Aircraft “hole punch” clouds over Wisconsin

November 10th, 2017 |

GOES-16 Visible (0.64 µm, top) and Near-Infrared

GOES-16 “Red” Visible (0.64 µm, top) and Near-Infrared “Snow/Ice” (1.61 µm, bottom), with surface station identifiers plotted in yellow [click to play MP4 animation]

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

GOES-16 “Red” Visible (0.64 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images (above) revealed a number of aircraft “hole punch” clouds over western Wisconsin on the morning of 10 November 2017.  These cloud features were caused by aircraft that were either ascending or descending through a layer of cloud composed of supercooled water droplets — cooling from wake turbulence (reference) and/or particles from the jet engine exhaust acting as ice condensation nuclei cause the small supercooled water droplets to turn into larger ice crystals (which then often fall from the cloud layer, creating “fall streak holes“). The darker gray appearance of the hole punch clouds on 1.61 µm images confirms that the features were composed of ice crystals (since ice is a strong absorber of radiation at that wavelength).

One isolated  hole punch cloud was also seen in 250-meter resolution Terra MODIS false-color Red-Green-Blue (RGB) imagery (source) over central Wisconsin around 16:52 UTC (below). In this type of RGB image (created using MODIS Bands 7/2/1), ice crystal clouds appear as shades of cyan, in contrast to supercooled water droplet clouds which appear as shades of white. With the low November sun angle, this cloud deck was casting a long shadow to the north — and sunlight filtering through the hole punch feature was brightening up a spot in the cloud shadow on the ground.

Terra MODIS false-color images [click to enlarge]

Terra MODIS false-color image [click to enlarge]

Lake/river effect clouds in North Dakota

November 7th, 2017 |

GOES-16

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

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

As cold arctic air continued to move eastward across North Dakota on 07 November 2017, GOES-16 “Red” Visible (0.64 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images (above) showed “lake effect” cloud plumes streaming east-northeastward from Lake Sakakawea (and also from Missouri River). The Snow/Ice images were the most useful for discriminating between supercooled water droplet cloud plumes (brighter shades of white) and the surrounding snow-covered land surfaces (darker shades of gray).

During the preceding nighttime hours, Suomi NPP VIIRS and Aqua MODIS Infrared Brightness Temperature Difference images (below) — the legacy “fog/stratus product” — revealed that the orientation of the Lake Sakakawea cloud plume changed as surface winds switched from northwesterly to westerly.

Infrared Brightness Temperature Difference images from Suomi NPP VIIRS (11.45 µm = 3.74 µm) and Aqua MODIS (11.0 µm - 3.7 µm) [click to enlarge]

Infrared Brightness Temperature Difference images from Suomi NPP VIIRS (11.45 µm = 3.74 µm) and Aqua MODIS (11.0 µm – 3.7 µm) [click to enlarge]

The Aqua MODIS Sea Surface Temperature product (below) indicated that the water in Lake Sakakawea was as warm as 47.9ºF (darker green enhancement) — significantly warmer than the surface air passing over it, which was generally in the 5 to 15ºF range.

Aqua MODIS Sea Surface Temperature product [click to enlarge]

Aqua MODIS Sea Surface Temperature product [click to enlarge]

The large cloud plume from Lake Sakakawea was also very evident on GOES-16 Day Snow-Fog Red-Green-Blue (RGB) images (below). Farther to the east, smaller and shorter-lived cloud plumes could also be seen originating from Devils Lake (along the Benson/Ramsey county line) and Stump Lake (in Nelson county).

GOES-16 Day Snow-Fog RGB images [click to animate]

GOES-16 Day Snow-Fog RGB images [click to animate]

Taking a closer look at the Lake Sakakawea area, the brighter signature of steam plumes rising from power plants located south and southeast of the lake (2 in Mercer county, and 1 in McLean county) could be spotted on the Day Snow-Fog RGB images (below).

GOES-16 Day Snow-Fog RGB images [click to animate]

GOES-16 Day Snow-Fog RGB images [click to animate]

Due to the low sun angle and the snow-covered land surface, morning shadows from these rising steam plumes could be seen on GOES-16 “Red” Visible (0.64 µm) images (below).

GOES-16

GOES-16 “Red” Visible images [click to animate]

Special thanks to Carl Jones (NWS Grand Forks) for bringing this case to our attention, and supplying the AWIPS RGB and Visible images at the bottom of the blog post.

