New Springtime of Old

It has been a busy spring! The hemispheric upper air pattern has set up such that fairly strong synoptic waves have been crossing the western and central U.S. in a way that allows a deep, moist boundary layer to return from the gulf on a fairly regular basis, in turn assisting in the severe weather outbreaks that have erupted between the southern Plains and Mid-South regions. This is quite unlike previous few years, when the upper air wavelength was too short and/or the phase speed too fast and/or the Hudson Bay vortex anchored an eastern PNA (persistent negative anomaly), any of which keeps robust moisture from returning anywhere near here.

What excites me, besides the moisture, is how far west in longitude it has been returning so far. I observed a supercell tapping a marginal, narrow moist sector in the east part of the TX Panhandle in February. In March, on a day I couldn’t chase due to work, we even had a small cluster-outbreak of tornadoes from a couple of supercells in extreme east New Mexico, with a killer tornado near Clovis. That, along with the casualties since, is the unfortunate side of this pattern, the good side being much needed precipitation to areas dessicated by drought.

Last week, on 28 March, a couple of my colleagues joined me for one of the most crazy and memorable storm intercept trips I can imagine, seeing at least six tornadoes from two supercells in one county of the Panhandle. That was only a small part of a major tornado outbreak, the likes of which are seldom seen so far west, so soon in the year.

With other storm intercepts in southeast Nebraska (coinciding with a preplanned trip up thataway) and near Del Rio (coinciding with a preplanned trip down thataway), this has been an unprecedentedly active season for me, for the period prior to April.

Perhaps most importantly, the rain is back in central OK. This hemispheric pattern is good for giving us the sort of synoptic- to shortwave-trough action suitable for period of most welcome rains. Now please note that it will take quite a bit more rain to recover our long-term (two year) deficit, where we’re still behind over 20 inches, but it is encouraging to see moist ground, creeks flowing and pond levels risen almost full. Even Lake Thunderbird (large reservoir with a small watershed) has come up a couple feet, but it still is much closer to the record low than to normal pool elevation.

The synoptic pattern temporarily has transitioned to an eastern trough, bringing us a nasty cold snap that threatens to break low temperature records and freeze off all the newly minted tree leaves. At my place, we’ll lose a lot of flowering plants and perhaps even a couple of fruit tree saplings, if they can’t regrow their leaves.

But longer term progs indicate more high amplitude waves crossing the western CONUS, the first of which may “only” bring us rain later next week, thanks to recycling of cold boundary layer air from the ongoing regime. Or it may bring some severe storms, especially south of here in TX. We shall see. ITMT this is a most welcome large scale pattern shift from the past few years, and reminds me of what springtime in the southern Plains should be like. I’m encouraged for the remainder of the early-middle spring.



Comments

2 Responses to “New Springtime of Old”

  1. Kent on April 9th, 2007 3:50 pm

    With gloabl warming getting press time now, how has it affected the number of tornados we are seeing in Texas? We’ve not seen an F5 since Jarrell and it seems like we’re getting fewer tornados statewide, as well as fewer strong ones. Is there a study being done on this with info available to the public to read?

    Kent Leverett

  2. tornado on April 9th, 2007 10:09 pm

    It’s way too soon to know — many decades, if not hundreds of years. The problems are that our tornado records are too short and unreliable, and the scale of global climate change and tornadoes are too far apart. I did a BLOG entry on this at Earth and Sky. See this link:

    http://www.earthsky.org/blog/50991/tornadoes-and-global-climate-change

    You’ll have to paste it into your browser since my BLOG comment section doesn’t accept HTML links (to thwart spammers).

    ===== Roger =====

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