How will storm season be distributed this year?

[George Tincher]

Will it be spread out well over April, May and June. Or will it mostly come in a two week window again as it has the last 2 years?

The 2003 year will be remembered for the first 2 weeks or so of May, as that was just nuts. And 2004 wasn't too different, only this time the last two weeks of May seemed to be when things went crazy. Of course there was June 24, 2003 and April 20, 2004. So there were a couple of big days outside these "2 week windows".

The year 2002 wasn't a great chase year, as the two biggest outbreaks came outside the Alley (Apr 28 and Nov 10). Other than May 5 and May 7, I don't remember much spectacular about that season in the Plains. I'll take the wild two weeks thing over that sort of situation again.

If things really come in 3's as you often hear, will we once again see things go nuts two weeks this Spring, only to see sporadic action otherwise? Or will the outbreak days be better distributed throughout the season this time?

I know, there's really no way to answer this. Just trying to generate something interesting to discuss storm related. The GFS is depressing me!

-George

 

[Jeff Snyder]

I think that we're going to see a more evenly-distributed tornado season this year, with a more active April than has been the case in the years past, and probably not a May assault as we have also had the past couple of years. What do I think this? First off, the southwestern U.S. has been in drought conditions for a while. When the soil is very dry, it tends to heat up very quickly (more insolation goes to sensible heating, rather than latent heating). Given the topography of the Plains, southwesterly flow aloft is, climatologically-speaking, the favored flow pattern for classic outbreaks in the Plains. This means that the elevated mixed layer / EML, which frequently provides us with steep lapse rates and a cap, has been relatively warm the past few years. Now, I think this has kept big April events from playing out, since we've either had cap-bust situations (much was the case in 2002) or 'bowling-ball lows' that produce widespread convection or squall line. So, when May comes around, there's enough of a cap to keep the busted chases to the minimum, while discouraging squall line development.

This year, however, there has been quite a bit of precipitation in the southwestern U.S.. I think that the EML will be a little cooler than in years past, yielding a better environment for supercells earlier in the season resulting from a climatologically-strong shear/flow and a breakable cap. That said, I think we'll see more squall line activity across the plains assuming a weaker cap. Therefore, I think we'll see a more climatologically-favored distribution, but I think we also won't see this May bombardment that we've seen the past couple of years.

Now, it's not entirely correct to relate capping strength to storm mode, as there are MANY other factors that affect storm mode (degree and "shape" of forcing, orientation of deeplayer shear vector to forcing boundary, etc), so this analysis will likely not prove entirely true. Generally speaking, however, I don't see why it wouldn't play out... Then again, I think it all comes down to the upper-air pattern in April and May... Whenever a nice west-coast upper-level trough sets up, gives us nice southwesterly flow aloft and lee troughing across the plains, I think we'll see the supercell activity ramp up, no matter if it is in early April, early May, or early June...

 

[George Tincher]

Interesting observations Jeff. I too think April will be more active this year, for the simple reason it seems to have been fairly calm the past two (at least over the SRN Plains and SERN US. April always seems to be a wildcard. It can be intense or there can be little activity.

 

[Larry J. Kosch]

Normal More or Less

After a record setting season in number of tornadoes last year (how many??), you would think we would have equal or greater numbers this year?? NOT. :cry: I think we would retro-grade back to a normal season or worse yet a slower year than normal.

If you look at the yearly tread of tornadoes in terms of numbers, you will find that there are years where the numbers run low, then there is a spike of higher than usual numbers. That is usually followed by a normal set of numbers. I don't have the stats to prove this theory, perhaps someone can help out here.

It's kinda like shooting dice. How often do you roll a 5 & 6 or a 6 & 6 in consecutive rolls? Once, perhaps twice maybe? Then again after shooting a pair of sixes, the odds are more in favor for a pair of ones (snake eyes!) to come up.

I'm still planning on taking two weeks off in late-May and do some serious storm spotting or chasing. Let the chase begin in May!! 8)

 

[Andrea Griffa]

Originally posted by George Tincher
Will it be spread out well over April, May and June. Or will it mostly come in a two week window again as it has the last 2 years?

The 2003 year will be remembered for the first 2 weeks or so of May, as that was just nuts. And 2004 wasn't too different, only this time the last two weeks of May seemed to be when things went crazy. Of course there was June 24, 2003 and April 20, 2004. So there were a couple of big days outside these \"2 week windows\".

The year 2002 wasn't a great chase year, as the two biggest outbreaks came outside the Alley (Apr 28 and Nov 10). Other than May 5 and May 7, I don't remember much spectacular about that season in the Plains. I'll take the wild two weeks thing over that sort of situation again.

If things really come in 3's as you often hear, will we once again see things go nuts two weeks this Spring, only to see sporadic action otherwise? Or will the outbreak days be better distributed throughout the season this time?

I know, there's really no way to answer this. Just trying to generate something interesting to discuss storm related. The GFS is depressing me!

-George

Cool considerations Jeff. Anyway this year I've seen that Polar Vortex is so much more active than "normal years": I'm speaking about Europe and America. This synoptic situation could favor some more major cold air descents, overall in the month of may that statistically is more affected by cold air descent. All of this could signify a major number of low pressure system. What do you think about?