Ephemeral Theresa

September 25th, 2021 |
Suomi-NPP Day Night Band Visible (0.7 µm) and M15 (10.8 µm) imagery, 0618 UTC on 25 September 2021 (Click to enlarge)

Theresa was a short-lived subtropical storm in the Atlantic Ocean north of Bermuda late on the 24th and early on the 25th of September. When Suomi NPP overflew the storm early on the 25th (imagery from this source), the low-level circulation was devoid of any significant convection; convection was displaced to the northeast of the storm. The toggle below of True-color imagery from CSPP Geosphere shows the storm structures at 1800 UTC on the 24th and 25th. Convection was nearly wrapped around the subtropical storm on the 24th; it was mostly absent near the storm center on the 25th.

CSPP Geosphere True Color Imagery at 1800 UTC on 24 and 25 September 2021 (Click to enlarge)

Note in the Day Night Band imagery at top that a dark region exists within the moonglint at around 29 N Latitude. Such features, discussed in this blog before (here and here, for example), suggest very light winds; an HY-2C overpass at 0330 UTC on 25 September, shown below (from this site; click here to see a similar image with wind flags), shows very light winds over/around 30 N.

HY-2C Scatterometry at 0330 UTC on 25 September 2021 (Click to enlarge)

Comments are closed.