5/13/17 Forecast Update

051317 Forecast Map

I really don’t have a whole lot to add to my previous posts. My feelings regarding the setup for Tuesday has stayed right on track with each model run. The NAM picked up on this setup with the 12Z run and shows weaker parameters with the dryline a little farther west. Usually that’s the opposite of what you can expect between the GFS and NAM. The NAM is usually the model that juices things a bit too much and shows stronger parameters relative to the NAM, but that’s not the case this morning. The GFS has been pretty damn consistent though run to run so for now I’m not going to worry about the NAM much. I’m also not going to spend much time forecasting or posting today. I have some things to get done today and I plan on going out tonight so I really don’t have much time for screwing off on the computer. Sunday is my day of rest and forecasting though so I will roll up my sleeves tomorrow morning and take a closer look at things.

Thursday’s setup is starting to become a bit more clear. It is strikingly similar to Tuesday in both location, spatial extent and parameters. It’s hard to tell I have two separate threat areas on the map for Tuesday and Thursday because they basically are on top of each other.

As far as Tuesday goes, the NAM keeps it dry with no precip coming off the dryline. I’m going to call bullshit there though (which is one more reason why I’m disregarding the 12Z NAM run). The GFS continues to initiate storms along the dryline from SW Oklahoma up into central Kansas. The strongest and most consistent signal for precip has been along the KS/OK border, which is where I intend to target at this point. I think there are two distinct targets people are gravitating towards for Tuesday and that is the KS/OK border area and the SW quadrant of Oklahoma. Either one is good. There has been a bit of a veer, back, veer trend with hodographs along the KS/OK border area that doesn’t seem as pronounced over SW Oklahoma, but that wouldn’t be enough to pull me away from Kansas since I want to help KWCH out with coverage. I’ll take a closer look at forecast soundings tomorrow and start to really pick apart those details.

Anyway, I gotta get some shit done so that’s it for today. I still think Tuesday looks like a moderate risk, especially over the two areas I pointed out as potential chase targets for Tuesday. SPC may stick to an enhanced risk for this one though strictly because it looks like storms will be very sparse with possibly only a few discrete supercells. You have to remember they are kind of forecasting for a different purpose and storm coverage, density of reports is a guide for them. I think more along the lines of how strong any given storm may be and I do think there that although this isn’t a real good tornado setup by any means, I do believe that there is strong tornado potential. Check back tomorrow for an update. My plan is to forecast and get a post up tomorrow morning whenever I get up.

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5/11 Extended Forecast

051117 Extended Forecast

It looks like next week will likely be the most active week for severe weather that we’ve had in the plains so far this year. How extensive any tornado threat will be is still a bit hard to judge since finer scale details are a much bigger factor in determining tornado potential, but the large scale pattern is obviously supportive of several rounds of a more general severe weather threat.

The Gulf of Mexico is going to take a beating this weekend as northerly winds on the back side of the east coast trough push dry air south. Low level winds don’t start to become favorable again for better quality moisture advecting back into the plains until Monday as a high amplitude west coast trough begins to nose into the plains.

Monday is the first day of interest, but it’s a lower tier of interest lol. I’m afraid moisture quality is going to be an issue. A dryline will be tightening up over the western edge of the plains, but it doesn’t look like there will be enough time for better quality moisture to move into the plains and pack in along the dryline by Monday evening. This will largely preclude any tornado threat that otherwise would exist. The GFS has been showing some precipitation along the dryline, so it is something to watch, but I would expect any tornado threat on Monday to be lower end. I could be wrong though. Low level shear will be quite strong, so if we can get storms off the dryline and they can work out into better moisture over the warm sector before the boundary layer decouples, then that could possibly open the door to better tornado potential. The primary area of interest for Monday should he ahead of the dryline from central Kansas down into the Texas panhandle, which I’ve highlighted on the map above in yellow.

