Brett Roberts
EF5
As someone who started chasing in 2006, this season (thus far) has been an eye-opener for me. In the nine seasons I chased prior to this, the total number of days I saw totally ruined by early/morning convection probably doesn't match the number I've seen this year just in April and May. Overnight MCSs and early initiation are both issues that, from experience chasing 2006-2014, I previously regarded as factors likely to modulate the location and upside of a chase day, but unlikely to decimate it the way we've seen many times this year (most prominently 5/7-5/9).
The dominance and orientation of the subtropical jet seems to be the largest culprit for this year's perpetual failure mode, perhaps augmented by relatively wet conditions in the typical EML source region upstream. Can any longtime chasers recall a year remotely similar to this, where numerous good troughs resulted in only marginal chase days that likely would've been high-end in the absence of early convection and widespread warm sector storms? The most similar year I've witnessed personally was 2007, pattern-wise, but it wasn't really even close to this. It was a wet year with lots of MCSs throughout the spring, but on most of the big days (e.g., 28 March, 21 April, 23 April, 4 May), the convective evolution was still prototypical of the Plains: the dryline was clear of convection by noon at the latest, instability built, and storms exploded by 4-6pm (without continuous, widespread warm sector convection initiating all day from lunchtime on).
I'm wondering if other years featuring relatively strong El Ninos during the spring, such as 1983, 1992, and 1998, might have had similar issues. Interestingly, though, it appears this is the first year since at least 1950 where ENSO 3.4 is >=1.0°C in May and on the rise, rather than subsiding after a cold season peak. Combined with the record +PDO, there are certain aspects of the background climate forcings that make this year very unique. Unfortunately, the results of this regime don't seem very conducive to quality chase setups (but do seem conducive to a large quantity of "needle-in-the-haystack" tornado days).
The dominance and orientation of the subtropical jet seems to be the largest culprit for this year's perpetual failure mode, perhaps augmented by relatively wet conditions in the typical EML source region upstream. Can any longtime chasers recall a year remotely similar to this, where numerous good troughs resulted in only marginal chase days that likely would've been high-end in the absence of early convection and widespread warm sector storms? The most similar year I've witnessed personally was 2007, pattern-wise, but it wasn't really even close to this. It was a wet year with lots of MCSs throughout the spring, but on most of the big days (e.g., 28 March, 21 April, 23 April, 4 May), the convective evolution was still prototypical of the Plains: the dryline was clear of convection by noon at the latest, instability built, and storms exploded by 4-6pm (without continuous, widespread warm sector convection initiating all day from lunchtime on).
I'm wondering if other years featuring relatively strong El Ninos during the spring, such as 1983, 1992, and 1998, might have had similar issues. Interestingly, though, it appears this is the first year since at least 1950 where ENSO 3.4 is >=1.0°C in May and on the rise, rather than subsiding after a cold season peak. Combined with the record +PDO, there are certain aspects of the background climate forcings that make this year very unique. Unfortunately, the results of this regime don't seem very conducive to quality chase setups (but do seem conducive to a large quantity of "needle-in-the-haystack" tornado days).