Dry, windy gusts increase wildfire risk in Texas
Thursday, January 11, 2018, 14:22 - Extreme southern Texas is a popular place for snowbirds to soak up the sun and dip their feet in the Gulf of Mexico or enjoy a cook out with friends and family. This Thursday you will have to be on guard though, when firing up the grill or campfire. Red Flag warnings are in place for the state due to very dry conditions. Relative Humidity is very low, especially in the South Texas. More on the wildfire weather below and the video that lead this article.
WHAT IS RELATIVE HUMIDITY?
We measure the amount of moisture in the atmosphere by the relative humidity. Relative humidity (RH) is the ratio of the partial pressure of water vapor to the equilibrium vapor pressure of water at a given temperature. RH is temperature dependent, it will fluctuate with how warm or cold our air is. In the morning the RH tends to be higher than later in the day. It requires less water vapor to attain high relative humidity at low temperatures; more water vapor is required to attain high relative humidity in warm or hot air.
Warmer air can hold more moisture. When the RH gets to levels lower than 30% in Texas, the National Weather Service (NWS) will issue a Red Flag Warning to inform area firefighting and land management agencies that conditions are ideal for wildland fire combustion, and rapid spread. Red flag warnings are issued differently in each state and is based on a based on the local vegetation type, topography, and how far the area is from a major water source.
THE FORECAST: Wildfire weather
Firstly, you can thank southerly flow off the Gulf to warm southern Texas up to the 80's for most of the day. A cold front will pass Thursday into Friday and that will increase the winds. We could see wind gusts up to 40-45 mph across the south.
In addition to strong winds, a line of severe showers and thunderstorms can be expected through the afternoon for the ArkLaTex region. Residents are advised to go indoors, when thunder roars.
With RH dropping to 15-25% behind the front and high winds expected, the danger of rapidly spreading fires will be enhanced. Any fires that develop will likely spread rapidly. Outdoor burning is not recommended.
The front will drop temperatures on Friday and Saturday back down to seasonal and even below seasonal. More on the temperature story, below.
Photo: Creative Commons/U.S. Air Force