Heavy snow across southern Minnesota, northern Iowa and southern Wisconsin

April 18th, 2018 |

24-hour snowfall ending at 12 UTC on 19 April [click to enlarge]

24-hour snowfall ending at 12 UTC on 19 April [click to enlarge]

A band of heavy snow fell across southern Minnesota (as much as 11.0 inches), northern Iowa (as much as 12.0 inches) and southern Wisconsin (as much as 9.4 inches) on 18 April 2018.

Animations of 1-minute Mesoscale Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm), “Clean” Infrared Window (10.3 µm) and “Low-level” Water Vapor (7.3 µm) images (below) showed the formation of convective elements and banding along the southern edge of the colder cloud shield — snowfall rates were enhanced when these convective features moved overhead, and thundersnow was noted at some locations.

GOES-16

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

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images, with hourly surface weather type plotted in yellow [click to play MP4 animation]

GOES-16

GOES-16 “Low=level” Water Vapor (7.3 µm) images, with hourly surface weather type plotted in cyan [click to play MP4 animation]

In south-central Wisconsin, Madison (KMSN) received 7.2 inches of snowfall, which set a new record for daily snowfall (and helped to make April the snowiest month of the 2017/2018 winter seeason). In addition, the daily maximum temperature was only 33 ºF, which was a record low maximum for the date. Over the southwestern part of the city, a cluster of GOES-16 Geostationary Lightning Mapper (GLM) Groups was detected from 1918 to 1919 UTC (below; courtesy of Dave Santek, SSEC) — the GOES-16 Visible image at that time did display a textured cloud top appearance characteristic of embedded convection across southern Wisconsin.

GOES-16 GLM Groups [click to enlarge]

GOES-16 GLM Groups [click to enlarge]

===== 20 April Update =====

GOES-16 true-color (daytime) and Infrared Window (10.3 µm, nighttime) images [click to play MP4 animation]

GOES-16 natural-color RGB (daytime) and Infrared Window (10.3 µm, nighttime) images [click to play MP4 animation]

A fast animation of GOES-16 natural-color Red-Green-Blue (RGB) images (above) revealed the rapid rate of snow melt — especially on 19 April — along the southern edge of the snow cover (where lighter amounts of snow fell). The effect of the high late-April sun angle also played a role in the rapid snow melt.

GOES-16 GLM data now available in RealEarth™

July 21st, 2017 |

GOES-16 Infrared Window (103 µm) images, with GLM Group data points plotted as white dots [click to play animation]

GOES-16 Infrared Window (10.3 µm) images, with GLM Group data points plotted as white dots [click to play animation]

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

Real-time GOES-16 Geostationary Lightning Mapper (GLM) data are now available for viewing using RealEarth™ (real-time GLM link). An example from 21 July 2017 is shown above, for an isolated thunderstorm that developed during the afternoon hours along a residual convective outflow boundary — which was evident on an animation of “Red” Visible (0.64 µm) imagery — draped across eastern Iowa. This storm produced 1.0-inch diameter hail and damaging winds within 7-22 minutes after the 2200 UTC end of the animation (SPC storm reports).  Both the GOES-16 “Clean” Infrared Window (10.3 µm) images and the GLM Group (GLM Events clustered by proximity; see this blog post) data points were available at 1-minute intervals, since the region was within the domain of one of the Mesoscale Sectors.

Note that during the early portion of the animation, a number of GLM Group points were located south of the rapidly-expanding cold cloud top shield — GLM data are parallax-corrected, assuming a cloud-top height of 12.5 km. The 18 UTC tropopause height was 15.0 km on the 18 UTC sounding at Davenport, Iowa.

GOES-16 ABI Mesoscale Sector imagery and GLM data with strong thunderstorms over Wisconsin

July 12th, 2017 |

GOES-16 ABI Band 13 (“Clean Window”) 10.3 µm Imagery, every minute from 1000 – 1359 UTC on 12 July 2017, with GLM Lightning Flash locations for each minute (yellow circles) superimposed (Click to animate)

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

Strong morning thunderstorms with a few severe weather reports, and abundant heavy rain (24-h totals ending 1200 UTC on 12 July 2017, from here), spread over the northern part of the GOES-16 default western Mesoscale Sector on the morning of 12 July 2017. The animation above shows the GOES-16 Advanced Baseline Imager (ABI) 10.3 µm imagery with Geostationary Lightning Mapper (GLM) Lightning Flash event locations superimposed, at 1-minute timescales. The top of the default Mesoscale Sector cuts through central Wisconsin.

Click here to see a graphic with the GLM Flashes for the 3 different hours.

Plotting GOES-16 GLM data in McIDAS-X

July 11th, 2017 |

GOES-16 ABI Clean Window (10.3 µm) imagery at 1002 UTC, along with GLM Lightning Observations of Events, Groups, and Flashes from 0959-1000 UTC (Yellow), 1000-1001 UTC (Green) and 1001-1002 UTC (Red). [Click to enlarge]

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.