Tuesday looks to be a bigger day. It’s still a long ways out so you can’t take details too seriously yet (let’s not forget how many times the GFS has burned us this year and prematurely started the hype train #choochoomotherfuckers lol). That being said, the GFS and ECMWF have been consistently depicting this as a fairly strong trough transitioning from a neutral to a negative tilt as it ejects into the plains Tuesday afternoon. That should get your attention when it happens in May. I am concerned about moisture quality a tad. I do not think moisture quality has any real shot of being a deal breaker for Tuesday, but it could be a mitigating factor. With higher end setups like this, the difference between a couple strong tornadoes and a major outbreak can be slightly better moisture quality/very strong instability vs. just moderate instability. Right now it looks like a moderate risk type tornado day. Stronger instability or shear profiles being a little better could easily nudge this up into more of the major tornado outbreak type parameters though. It also looks like this could be a fairly widespread event. The best tornado potential has been focused either side of the Kansas/Oklahoma border area with the GFS, but parameters supportive of tornadoes should exist across a large area ahead of the dryline from North Texas up into Nebraksa. It’s a textbook plains severe weather setup. It looks good enough that I canceled a business trip I was supposed to go on Monday and Tuesday so I could make sure I was here to chase. I don’t miss major tornado days in Kansas and this setup is showing the potential for that at least. Again it’s a long ways out and a lot can change, I’m just saying the potential is there for a moderate to higher end tornado setup. It is still a little far out to get into any real detail, but I’ll just hit on the handful of things that I do think you can put some weight in and are raising red flags for the severe/tornado potential. As I said above, the models have consistently shown a high amplitude trough that is taking on a negative tilt as it ejects into the plains. That’s important. The strength and tilt of the trough along with moisture availability are the biggest things I watch in longer range forecasting. The mid level jet associated with this trough is forecast to have 500mb winds in the 55-60kt range Tuesday. That’s good, but it’s not great. A lot of the major outbreaks this time of year have 70kts at 500mb, so again good, but not great. Dewpoints are forecast to be in the low to mid 60’s, which should get the  job done. It’s not ideal, but low 60’s would get us by for a solid tornado threat. With the trough just taking on a negative tilt we should have stronger wind fields over the warm sector, but still have decent directional shear to work with (when you start to get a more negative tilt you loose the turning of the winds with height). And finally the broader details would imply that neither morning storms working over the warm sector or storm mode should be problems. With a north south dryline and storm motions to the northeast, discrete supercells are very likely to be the favored mode of convection during the evening. Alright, so just to sum things up in my opinion if you take the models literally at this stage 5 days out, it looks like a moderate risk for tornadoes to me (I’m speaking in SPC terms, if you don’t know what that means then you probably don’t need to know). I’m keeping a close eye on this setup so I should update regularly.

After Tuesday, my attention is focused on Thursday, Friday and Saturday as the west coast trough fully moves into the plains. There will be severe weather chances in the plains on Wednesday with SW flow aloft, but I look at it as more of a lull in the action between the two primary troughs moving through the plains. Thursday looks like there could be some good dryline storms across the western plains, with SW Kansas and Texas looking like the best areas. Friday looks like it could be a more widespread severe weather event. I’m a little concerned about shear profiles and how favorable they’ll be for tornadoes since mid/upper winds may begin to back and take on more of a meridional flow look. Another potential issue is precipitation over the warm sector botching things on Friday and Saturday. That always seems to be an issue with multi-day negative tilt troughs like this and a lot of times it tends to push the best tornado potential a little farther south than you may have anticipated to where the southern edge of where earlier storms tracked through and moisture quality with uncontaminated air is better. For that reason I’m thinking the greatest tornado potential for Friday may end up being down in the southern Oklahoma and north Texas area. That’s a total guess at this point btw lol. Anyway, we are looking at tornado potential on any one of those three days from Thursday through Saturday. I’ll start to get into it more as we get closer.

Alright that’s it for tonight. I should pretty much be posting daily now that we actually have something to talk about, so check back for updates if you’re interested.

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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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