z sounding from OUN is ugly if you want tornadoes. At least for the next several hours, as there’s a stable near surface layer.

Trying to save data, so embedding tweets instead of uploading more images. 

Low level lapse rates look to be a noteworthy limiting factor for central Oklahoma, in terms of tornado potential this afternoon. Not all that much different from 5/20/19. If lapse rates stay low, as is expected through 6-7 PM, the tornado threat may be limited to closer to the Red River. 

This doesn’t mean that tornadoes can’t happen, but that the threat with northward extent may be more marginal and could hold off until after 00z/7 PM.

HREF ensemble probability for intense (>150 m2/s2) helicity tracks. Keep in mind these don’t explicitly/necessarily indicate tornado potential, but given low level moisture and wind fields today, there is a bona fide tornado threat. 

The cluster near/NE of OKC is mostly FV3 driven, but still plausible near the warm front, IF low level thermodynamic fields improve enough to support supercells rooted near the surface. 

46 minutes ago, andyhb said:

So far the HRRR has the best handle on current convective evolution, with the NAM 3 km and NSSL WRF being far too bullish on early elevated convection. The environment close to the warm front later looks pretty dangerous from CDS towards OKC. Seems like a low-level flow has ramped up in forecasts as well the closer we've gotten to verification.

It’s concerning that HRRR is not showing much of any convective initiation through mid-afternoon. Some elevated activity races north with the warm front, but it looks like the WF is going to be draped close to the I-40 corridor. 

Right now, low level lapse rates are pretty bad (< 5 C/km across all of Oklahoma) and capping will probably limit CI for a while. Not really sure how convection evolves, but any discrete/semi-discrete cells initiating after 3-4 PM will need to be watched very closely.

Based on near term trends, those cells coming out of the panhandle later will probably remain at least semi-discrete as they move into southwestern Oklahoma. Looks like odds are increasing for at least 1-2 long-track, intense supercells, with other tornadic supercells possible in the warm sector and near the warm front. 

Pretty classic localized outbreak setup unfolding, around the SE Texas panhandle/far NW Texas vicinity.

Morning radar and water vapor imagery suggest little to no airmass disruption will evolve SW of a lifting warm front across NW Texas. High res model consensus shows deep shear vectors (~50 knots) just about perpendicular to the dryline. Point forecast soundings show a reservoir of 8-8.5 C/km mid-level lapse rates, favoring large to very large hail. Low level hodographs enlarge as early as 21z in the SE panhandle, as storms initiate.

As I see it, the three main limiting factors from this being a higher end regional (vs localized) event are:

1. Convective overturning is still possible from western North Texas into SW Oklahoma, where warm air advection showers/storms could still blow up by early afternoon. This would limit how far east the significant tornado threat (associated with discrete/semi-discrete supercells) could extend into Oklahoma.

2. Storm mode near the triple point could get messy as storms interact with the warm front. Clustering and storm interactions might disrupt potential longevity of discrete storm modes.

3. Several models show discrete supercells firing farther south across West Texas ahead of the dryline, but here, hodographs are more straight and elongated, suggesting less of a tornado threat. 

While the epicenter may be near the SE Texas panhandle, look for isolated storms as far south as Southwest Texas, while mixed storm modes with embedded supercells will also be possible across North Texas and much of Oklahoma.

This setup reminds me a bit of 5/16/15 (Tipton/Elmer tornado). I remember that was a grungy HP setup. I started chasing in the Texas panhandle and then bailed east just in time for Tipton. I recall that the northern threat area (N of I-40) was convectively overturned and mostly a bust. There were nocturnal tornadoes into northeastern Oklahoma, which could happen again.

Interestingly, CIPS analog data pegs 5/19/15 as the top analog, but 5/16/15 seems to fit the pattern a bit better. 5/16 has some differences, so I’m not saying that it’s a perfect match synoptically.

HRRR seems to be on the higher end of the ceiling here. ARW also goes kinda bonkers with discrete/semi-discrete cells over a broad swath of the southern Plains. 3km NAM blows an MCS through NW Texas/southern OK in the morning, chewing away at most of the threat area. As a result, the NAM is on the lower end of the spectrum. 

Still a complicated setup, but I’d think that areas west (dryline) and south (tail end Charlie near FST?) have the greatest potential for at least semi-discrete storms. Oklahoma is a wildcard, but it could be more of a late show there. North Texas might even get in on the action, if early convection isn’t too disruptive. 

The two major 18z CAMs show very different convective evolutions tomorrow:

3km NAM shows a morning MCS that effectively overturns the environment from much of northwest Texas into southwestern Oklahoma. Isolated cells by the dryline (near I-27) struggle to mature and blobby convection affects parts of North Texas into southern Oklahoma.

HRRR shows minimal early day convection, resulting in a cluster of intense supercells forming off the dryline, near the Caprock, and moving east into southwestern Oklahoma. 

I think in this setup, I’d lead toward the messier convective evolution, but let’s see how trends lean tonight. 

