
GOES-16 “Red” Visible (0.64 µm) images, with GLM Groups plotted in red [click to play animation | MP4]
1-minute
Mesoscale Domain Sector GOES-16
(GOES-East) “Red” Visible (
0.64 µm) images
(above) and “Clean” Infrared Window (
10.3 µm) images
(below) showed the formation of Tropical Storm Iba off the east coast of Brazil at
16 UTC on 24 March 2019 (
surface analyses). Plots of
GLM Groups revealed some intermittent lightning activity. Tropical cyclones in the South Atlantic basin are rare — the last was in 2010, and only one example (
Catarina in March 2004) is known to have reached hurricane intensity.
![GOES-16 "Clean" Infrared Window (10.3 µm) images [click to play animation | MP4]](https://cimss.ssec.wisc.edu/satellite-blog/wp-content/uploads/2019/03/G16_IR_TS_IBA_24MAR2019_2019083_160056_GOES-16_0001PANEL.GIF)
GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play animation | MP4]
A toggle between NOAA-20 VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) from
RealEarth (below) showed Iba at 1610 UTC.
![NOAA-20 VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images at 1610 UTC [click to enlarge]](https://cimss.ssec.wisc.edu/satellite-blog/wp-content/uploads/2019/03/190324_16utc_noaa20_viirs_ttuecolor_infrared_TS_Iba_anim.gif)
NOAA-20 VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images at 1610 UTC [click to enlarge]
GOES-16 Infrared images with an overlay of
deep-layer wind shear valid at 18 UTC from the
CIMSS Tropical Cyclones site
(below) revealed a very tight gradient of shear over Iba. However, the shear gradient began to relax somewhat by
21 UTC.

GOES-16 “Clean” Infrared Window (10.3 µm) images, with an overlay of 18 UTC deep-layer wind shear [click to enlarge]
In a sequence of GOES-16 “Clean” Infrared Window (10.3 µm) and Infrared-Water Vapor (10.3-6.9µm) brightness temperature difference (BTD) images
(below), the clusters of deep convection propagating southward — east of Iba’s center of circulation, denoted by “I” — exhibited large negative BTD values
(darker shades of red) suggestive of significant cloud-top penetration into the lower stratosphere (
reference).

GOES-16 “Clean” Infrared Window (10.3 µm) and Infrared-Water Vapor (10.3-6.9µm) BTD images [click to enlarge]
GOES-16 Visible images with an overlay of 1138 UTC ASCAT surface scatterometer winds from the Metop-A satellite
(below) showed speeds in the 40-49 knot range
(yellow barbs).

GOES-16 “Red” Visible (0.64 µm) images, with Metop-A ASCAT winds at 1137 UTC [click to enlarge]
The
MIMIC Total Precipitable Water product
(below) showed that Iba was embedded within a plume of moisture that extended southeastward off the coast of Brazil.
![MIMIC Total Precipitable Water product [click to play animation]](https://cimss.ssec.wisc.edu/satellite-blog/wp-content/uploads/2019/03/190324_16utc_mimicTPW.png)
MIMIC Total Precipitable Water product [click to play animation]
Sea Surface Temperature values
(below) were around 30ºC in the waters where Iba intensified.
![Sea Surface Temperature analysis at 2230 UTC on 23 March [click to enlarge]](https://cimss.ssec.wisc.edu/satellite-blog/wp-content/uploads/2019/03/190323_2230utc_sst_Iba.png)
Sea Surface Temperature analysis at 2230 UTC on 23 March [click to enlarge]
===== 25 March Update =====

GOES-16 “Red” Visible (0.64 µm) with GLM Groups (left) and “Clean” Infrared Window (10.3 µm, right) images [click to play animation | MP4]
A comparison of GOES-16 Visible and Infrared images
(above) showed that increasing
deep-layer wind shear had exposed the low-level circulation center of Iba. However, GLM Groups plotted on the Visible images revealed an increasing amount of lightning activity associated with a convective burst that began to wrap around the southern edge of the storm center after 15 UTC — and a brief cloud-top infrared brightness temperature of -90ºC
(yellow pixel embedded with darker purple shades) was seen at
1635 UTC.
A timely overpass of the Suomi NPP satellite at 1639 UTC provided 375-meter resolution VIIRS True Color RGB and Infrared Window (11.45 µm) images (below), which showed a large overshooting top that exhibited infrared brightness temperatures of -90ºC and colder (yellow), with a warmer ring of compensating subsidence immediately surrounding it. The coldest pixel had a brightness temperature of -103.7ºC — which is almost 1ºC colder than the -102.96ºC value noted over Australia in 2008.
![Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]](https://cimss.ssec.wisc.edu/satellite-blog/wp-content/uploads/2019/03/190325_16utc_suomiNPP_truecolorinfraredWindow_Iba_anim.gif)
Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]
The explosive growth of that convective burst was very apparent in a toggle between VIIRS Infrared images from NOAA-20 at 1549 UTC and Suomi NPP at 1639 UTC
(below, courtesy of William Straka, CIMSS). Note that the images use a slightly different variant of the color enhancement. A comparison of VIIRS True Color and Infrared images from NOAA-20 and Suomi NPP viewed using RealEarth is available
here.
![VIIRS Infrared (11.45 µm) images from NOAA-20 at 1549 UTC and Suomi NPP at 1639 UTC [click to enlarge]](https://cimss.ssec.wisc.edu/satellite-blog/wp-content/uploads/2019/03/190325_noaa20_suomiNPP_viirs_truecolor_infraredWindow_Iba_v2_anim.gif)
VIIRS Infrared (11.45 µm) images from NOAA-20 at 1549 UTC and Suomi NPP at 1639 UTC [click to enlarge]