A Grasp for the Diamond in the Rough: A Challenging Chase Season and Brief Forecast

2012: The year of the EML bust, overmixed moisture, and the model fail.

This chasing season has been a struggle for many - aside from the intense early April outbreaks - and for good reason.  Mother Nature has not been cooperating in the slightest.  From abnormally hot temperatures leading to high dew point spreads to the northerly troughing and, again, abnormal heat leading to excessive EML issues, many potential lifetime chases have turned into nothing more than blue skies or thundershowers.  However, there is cause to have hope.  June always holds promise in the Northern Plains as moisture sneaks its way through the States, and with a more northerly jet this could pan out nicely.  The season is not over until..well..the season is never over, as seen in the past few years' late fall and even winter events.

That being said, since the chase of my career on April 14, my chases have been largely dull and depressing.  Cap busts followed by moisture problems followed by unlucky mesoscale features have kept my storm count on the minimum.  Additionally, models have failed to nail down specifics until hours before the event which causes troubles in the "should I go or not?" department - this has hammered a sizable dent in the bank account.  I am still resilient, though.  Due to my unhealthy obsession, I don't spend money on relatively anything except for living expenses and chasing, so I have the opportunity to keep on chugging on, going out on a limb for most events in hopes of catching that elusive lightning strike of luck.  On top of this, optimism is bubbling throughout the chaser community as we look ahead toward a week or so of active weather pattern.

The fun looks to start on Friday, where yet another high risk-high reward type set up will set stage across most of Kansas and Nebraska/Iowa.  In my opinion, the more favorable target will be the dryline play across west-central Kansas where stronger forcing and less subsidence will reside in comparison to the northerly warm front play.  The ECMWF calls for an outbreak while the GFS culls the tide slightly, but still hints at some optimal chasing parameters.  On the other hand, the NAM is much less optimistic, blasting in scorching 700 mb temperatures, leading to an "atomic" (or the opposite of that?) EML.  However, the NAM and various WRF runs have still broken out a couple storms along the dryline, so even with these models there still is reason to chase.  I'm watching for a couple supercells along the northern sector of the dryline with cyclic tornado potential if they can become well established before the cap crushes them.

The line of sight then shifts to Sunday, where a dynamic event looks to take shape across western and central Kansas.  The SPC has highlighted an area from Nebraska up to Minnesota, but I believe the uni-directional shear will make for a mess of storms and relatively low chasing appeal, so I will focus on the dryline.  Much cooler upper level temperatures will be advected in by the approaching upper level trough, minimizing the risk of a cap bust.  In addition to this, the mid and upper level energy will be impressive to astounding, with southerly to backed winds at the surface leading to rotating storms along the dryline.  CAPE shouldn't be on the extreme side, but there should be enough moisture and resultant instability to get the job done.  We'll leave a more specific, enthusiastic forecast for this day for when the models start to nail down the specifics.  The GFS and ECMWF have both been consistent, albeit in different locations, so that is a major plus.

Let's get this show on the road!  Hopefully the more dedicated, high risk pursuing chasers will be able to sneak out a couple diamonds from the rough this late May and recuperate the optimism they have lost throughout the last month.

And as always, happy chasing!

Ben Toms

April 12-14 Pre-Event Forecast

Hey everyone, it's been a while since my last post!  School and the college life has gotten the best of me for the past few months, but that's all changing now that the chase season is back in action.  I've already been out on two decent non-tornadic chases on March 27/28 to get me back in the flow of things, so I'll have reports on those events shortly.

Starting off with tomorrow, Thursday, I have a strong feeling this will be a significant chasing day for multiple reasons: not only will storm motions be extremely slow for the month of April, but directional shear and instability will overly each other in almost the most the most optimal areas along the dryline.  The helicity lines up with the proper dewpoint spreads so that there isn't massive 0-3km EHI over sky high LCL's.  This is the main problem with the target area down south in the Texas Panhandle into Oklahoma.  Many people have been obsessing over the morning convection feeding over the lifting warm front, but I honestly do not see how big of a problem this will be.  Sure, it is limiting our warm sector to about 100 miles wide, but if storms are moving at 10-15kts or less this won't be an issue - especially if our warm sector is continuously growing throughout the afternoon and evening.

I don't see much of anything wrong with that Skew-T/Hodo.  If that does, in fact, verify, storms will have no problem producing tomorrow afternoon and evening.  The initial target as of the 18z NAM is a Liberal to Dodge City to Scott City triangle.