Today looks like a quieter day, but Texas could see a few isolated severe storms. Some CAMs show a supercell or two trying to form in East Texas, although deep layer shear looks marginal.

Another area of focus would be the Edwards Plateau/Hill Country area. Isolated supercells seem likely over in Mexico, but a storm or two could form over or move onto the Texas side. 

Tomorrow could be much more active, although the effects of early day convection complicate the forecast. I’d tend to think that areas near and north of I-40 will probably be overturned and miss out on the strongest storms. There seems to be more confidence for isolated/scattered supercells in west/northwest Texas. Oklahoma is a wild card, but storm mode will probably be more messy, rather than discrete, in these parts. 

Chased a supercell for almost two hours from SW of OKC to east of Norman. 

The sunset tonight back home in Moore really topped off a successful local storm chase. 

I couldn’t leave OKC until 4:30ish, so I took my chances with the supercell SW of the city. Neat structure and several photo opportunities:

I may post a few more pictures after I can upload from the actual camera. 

Just a few thoughts regarding tomorrow…

Models have trended south with the warm front. It was central Kansas a few days ago, to southern Kansas earlier today. Now 00z CAMs place the warm front across northern Oklahoma between 21-00z.

There’s strong model agreement that semi discrete storms or a cluster develop near the triple point and ride the warm front, now expected to be draped WNW to ESE across northern to east-central Oklahoma.

My concern is that early day convection could possibly keep the effective warm front even farther south, possibly close to OKC. It probably won’t be quite that far south, but effects from morning convection, including outflow boundaries/intersections with the warm front will need to be watched.

Down the dryline, most guidance does not convect. Point forecast soundings from the HRRR between OKC and Lawton seem to suggest CI is unlikely, given lower quality boundary layer moisture, as opposed to the 3km NAM. The latter shows a more volatile environment right down to the Red River, but this could be overdone, similar to how Friday was modeled. The most realistic scenario is in between.

Bottom line, tomorrow looks similar to this past Friday, only shifted about 150 miles south. The significant severe threat could be pushed close to OKC, especially if early day convection keeps the warm front suppressed. Betting odds favor north-central OK at this point, with dryline initiation near/south of I-40 leaning toward unlikely. 

That early day convection can throw several variables into the equation. Some favorable and others potentially unfavorable:

Convection can leave outflow boundaries.

Early day moisture could also help limit mixing, keeping LCLs a bit lower and a slightly more saturated boundary layer.

Flip side, too much cloud cover could limit surface heating.

If early convection is too robust, that could augment wind fields a bit. 

With that said, this does show a regional signal, where even morning convection could have little to no affect, as rapid recovery takes place in the afternoon. 

I compared this setup to last Friday and synoptically, it is very similar.

Differences: 
Slightly faster. Convection seems likely by early afternoon in Kansas. The system is also a nudge farther south. 06z NAM was showing heights falling as far south as I-40 in Oklahoma by 18-21z. This should be a bit alarming. 

I also noticed less mid-level dry air and somewhat better moisture (think mean mixing ratios) through the column.

Prime example of a tail end Charlie storm going nuts right around sunset. Hope there weren’t any serious injuries. 

Not sure I’ve ever seen this. Most guidance backed off of dryline storms in OK/southern KS until last minute, then brought them back. Only to lose them last minute as well. WoFS is looking pretty bad right now too. Almost all cu along the dryline is dissipating. One of the harder busts of my career, but it can be a learning experience. 

Initial cells are struggling to mature. What a delicate situation. So much potential for one or two intense storms, but also the likelihood that a lot of areas don’t see anything at all. 

HRRR is playing catch-up with surface moisture, as is often the case. Latest mesonet data shows widespread 65-66F dew points across central Oklahoma. Latest HRRR run tries to initiate a cell in north-central Oklahoma and I wouldn’t be surprised if future runs favor more intense convective development. 

My thoughts: Relatively high confidence of isolated supercells from central KS into north-central OK. Think a secondary area is favored for CI in southwestern Oklahoma, but still have questions about how intense/long lived any convection might be there. OKC isn’t out of the woods either. That 12z OUN sounding showed some thick CAPE profiles and steep lapse rates above the capping inversion. 

I won’t be able to update for a few more hours and by then, it’s almost game time. Stay safe today!

Just now, StormChaser4Life said:

@Quincyhow do you feel about initiation on dryline in south central KS? TP is obvious play but looks to get messy quick and could get undercut by front

Analog guidance coupled with the trajectory of the nose of the upper jet would suggest better than 50/50 odds that a storm could form in south-central Kansas or possibly north-central Oklahoma. 

NAM/ARW suite doesn’t convect, but also shows a lot of residual cloud cover in Oklahoma, limiting daytime heating. NSSL still tries to pop a storm in north-central Oklahoma, while most other guidance shows nada south of the KS/OK border. 

Morning satellite and obs will play a big role in pinning down tomorrow’s threat.