Extended Forecast Update

It looks like tornado season will likely be ramping up with what appears to be a very active stretch coming together for next week. Details are still a little sketchy, but for south central Kansas Tuesday has some tornado potential and then the Friday/Saturday window may pose another tornado threat. I plan on posting a map tonight with more details so check back if you’re interested. 

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Update

Sorry I didn’t update last night. I found out I was doing some stuff on storm chasing for KWCH morning show today yesterday afternoon so I had to get all my equipment setup last night and didn’t have time to make a post. I’m still doing the morning show stuff right now so I won’t get a chance to check data and update for a couple hours still. The OFB in the Texas panhandle is still looking like the play for tornadoes today. I think I’m going to pull the trigger and head down there as soon as I get done with KWCH around 9am. I’ll get a target posted on my way down there, but I’m targeting the triple point/OFB and that should be over the east Texas panhandle by later this afternoon. 

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Wednesday May 10th Forecast

I haven’t had much time to forecast tonight. I worked late, took Duck for a run in the park and then worked out, so I’m just now getting a chance to look at data. I skipped over tomorrow’s setup because I’m not going to New Mexico for a lower end tornado threat and went straight into Wednesday’s forecast, which I might chase. I’m going to get straight to the heart of it and talk tornado potential. I don’t have the time to run through the surface pattern and all the basic details tonight or get a map made. I will try to get a map up tomorrow night though.

My thinking with Wednesday’s potential hasn’t changed a whole lot since my last post. Morning precipitation and how the surface pattern will setup through the day has been jumping around a bit from model to model, so it’s still tough to pin down the exact location of the greatest tornado threat on Wednesday. Current thinking is that the best tornado potential is going to be along an outflow boundary leftover from morning storms tracking through the Texas panhandle. Where this OFB may end up being has changed a fair amount over the last few days, so details are still a bit sketchy. However the models have been consistent with storms tracking through that area in the morning with an OFB intersecting the dryline somewhere over the western plains. With the 00Z NAM it looks like the OFB/dryline intersection will set up Wednesday afternoon. With ambient low level shear ahead of the dryline being fairly weak, if there is an OFB that would be an obvious choice for better tornado potential (where low level shear may be more supportive of tornadic supercells). This is supported by 1km SRH solutions from the NAM, with low level shear being strongest in the vicinity of the OFB triple point around 00Z. With storm motions somewhat normal to the boundary, you’d expect storms to be at least semi discrete coming off the dryline. It’s a little iffier with any triple point storm. I’m never quite sure what to expect with convective evolution in that type of situation. It may be one discrete supercell or you may get a couple cells with it getting a little sloppy as the day unfolds. For this reason and also because hodographs are forecast to enlarge significantly in the 00-03Z timeframe, I’m a little worried about timing with any OFB storms. I think it would be good if they held off until later in the afternoon. Overall parameters are pretty good for supercells with moderate instability and deep layer shear around 60kts in the Texas panhandle. With fairly weak low level shear until perhaps right before dark when it ramps up, I think the tornado potential is towards the lower end of the spectrum, but the potential seems a little higher with an OFB potentially helping and the fact that it’s now May and these types of setups tend to start coming together this time of year. I’m having a hard time talking myself out of chasing this one. It’s been slow this season and I’d be super pissed if I missed out on a good tornadic storm, so I’m definitely leaning towards chasing. I was hoping the better tornado potential would be in SW Kansas, but it’s not looking like that will be the case right now. At this point I’m hunting elephants, so I’ll absolutely pass on lower end tornado potential closer to home for where I think the best tornado potential will be. I thin the east central Texas panhandle looks best right now, so at least for the moment, that’s where I’m planning on going.

I’ll try to update tomorrow night with a map. I’m curious whether or not SPC will go with an enhanced risk on the day 2. If they don’t do it on the first day 2, I’d be willing to be that’s what they’ll take it to with the second day 2 outlook. That’s all for tonight, but check back tomorrow for an update if you’re interested.

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Extended Forecast

050617 Extended ForecastWell, it’s been a while since I posted. I usually try to start posting to my blog by March, but it’s been a slow tornado season for the plains so far and I’ve been real busy so here we are into May and I’m just getting my first post of the season up. I’ve chased a handful of times already this year. Most of them were just opportunities to test out some new equipment, but I’ve gotten on a couple tornado warned storms so it hasn’t been totally worthless. It is starting to look like we may be transitioning into an active weather pattern next week though so it’s time to dust off the blog and starting posting regularly again.