Friday and Saturday both have definite tornadic supercell potential, although Saturday looks more like the potential significant outbreak.  That's all I'll talk about Saturday until we get within 48 hours, but for now it looks fantastic all the way from the warm front in Nebraska to the dryline intersection with the warm front all the way down into Central Texas.

Friday looked slightly marginal there for a while because of the models spitting out a squall line early in the afternoon (18z) due to capping issues, but that has been somewhat minimized in the recent model runs.  For this day, I'm eyeing a target in SW Oklahoma.  Yes, there will be storms up in Kansas and they should be supercellular, but in my opinion the true tornadic potential lies further down the dryline in Oklahoma.

A little less directional shear, but much better speed shear will help compensate for this.  Shear vectors perpendicular to the dryline should help keep things down south isolated more compared to up north where it could be more of a mess.

I'll be sending in pictures to my Facebook account as the event unfolds, so be sure to add me on there if you haven't already.

Thanks for reading, and look for more forecast posts in the coming days!  Happy chasing!

Ben Toms

Pictures of 2010-2011 Revisited

The 2011 severe weather season was largely a let down in Colorado this year, so many of these pictures are still from 2010.  However, I did add a few favorites of mine from 2011.  I kind of messed these up because of the fact that this was my first season with my new camera, and I accidentally left the on-camera photo editing options on the standard setting.  Ugh, oh well.  They still came out pretty well!

Enjoy.

Ben Toms

11/7/2011 Would-Be Forecast

College and a lack of a car are keeping me from chasing the potentially epic set up tomorrow, but here's a forecast of what I'd be looking at if I had been able to make the venture to the southwest Texas/Oklahoma border.

These are the main three maps I would like to look at for this particular set up.  From what I've seen over the past few events (some a lack thereof), moisture is one of the key factors in fall events.  In the past, we've had a lack of moisture and therefore a lack of instability, but this time we have ample amounts of it.  Dews in the low to mid 60's will lead to CAPE values in the 1000+ range with some areas peaking a tad over 2000 J/Kg around 3 P.M.. Layered on top of this moisture is helicity in the 200-300 range which is also adequate for rotating updrafts and, assuming other ingredients are in place, tornadoes.  I feel that it is appropriate to mention tornadoes in this forecast because of the fact that the shear (both speed and directional), moisture, instability, and LCLs all qualify this possibility.  The SPC even mentions strong tornadoes in their day before afternoon forecast.

I won't go much more in depth than this because I won't be able to chase tomorrow, but basically, in my opinion, we are looking at a fairly potent system that will kick off strong supercells tomorrow around the southwest border of Oklahoma and Texas with some tornadoes possible.  Now, since I can't chase this, I've been focusing my attention on the significant rainfall that will affect my location starting tomorrow afternoon.  According to the NAM, Lawrence is pegged to get 2+ inches of rainfall by Tuesday night with localized amounts reaching 3+.  Although most of the rain will be steady, there is potential for embedded thunderstorms so these numbers are just generic ranges - some places could be well below or well above these numbers.

Most of Kansas has been in a drought for the past few months, so this significant rainfall event will help loosen the grip of that drought along with helping my worst-of-my-lifetime allergies.  Overall, I'm just as excited about the potential of 3+ inches of rainfall in a 24 hour period as I am the prospect of tornadoes in Oklahoma.  Being that I've lived in Colorado my whole life, I've never experienced an event like that so it should be something new and interesting.

Good luck and have fun to anybody chasing the storms tomorrow in Oklahoma and Texas, and to everybody in Kansas...stay dry! (Isn't it nice to finally hear that??)

Until next time,

Ben

Tuscaloosa: Just Unlucky or the Result of Microscale Changes

Video of the infamous Tuscaloosa/Birmingham tornado developing just outside of Tuscaloosa

     As I move into a more serious, vigorous education environment, I am finding myself asking more and more questions relating to my studies - most of which have been pointed towards my study of Atmospheric Sciences.  Throughout the first few weeks of my college experience, my Atmo 101 class had been touching on the more generic concepts of meteorology such as humidity, heat, dew points, and the related concepts.  It amazes me that even such basic of knowledge can spur some of the deepest thought I've ever experienced towards my passion.  Due to this increase in thought, I've started a list of questions that I believe are either very difficult, or even impossible, to answer given our current understanding of tornadogenisis.  Throughout the next few months, and probably even years, I will be exploring many of these topics through observational studies and suggestions.  However, to start with I will merely throw out my first major questions and generic comments on both.

