AUSTIN (KXAN) — With extreme to exceptional soil drought conditions in place across nearly all of Central Texas, we take a closer look at what heavy rain in the forecast this week could do for our drought.
The current dry period has been most intense since March 1. We analyze Austin and Llano, two communities in our viewing area that are both in the worst drought category and have long climate records of 100 years or more from which to draw better perspective.
Over the last 180 days since roughly that date, Camp Mabry has recorded 8.70″ of rain — just 51% of normal rainfall. During the same period, Llano has tallied a meager 6.40″ of rain — only 43% of its normal rainfall. Most of Central Texas is missing 7-11″ of rain we should have received since March.
The U.S. Drought Monitor drought levels are constructed not purely upon rainfall deficits but also take into account extra soil moisture lost due to extreme heat. The hottest summer on record to date in our area has been the equivalent of erasing 1-2″ of rainfall we have received since March, meaning Austin’s “adjusted” rainfall since March 1 is closer to just 7″, and Llano’s is less than 5″.
This places both Llano and Austin in the second percentile for rainfall received since March 1 — sufficient to place both areas in the most intense “exceptional” drought classification.
Entering Wetter Period
Periods of heavy rain are in the forecast beginning Monday afternoon and lasting through midday Tuesday. A Flood Watch is in effect during this period for the potential of dangerous flash flooding. Additional periods of rain are possible through the work week, potentially totaling the heaviest, most widespread rainfall we have recorded in more than six months.
But will this be enough to erase drought conditions?
If both Llano and Austin end up completely missing out on this week’s rainfall or receiving 0.50″ or less, both areas will remain in top tier “exceptional” drought conditions.
But assuming the forecast of 2-3″ of rain in both locations, that could bring Camp Mabry’s rainfall total between March 1 and Aug. 26 to 11.20″, and Llano’s rain total from March 1 to Aug. 26 to 8.90″.
Even after adjusting these rain totals downward 1-2″ to account for this summer’s extreme heat and soil moisture loss, that would move both locations from second-percentile rainfall to 10th-percentile rainfall, potentially leading to a two-category improvement across our drought map. This could be a significant improvement and also dramatically reduce wildfire risk.
Below is a preview of what the Drought Monitor map could look like next week, assuming this week’s widespread heavy rainfall plays out as predicted.
The idea of drought improvement not only this week but through the late summer and early fall season is reinforced by the NOAA Climate Prediction Center below, which predicts widespread improvement in drought conditions in Central Texas through Nov. 30.
Stay with the KXAN First Warning Weather team all week as the threat of heavy rain may lead to flash flooding. Download the First Warning Weather app to stay ahead of the storms.
This article was written with statistical analysis assistance from the Texas State Climatologist Dr. John Nielsen-Gammon (Texas A&M University). Drought projection maps herein are a forecast only and are not considered official.