When is "dry" a good thing?

Oct 20, 2010 - It's the second week of October, and the local weatherman -- uh, that's me -- is telling viewers that they'll need an umbrella tomorrow.

Now let's face it, for the nation's "wettest" state that would normally not be much of a news bulletin.  But for 2010, and especially over the past several weeks, rain has been in short supply around the state.  A statewide "burn ban" has been issued by the State Fire Marshal, and a good soaking would be more than welcomed.

Rainfall from mid-August through early October was rather "hit or miss" across northern and central Louisiana, with some sites reporting under 1" of rain for the period.  True, August was a "wet" month for much of southern Louisiana, but since early September, rain has been lacking virtually statewide.

We've talked about it before:  when it comes to rainfall, "how much" is sometimes less important than "when" during the growing season.  For example, a review of the weekly U.S. Drought Monitor (www.drought.unl.edu/dm/) indicates that portions of northern and central Louisiana have been suffering through "severe" to "extreme" drought since June.  Now there can be no doubt that farmers in the impacted parishes have been grumbling about the lack of rain, and the impact has been made more notable with the summer of 2010 ranking among the "hottest" summers on record.

We won't know for sure until the production numbers have been compiled, but from what I can tell, the combination of extreme temperatures and below-normal rainfall has been far from crippling.  Sure, the recent lack of rain is leaving pastures in rough shape and hay is behind as well.  But the harvest has been progressing extremely well thanks to the recent dry spell.  Add to that the break in the extreme heat over the past couple of weeks and everyone seems to be in better spirits.

So what's in store for the coming month?

The long-range outlook calls for rainfall to remain below seasonal norms statewide through the remainder of 2010.  Indeed, there is a fairly good chance that drier-than-normal conditions could persist through the spring.  La Niña is back, and 'she' may even intensify a bit over the next month or so, with experts suggesting that 'she' will likely remain a key factor for Gulf Coast weather into April and May.

We've talked about La Niña many times over the years:  as a reminder, La Niña is the term used to define cooler-than-normal sea-surface temperatures (SSTs) over the equatorial Pacific Ocean.  In the winter and spring, La Niñas are associated with shifts in the jet stream flow over the U.S., with weaker fronts and fewer winter Gulf lows impacting the Bayou State.  The bottom line: better than 7-in-10 winter/springs are drier-than-normal for Louisiana when La Niña is in-phase.

La Niña means drier-than-normal winter/springs, but not bone dry.  We still get rain when La Niña is in place, just not as much.  Fact is, we really don't need "normal" rainfall in winter and spring, just as long as we get some rain.  From that perspective, a La Niña during winter and spring is usually a good thing.  Weaker fronts mean fewer outbreaks of severe weather, and more importantly, less rain in the cool months means a reduction in the flood threat -- something like 70% or more of flooding in the Bayou State comes during the winter and spring.

What is becoming critical is the current  state of the environment and the elevated wildfire threat.  Statistics from the LDAF indicate that wildfire numbers and acreage for August and September were above the five-year average, with October on a pace to continue that trend.  Until we can get a string of "wet" fronts through the state, that threat will continue.  In addition, preparation and planting for winter crops are going to be slowed until we get a little rain to moisten the upper soil layers.

But given the recent drought, early indications are that we've "done alright" around the state in terms of ag-production across Louisiana.