We are currently in what’s known as an Omega block pattern, which is where a somewhat stationary high pressure resides over the central US with west and east coast troughs. Upper air charts in this pattern look like the greek letter Omega, hence the term omega block. We will begin to transition out of this pattern early next week as the west coast trough transitions to a cutoff low that will slowly meander into the plains around Tuesday/Wednesday of next week. The gulf has been scoured of quality moisture by the east coast trough, but by tomorrow morning favorable trajectories will start to advect better quality moisture back into the western gulf. This moisture advection will continue through the first half of the week, with dewpoints in the 60’s expected back in the central plains by Tuesday, which is the first day of interest.

Right now I think moisture quality is a big question mark for Tuesday as the closed low first starts to nose into the western plains. The GFS tends to be a little fast with moving troughs into the plains, so between that and the fact that there won’t be much time for good quality moisture to tighten up again the dryline. Given those concerns, for now we’ll skip over Tuesday, but it is something to keep an eye on and there may be some potential for severe storms over the west central plains.

By Wednesday good quality moisture is expected along a tightening dryline. Mid level winds are forecast to veer a bit more as the closed low starts to transition to more of an open wave style trough. Right now the threat area looks to be located along a dryline that will run from a surface low near SE Colorado down towards the far SW corner of Oklahoma. This setup doesn’t look like anything major, but there may be a lower end tornado threat. My main concerns at this point with regards to tornado potential is directional shear. With closed lows, the low pressure tends to get stacked through the atmosphere and you get little turning with height/poor directional shear due to mid/upper winds backing. The mid/upper level winds should be tending to veer more as the closed low moves into the plains and transitions to more of an open wave as it phases back into the polar front jet over the eastern part of the country, but directional shear still doesn’t look real good Wednesday with only modest turning in the 0-6km layer. I’ll get into a little more detail in the coming days, but I think we are only looking at a lower end tornado threat Wednesday. It kind of seems like a big deal though given the slow stretch we’re coming out of.

By Thursday it looks like we could have high quality moisture back into the plains ahead of a dryline running north-south across central Kansas/Oklahoma, but the closed low will be tying back in with the east coast trough/polar front jet and it is forecast to take on a positive tilt as it does. This will veer low level winds and be detrimental to any tornado potential on Thursday. It’s still a long ways out so I don’t think it’s worth discussing mesoscale details too much. It is worth mentioning that slight differences in timing or the tilt of the trough can easily take the tornado potential up for Thursday and the models have not been at all reliable with details this far out, so Thursday is definitely worth keeping an eye on for chase potential. It’s just not the type of setup you’d expect a big tornado day out of though.

After Thursday we’ll get a bit of a break in the plains as the closed low/trough pushes off to the east and high pressure takes over the plains again. The pattern is forecasting to change pretty quickly though as southwest flow could return to the plains as early as Tuesday May 16th. Long ways out still, but the models have been showing a higher amplitude west coast trough taking shape and ejecting into the plains the second half of the week. Climatology would back that up, given the fact that we are coming into the historical peak of tornado season in the plains during the second half of May, so I’m optimistic.

Well that’s it for today. I’ll be keeping a close eye on the models and updating regularly so check back if you’re interested.

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Interview on El Reno Tornado

bbc-interview

I was lucky enough to get another TV deal for storm chasing. The show should air on BBC next year and is part of a series on extreme weather. I won’t know for a while how much of my interview and storm chasing video will appear in the show, but I think I’ll get a decent amount of time in it. I said a few things that I may end up catching some flack over lol. We’ll see. I’m not sure they’ll use the portion of the interview I’m talking about, but I have a feeling they will. Whenever the show airs I’ll try to make a post on it in case you’re interested in watching.

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Update 

sitting in Kingman watching towers trying to get going to my SW along the dryline. The boundary intersection is easily visible on radar and satellite and is approaching Sterling, KS. I can’t bring myself to shoot north to it though. At least not as long as this area of convergence along the dryline SW of Kingman looks like it may put a storm off. So I sit here and wait. 

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10/04 Tornado Forecast

100416-forecast-map

The fall tornado season looks like it very well may kick off tomorrow as a strong negatively tilted trough ejects into the plains. A surface trough draped north south through the plains will start to transition into more of a cold front overtaking a dryline in type surface pattern in the central plains surface pattern through the day. The map above shows the rough locations of the initiating boundaries in the central plains at 21Z.

