Sheared Tropical Storm Peter

September 20th, 2021 |
Suomi NPP Day Night Band visible (0.7 µm) imagery and GOES-16 infrared (10.3 µm) imagery, 0620 UTC on 20 September 2021 (Click to enlarge)

Suomi NPP Day Night imagery, in a toggle above with infrared imagery from GOES-16, (both displayed in RealEarth) depicts a classic sheared Tropical Cyclone structure to the east-northeast of the Caribbean Sea. The low-level circulation (very apparent in the nighttime visible imagery under the illumination of a near-full moon) is displaced to the west of the deep convection near the edge of this Suomi NPP scan. Indeed, the low-level circulation is difficult to discern in the single enhanced infrared image (animation better reveals its structure however). An earlier (0527 UTC) overpass from NOAA-20, below (VIIRS imagery courtesy William Straka, CIMSS), also shows the circulation to the west of the main convection. It would be a challenge to locate correctly the storm center based solely on the VIIRS infrared imagery!

NOAA-20 VIIRS I05 (11.5 µm) and Day Night Band Visible (0.7 µm) imagery at 0527 UTC on 20 September 2021 (Click to enlarge)

The shear that is disrupting TS Peter’s structure is shown below (imagery from the SSEC Tropical website), overlain on top of 1-km visible imagery at 1300 UTC.

GOES-16 Visible (0.64 µm) Imagery, 1300 UTC, along with an analysis of 200-850 mb wind shear (Click to enlarge)

For more information on struggling Tropical Storm Peter, visit the website of the National Hurricane Center.