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About Quincy

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    Oklahoma City, OK

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  1. It's also the max of where the parameters overlap (larger 0-1km SRH north/larger buoyancy south). That's why SPC SREF tornado ingredients/probability has been 75-90% in that same part of southwestern Oklahoma. The bullseye isn't always where the most storms verify.
  2. Well, I'm not able to pull sounding data from the HRRR right now (server issue I think), but by 18hr with the 01z run, which lines up with the longer 00z run, there's upwards of 5000 J/kg SBCAPE with negligible convective inhibition in the DFW area. While forcing is weak/nebulous, anything that can initiate in North Texas given the thermodynamic/kinematic fields, would, at least conditionally, have the potential to become supercellular with a tornado threat.
  3. That 12z MAF sounding is going to be a sharp indicator of how quickly things could start firing in the morning, assuming it does sample on the east side of the dryline. Data suggests there may not be much convective inhibition remaining with strong instability already in place, which is pretty unusual for a 12z sounding that far west. Downstream sounding from DRT shows a 69F dew-point as of 00z. While that's not extreme high-end given SPC sounding climo, the 80F dew-point at CRP is close to a record. In fact, it's pretty rare in any month of the year for an 80F dew-point there, as sounding climo records show the all-time record of 83F. That was in September, either associated with a tropical system or return flow off of the Gulf, which reaches peak temperature around that time. Here is a surface map I put together, highlighting potential tornado threat areas, based on the 00z HRRR. The 00z 3km NAM is not far off and it shows hints of at least semi-discrete convection near/south of I-40 in Oklahoma during the afternoon/early evening. Local climatology suggests backing of low-level flow in central/northern Arkansas given the warm frontal placement tomorrow would support an "enhanced" tornado threat there as well.
  4. Ah, yes. Flooding is another major and perhaps more widespread concern with this system, especially from central/northern Oklahoma into parts of Kansas. Not only is Southern California getting an unusual amount of rain this year, but it’s been very wet in the Plains too. (The whole country for that matter as drought areas have been dwindling)
  5. The HRRR, in general, is good with convective evolution and is more conservative with moisture return than the 3km NAM. That’s why I’d take the dew-point progs seriously. They’re fairly close to what the NAM shows. However, this is a complex, multi-round setup. If morning convection evolves differently than progged, that would change how the rest of the day transpires, especially across the northern part of the risk area. If the HRRR remains consistent and shows a similar evolution with 00z and subsequent model runs, then confidence will be very high. If the model waffles back and forth, that will speak to the complexity even more. As with any convection allowing model, obs and trends will be of the utmost importance. Even if you dial back the HRRR some, it still looks like a tornado outbreak with multiple significant tornadoes is just about unavoidable at this point. There still is a scenario where convective evolution stays messy near/north of I-40, but that’s the best case at this point and probably wouldn’t spare West/Northwest Texas to southwestern Oklahoma.
  6. Based on the HRRR: It starts with West Texas already seeing 3000-4000+ J/kg SBCAPE with minimal CINH by 14z. The low-level jet remains stout, averaging 30-50 knots at 850mb throughout the entire day across the moderate risk area and most of the state of Oklahoma. The shear across Oklahoma would support intense to violent tornadoes, IF storm modes are at least semi-discrete. We’re talking about upwards of 50 knots of 0-1km shear by early afternoon. The parameter space moves into a nearly unprecedented categories over west/northwest Texas in the afternoon with 4000-5000+ CAPEs with increasingly intense wind profiles. Dew-points of 70 degrees up to I-40, even in the eastern Texas panhandle? The HRRR is ominous looking and even if there is some convective contamination, you won’t need much recovery/instability to see numerous intense supercells. The instability advertised on the High Plains given the expected wind profiles is extreme and could very well lead to 4”+ hail reports.
  7. It's still early to call boom or bust. The linear mode (especially up north) advertised on some models might be right. Remember in 2017 when a few of the high shear/high CAPE setups in May across Oklahoma failed to meet expectations? Just because there's substantial instability with strong wind shear does not equal a supercell tornado outbreak. That 5/18/17 tornado-driven high risk busted hard, especially when CAMs were in good agreement about messy storm modes. There was a moderate risk later in the month that was very junky from eastern Oklahoma into the Ozarks. With that said, this event has a higher ceiling than most we've seen over the past 4-5 years across the Southern Plains. Aside from storm mode, I'd also be concerned about a mass of convection moving from the panhandles into Oklahoma during the morning. This is advertised on the GFS/Euro/RGEM and to a lesser extent, then 3km NAM. I