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

Severe thunderstorms developed in the warm sector of a mid-latitude cyclone that was moving eastward along the US/Canada border on 11 July 2017.  GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) showed the storms that produced tornadoes, wind gusts to 80 mph and hail as large as 2.00 inches (SPC storm reports) across far eastern North Dakota and far northwestern Minnesota (NWS Grand Forks summary). Time-matched SPC storm reports are plotted on the images — the report locations are parallax-corrected to match the location of the cloud-top features. Overshooting tops were very evident on the Visible and Infrared imagery; in addition, pronounced cold/warm Thermal Couplets and/or Enhanced-V signatures were seen in the Infrared images.

Farther to the south, other storms (below) produced hail as large as 3.00 inches and wind gusts to 75 mph across northeastern South Dakota (NWS Aberdeen summary).

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

 

The GOES-16 Geostationary Lightning Mapper (GLM) has achieved Beta Maturity and is being distributed via GOES Rebroadcast (GRB). A release of McIDAS-X slated for September 2017 has a GLM display, prototyped above.  GLM data processing in the Ground System groups lightning flashes from smallest increments (Events), to aggregates of Events (Groups) to aggregates of Groups (Flashes). Thus, Events, as shown above, are on a rectangular grid wherein each gridpoint is a GLM Field of View. Groups are plotted at the centroid of the Events that comprise the Group, and Flashes are plotted as the centroid of the Groups that comprise the Flash. Typically, the number of Events is greater than the number of Groups, which is greater than the number of Flashes.

Convection developing over east-central Illinois and west-central Indiana this morning at 1002 UTC (as depicted by the 10.3 µm imagery, above) was electrically active. Events, Groups and Flashes are shown for 1-minute increments. For this particular (small) increment of time, the large convective complex over central Indiana was electrically quiet.  (Here is an animation that shows a similar scene — but with three events, groups and flashes grouped in 5-minute intervals rather than 1).

Note:  The ‘+’ sign used in the plot does not describe the electrical polarity of the flash;  GLM cannot distinguish positive from negative activity.

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

High Dewpoints in mid-Summer in the Upper Midwest often leads to stratus and fog over Lake Superior. Such was the case on 10 July 2017, with dewpoints in the 50s and 60s F (GOES-16 Visible images with surface observations) and mid-lake water temperatures as cold as 40º F (buoy reports | MODIS SST values) — and very interesting waves were observed in the stratus deck. They had the appearance of Atmospheric Bores: parallel lines of clouds moving in one direction. It is unusual to have Bores moving in different directions at the same time, however.

One possible explanation for the differing motion of these undular bores could be internal reflection off the rugged northern and southern shorelines of Lake Superior.

The RTMA surface wind analyses at 17 UTC and 19 UTC, below, showed complex flow patterns over the lake — however, the surface wind flow did not always correspond well to the motion of the undular bores.

(Thanks to TJ Turnage, the SOO in Grand Rapids MI, for alerting us to this mesmerizing event).

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

Very heavy rain (4-5″) fell over parts of southwestern Wisconsin early on 10 July 2017 as a Mesoscale Convective System traversed the Upper Midwest (0831 UTC VIIRS Infrared vs Day/Night Band). The animation above blends the Clean Window (10.3 µm) from GOES-16 with the Total Precipitable Water Baseline Product (This product is available online — with a time delay — here). Note that the largest values of Precipitable Water are diagnosed to be over southern and western of Wisconsin. Looking at the animation of the 10.3 µm imagery, can you decide where the heaviest rain fell?

A screen capture from this website, below, shows 24-hour precipitation over the Upper Midwest, with a northwest-to-southeast oriented maximum near the northwest-to-southeast gradient of diagnosed total precipitable water field shown in the animation above. (This summary from the National Weather Service in Milwaukee shows accumulated precipitation ending at 0900 Central Time).

The Hazardous Weather Testbed at the Storm Prediction Center evaluates GOES-16 (and other satellites, such as Suomi NPP) products. There have been many instances that noted convection was most intense along the gradient of the moisture (See this summary, for example, or this one.) When GOES-16 Baseline Products indicate a gradient, pay close attention when strong convection develops upstream.

Added: One day later, again, convection initiated (and/or persisted) north of the diagnosed Total Precipitable Water maximum over Illinois and Iowa (link), i.e., in the gradient of Total Precipitable Water.

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