Terry’s Take: Bermuda High means summer sizzle

Posted on: 10:27 pm, July 4, 2013, by

Terry Swails Weather Blog

About this time every year, the Bermuda high begins to flex its muscles leading to periods of hazy, hot and humid weather. The annual occurrence of this steamy pattern is a sure sign that summer has kicked into high gear.

The big high pressure forms over the Atlantic Ocean during the longest days of the year. Located southeast of the Mid-Atlantic Coast near Bermuda, the high’s summertime position is a key factor in just how uncomfortable our weather gets and how much the air conditioner runs.

THE BERMUDA HIGH

THE BERMUDA HIGH

The Bermuda high typically forms over the Atlantic from late-spring and lasts until early fall. It’s the clockwise (heat pumping) circulation around the high that brings hot, moisture filled air to the Midwest during summers peak. It can often lead to many days or even weeks of hot and sticky weather that lead to the dog days of July and August.

Not only does it heat up summer-time temperatures over the central and eastern U.S., the Bermuda High also affects the intensity of tropical storms and hurricanes. The sinking motion caused by this high pressure causes the air to become drier and warmer. This drier and warmer air can suppress cloud formation off the water, and the sun is better able to directly heat the ocean surface. This can allow water temperatures to increase, and warmer sea surface temperatures can be major breeding grounds for strengthening and aiding the formation of hurricanes.

Due to the clockwise direction of flow it causes, African easterly waves are often forced away from the coast of West Africa towards North America and the Caribbean. Depending on where the high lies each summer, the exact location of the high pressure system can be a major factor in determining the direction hurricanes will go.

THE BERMUDA HIGH NAVIGATES HURRICANES

THE BERMUDA HIGH NAVIGATES HURRICANES

Now that you know the basics, it appears the Bermuda will strengthen and expand westward this weekend sending a burst of warm moist air in our direction. As early as Sunday we should see temperatures nearing 90 with dew points closing in on 70. Precipitable moisture is projected to exceed 2″ indicating any thunderstorms that form have the potential to be big rain makers.

HOTTER, STORMIER PATTERN BY NEXT WEEK

HOTTER, STORMIER PATTERN BY NEXT WEEK

What is yet to be derived is the exact location of the thunderstorm firing zone. At some point we will be in it but for how long will determine the extent of our next round of heavy rain and potential severe weather. It looks like the window should open Sunday night and could stay open into Thursday. You can thank the Berumda high for that!