 

Severe weather across Indiana and Ohio

November 5th, 2017 |

GOES-16 Visible (0.64 µm, top) and Infrared Window (10.3 µm, bottom) images, with SPC storm reports plotted in red (on Visible images) and black (on Infrared images) [click to play MP4 animation]

GOES-16 Visible (0.64 µm, top) and Infrared Window (10.3 µm, bottom) images, with SPC storm reports plotted in red (on Visible images) and black (on Infrared images) [click to play MP4 animation]

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

An outbreak of severe weather occurred across the Midwestern US on 05 November 2017, with a number of tornadoes (including a 39-mile long track EF-2 tornado) in Indiana and Ohio. A GOES-16 Mesoscale Sector provided imagery at 1-minute intervals during this event — “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) with plots of SPC storm reports (T=tornado; W=damaging winds; H=hail) showed the development and motion of the severe thunderstorms. The locations of the plotted SPC storm reports have been parallax-corrected upward from the surface, to match a mean storm-top height of 10 km.

A toggle between Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images (below) showed a snapshot of the storm at 1803 UTC. SPC storm reports within about  +/- 30 minutes of the image time are also plotted. The coldest storm-top infrared brightness temperatures were -71ºC (black enhancement), over southern and eastern Indiana. The VIIRS instrument will also fly on the JPSS series of satellites.

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images, with plots of SPC storm reports [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images, with plots of SPC storm reports [click to enlarge]

One interesting aspect seen on 1806 UTC Aqua MODIS Water Vapor (6.7 µm) imagery (below) was the signature of strong subsidence (darker blue enhancement) immediately upwind — along the western edge — of the 2 larger areas of severe convection. Once again, SPC storm reports within about +/- 30 minutes of the image time are plotted.

Aqua MODIS Visible (0.65 µm), Infrared Window (11.0 µm) and Water Vapor (6.7 µm) images, with SPC storm reports [click to enlarge]

Aqua MODIS Visible (0.65 µm), Infrared Window (11.0 µm) and Water Vapor (6.7 µm) images, with SPC storm reports [click to enlarge]

Additional information on this event can be found on the Satellite Liaison Blog, as well as the NWS forecast offices at Indianapolis IN, Northern IN, and Wilmington OH.

Lake effect and river effect clouds in northeastern Montana

November 4th, 2017 |

GOES-16 "Red" Visible (0.64 µm, top) and Near-Infrared "Snow/Ice" (1.61 µm, bottom) images, with hourly plots of surface observations [click to play MP4 animation]

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

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

As arctic air began to spread eastward across Montana — where the coldest temperature in the US was -12ºF — behind an inverted trough (surface analyses) on 04 November 2017, GOES-16 “Red” Visible (0.64 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images (above) revealed bands of “lake effect” (from Fort Peck Lake) and “river effect” (slightly upstream, from the Missouri River) clouds. On the Snow/Ice images, sow cover (and cold ice crystal clouds) appear as darker shades of gray, in contrast to supercooled water droplet clouds which are brighter white. Note that surface air temperatures at Glasgow (KGGW) and Jordan (KJDN) were generally in the 15 to 20ºF range.

A 1-km resolution Aqua (overpass times) MODIS Sea Surface Temperature product (below) indicated that SST values were still 50ºF and warmer (darker shades of green) in parts of Fort Peck Lake. Farther to the west, a deeper portion of the Missouri River exhibited SST values in the mid-40s F (cyan) — this area  was likely the source of the river-effect cloud features. The temperature difference between the surface air and the warmer lake/river water was therefore in the 30-35ºF range.

Aqua MODIS Sea Surface Temperature product [click to enlarge]

Aqua MODIS Sea Surface Temperature product [click to enlarge]

In a toggle between 250-meter resolution Terra (overpass times) MODIS true-color (Bands 1/4/3) and false-color (Bands 7/2/1)  Red-Green-Blue (RGB) images from the MODIS Today site (below), the false-color image helps to highlight the bands of supercooled water droplet river effect and lake effect clouds (brighter white) — snow cover (and high-altitude ice crystal clouds) appear as shades of cyan.

Terra MODIS true-color and false-color RGB images [click to enlarge]

Terra MODIS true-color and false-color RGB images [click to enlarge]

A 30-meter resolution Lnndsat-8 false-color image (below) captured the dissipating remnants of the Missouri River cloud plume at 1800 UTC; a few cumulus cloud streets could also be seen over Fort Peck Lake, along the far eastern edge of the image swath.

Landsat-8 false-color image [click to enlarge]

Landsat-8 false-color image [click to enlarge]