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

Consider the visible image above. Can you tell where the eastern and southern edge of the cirrus shield is over the eastern United States? When the Sun is not on the horizon, thin cirrus can be very hard to detect in visible imagery because cirrus clouds are not efficient back-scatterers of solar radiation (all clouds forward-scatter very effectively, but cirrus are optically thin). In a still image, then, with a high sun angle, cirrus can be hard to discern.  There are brightness temperature difference fields that can also be used to infer the presence of cirrus.  For example, the Split Window Difference field (10.3 µm – 12.3 µm) and the Cloud Phase Difference (8.5 µm – 11.2 µm), toggled below, will highlight regions of cloudiness.  But do they also capture very thin cirrus?

 

The Cirrus Channel on GOES-16 (1.38 µm), below, better captures the areal extent of the cirrus.  This is because it is very sensitive to reflective features such as cirrus clouds, and because it is in a region of the electromagnetic spectrum where water vapor absorption occurs — so surface features that might complicate the interpretation are masked (Note, for example, that cumuliform clouds over Northwestern Pennsylvania are not apparent in the Cirrus Band imagery). Click here to toggle between all 4 images.

One of the GOES-16 Baseline Products is a Cloud Mask — this is important because many other Baseline Products use the output from the Cloud Mask in decision trees. The toggle below shows the Cirrus Band (1.38 µm), the Red Visible (0.64 µm) and the Cloud Mask for 1557 UTC on 28 June 2017.

 

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

Clusters of severe thunderstorms developed over eastern Wyoming and the Nebraska panhandle during the afternoon on 27 June 2017, and increased in areal coverage and intensity as they moved eastward into the overnight hours. 1-minute interval Mesoscale Sector GOES-16 Infrared Window (10.3 µm) images with plots of SPC storm reports (above) showed a number of locations with wind gusts in excess of 60 mph — including 79 mph in Rapid City SD at 2341 UTC and 100 mph in Custer NE at 0200 UTC. Many of these high wind reports were in the general vicinity of thunderstorm overshooting tops, which exhibited cloud-top infrared brightness temperatures in  the -70 to -80º C range (black to white enhancement).

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

Dora became the first hurricane of the Eastern Pacific 2017 season on 26 June, and was also the first hurricane to be sampled by GOES-16. On Visible (0.64 µm) and Infrared Window (10.3 µm) images (above), Dora displayed an improving appearance as the day progressed — mesovortices were seen within the eye on Visible imagery, while the overall eye/eyewall structure improved as the eye diameter increased on Infrared Window imagery.

Early in the morning, a comparison between DMSP-17 SSMIS Microwave (85 GHz) and GOES-15 Infrared Window (10.7 µm) images from the CIMSS Tropical Cyclones site (below) showed  that a well-defined eye was more apparent on microwave imagery. Dora was moving over fairly warm Sea Surface Temperatures, and was also in an environment characterized by low values of deep-layer wind shear.

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#GOES16 RGB imagery shows rain and hail swath from a t-storm today. #NEwx #KSwx pic.twitter.com/pFooa7C5KZ

— NWS Hastings (@NWSHastings) June 26, 2017

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

As indicated in the Tweet above from NWS Hastings, GOES-16 imagery highlighted the presence of a narrow swath of rainfall and hail in the wake of a small thunderstorm that moved south/southeastward across the Nebraska/Kansas state line area on 26 June 2017.

A 3-panel comparison of GOES-16 Visible (0.64 µm), Snow/Ice (1.61  µm) and Shortwave Infrared (3.9  µm) images (below) revealed a subtle signature of the hail swath on the Snow/Ice images (where ice features appear as darker shades of gray: southern NE  | northern KS), while the Shortwave Infrared images showed that the hail and rainfall swath — accumulations in southern Kansas included 0.58″ at Clay Center and 0.49″ at Hebron — remained slightly cooler (lighter gray) as the adjacent dry land surfaces continued to warm during the early to middle afternoon hours. SPC storm reports listed hail of 1.75 inches in diameter in southern Nebraska and 1.25 inches in northern Kansas.

Regarding the cooling seen associated with the rainfall/hail swath, a Land Surface Temperature (LST) product derived using Aqua MODIS data (below) indicated that LST values were generally in the upper 60s to upper 70s F within the narrow swath,  in contrast to LST values in the 90s to around 100º F adjacent to the swath.

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