Sea-breeze showers bring daily rain to Austin despite distance from coast

Austin is finding itself caught between three distinct weather systems: with high atmospheric pressure to the east, a trough of low pressure to the northwest, and tropical moisture to the southwest.

Forecast models previously projected that high pressure would strengthen and squash our rain chances by Thursday, but the timing of that has now shifted, thanks to the addition of tropical moisture and the weakening of the high pressure. This change, instead, brings the best rain chances on Thursday, during what is typically an especially dry month.

Remnants of Barry

Remember Tropical Storm Barry, which made landfall in central Mexico earlier this week? Its remnants are currently drifting through South and West Texas, delivering showers and thunderstorms to the Rio Grande region, Edwards Plateau and Hill Country.

At the same time, a high pressure system’s clockwise air flow is drawing in abundant atmospheric moisture from the Gulf of Mexico via southeast winds. All of this has triggered sea-breeze showers and thunderstorms in Austin each afternoon like clockwork.

What are sea-breeze showers?

Sea-breeze showers occur when sufficient moisture or humidity is present, even in Austin, 200 miles from the coast. As the day progresses, the sun heats the land, causing surface air to rise and condense into clouds, leading to rain and thunderstorms.

These storms typically form closer to the coast and, because of the persistent south-to-southeast winds, they travel into Central Texas around the same time every day, which is in the late afternoon or early evening. However, they often fizzle once they get to the Interstate 35 corridor and encounter drier air in the atmosphere. Watching these storms on weather radar can be fascinating, especially when the storm cells appear to be racing against each other to reach Austin first.

Austin’s rain chances

Thanks to the surge of tropical moisture streaming into Texas, precipitable water values are more than 2 inches. This forecasting tool measures the amount of rain that could potentially fall from the sky based on the current moisture in the atmosphere above a certain location. A higher value indicates a greater threat of heavy rainfall, which could cause minor or localized flooding in low-lying areas with poor drainage.

The best opportunity for scattered rain and thunderstorms will occur Thursday afternoon and evening, with a 30-40% chance of rain. Rainfall totals are expected to range from a half-inch to an inch. This would be a welcome development, as July is normally Austin’s second-driest month, averaging just 1.96 inches of rain.

Temperatures will be near seasonal normal levels on Thursday with morning lows in the mid-70s. Afternoon temperatures, though, will be a little cooler with highs in the upper 80s to near 90 degrees.

Independence Day forecast

While it’s unlikely that Mother Nature will spoil fireworks displays this Friday, a few isolated showers and thunderstorms may still linger across Central Texas. The ridge of high atmospheric pressure will strengthen and shift slightly westward, but not enough to eliminate all rain chances.

Lingering tropical moisture will enhance scattered showers and a possible storm over the Rio Grande and the Hill Country. Fortunately, these will be short-lived and unlikely to disrupt outdoor plans. Expect gusty winds, manageable high temperatures in the low 90s, and humidity-driven heat index readings approaching 100 degrees.