![\"GOES-16](\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2019\/03\/190324_goes16_visible_glm_TS_Iba_anim.gif\")
<\/a>GOES-16 “Red” Visible (0.64 \u00b5m)<\/em> images, with GLM Groups plotted in red [click to play animation | MP4<\/strong><\/a>]<\/p><\/div>1-minute Mesoscale Domain Sector<\/strong><\/a> GOES-16 (GOES-East)<\/em> “Red” Visible (0.64 \u00b5m<\/strong><\/a>) images (above)<\/strong><\/em> and “Clean” Infrared Window (10.3 \u00b5m<\/strong><\/a>) images (below)<\/strong><\/em> showed the formation of Tropical Storm Iba off the east coast of Brazil at 16 UTC<\/strong><\/a> on 24 March 2019 (surface analyses<\/strong><\/a>). Plots of GLM<\/strong><\/a> 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<\/strong><\/a>) is known to have reached hurricane intensity.<\/p>\n GOES-16 “Clean” Infrared Window (10.3 \u00b5m)<\/em> images [click to play animation | MP4<\/strong><\/a>]<\/p><\/div>A toggle between NOAA-20 VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 \u00b5m) from RealEarth<\/strong><\/a> (below)<\/strong><\/em> showed Iba at 1610 UTC.<\/p>\n NOAA-20 VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 \u00b5m) images at 1610 UTC [click to enlarge]<\/p><\/div>GOES-16 Infrared images with an overlay of deep-layer wind shear<\/strong><\/a> valid at 18 UTC from the CIMSS Tropical Cyclones<\/strong><\/a> site (below)<\/strong><\/em> revealed a very tight gradient of shear over Iba. However, the shear gradient began to relax somewhat by 21 UTC<\/strong><\/a>.<\/p>\n GOES-16 “Clean” Infrared Window (10.3 \u00b5m)<\/em> images, with an overlay of 18 UTC deep-layer wind shear [click to enlarge]<\/p><\/div>In a sequence of GOES-16 “Clean” Infrared Window (10.3 \u00b5m) and Infrared-Water Vapor (10.3-6.9\u00b5m) brightness temperature difference (BTD) images (below)<\/strong>,<\/em> 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)<\/em> suggestive of significant cloud-top penetration into the lower stratosphere (reference<\/strong><\/a>).<\/p>\n GOES-16 “Clean” Infrared Window (10.3 \u00b5m) and Infrared-Water Vapor (10.3-6.9\u00b5m) BTD images [click to enlarge]<\/p><\/div>GOES-16 Visible images with an overlay of 1138 UTC ASCAT surface scatterometer winds from the Metop-A satellite (below)<\/strong><\/em> showed speeds in the 40-49 knot range (yellow barbs)<\/em>.<\/p>\n GOES-16 “Red” Visible (0.64 \u00b5m)<\/em> images, with Metop-A ASCAT winds at 1137 UTC [click to enlarge]<\/p><\/div>The MIMIC Total Precipitable Water<\/strong><\/a> product (below)<\/strong><\/em> showed that Iba was embedded within a plume of moisture that extended southeastward off the coast of Brazil.<\/p>\n MIMIC Total Precipitable Water product [click to play animation]<\/p><\/div>Sea Surface Temperature values (below)<\/strong><\/em> were around 30\u00baC in the waters where Iba intensified.<\/p>\n Sea Surface Temperature analysis at 2230 UTC on 23 March [click to enlarge]<\/p><\/div>\n ===== 25 March Update =====<\/strong><\/p>\n GOES-16 “Red” Visible (0.64 \u00b5m)<\/em> with GLM Groups (left)<\/em> and “Clean” Infrared Window (10.3 \u00b5m, right)<\/em> images [click to play animation | MP4<\/strong><\/a>]<\/p><\/div>A comparison of GOES-16 Visible and Infrared images (above)<\/strong><\/em> showed that increasing deep-layer wind shear<\/strong><\/a> 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 -90\u00baC (yellow pixel embedded with darker purple shades)<\/em> was seen at 1635 UTC<\/strong><\/a>.<\/p>\n A timely overpass of the Suomi NPP satellite at 1639 UTC provided 375-meter resolution VIIRS True Color RGB and Infrared Window (11.45 \u00b5m) images (below)<\/strong>,<\/em> which showed a large overshooting top that exhibited infrared brightness temperatures of -90\u00baC and colder (yellow),<\/em> with a warmer ring of compensating subsidence immediately surrounding it. The coldest pixel had a brightness temperature of -103.7\u00baC — which is almost 1\u00baC colder than the -102.96\u00baC value noted over Australia in 2008<\/strong><\/a>.<\/p>\n Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 \u00b5m)<\/em> images [click to enlarge]<\/p><\/div>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<\/strong>, courtesy of William Straka, CIMSS)<\/em>. 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<\/strong><\/a>.<\/p>\n<\/a><\/a><\/a><\/a><\/a><\/a><\/a><\/a><\/a>