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.
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.
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.
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.
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.
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.
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