Question 1:  How significant of a factor do localized heat islands and moisture pools (both due to a very localized change in surface material/various other influencing factors) have on tornadogenisis and/or tornado strength?

Comments:  I can come up with multiple instances where I have seen videos of tornadoes either strengthening or dissipating entirely when coming in contact with a new surface environment - the Tuscaloosa/Birmingham tornado being the most extreme.  Yes, it is well known this tornado was on the ground for a significant duration before it impacted the city of Tuscaloosa, but when watching the provided video one can not help but stop and think:  was it simply terrible luck that the tornado developed as it did as it neared the city, or was there some other factor that came into play?  Yet another instance of this, but one I am not as familiar with, is the infamous 1999 Moore F5.  I have watched every video I can find of this event, and my suggestion that various, very localized factors may have had a play in this event, as well.  The tornado was visibly of strong to violent nature before it impacted the Oklahoma City metro area, but there was a marked increase in width and apparent strength as it neared the city.  Obviously, no conclusions can be made with the given information, which is why I have placed this on my list of questions.  I can't help but to imagine that even a subtle difference in dew point/ temperature could have led to these apparent increases in tornado strength.

Question:  How does large to extremely large hail production in a supercell thunderstorm affect tornadogenisis?

Comments:  Unfortunately, I couldn't scrounge up the video I wanted to use to support this question, but I think most knowledgeable chasers and meteorologists will know the days I am referring to.  Before I get into my comments, I would like to suggest that more research needs to be done to understand these events entirely when comparing them to my question.  

     In September 2010, a moderately potent system kicked across Mid/Eastern Kansas and sparked off numerous raging supercells, most of which sported extremely large hail and violent surface based rotation.  However, given the parameters and strength of the storms, the significance of these tornadoes was seemingly under par.  Why?  A suggestion would be that the required energy to keep these hail stones aloft along with the required energy to change the liquid precipitation into ice would pull from the storm's energy needed to produce a tornado.  Assuming it takes an exponential amount of energy to maintain the buoyancy of a given hail stone as it increases with size, the production of a copious amount of extremely large hail would require a significant amount of energy output from the storm.  This is not the only instance of this occurring, but it is the best example to use for the purposes of these comments.  Many more events of similar nature can be observed on a multiple-per-year basis.

     Many significant hail events go without tornado reports, and visa versa; however, that is not to say they can not go together.  This is merely an observation of the generic trend of severe weather events.

These are mere excerpts of the detailed analysis that must go into the answering process of these questions, but that is all it is meant to be - at least for now.  The questions are meant to be food for thought, and hopefully a trigger for the expansion of our knowledge of tornadogenisis at some point in the future. 

Ben

Pre-Day Forecast #2

See my previous post for an actual forecast for tomorrow.

Let it be known: If a morning supercell goes up over NE Colorado, I saw it, and thought of chasing it, but was too lazy to get out of bed at 7 A.M. to get to Sterling in time to see it.  Maybe the WRF, SREF, and NAM are all going crazy on this one, but it looks like a morning supercell in Northeast Colorado is a possibility.  The problem is I don't see any upper level support of any kind to promote this development - so I'm leaning towards this being a fib - but with upslope flow in Colorado anything is possible.

Ben

8/9 Pre-Day Forecast

Tomorrow looks to be a decent day for supercells across the Cheyenne Ridge/Northeast Colorado plains.  Unseasonably strong shear along with moderate instability will overlap to create conditions favorable for severe, rotating storms.  The tornado potential looks low due to the sky high LCLS, but I'll take a few early August supercells no problemo.

The above images display the shear/instability values at around 3 P.M..  I won't nitpick the other ingredients seeing how this is just a "hold off the SDS until September" kind of chase, but everything looks pretty solid for a High Plains supercell.

Generally, I look for LCLs below 1500 for tornadoes across the High Plains (the High Plains give us a little bit of cushion room compared to the adjacent Central Plains), and it's looking like they should be in the 1500-2250 range which means not much tornado potential.  We might have a chance should the storms survive until the 7-9 P.M. time period when things start cooling off and LCLs lower, but that's a bit of a long shot.

Hopefully I'll see some fellow chasers out there before I make my way to Kansas for college!

Ben