Mostly clear skies over Puerto Rico early on 25 September 2017 allowed the Day Night Band on Suomi NPP to observe man-made sources of light on that island as shown in the image above (Courtesy of William Straka, CIMSS).  (A previous example on this blog showed lights through clouds).  A similar view is available at NASA’s Worldview site, or at Real Earth. The Lunar Phase on 25 September 2017 is Waxing Crescent with 26% illumination; similar illumination occurred on 24 August, and a link to the Day Night Band imagery at NASA Worldview on that day is here. The differences are stark.

A RealEarth examination of two Suomi NPP VIIRS Day/Night Band (0.7 µm) images — an archived “clear sky” view from 31 December 2015, and an “after-Maria” image from 26 September 2017 (below) — provides a good before/after comparison showing a reduction in the amount of city light illumination following the passage of the hurricane.

The Infrared Imagery, below, suggests a few clouds over northwest Puerto Rico. Such clouds could alter the perception of light sources in that region.

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* GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing *

Hurricane Maria was downgraded to a Category 2 storm at 12 UTC on 24 September 2017 (above), when it was located about halfway between Miami and Bermuda.

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (below) showed a close-up view of the eye region of Maria during the daylight hours.

Due to the large size of the radius of Tropical Storm force winds, a Tropical Storm Watch was issued late in the day for the Outer Banks and adjacent inland areas of North Carolina (below).

UPDATE: 12 hours later, much of the Tropical Storm Watch was upgraded to a Tropical Storm Warning.

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GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing

Hurricane Maria presented a very interesting eye structure during the course of the day on 21 September 2017, as shown in the mp4 animation above (also available as a YouTube video).  The animation shows 10.3 µm imagery every 2 minutes from 0849 UTC through 2122 UTC on 21 September 2017.

Pete Pokrandt, at the University of Wisconsin Atmospheric and Oceanic Sciences Department, created a similar animation using the 0.64 µm Visible channel on GOES-16.

30-second interval (using overlapping 1-minute interval Mesoscale Sector) GOES-16 Visible (0.64 µm) and Infrared Window (10.3 µm) images covering the 6-hour period from 1031-1631 UTC are shown below. During this time, Maria re-intensified to a Category 3 hurricane, with the eye centered just off the northeastern coast of the Dominican Republic.

For more information on Maria, visit the National Hurricane Center website.  The CIMSS Tropical Weather Website has information as well.

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Suomi NPP Overflew Puerto Rico at ~0555 UTC on 21 September, and the Day Night Band Visible Imagery (0.7 µm), above (from Real Earth, direct link here), shows city lights from San Juan and Ponce on the northeast and southwest shores, respectively, shining through relatively thick clouds to the southeast of the eye of the storm.

Annotated Imagery from Suomi NPP (VIIRS Day Night Band Visible (0.7 µm) Imagery and Infrared (11.45 µm) courtesy of William Straka) are shown below.

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