Tropical Airmass RGB and the Sea surface temperature from the accumulated products from AVHRR

Subtropical Storm Theta

11 November 09:00 UTC-13 November 2020 09:30 UTC

Tropical Airmass RGB and the Sea surface temperature from the accumulated products from AVHRR
Tropical Airmass RGB and the Sea surface temperature from the accumulated products from AVHRR

Subtropical storm Theta formed in the Atlantic Ocean early morning 10 November 2020.

Last Updated

01 December 2020

Published on

13 November 2020

By Mark Higgins (EUMETSAT)

According to the National Hurricane Center, Theta is the record breaking 29th storm of this North Atlantic hurricane season.

Figure 1 shows the storm at 09:00 UTC on 11 November 2020. In this water vapour image the storm is seen as the rotation in the centre.

Met-11 WV 10 Nov 2020 09UTC
Figure 1: Storm Theta seen from Meteosat-11 at 09:00 UTC on 10 November 2020.

The National Hurricane Centre chart shows the initial storm location (Figure 2).

NOAA National Hurricane Centre forecast chart for Subtropical Storm Theta
Figure 2: NOAA National Hurricane Centre forecast chart for Subtropical Storm Theta.

This storm formed very late in the hurricane season, and quite far north. It formed in an area of cooler sea surface temperatures, as can be seen in Figure 3.

Tropical Airmass RGB and the Sea surface temperature from the accumulated products from AVHRR
Figure 3: Subtropical Storm Theta - the clouds are from the Tropical Airmass RGB and the Sea Surface Temperature from the accumulated products from AVHRR.  

The warmer waters are shown in red/orange (28-29 degrees), the cooler area (yellow) is still warm enough at 25 degrees to supply energy to sustain the storm.

Theta subsequently since travelled north-east and on 13 November was just off the coast of the Azores (Figure 4).

Theta a seen with the AVHRR instrument onboard Metop-C - at 0930 UTC on 13 November 2020
Figure 4: Theta as seen with the AVHRR instrument onboard Metop-C at 09:30 UTC on 13 November 2020.

The season is not yet over (it officially ends on 30 November) - NHC forecasters are monitoring Tropical Depression 31, which is forecast to become a hurricane over the next few days.