Moisture return looks to be a little bit of a question mark. I haven’t forecasted much so I don’t have much room to talk here, but my guess is the NAM is overdoing dewpoints a tad. 00Z sounds at OKC and DFW show moisture depth is decent, but dewpoints are still in the upper 50’s with 60’s confined to south Texas. The NAM shows moisture return really ramping up with mid 60’s nosing into the target area by tomorrow afternoon though. With a strong low level jet I don’t doubt the NAM too much on moisture return, but like I said I think it’s probably juicing it a couple degrees. My only other slight concern for tomorrow is morning convection clearing out. The NAM and latest runs of the HRRR have it clearing out, at least over south central Kansas so I’m not too concerned. Even if it did geek things up a bit it would likely be further north so I’d adjust south if I needed to.

Minor concerns listed above aside, moderate instability should develop through the afternoon over north central Oklahoma and Kansas ahead of the surface trough. With a 50kt mid level jet nosing into south central Kansas during the afternoon, deep layer shear will be favorable for supercells. A very strong low level jet (40-60kts over the threat area) out of the south will create good length and curvature in low level hodographs and a tornado threat could become a possibility with any discrete or tail end storms tomorrow afternoon from central Kansas to central Oklahoma. If we get the mid 60 dewpoints with moderate instability, I don’t think a strong tornado would be out of the question given the respectable hodographs from central Kansas to northern Oklahoma. I’d just go 5% on the tornado probabilities in the initial Day 1 outlook if I were SPC, but if the NAM looks on track and the HRRR is showing several discrete cells from central Kansas into northern Oklahoma, then I’d probably up the tornado probs in a later day 1 outlook. For what it’s worth the NAM and 4km NAM have been pretty consistent with the precip pattern being more linear convection over northern Kansas with a transition to more of a tail end to the line in central Kansas and more discrete storms from there south into central Oklahoma ahead of the dryline (coverage gets sketchy in Oklahoma). That makes perfect sense to me given the surface boundaries and how similar patterns in the past have played out.

As far as targeting goes, I’m thinking I want to play the area where the cold front is starting to overtake the dryline. A lot of times that boundary intersection puts off the best tornadic storm with cold front/dryline setups (El Reno was a cold front/dryline triple point storm). It looks like that will be in central/south central Kansas (see my map). I think tornadoes are possible anywhere I boxed in on the map, but I’d put the greatest tornado threat over south central Kansas where storm mode tends to more discrete. This is where the best overlap over the mid and low level jet is, this is the area where you should transition from more strongly forced linear convection north to more discrete storms, this is the portion of the target area where sustained convection is more of a certainty. It’s also in the nose of the better quality moisture. Sooo, everything is pointing me towards a south central into central Kansas target. I may adjust that as surface boundary locations become more clear and we get short range CAM guidance. For now though I’m thinking Kingman is a good starting point. I marked my rough target with a star on the map.

As far as the extent of the severe threat goes, I think we could see some big hail, especially with the storms over south central Kansas and northern Oklahoma that tend to be more discrete and could be persistent supercells through the afternoon. I think there is a lower end tornado threat anywhere from north central Kansas into central Oklahoma, with the area most likely to see a few tornadoes being south central into central Kansas. I do think we’ll get some tornadoes tomorrow, just a matter of where. I don’t think this is a real good tornado setup, but with decent parameters across the board we may be able to eek out a strong tornado. I got the car loaded tonight so I’m ready to go. I plan on heading out a little after noon tomorrow and I’ll update again sometime before I leave. Sorry for the long rambling forecast btw lol. I literally just sat down and winged this one so I know it’s not my best work.

 

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Today

Well I pretty much botched today’s chase. Once I got on the road and did some forecasting my plan was to take 160 down into far southeast Colorado and setup by Springfield until I saw how CU fields looked along with a few other things before moving in close to where storms were going to fire. I knew I was cutting it a little close leaving at 8:15 this morning too, since storms were going to fire as early as 1pm. Still I think I had it timed right until I made one crucial mistake. I stopped in Dodge City and debated taking the northern route up through Lamar rather than sticking to my plan, committing south and going down 160 on a more direct course to my target. I have a bad habit of hedging my bets rather than fully committing to my target and a lot of times it costs you since your reaction time to getting on a storm is slower when you play the middle like that. I was a little too late getting down to 160 as a result and missed the tornado by Trinidad, Colorado. I don’t feel too bad, but it always sucks missing a tornado. I have a work meeting at lunch tomorrow I need to be at, so I’m playing the Kansas/Oklahoma target. The NAM spikes composite indices over north central Oklahoma. It seems to want to lay down an OFB right there from overnight/morning precip which serves as a focus for convection later in the day. Take that with a grain of salt btw. I just glanced at model data. Problem with this scenario as I see it, the NAM does not seem to have a good handle on how precip is evolving up to this point. Precip seems to be farther south than the NAM and 4km have it. So it’s still a little tricky trying to figure out any exact targets or the extent of any tornado threat until we can get some idea of how precip will impact the surface pattern. That probably won’t be real clear until morning. I’ll try to get a post up in the morning from work if I can. I do plan on chasing tomorrow. High quality moisture should reside over at least parts of the plains tomorrow and with seasonably good wind fields, the odds seem favorable for a few tornado reports. Soooo, I”ll be out there.

