Weather Blog: What does an “inverse summer pattern” mean?

Cloudy skies in St. Petersburg Wednesday morning. (Patricia Price via our Spectrum Bay News 9 app)

ST. PETERSBURG, Fla. – If you’ve looked in the past few days, you may have heard us use the phrase ‘Inverted Summer Pattern’ this week to describe our pattern.

Well what does that mean?

It specifically refers to the timing of our daily showers and storms. In a “normal” pattern we usually have an eastern component for our wind. Often both as the surface and up.

This is usually due to the location of a persistent high pressure area in the summer. Typically, this covers much of the Atlantic Ocean and is located in a position to the northeast allowing an east or southeast wind to be the predominant wind flow. Under that pattern, here on the west coast of Florida, we start the day with sunshine. As things heat up, the sea breeze forms and moves just a few miles inland. With the normal east or southeast wind and deep humidity in place, the scattered showers begin on the east coast of the state in the morning and then move west to our area. Those showers are intensified by the late afternoon in our area after we warm up and the sea breeze front provides additional lift into the atmosphere.

What is happening this week?

The high pressure has shifted south and a trough in the higher atmosphere is above the eastern United States. This sets us up with a fairly well-established west or southwest wind pattern. The result is therefore opposite to the ‘normal’ pattern.

With the westerly wind we get showers in the Gulf in the morning to go ashore. Then they steadily march through the state and are fortified on the east coast with the sea breeze off the east coast. Sometimes the East Coast sea breeze front can move far inland enough that we can get more intense storms in Polk County with this pattern.

In this case, the top pattern has been blocked this week so that the top level feature that keeps us in the west wind pattern is stuck. We will not return to a normal east wind pattern until things can continue. At this point, it looks like it won’t happen until early next week. So enjoy the morning showers and your outdoor beach plans look good every day, for now, on the beach and on the water.

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