Rio Grande Valley/Deep South Texas Spring Weather potential for 2011: La Nina, other considerations raising confidence for drought, wild fire growth

Weather and drought conditions as of the end of February and early March, 2011.	Potential weather evolution for Deep South Texas, March and April, 2011. Winds will continue to be frequently strong; warm to hot temperatures will develop ahead of each less frequent front in the Mid and Upper Valley, most likely in late February and March. The track of low pressure systems will be well north of the area, and much faster, than during the 2009/2010 late winter/early spring period.
Spring 2011 Outlook for Deep S. Texas/Rio Grande Valley: Dry, Warm, Windy: Drought, Wildfire Danger to Worsen
Main Points Moderate La Niña continues (below), but is weakening. Historical trends strongly suggest continued low to very low area wide rains through March, persistent winds, and less frequent but more intense drying fronts. Click here for charts showing rainfall differences between La Niña and average. More than a dozen drying fronts between October and early January, followed by a significant February Freeze left grasses and brush highly cured... ...though some greenup began toward the end of February in Cameron through Kenedy County, where mid January heavy rainfall and late February warmth and humidity helped soften soils. The threat for explosive wildfire growth is expected to continue through at least March. April and May may feature more of the same pattern as heat builds. Uncertainty remains as La Niña trends toward neutral and primary storm tracks shift farther north... ...which may allow easterly waves of tropical moisture to bring much welcomed rainfall late in the period. Until then, the March and April storm track may be quite familiar, similar to that in 2009. Statistical Correction of the Climate Forecast System Forecast for the Niño 3.4 Sea Surface Temperature Anomalies in the eastern equatorial Pacific. Six consecutive months of values above +0.4 signify El Niño; six consecutive months of values below -0.4 signify La Niña.	Preparing/Decision Making While predicting specific weather events such as cold fronts, severe weather outbreaks, rain, and windstorms more than a week or two out is beyond the scope of sound science, the high confidence for a continued rain–starved Rio Grande Valley and Deep South Texas through March and much of April requires persons tasked with agricultural and rangeland responsibilities to maintain high awareness for wildfire growth and drought dangers. It is always a good time to revisit plans to move people and equipment efficiently to wildland or urban/wildland interface fires. Growers and ranchers should ready for irrigation efficiency and water conservation that will become reality this spring. As always, continue to monitor information on our website, including the RGV Drought Page through the remainder of spring 2011 including future "Droughtlooks", rangeland fire danger statements, Fire Weather Watches and Warnings, and Wind Advisories or Warnings. Weather Decision Support is part of our mission, and we’re here to help, 24 hours a day, 365 days a year. Box and whisker chart of February through April precipitation distribution for climate division 63, Deep South Texas, El Niño, Neutral, and La Niña. Lines at either end of each ’whisker’ represent the 10th and 90th percentile; the box represents the 33rd through 67th percentile, with the red line the 50% level. For full details, click here for much more.
What About Flooding? Given the circumstances described above, there is a *below average* probability of significant spring flooding across the Rio Grande Valley, including tributaries and reservoirs feeding the Lower Rio Grande. For current river stage information, check out our Advanced Hydrological Prediction Service site. Specific details on Falcon International Reservoir can be found here. Though area wide spring rain totals are expected to be low, there remains the possibility for localized torrential rainfall and flooding during individual events such as slow moving thunderstorms or repeated rains from upper level disturbances. Stay flood safe year–round by frequenting our flood safety webpage.
Current three month temperature outlook for the U.S. "Valid NDJ" means November through January. "Valid DJF" means December through February, etc.	Current three month precipitation outlook for the U.S. "Valid NDJ" means November through January. "Valid DJF" means December through February, etc.

National Weather Service Weather Forecast Office