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Today

Heading west to chase in Colorado (and possibly into western Kansas) this afternoon. It’s a lower end tornado threat, but today and tomorrow look like they will probably be the last chance for tornadoes in the central plains this spring so I’m in. Flying solo today so I won’t post a whole lot, but I will try to get a brief forecast post up after I’ve looked at data. Right now my plan is to head towards the moisture tongue wrapping into Colorado. I like that area and then along I70 farther north as targets today. I think we could get a couple tornadic supercells and the tornado threat looks about the same regardless of which target you go with. It looks to be a fairly early show with storms firing between 1-3 across eastern Colorado. I’m still somewhat undecided on my exact target, but I’m thinking I’ll probably play the southern half of the threat area today and setup along the moisture tongue wrapping into Colorado. I’ll figure it out over the next few hours and update with a quick forecast post and target when I do. Good luck if you’re out today.

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Tornado Forecast Update

I’ve been watching the models the last few days, but haven’t spent a lot of time on it so take this for what it’s worth. Saturday looks to have a lower end tornado threat up in Montana. I’ve been debating going, but there are a few things making me think it’s not worth the brutal drive. I want to keep this short, but I’ll give a quick run down of the setup. A surface low initially over northeast Wyoming will migrate north through the day and will be located in southeastern Montana by 00Z. Moisture wrapping around the north side of the surface low will probably be the area most favorable for tornadoes. I’d probably target near Miles City, Montana or just off east of there. The models have been fairly consistent with precip developing between 21 and 00Z near and north of the surface low, so I do think we’ll get some storms, but the amount of CIN the models have been showing concerns me a bit. I’m also bothered by the extremely narrow corridor of decent moisture/instability along the warm front/moisture wrap around that storms may have to work with. CIN will likely increase fairly quickly as you move north of the warm front and make it difficult to keep storms surface based/tornadic. If supercells are established they can maintain themselves a little better/longer as they track into more stable surface air, but I’m not sure that’s going to be the case Saturday. At least not sure enough to feel confident when you’re staring at a 14.5 hour drive lol. With meridional mid level flow storm motions will have a strong northerly component and move towards the less favorable thermodynamic environment north of the warm front. At the same time though hodographs will be quite impressive, with solid low and deep layer shear. It’s a tough call for me. The narrow swath of favorable thermodynamics along the warm front, northerly storm motions and CIN all make me think I’m better off sitting this one out, especially since it looks like there will probably be other northern plains opportunities coming up in June. If you are going to go that far north you really want to get two chase days out of the deal too and it isn’t looking like that would be the case if I chase Saturday. In order for me to go that far north (looking at about 14.5 hours to Miles City), I really need to buy into the idea that there’s going to be strong tornadoes or there needs to be a multi-day event. Sooo, I’ll make the final call tomorrow, but I think I’m sitting this one out and going out downtown Saturday instead. Watching fireworks at Riverfest from a bar Saturday night sounds a lot better than 40 hours in the car lol. I’ll decide by noon tomorrow because I need to hit the road by about 5pm if I’m going. I’m charging the cameras just in case, but I’m 75% sure I’m not chasing.

Beyond Saturday attention turns to Tuesday in Kansas and Nebraska as a weak trough moves through the central plains. There is a fair amount of spread from run to run still with the GFS regarding some of the finer scale details, so I’ll hold off for tonight on getting into that setup much. A dryline will likely be the focus for convection. Directional shear will likely be better farther north closer to the surface low, with poor 850-500 crossover farther south, but decent turning in the lowest 1km is making me think we may be able to eek out a few tornadoes along the dryline in the central plains. The few hodographs I pulled showed a bit of a veer, back, veer profile so that’s something to keep an eye on. It wasn’t horrible, but it was there. Upper level SR winds are pretty weak too. Still with good curvature and decent length in the lower portion of the hodograph and good thermodynamics we may be able to get it done. I’ll take a closer look at model data and update again in the next day or two with more details.

And in the really long range forecast it looks like the jet stream will stay north and we may continue to get a few high plainest/Canada setups through the middle of the month and troughs crest the death ridge. Still too far out to get into any specific days or threat levels though.

I’ll try to get another forecast update posted tomorrow. If I don’t get one up then I’ll definitely get a post up Saturday though so check back then if you’re interested.

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