have the most confidence in the dryline lighting up with a potentially significant tornado threat. The instability progs ahead of the dryline are pretty ridiculous, on the order of 3,000-4,000+ J/kg MLCAPE by peak heating and that's across relatively high terrain, in the Lubbock-Midland-Fort Stockton zone. Speed shear is substantial and directional shear is good with plenty of veering with height. There is a southwesterly component to the upper level winds and although the angles with respect to the dryline probably won't be 90 degrees, it will still get things done with S to SE near-surface winds. The biggest question mark is up north, in my view, from the panhandles/northwest Texas into western/central Oklahoma. That's where the parameter space is maxed out, but where there could also be convective overturning earlier in the day. Another scenario is a reinforced boundary being left somewhere between the Texas panhandle and the Red River Valley from morning convection, but it's early to speculate where that might setup, if such a boundary does get laid down.
  8. Let's look at the 00z sounding from DDC, a lucky RAOB very close to where a tornadic supercell formed just a short time later. Note the enlarged low-level hodograph. The vast majority of the SRH was contained in the lowest 0-1km. Even though wind fields look unidirectional above 700mb, it's really all about the lower level wind fields. 32 knots of 0-1km shear and >300 m2/s2 0-1km SRH and I'm sure that only increased leading up to the cyclic supercell. Of course, there was large buoyancy, relatively steep lapse rates and more than adequate deep layer shear as well. A faint convective signal along the dryline in the models can end up going big one way or the other (blue sky bust vs. intense supercell). In this case, there was more than ample large scale forcing and substantial height falls impinging on western Kansas was enough. I will admit that I wasn't overly focused on this event since I was not chasing, but I would have favored the southern target (Southwest Texas) due to the questions regarding convective initiation.
  9. To recap the next several days with some recent model data... Today: Severe storms are likely across the central High Plains, eastward across the central Plains this evening. A few other isolated storms can't be ruled out to the south, particularly over Southwest Texas. Tomorrow: Severe storms seem probable in at least two regimes. The first will be with an MCS that could rejuvenate later in the day from Northeast Texas into the Arkansas/Missouri vicinity, or evolve into a broken line of storms. The second area will be in the wake of the MCS, assuming there is adequate recovery, from Oklahoma into parts of Kansas. This is still somewhat conditional, but odds appear to be increasing a bit for at least isolated storm development near/just west of I-35. Sunday: Looks like a relatively quiet day as storm threats largely shift east of this sub-forum. For anyone out chasing, it may be a good day to relax and get ready for the coming week... Monday: Not quite sure what to make of this day, just yet, as confidence is somewhat low. There does remain at least the potential for a significant event, particularly across the Southern Plains vicinity. Even if isolated storms aren't dominant, there should be some severe weather. Tuesday: The severe threat will likely shift northeast toward the lower to mid-Missouri Valley. Wednesday into next weekend: The synoptic pattern should remain favorable for steady bouts of severe thunderstorm activity around the central U.S. General ridging across the Southeast is modeled with favorable upper level flow continuing to eject from the Four Corners region, eastward across the Plains. It's not clear if there will be a higher-end severe threat, but at the very least, multiple severe storm days are likely, possibly with no single day that goes quietly. The operational 00z Euro shows another seasonably strong surface low ejecting from Colorado into the central Plains around late-week, but that could change. It still looks like an at or above average stretch of severe thunderstorm activity across the Plains vicinity through the next 7-10 days.
  10. The 12z model suite is trending toward less convective overturning across Oklahoma tomorrow morning, allowing for the atmosphere to at least partially recover by peak heating Saturday. A consensus of model solutions bring a sub-1000mb low into northwestern Oklahoma between 21z SAT to 00z SUN. Ahead of a sharpening dryline, the SREF/NAM/HRRR all show mid to upper 60s dew-points recovering in central Oklahoma with dews around 70F in south-central Oklahoma by 00z. Models also show less veering of the low-level jet, suggesting that wind profiles will remain favorable for supercells, assuming that early day convection is not overly abundant, in order to disrupt the kinematic fields. If there is a silver lining in a relative lack of convection overnight (NW Texas/western Oklahoma), it is that it could bode well for a more robust severe threat across the risk area tomorrow.
