WRAL WeatherCenter Blog

As a child I remember "Bermuda Highs" being a domninant feature of summer weather here. Are these weather features normally associated with extremely dry periods? How have these weather periods in the past related to this one with regard to drought?

Posted September 5, 2007

MIKE MOSS SAYS:     Joseph,     The Bermuda high is the westward extension of a large semi-permanent high pressure ridge over the north Atlantic ocean, and usually is centered between 25 and 35 degrees north. It plays several significant roles in modulating weather conditions over NC, and in steering many of our tropical disturbances as well. The Bermuda High itself is not a reason for drought per se, but is one component in larger scale trends that play a part in how much rainfall we receive compared to "normal." A typical summertime pattern features the axis of the Bermuda high positioned a little to our south and east, where we end up with a broad southwest flow that leaves us hot (but not extremely so) and humid, with a chance of isolated to scattered showers and thunderstorms on many afternoons. The hit and miss nature of these storms tends to average out over time, usually with a remnant or two from tropical systems that produce more widespread coverage making up to some extent  for otherwise dry stretches through the warm season.


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  • UNCalumnus Sep 10, 2007

    Thanks to both of you. I have begun to become curious about weather, and I have no formal training in the topic. These forums are very interesting.

    Take Care both of you..

  • donndeboer Sep 9, 2007

    Thanks for the clarification Mike.

  • Mike Moss Sep 9, 2007

    Thought I'd chime in a little about the ridges that have led to some of the extreme temperatures and dryness. While there ca be kind of a fuzzy boundary at times, and one ridge can merge into or bridge into another, our hottest temperatures this summer usually were associated with a separate ridge building in from the nations' interior to our west, with that risge often separated from the classic Bermuda High by a weak trough near the east coast or over the western Atlantic. However, there are occasions when the Bermuda High can extend westward, with the axis a little south of us, and that can also lead to above normal temperatures, though usually not quite as extreme as the continental ridges building our way from the southern plains. As an aside, we may be setting up for a pattern change that could bring a trough to our west and leave us cooler and more prone to showers through the latter half of this week and into the weekend. Here's hoping, anyway!

  • donndeboer Sep 9, 2007

    According to my Idiots Guide to Weather, the bermuda high is an area of diverging air that causes air to sink. Also called the horse lattitudes these areas of sinking air warm up and dry out.Many of the worlds deserts are found at this lattitude (approximately 30 degrees north or south lattitude). A westward shift of this phenomenon would explain our desert-like conditions. I hope this doesn't become the norm every summer.

  • UNCalumnus Sep 8, 2007

    Thank you. From the term that seems to be a "crossroads" for weather features from different regions to meet. Bermuda High as I am aware, can be quite large high pressure zones that dominate summer weather here in North Carolina. I must admit I love summer weather. I only wish it wasn't so dry this year.

  • SaveEnergyMan Sep 8, 2007

    Inter tropical convergence zone, I believe.

  • UNCalumnus Sep 8, 2007

    Pardon my ignorance, but what is the I.T.C.Z.?

  • donndeboer Sep 7, 2007

    Is the ridge of high pressure that has been sitting over the region most of the summer a westward extension of the bermuda high? Is the bermuda high a counterpart of the I.T.C.Z.?