Interesting Bore Features in Lake Superior Stratus

July 10th, 2017 |

GOES-16 Visible (0.64 µm) Imagery [click to play animated gif]

GOES-16 Visible (0.64 µm) Imagery [click to play animated gif]

GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing

High Dewpoints in mid-Summer in the Upper Midwest often leads to stratus and fog over Lake Superior. Such was the case on 10 July 2017, with dewpoints in the 50s and 60s F (GOES-16 Visible images with surface observations) and mid-lake water temperatures as cold as 40º F (buoy reports | MODIS SST values) — and very interesting waves were observed in the stratus deck. They had the appearance of Atmospheric Bores: parallel lines of clouds moving in one direction. It is unusual to have Bores moving in different directions at the same time, however.

One possible explanation for the differing motion of these undular bores could be internal reflection off the rugged northern and southern shorelines of Lake Superior.

The RTMA surface wind analyses at 17 UTC and 19 UTC, below, showed complex flow patterns over the lake — however, the surface wind flow did not always correspond well to the motion of the undular bores.

Terra MODIS Visible (0.65 µm) image, with RTMA surface winds [click to enlarge]

Terra MODIS Visible (0.65 µm) image, with RTMA surface winds [click to enlarge]

Aqua MODIS Visible (0.65 µm) image, with RTMA surface winds [click to enlarge]

Aqua MODIS Visible (0.65 µm) image, with RTMA surface winds [click to enlarge]

(Thanks to TJ Turnage, the SOO in Grand Rapids MI, for alerting us to this mesmerizing event).

3 Responses to “Interesting Bore Features in Lake Superior Stratus”

  1. Paul McKinney says:

    I noticed these in the MODIS today images. Thanks for posting the explanation !

  2. Mike Boschat says:

    Hi:

    I thought these were called gravity waves? I saw them also on a weather site..

    Thansk,,,

  3. Scott Bachmeier says:

    Undular bores are a type of gravity wave. See https://en.wikipedia.org/wiki/Undular_bore

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