  11. I would always advise caution with getting too specific about convective evolution, especially beyond days 2-3. Regardless, the synoptic pattern looks, at a minimum, favorable for at or above average tornado activity across the Plains through the next 7-10 days. Will there be a high risk, outbreak, or photogenic tornadoes? Who knows. That will come down to mesoscale details and other things that will usually not be clear until much closer to a specific day. If you wanted a favorable pattern for mid to late May tornadoes across the Plains, that's what most ensembles and medium range models are pointing at. Here is a look at the latest CPC day 6-10 hemispheric pattern with analogs, as well as the GEFS day 8-12 mean 500mb height anomaly forecast: Not only does the GEFS show this, but the Euro weeklies and EPS are in fair agreement as well. This pattern, one with troughing across the West and ridging over the East, will support severe thunderstorm activity, possibly significant, across the Plains. The model agreement for this weekend is very good for the big picture and there is reasonable agreement that the general pattern persists through much of next week. Of course, that doesn't mean that every event will perform on the higher end of the spectrum and it doesn't mean that mesoscale details can't put a damper on what appears to be a potentially significant event. It also does not mean that every single day between May 17-25 is going to be a day with a lot of tornadoes. I will say that if you look at the top 5 extended periods (5 days or longer) with well above average tornado counts in the Plains since 2003, you will see that the signal is there. The CPC analog data is also popping 5/23/08, which was near the beginning of the historic stretch in 2008. One thing you want to see is negative height anomalies across eastern Canada, otherwise there is reason to believe that the pattern will break down, allowing for eastern U.S. ridging to move offshore. For the record, here are the top 5 (2000s) stretches for Plains tornadoes in mid/late May that I identified: May 22-29, 2008 – 23 tornadoes/day May 18-25, 2010 – 17 tornadoes/day May 23-28, 2015 – 16 tornadoes/day May 16-30, 2004 – 14 tornadoes/day May 21-30, 2016 – 12 tornadoes/day The climatological average is approximately five tornadoes per day across the Plains in mid to late May. Read more.
  12. As has been discussed in the medium/long range threat, there is a strong signal for a synoptic weather pattern that will be favorable for severe weather across the central United States over the next week or two. Based on (multi model/ensemble progs) the positioning of western U.S. troughing, presence of ridging across the southeastern U.S., favorable upper level wind profiles and poleward moisture transport, the period beginning on May 17th and lasting for potentially 7-10 days or more, will likely feature at or above average severe thunderstorm activity around the Plains and adjacent portions of the central states. I'll leave more specific discussion of individual days to the replies, but the first in a series of embedded shortwave troughs should impinge on the High Plains vicinity by Friday. This trough is forecast to rotate around the base of a broader trough through this weekend, before reloading. Another trough, potentially more significant, is then progged to approach the High Plains early next week. Ensemble guidance, including the GEFS, Euro ensemble and Euro weeklies suggest that the overall pattern will continue to more or less repeat itself through much of next week (May 19-25). It is unclear how long the pattern may continue, but the weeklies suggest that the pattern may turn more zonal (at least as reflected in the mean upper level pattern) toward the final 3-5 days of May. Another consideration in the pattern is the signal for blocking across eastern Canada. This feature is what can help keep the pattern "blocked" up, meaning that ridging remains in place over the Southeast, while general troughing continues across the western half of the CONUS. If there were less downstream blocking, one might expect the pattern to be short-lived, but this is what makes this upcoming period potentially long. The model data also shows seasonably strong upper level winds streaming east across the Pacific into the West, which is another signal that makes this upcoming pattern intriguing. I'll reply back in a bit with some comparisons of this upcoming pattern to previous historical stretches with above average tornado activity in the Plains in mid/late May.
  13. Quincy

    Severe storms and flash flooding for May 7-13

    Tomorrow is a good example of why it's usually not a good idea to be cautious about getting too specific with tornado threats more than a day or two out. Especially when convection the morning of is going to, potentially, play a major role in late-day redevelopment of storms. There are exceptions to this rule, when the large scale signal is very clear, but this is not one of those cases. It was clear by yesterday than an MCS was going to alter tomorrow's "threat" around peak heating and the signal was there as early as Sunday within some of the models.
  14. Quincy

    April 29-May 1 Severe Weather

    Some footage of a tornado I witnessed in Clay County, TX this afternoon, about four miles northwest of Petrolia: Prior to this tornado, there was a narrow stovepipe tornado just north of Dean, TX. The tornadic supercell cycled and either briefly produced two tornadoes at the same time (not completely conclusive) or at the very least two tornadoes, overall. The second was the more dominant one, which bounced up and down for roughly 15-20 minutes,
  15. Quincy

    April 13th-14th Severe Threat

    SRH was more impressive (than forecast for tomorrow) over a large chunk of Louisiana on 4/2/17. That being said, each outbreak is different.