• Wed. Dec 6th, 2023
Lows block high weather patterns

High pressure systems usually bring blue skies, sunshine, and light winds—all the most desirable conditions. Its positive connotations make it more favorable than its counterpart, low pressure.

But sometimes strong areas of high pressure can disrupt or block our weather patterns, ultimately bringing about undesirable consequences.


What you need to know

  • A stubborn area of ​​high pressure will block the weather pattern
  • High inhibition is associated with extreme heat and drought conditions
  • However, other areas outside the highlands can experience heavy rainfall and flooding

Although associated with mild and pleasant weather, high pressure systems can have consequences.

As an area of ​​high pressure grows and strengthens, it can become a block, preventing fronts and other weather systems from flowing through the area it dominates.

A graphic showing an example of blocking a high setting. (NOAA)

As with other blocking patterns, this can lead to disastrous results.

Most commonly, these stubborn areas of high pressure create what is called a heat dome, bringing dangerous heat and extreme dryness to the areas that live beneath it.

A heat dome brought triple-digit temperatures to the state of Texas in the summer of 2023. In the photo above, a woman fanned herself to cool off during a June 17 Houston Astros game. (AP Photo/David J. Phillips)

However, sometimes, high blocking can prevent a low pressure system from moving around. As a result, a low-lying area is trapped in an area for a long time, causing heavy rains and floods.

Prevents highs and storms

In August 2017, Hurricane Harvey made landfall near Port Aransas, Texas, as a Category 4 hurricane. Despite its weakness on land, a large and prominent area of ​​high pressure centered to the north and west is strong enough to stop Harvey in its tracks—literally.

Satellite image of Harvey moving over the Texas coast in August 2017. (NOAA)

Had it stalled further inland, Harvey would likely have been out. However, the storm stopped at a suitable location close to the coast.

Because of this, it can be fueled by the warm waters of the Gulf of Mexico, bringing days of heavy rain across a good portion of East Texas.

Rescue boats wade through flooded streets to rescue Harvey victims in Houston on August 28, 2017. (AP Photo/David J. Phillips)

The city of Houston, which saw nearly a year’s worth of rain in a matter of days, was ravaged by massive flooding for days. The flooding caused $125 billion in damage, making it the second costliest hurricane in the US, and claimed more than 100 lives.

High pressure to the northwest reduced its intensity, allowing Harvey to move away from the area.

Our team of meteorologists delve into the science of weather and break down timely weather data and information. For more weather and climate stories, check out our Weather Blogs section.

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