Tropical Storm Gonzalo in the Atlantic

July 24th, 2020 |
NOAA-20 I05 (11.35 µm) imagery of Tropical Storm Gonzalo, ca. 0400 UTC on 24 July 2020

Real Earth captured the cold cloud tops associated with vigorous convection with tropical storm Gonzalo shortly after midnight on 24 July 2020.   The VIIRS Imagery from NOAA-20, above, (the day’s NOAA-20 passes in the region (from this site) are shown here) shows numerous cloud tops colder than -80ºC (the purple enhancement).

True-color imagery from GOES-16, below, at 1210 UTC (from an experimental CSPPGeo-driven website at CIMSS), shows the storm off the coast of South America.  It does not appear to be well-organized.

GOES-16 True-Color imagery, 1210 UTC on 24 July 2020 (Click to enlarge)

GOES-16 imagery, below, from 1230 UTC, shows the small nature of Tropical storm Gonzalo as it sits north of South America. It is smaller than the very large tropical wave coming off the coast of Africa, for example, and smaller than the cluster of thunderstorms to its east, and smaller than the cluster of thunderstorms north of Hispaniola and Puerto Rico.  Small storms are often very susceptible to weakening effects in hostile environments.

GOES-16 ABI Band 13 (10.3 µm) infrared imagery, 1230 UTC on 24 July 2020 (click to enlarge)

The toggle below of the GOES-16 Split Window (10.3 µm – 12.3 µm, color-enhanced to bring out dry air — in yellow, red and pink — as might be associated with a Saharan Air Layer) and the Air Mass RGB, both taken from this website, show the inhibiting factor (moisture-rich tropical air is green in the RGB; drier air has an orange tint) that might prevail in Gonzalo’s future: the South American Continent is to the storm’s south; dry air prevails to the north and east of Gonzalo. What is a storm to do? The forecast from the National Hurricane Center is for the storm to rake the Windward Islands with tropical storm-force winds and subsequently dissipate. Interests in northern South America and the Windward Islands, and indeed all of the Caribbean, should continue to monitor the storm.

GOES-16 Split Window Difference and Air Mass RGB at 1200 UTC on 24 July 2020 (Click to enlarge)

NUCAPS data also shows the dry environment surrounding the storm. The 850-500 mb relative humidity field, below, from two NOAA-20 passes, one near 0415 UTC and one near 0545 UTC, show the dry air north and east of the storm. (Gonzalo during this time was near 10ºN Latitude and 50ºW Longtiude)

Gridded NUCAPS observations of 850-500 mb Relative Humidity, 0415 and 0545 UTC on 24 July 2020 (Click to enlarge)

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