High Threat for Erratic Wildfire Behavior through New Year's Day
Burn Bans In Effect; Fireworks Pose a Threat
Counties in burn ban in the Rio Grande Valley as of December 26, 2007

The combination of fast moving frontal systems with limited deep moisture continues to dry out the Rio Grande Valley as we approach the new year. Rainfall during the last 90 days has been unusually low. Brownsville has received 1.90 inches of rain since October 1 and 0.88 inches since November 1, which equals about 30% of normal for both time periods. Harlingen has received 1.44 inches since Oct. 1 and 0.29 inches since Nov. 1, equaling 25% of normal since October and 10% of normal since November 1. McAllen is faring no better, receiving 1.40 inches since October 1 and 0.26 inches since November 1, equaling 30% of normal since Oct. 1 and 12.5% of normal since November 1. McAllen has not received measurable rainfall since November 25th. The image below shows the percentage of normal rainfall for the 60 days ending December 25th. Note the very dry conditions in the circled area.

Percent of Average Rainfall, October 25 through December 25, 2007, for Deep South Texas

Through the start of 2008, a series of cold fronts, each accompanied by brisk northwest winds, will exacerbate the dry conditions even further (above, right). The first front produced wind gusts over 35 mph on the 26th; another on the 28th will likely produce northwest winds gusting to 25 or 30 mph along with humidity below 20 percent in some locations. A lesser front is expected over the weekend, and a stronger system could be on the horizon as we enter 2008.

National precipitation forecast departure from average, week of December 30 2007 to January 3 2008

The outlook for the first 3 months of 2008 (below) does not look any better. January through April is normally the driest period of the year , with March being the driest month of the year. These conditions will likely be amplified due to the ongoing effects of the current moderate La Nina in the equatorial Pacific. La Nina conditions usually lead to much drier and warmer conditions for Deep South Texas. The latest discussion and model data from the Climate Prediction Center notes that this La Nina episode is expected to strengthen further, with peak strength during the February to April time period. The first three months of the year are often the windiest time of the year, with gusty southeast flow interrupted periodically by surges of dry northwest winds with cold fronts and the occasional dry line intrusion.

National precipitation forecast departure from average, January - March, 2008
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