Remnant circulation of Tropical Storm Erika

September 3rd, 2015

GOES-13 Visible (0.63 µm) images [click to play animation]

GOES-13 Visible (0.63 µm) images [click to play animation]

GOES-13 (GOES-East) Visible (0.63 µm) images (above; click to play animation) revealed the low-level circulation of the remnants of Tropical Storm Erika moving off the coast of Georgia early in the day on 03 September 2015 (15 UTC surface analysis). Although there was one brief convective burst over the low-level circulation center (LLCC), it is unclear whether this was initiated by an outflow boundary from the ongoing thunderstorm activity farther offshore or was aided by enhanced boundary layer convergence in the vicinity of the LLCC.

During the preceding nighttime hours, the remnant LLCC could be seen on a Suomi NPP VIIRS Day/Night Band image at 0631 UTC or 2:31 AM local time (below), still inland over southeastern Georgia.

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared (11.45 µm) images [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared (11.45 µm) images [click to enlarge]

The LLCC was also seen on the morning Terra MODIS Visible (0.64 µm) image (below); the coldest MODIS Infrared (11.0 µm) cloud-top IR brightness temperatures associated with the deep convection east of the LLCC were -82º C (violet color enhancement).

Terra MODIS Visible (0.64 µm) and Infrared (11.0 µm) images [click to enlarge]

Terra MODIS Visible (0.64 µm) and Infrared (11.0 µm) images [click to enlarge]

The 10-day motion of the vorticity field associated with Tropical Storm Erika (and its remnants) can be followed using the atmospheric motion vector (AMV) 850 hPa Relative Vorticity product from the CIMSS Tropical Cyclones site (below; click to play animation).

Atmospheric motion vector 850 hPa Relative Vorticity product [click to play animation]

Atmospheric motion vector 850 hPa Relative Vorticity product [click to play animation]

Hourly GOES Animations from August 2015

September 1st, 2015


The YouTube video embedded above shows GOES-13 Water Vapor (6.5 µm) images each hour for all of August 2015. The 10.7 µm Infrared window channel animation is shown below. Both show a remarkable lack of thunderstorm activity in the Caribbean Sea.


Hourly Water Vapor (6.5 µm) imagery from GOES-15 is below. The 10.7 µm Infrared window channel from GOES-15 is beneath it.



The GOES-15 imagery includes the northern fringe of the Intertropical Convergence Zone, and the active Eastern Pacific hurricane season is apparent, including several storms that have threatened the state of Hawai’i. The atypically strong August storm that hit the Pacific Northwest is also seen at the end of the animations.

Hurricane Fred

August 31st, 2015

GOES-13 Visible (0.63 um) and Infrared (10.7 um) images [click to enlarge]

GOES-13 Visible (0.63 um) and Infrared (10.7 um) images [click to enlarge]

Tropical Storm Fred reached hurricane intensity east of the Cape Verde Islands late in the day on 30 August 2015.  As mentioned in the NHC discussion on the following morning, Fred was the first hurricane to pass through the Cape Verde Islands since 1892. While no central eye was apparent on GOES-13 (GOES-East) Visible (0.63 um) and Infrared (10.7 um) images at 0845 UTC (above), a DMSP SSMIS 85 GHz microwave image sourced from the CIMSS Tropical Cyclones site did reveal a small eye at 0904 UTC (below).

DMSP SSMIS 85 GHz microwave image [click to enlarge]

DMSP SSMIS 85 GHz microwave image [click to enlarge]

Later in the day, a few Tropical Overshooting Tops were analyzed using Meteosat-10 Infrared (10.8 um) imagery (below).

Meteosat-10 Infrared (10.8 um) images with overlay of Tropical Overshooting Top product [click to enlarge]

Meteosat-10 Infrared (10.8 um) images with overlay of Tropical Overshooting Top product [click to enlarge]

More information about Hurricane Fred can be found here.

Category 4 Hurricanes Kilo, Ignacio, and Jimena in the Pacific Ocean

August 30th, 2015

Suomi NPP VIIRS true-color image composite [click to enlarge]

Suomi NPP VIIRS true-color image composite [click to enlarge]

A composite of Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images from the SSEC RealEarth site (above; click to enlarge) showed Hurricanes Kilo, Ignacio, and Jimena in the central and eastern North Pacific Ocean on 29 August 2015. All three of these Category 4 North Pacific hurricanes were located east of the International Dateline, which is the first such occurrence since reliable records began in the satellite era.

An animation of GOES-15 (GOES-West) Infrared (10.7 µm) images (below; click image to play animation) showed the evolution of these 3 tropical cyclones during the 29-30 August period.

GOES-15 Infrared (10.7 µm) images [click to play animation]

GOES-15 Infrared (10.7 µm) images [click to play animation]

The MIMIC Total Precipitable Water product (below; click image to play animation) indicated that all 3 storms were easily able to tap abundant moisture from the Intertropical Convergence Zone (ITCZ).

MIMIC TPW product [click to play animation]

MIMIC TPW product [click to play animation]

A longer animation of the MIMIC TPW product covering the period 21 August to 01 September is shown below.

MIMIC Total Precipitable Water product [click to play animation]

MIMIC Total Precipitable Water product [click to play animation]