Expected general weather trends for Deep South Texas, November 2010 to January 2011 (click to enlarge
Potential weather evolution for Deep South Texas, November 2010 to January 2011. While there will be bouts of chilly weather behind each front, the expectation is breezy, dry, and mild conditions much of the time.
Expected general weather trends for Deep South Texas, February to March 2011 (click to enlarge)
Potential weather evolution for Deep South Texas, February and March 2011. Winds will be very noticeable; warm to hot temperatures will develop ahead of each 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.
Winter Outlook for Deep S. Texas/Rio Grande Valley:
Dry, Warm, Windy: Recipe for Drought and Wild Fire Danger

Early December Update

  • Abnormally Dry conditions cover all of Deep South Texas (December 2nd).
  • Moderate Drought conditions may arrive at any time across the mid and upper RGV north through the Brush Country
  • Two minor freezes have occurred in rural locations of the mid and upper Valley to the Brush Country: November 27th and December 1st.
  • One wildfire grew quickly out of control during the afternoon of December 1st on the Burns Ranch, near the corner of Hidalgo, Starr, and Brooks County (near/along FM 755). The fire grew to between 1800 and 2000 acres before containment.
  • Dry cold fronts – those with little or no rainfall along them and quickly followed by very low humidity, have been common since November. These include: November 2nd, November 18th, November 26th, and November 30th.
  • Current long range forecast data suggest no change to the "Main Points" listed below.

 

Main Points

  • Moderate to Strong La Niña is underway (below).
  • Historical trends strongly suggest low to very low area wide rains through February, persistent winds, and occasional to frequent drying fronts. Click here for charts showing rainfall differences between La Niña and average.
  • Deep soil moisture from persistent rains for the first 9 months of 2010 may help slow the potential for drought and wild fire spread potential as the days shorten...
  • ...but this will be highly dependent on how many drying fronts sweep through between November and early January
  • Most fronts in winter 2009/2010 were "wet" – featuring a day or more of drizzle and chilly temperatures after passage, or developing low pressure along the Lower Texas Gulf coast and heavier rains inland
  • Many fronts this coming winter should be dry, but a few will have some rain on one of both sides of them.

 

Stastical correction of the Climate Forecast System model prediction for the Nino 3.4 Sea Surface Temperature region of the equatorial Pacific (click for more)
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.
Expected general weather trends for the United States, winter 2010/11, based on moderate to strong La Nina (no other considerations included) (click to enlarge)

Main Points (continued)

  • Drying will become pronounced in late winter and early spring. Abundant rangeland and plant growth in 2010 may become tinder or "duff" by the first few months of 2011.
  • Will there be a killing freeze? The two killing freezes in the 1980s (December 1983 and 1989) both occurred in neutral/La Niña leaning situations. The past two similar La Niña winters (1988/89 and 1999/2000) had no widespread killing freezes, but one notable cold snap occurred in early February, 1989. Check back here for more details.

 

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 in a complete turnabout from a verdant Rio Grande Valley to a rain–starved region within the next six months provides persons tasked with agricultural and rangeland responsibilities the opportunity to prepare now for the coming change. Today is a good time to revisit plans to move people and equipment efficiently to wildland or urban/wildland interface fires. Growers and ranchers should plan now for irrigation efficiency and water conservation that may well become reality next February through April or May. As always, continue to monitor information on our website, including the RGV Drought Page through the remainder of Autumn, next Winter, and 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 November through January rainfall for El Nino, Neutral, and La Nina seasons, U.S. climate region 63 (Deep S. Texas) (click to enlarge)
Box and whisker chart of November through January 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.
Most recent three month long lead outlook, temperature departures from average
Current three month temperature outlook for the U.S. "Valid NDJ" means November through January. "Valid DJF" means December through February, etc.
Most recent three month long lead outlook, precipitation departures from average
Current three month precipitation outlook for the U.S. "Valid NDJ" means November through January. "Valid DJF" means December through February, etc.

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