HOUSTON – Hurricane forecasts over the last few decades have improved significantly, but did you know fair weather often determines where we see the worst storms? Let’s dive in.
High pressure systems rotate clockwise in the Northern Hemisphere (where we live) and they create sinking air. This air is compressed, which heats it up! This is why often in the summertime we have a large “summer high” that keeps us hot, hot, hot.
Not only does the sinking air keep us hot, but it keeps us dry. We need rising air to create storms. For this reason, high pressure systems could be considered “blockers” from thunderstorms. This is why we can see low pressure systems and storms form along the outside of the high.
These highs can be large, synoptic scale features that can influence the weather pattern across thousands of miles. Often the high-pressure systems surrounding a hurricane determine where it will move, and if it can move. Let’s talk about two different scenarios with highs and tropical systems in Houston.
Highs can push storms away from Houston:
The tropical system we are currently tracking in the Bay of Campeche is being influenced by a strong high-pressure system in the Southeast United States. You’ve likely heard about this high-pressure system, as the east coast is seeing record heat because of it! Here in Houston, it’s steering our storm due west into Mexico.
Highs caused Hurricane Harvey to stall:
There were several highs that influenced Harvey. Highs act as a blocking system, and lows tend to travel in the path of least resistance. During Harvey there were several highs that blocked the hurricane from moving, which is why we saw a multi-day flood event.