CSPP True Color imagery (link) above suggests a region of apparent dust over the eastern Caribbean Sea. That is, there is a hazy look to the imagery that persists even as the region of sun glint moves past. Suspended dust in the tropical Atlantic is known to suppress convection. Other products besides true-color imagery can be used to show dry the air (qualitatively and quantitatively) over the Caribbean. For example, the toggle below (from this site) of the Saharan Air Layer analysis (via the Split Window Difference) and the Airmass RGB shows very dry air south of Hispaniola and Puerto Rico — orange in the Split Window Difference, and also an orange tint to the Airmass RGB.

Air over the eastern Caribbean also shows large values of Aerosol Optical Depth (from the AerosolWatch site); the enhanced values are most likely a result of suspended dust from the Sahara. AOD is not computed in the region of sun glint — that’s the cause of the smooth curved line that arcs through extreme eastern Cuba.

Total Precipitable Water (TPW) from the MIMIC site (link) shows dry air over the eastern Caribbean (and over much of the tropical Atlantic Ocean north of 10^oN). Total precipitable water derived from gridded NUCAPS fields (here), and relative humidity at 700 mb (here), also show dry air over the eastern Caribbean; they are also shown in a toggle with NUCAPS Quality Flags below.

An interesting feature in the animation at the top of this blog post is the development of convection over Hispaniola, over the topography, even in the presence of fairly dry air. NUCAPS analyses of 500-mb air temperature (here), show a cold pocket of air over Puerto Rico and Hispaniola, helping the development of convection there.

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When assessing the environment of a region with sparse conventional data, such as the Atlantic (or Pacific) Ocean, or the Caribbean Sea, take advantage of information that satellite observations can give you.

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1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed the evolution of the eye of Hurricane Darby as it moved westward across the East Pacific Ocean on 11 July 2022. Mesovortices were evident within the eye, along with a stadium effect eye structure — as Darby ended its period of rapid intensification and leveled off as a Category 4 storm (ADT | SATCON). Darby was moving through an environment of low wind shear and across relatively warm water (SST | OHC), factors which favored intensification.

A NOAA-20 VIIRS Infrared Window (11.45 µm) image from RealEarth (below) revealed an arc of slightly colder cloud tops (shades of white within dark black) in the northern portion of the eyewall.

A NOAA-20 ATMS Microwave (183 GHz) image from the CIMSS Tropical Cyclones site (below) also showed the compact eye, along with a band of precipitation spiraling northward.

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This NOAA/NESDIS website shows small footprints where SAR observations of ice and wind (from the RADARSAT Constellation Mission — RCM — satellites and from Sentinel) are available. AWIPS-ready data are also available from an ftp site. Consider the animation of GOES-17 Band 13 imagery above, just south to the Equator, and to the west of 160^oW longitude. The slightly cooler brightness temperatures at the eastern edge of the arc of clouds moving to the west is associated with two patches of strong surface winds. The toggle below zooms in on the region of winds. Surface wind speeds are close to 15 m s^-1 with this weak line of tropical convection.

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GOES-18 images in this blog post are preliminary and non-operational

Overlapping 1-minute Mesoscale Domain Sectors provided GOES-18 “Red” Visible (0.64 µm) images at 30-second intervals (above), which include time-matched SPC Storm Reports. This imagery showed widespread thunderstorms that moved eastward across Montana on 09 July 2022, which produced damaging straight-line winds as strong as 78 mph and hail as large as 2.00 inches.

30-second GOES-18 “Clean” Infrared Window (10.35 µm) images (below) extended for several hours past sunset, and indicated that the coldest overshooting tops exhibited infrared brightness temperatures around -70ºC (darker black enhancement). Given that the radar at NWS Glasgow was out of service (due to a lightning strike the previous night), this type of 30-second GOES imagery could have served as a valuable source of information to help monitor thunderstorm evolution.

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