New weather pattern begins this week

Storm clouds in Central Texas. (Alex Penrose/KXAN)

AUSTIN (KXAN) — Rain chances return to the forecast starting on Wednesday. Storms will be scattered, mainly confined to the afternoon and early evening, and will mostly affect areas east of the Interstate 35 corridor. Sea breezes from the Gulf of Mexico create these conditions, and the sea breezes are the late spring/early summer pattern shift that is beginning to take hold of Central Texas.

Equal energy from the sun heats land and water differently, as land heats more quickly than water. Over land, hot air expands and rises, lowering pressure over the coastal counties and the southeastern fringes of Central Texas. The ocean heats up more slowly, staying more stable, forming high pressure over the water. The flow of high pressure to low pressure creates wind, as the atmosphere constantly tries to equalize itself. In Texas, the high pressure from the Gulf of Mexico creates a deep east southeasterly wind into Central Texas.

This wind is full of moisture, raising the humidity in the area and carrying enough water in the clouds to create locally heavy rainfall, which is usually scattered. This system relies on daytime heating to form, so most rain chances begin hours after the sun has risen and has begun to heat the land, usually in the late afternoon and early evening. According to Paul Yura with the National Weather Service, chances of precipitation each day will be light — around 20-30 percent — mainly for Bastrop, Lee, Caldwell and Fayette counties.

Yura says this pattern can begin as early as March (though this year is an exception), and last until early fall. This does not occur at other times of the year when fronts move through the state. Breezy conditions from frontal passages keep the land/sea breeze connection centered over the coast, in areas like Houston. Winds this week are predicted to be light, 3-7 mph, which creates an open door for sea breezes to reach the I-35 line.

Though most of these showers will remain spotty and light, stronger storms are possible from sea breezes. The threat of hail lessens significantly when they arrive, as most systems are just too warm to ice raindrops over. Wind gusts will be the larger threat, as the scattered storms occasionally collapse on themselves and create microbursts, fast-moving winds upward of 50-60 mph that can spread in all directions from the base of a storm.

Always stay up-to-date on the latest forecast for your area with KXAN First Warning Weather and the KXAN Weather App.

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