National Weather Service United States Department of Commerce

 

Another Bout of Quick-Spreading Wildfires
3.9 micron infrared satellite image, 530 PM CT, April 30th (click to enlarge)
3.9 micron infrared satellite image, 530 PM CDT April 30th. Note "hot spots" in the box.
Visible satellite image, 530 PM CT, April 30th (click to enlarge)
Visible satellite image, 530 PM CDT April 30th. Note long plumes in thin blue boxes. Encino fire was still growing at time of image.
Despite Moderate Winds and Humidity, Fire Growth Continues April 30, 2008

Two grass and scrub fires, developing at nearly the same time and within about a dozen miles of each other, burned more than 2000 acres of land, mainly in Brooks County, with some acreage burned in extreme eastern Jim Hogg County, during the late afternoon and into the night of April 30th. The rapid spread of the fires would normally have been unusual, given the fairly high humidity in the area (generally between 40 and 50 percent), as well as moderate sustained winds (generally around 20 mph, with gusts to 30 to 35 mph).

However, the continuing extreme to exceptional drought across Deep South Texas and the Lower Rio Grande Valley, combined with both two dry days preceding the fires, along with a low rain total from the event of April 27-28th (below, left), likely contributed to continued below normal one-hour fuel moisture. Another factor that may have contributed to the rapid spread is the dispersion potential (bottom right). The combination of gusty winds through the mixing layer (red box) with a layer of dry air at the same level (yellow box) likely enhanced the potential for rapid growth of the fires, despite the lack of conditions necessary for a Red Flag Warning.

As of this writing, there had been no mandatory evacuations near Encino, where the fire burned an estimated 1900 acres, but some residents did leave their homes while the fire was nearby. Preliminary information from local and state officials on the scene indicated that two residential structures were destroyed (one had no persons living in it), as was one outbuilding, in Encino. Another outbuilding burned down along the Brooks/Jim Hogg County line, where an estimated 697 acres burned.

South Texas rainfall estimate from rainfall and gages, from 7 AM CDT April 27th through 7 AM CDT April 28th (click to enlarge) 7 AM CDT April 30th atmospheric sounding, Brownsville, TX