Wednesday, January 18, 2012

La Nina is Peaking

NASA released today that La Nina appears to be peaking which increases "the odds that the Pacific Northwest will have more stormy weather this winter and spring, while the southwestern and southern United States will be dry."  NASA's satellites Jason-1 and -2 have been monitoring the progress of La Nina.  They recent detected an increase in La Nina conditions in the Pacific, but it is not expected to get any stronger.

The latest image of sea surface heights in the Pacific Ocean from NASA’s Jason-2 satellite shows that the current La Niña is peaking in intensity. Yellows and reds indicate areas where sea surface height is higher than normal (due to warm water), while blues and purples depict areas where sea surface height is lower than normal (due to cool water). Green indicates near-normal conditions. Image credit: NASA/JPL Ocean Surface Topography Team.
"Conditions are ripe for a stormy, wet winter in the Pacific Northwest and a dry, relatively rainless winter in Southern California, the Southwest and the southern tier of the United States," says climatologist Bill Patzert of JPL. "After more than a decade of mostly dry years on the Colorado River watershed and in the American Southwest, and only two normal rain years in the past six years in Southern California, low water supplies are lurking. This La Niña could deepen the drought in the already parched Southwest and could also worsen conditions that have fueled recent deadly wildfires."

This is the second consecutive year that the Jason altimetric satellites have measured lower-than-normal sea surface heights in the equatorial Pacific and unusually high sea surface heights in the western Pacific associated with La Nina.

It is not unusual to see back-to-back La Ninas.  This happened most recently in 1973-74-75, 1998-99-2000, and 2007-08-09.  Such events are often followed by an El Nino which is the opposite of La Nina.

This goes along with forecasts from NOAA's Climate Prediction Center (CPC).  The ensemble of computer forecasts shows a weakening La Nina into the spring with neutral conditions this summer into the fall.

The likely scenario for South Carolina is for the winter to remain mild and dry.  The dry conditions will likely continue into the spring and will worsen the drought.  There may not be much relief until the summer rains commence.  Hopefully with the El Nino/Southern Oscillation (ENSO) in a neutral phase this summer, rainfall may be near normal.  However, conditions could be quite challenging for spring planting.

The seasonal  outlook will be released tomorrow.  Stay tuned!