River valley fog in the Upper Midwest

June 28th, 2018 |

NOAA-20 VIIRS Day/Night Band (0.7 µm) and

NOAA-20 VIIRS Day/Night Band (0.7 µm) and “Fog Product” Infrared Brightness Temperature Difference (11.0 – 3.7 µm) images, with plots of Ceiling and Visibility [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and "Fog Product" Infrared Brightness Temperature Difference (11.0 - 3.7 µm) images, with plots of Ceiling and Visibility [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and “Fog Product” Infrared Brightness Temperature Difference (11.0 – 3.7 µm) images, with plots of Ceiling and Visibility [click to enlarge]

Comparisons of NOAA-20 and Suomi NPP VIIRS Day/Night Band (0.7 µm) and “Fog Product” Infrared Brightness Temperature Difference images (above) showed the nighttime formation of river valley fog in parts of the Mississippi River and its tributaries in Minnesota, Wisconsin and Iowa on 28 June 2018.  Due to ample illumination from the Full Moon, the Day/Night Band provided a “visible image at night” with better fog detail in some areas than was seen using the traditional “Fog Product”. (Note: the NOAA-20 images are incorrectly labeled as Suomi NPP)

A toggle between NOAA-20 and Suomi NPP VIIRS Day/Night Band images acquired by the SSEC Direct Broadcast ground station (below) revealed increased fog formation over portions of the Mississippi River between Rochester MN and Madison WI during the 52 minutes separating the two images.

NOAA-20 and Suomi NPP VIIRS Day/Night Band (0.7 µm) images [click to enlarge]

NOAA-20 and Suomi NPP VIIRS Day/Night Band (0.7 µm) images [click to enlarge]

During the subsequent daylight hours, GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (below) showed that the fog dissipated by 15 UTC or 10am local time.

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with hourly plots of surface weather type [click to play animation | MP4]

GOES-16 Natural Color Red-Green-Blue (RGB) images are shown below.

GOES-16 Natural Color RGB images [click to play MP4 animation]

GOES-16 Natural Color RGB images [click to play MP4 animation]

Valley fog and mountain snow in the Catskills of New York

May 1st, 2018 |

As pointed out by NWS Binghamton, valley fog and higher-elevation snow cover was apparent on GOES-16 (GOES-East) Visible imagery in the Catskills of southeastern New York on the morning of 01 May 2018. A closer view comparing GOES-16 “Red” Visible (0.64 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images (below) showed the dissipation of the valley fog, followed by the melting of the snow cover in higher terrain (snowfall amounts of up to 3-4 inches fell in the area on 29 April). The Snow/Ice imagery was helpful in discriminating between the brighter valley fog features and the darker snow cover.

GOES-16

GOES-16 “Red” Visible (0.64 µm, left) and Near-Infrared “Snow/Ice” (1.61 µm, right) images, with hourly plots of surface reports [click to play animation | MP4]

A 250-meter resolution Terra MODIS True-color Red-Green-Blue (RGB) image acquired from the SSEC Direct Broadcast ground station (below) showed the remaining snow cover over the Catskills (near the center of the image) at 1539 UTC.

Terra MODIS True-color image [click to enlarge]

Terra MODIS True-color image [click to enlarge]

Supermoon VIIRS Day/Night Band imagery

December 3rd, 2017 |

Composite of Suomi NPP VIIRS Day/Night Band swaths [click to enlarge]

Composite of Suomi NPP VIIRS Day/Night Band swaths [click to enlarge]

The only Supermoon of 2017 occurred on 03 December — and a composite of Suomi NPP VIIRS Day/Night Band (0.7 µm) swaths viewed using RealEarth (above) demonstrated the “visible image at night” capability of that spectral band. A VIIRS instrument is also part of the payload on recently-launched JPSS-1/NOAA-20.

A few examples providing closer looks using VIIRS Day/Night Band (DNB) imagery are shown below, beginning with the western portion of an Atlantic storm that had been producing Gale Force winds during the previous 6-12 hours.

Suomi NPP VIIRS Day/Night Band (0.7 µm) image centered over the western Atlantic [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) image centered over the western Atlantic [click to enlarge]

A toggle between Day/Night Band (0.7 µm) and Fog/stratus Infrared Brightness Temperature Difference (11.45 µm – 3.74 µm) images, centered over the Southeast US (below) showed widespread areas of fog and/or stratus The brighter fog/stratus features were generally brighter on the DNB image..

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Fog/stratus Infrared Brightness Temperature Difference (11.45 µm - 3.74 µm) images, centered over the Southeast US [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Fog/stratus Infrared Brightness Temperature Difference (11.45 µm – 3.74 µm) images, centered over the Southeast US [click to enlarge]

Another toggle between DNB and Fog/stratus Infrared Brightness Temperature Difference images, this time centered over Minnesota, Wisconsin and the UP of Michigan (below) revealed snow cover that was much below average for the date — especially across the UP of Michigan.

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Fog/stratus Infrared Brightness Temperature Difference (11.45 µm - 3.74 µm) images, centered over Minnesota and the UP of Michigan [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Fog/stratus Infrared Brightness Temperature Difference (11.45 µm – 3.74 µm) images, centered over Minnesota, Wisconsin and the UP of Michigan [click to enlarge]

Finally, a toggle between DNB images from consecutive overpass times (0935 and 1116 UTC), showing small clusters of rain showers moving inland along the coast of Oregon and far northern California (below). Because of the wide scan swath of the VIIRS instrument (2330 km), there are times when the same area will be imaged during 2 consecutive overpasses.

Suomi NPP VIIRS Day/Night Band images, centered off the coast of Oregon [click to enlarge]

Suomi NPP VIIRS Day/Night Band images, centered off the coast of Oregon [click to enlarge]

Dissipation of nocturnal valley fog across New England

October 28th, 2017 |

GOES-16 Visible (0.64 µm) images, with hourly surface reports of fog plotted in yellow [click to play animation]

GOES-16 Visible (0.64 µm) images, with hourly surface reports of fog plotted in yellow [click to play animation]

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

With high pressure dominating across the region during the pre-dawn nighttime hours (surface analyses), strong radiational cooling (minimum temperatures) aided in the formation of widespread valley fog across New England on 28 October 2017.  Post-sunrise GOES-16 “Red” Visible (0.64 µm) images revealed the areal extent of the valley fog; however, fog dissipation was fairly rapid during the morning hours as surface heating from abundant sunlight promoted sufficient boundary layer mixing.

During the preceding nighttime hours, development of widespread valley fog could be seen on Suomi NPP VIIRS Infrared Brightness Temperature Difference (11.45 µm – 3.74 µm) images (below) — although surface fog features were obscured at times by patchy cirrus clouds aloft (black enhancement). This example demonstrates that because of the wide (3000 km) scan swath of the VIIRS instrument, in many cases the same region might be sampled by 2 consecutive overpasses. VIIRS will also be part of the instrument payload on the upcoming JPSS series of polar-orbiting satellites.

Suomi NPP VIIRS Infrared Brightness Temperature Difference (11.45 µm - 3.74 µm) images [click to enlarge]

Suomi NPP VIIRS Infrared Brightness Temperature Difference (11.45 µm – 3.74 µm) images [click to enlarge]