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Agriculture Weather Forecast - La Nina Its Impact - Weather Forecast

published: August 23rd 2010
by: Weather Wise by Brain Bledsoe

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Hey folks, hope everyone is having a good Summer.  Where does it go?  It seems like Summer is over before it even starts.  I used to say that Summer was over Fourth of July Weekend.  Now I say it is over Memorial Day Weekend...
 
Anyhow, let's get down to business with our long range projections.  As expected, La Nina has strengthened and will enter the strong category in the next month or so.  Sea Surface Temperatures are a good 3 degrees Celsius below normal, in the central and eastern Pacific Ocean.  See graphic below:
 

Two things of note, during this transition to La Nina.
 
1.  Drought has been kept at bay, by a decent monsoon pattern over the Southwest and adequate moisture in many other parts of the country.  The graphic below shows precipitation trends ranging from the past couple weeks to the past few months.

Like the legend shows, blue and purple wet, yellow and red dry.  Recently, ( the past two weeks ) it has been quite dry and very hot across portions of the Central and Southern Plains.  However, the previous few months have been generous with rain totals to most of the Plains.  Thus, drought hasn’t been a concern.  The same pattern has been shorting some folks in the Southeast quadrant of the US.  It is the last couple of weeks that I am focused on, because I think this will be a building trend for a large part of the Southern Plains.
 
2.  Hurricane and tropical storm activity has been squelched recently.  Tough to say why this has occurred, as all of the classic indicators pointed to a very active storm season.  However, I think it has just been a sleeping giant.  Everything is in place for plenty of tropical storms and hurricanes from late August through October.  That's right, I said October.  I think tropical action may linger a little longer this year, but many of those October storms may stay out to sea or only impact a very small area of the U.S.  Tough call on that one... 
 
Factoring in the above reasons, I am releasing my precipitation forecast for September and for the months of October through December.  Nothing has really changed in my forecast, as the La Nina pattern will be the dominant feature, especially after September.

Per the text on the above graphic, I think much of the above normal moisture over the Southeast will be attributed to an increase in tropical storm activity.  The Texas Gulf Coast is on the western fringe of the contour.  Was a bit unsure what to do with the Texas Coast, but since I think there should be another Gulf storm or two, I think there is a shot for above normal moisture.  Notice the drier than normal conditions building in the Southwest part of the country.  This is right on schedule.  The wetter than normal in the Northern Plains is just a continuation of the active pattern that they have seen.

After we get past September, I think the tropical activity will still be going, but not as influential on the moisture totals for western areas.  Thus, this is traditionally the time when La Nina takes over and flexes its' muscle.  That is why the drier than normal contour for most of the southern US.  The storm track will likely favor the northern tier of the US and that is why the wetter than normal conditions in that region.  Don't get me wrong, there will still be some storms that come through and give us some moisture.  However, they will not be nearly as frequent as last year and likely not as strong.  The main threat for big storms this Fall and early Winter will be confined to the northern part of the country.
 
If you have been following my recent articles, this should come as no surprise to you.  I foresaw the El Nino to La Nina transition about 10 months ago and it has worked out pretty much as I thought.  I see no change in this pattern for the next several months.  La Nina's come on strong and take a long time to go away.
 
As always feel free to drop me a line if you have questions:  bbledsoe@southernlivestock.com