While folk history would have us believe that lightning never strikes twice in the same place, National Weather Service forecasters are saying just the opposite is true when it comes to an infrequent climate development in the Pacific Ocean, one that can cause an exceptionally wet spring for parts of the Southwest this year.
Andrew Church is a meteorologist for the National Weather Service in Albuquerque and was one of the primary weather scientists to develop a spring precipitation outlook for the Southwest this year. In the process, the forecaster made a discovery, namely, Pacific waters near the equator are warming up, a trend that could bring substantial rain to New Mexico and other areas in the Southwest throughout the spring season.
Looking back through the annals of weather history, Church discovered that the same type of weather anomaly has occurred before, including during the spring seasons of 1941, 1987, 1988, 1994, and 2003, and in each case steady rain was realized in parts of the Southwest.
Church says there is a historical precedent between warmer sea temperatures in the equatorial Pacific and the amount of spring rain that falls in the Southwest, especially in northern and central New Mexico.
For the latest on southwest agriculture, please check out Southwest Farm Press Daily and receive the latest news right to your inbox.
"When we look at previous years with similar sea surface temperatures in the Pacific Ocean, places in New Mexico have done well compared to their average for March, April and May," Church said.
He says the development of a weak El Niño makes this spring season outlook slightly more straightforward than usual. Extraordinarily, since 1900, a Sea Surface Temperature Anomaly (SSTA) scenario ̶̶ like the one that has formed this year ̶̶ is highly infrequent. In the vast majority of instances, when the Pacific Decadal Oscillation (PDO) was very warm as it is currently (March 2015), the equatorial Eastern Pacific was typically rather warm and in at least a moderate El Niño state.
Current water temperatures off the coast of Mexico and Central Mexico this month are exceptionally warm, setting up what Church and other forecasters call a favorable climate for development of low pressure systems that will pump moisture across the Baja and into the Southwest through much of the spring.
"Unless conditions in the equatorial Pacific change rapidly, which is not expected, we are likely looking at rarely chartered territory for March, April and May [in the Southwest]," Church said in his spring forecast, and that means rain throughout much of March, April and May.
Forecasters say more evidence of a possible wet spring this year include spring snowfall during other analog years ̶ those years that demonstrated similar higher temperature readings in the equatorial Pacific that resulted in increased precipitation in the Southwest. Since the beginning of March, forecasters say increased snow levels have been reported across parts of the Rocky Mountains, including northern and central New Mexico ranges.
Church concludes that all the evidence points to an active El Niño in March, April and May that will likely extend wet winter conditions into the warmer spring season, especially in New Mexico and other parts of the Southwest as far south as the lower Gulf Coast. If that happens, Church said a wet monsoon season could follow across New Mexico in late summer this year as well.
The official NOAA Climate Prediction Center's spring meteorological outlook is calling for above average precipitation across virtually all of New Mexico, most of Colorado and the Texas Panhandle, the southern plains, and most of West and South Texas. Conditions favorable to the development of a series of rain events stretching through spring will be driven by increased convection in the eastern tropical Pacific Ocean which is expected to result in the breakdown of the upper level ridge along the west coast, allowing upper level Pacific troughs of low pressure to move eastward through the southwest United States.
Wet weather conditions across much of the Southwest last fall and into the winter season so far have provided some relief from the multiyear drought that has plagued the region. Soil and sub-soil moisture profiles have improved greatly in eastern and southern regions of Texas and slight improvements have been noted in parts of south central New Mexico.
But crop analysts say while there is generally adequate ground moisture to get a spring crop started, additional rains will be required as temperatures heat up for the summer. Steady spring showers, therefore, would help prepare farmers in the event of a dry summer season.