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 was the second-highest daily snowfall amount for the month of April). 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).

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

A fast animation of GOES-16 true-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.

Some satellite signatures of Winter remaining on 01 April

April 1st, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm, left) and Near-Infrared “Snow/Ice (1.61 µm, right) images [click to play animation]

Some remnant signatures of Winter could be seen on 01 April 2018 — the first were seen  on GOES-16 (GOES-East) GOES-16 “Red” Visible (0.64 µm) and Near-Infrared “Snow/Ice (1.61 µm) over North Dakota and South Dakota, in the form of snow cover and snow/ice on parts of the Missouri River (above). With the high April sun angle, the lesser snow cover over northern South Dakota melted rather quickly, and the southern edge of the deeper snow cover in southern North Dakota also receded during the day.

Farther to the east, the motion and breakup of ice in Green Bay was evident on GOES-16 “Red” Visible (0.64 µm)  images (below).

GOES-16

GOES-16 “Red” Visible (0.64 µm) images [click to play animation]

The March of Cyclones in a ‘Foureaster’ Animation

March 27th, 2018 |

GOES-16 ABI Imagery from 28 February through 24 March 2018 at 15-minute time steps. CIMSS Natural Color imagery is shown during the day, a blend of GOES-16 ABI Shortwave (3.9 µm) and Longwave (10.3 µm) Infrared imagery is shown at night. (Click to open YouTube animation)

Four weeks of GOES-16 Full-Disk imagery, spanning 28 February to 24 March at a 15-minute interval, showing four Nor’easters, are available via the image above at YouTube.  The imagery shows CIMSS Natural Color during the day and a blend of GOES-16 ABI Shortwave (3.9 µm) and Longwave (10.3 µm) Infrared imagery at night.

The original mp4 (200 megabytes) is available for download here.

Icebreaking in Whitefish Bay on Lake Superior

March 24th, 2018 |

GOES-16 ABI Band 2 “Red” (0.64 µm) Visible imagery, 2202 UTC on 22 and 23 March 2018 (Click to enlarge)

Dan Miller, the Science and Operations Officer (SOO) in Duluth sent the imagery above. Constant icebreaking has been ongoing on Whitefish Bay prior to the opening of the SOO Locks this weekend. A faint black line representing open water is apparent in the 22 March imagery, and it’s even more apparent in the 23 March imagery.

A toggle below, from 24 March 2018, shows the Band 2 “Red” (0.64 µm) Visible and the Band 5 “Snow/Ice” (1.61 µm) Near-Infrared images. The open water is apparent in both images — dark in contrast to the white snow and lake ice in the visible, darker than the adjacent ice in the 1.61 µm. Recall that horizontal resolution in Band 2 is 0.5 km at the sub-satellite point (nadir), and in Band 5 it is 1 km.

GOES-16 ABI Band 2 “Red” (0.64 µm) Visible and Band 5 “Snow/Ice” (1.61 µm) near-infrared imagery, 2202 UTC on 22 and 23 March 2018 (Click to enlarge)

Suomi NPP and NOAA-20 also viewed the icebroken path on 24 March, and favorable orbit geometry for NOAA-20 and Suomi NPP on 24 March (orbit paths from this site) meant 2 sequential passes from both satellites both viewed Whitefish Bay. The 4 images are shown in an animation below, with imagery from NOAA-20 first, then Suomi NPP (the labels all say Suomi NPP erroneously). Note that NOAA-20 data are provisional, non-operational, and undergoing testing still).

VIIRS Visible (0.64 µm) Imagery from NOAA-20 (1708, 1846 UTC) and Suomi-NPP (1756, 1937 UTC) on 24 March 2018 (Click to enlarge)

The break in the ice was also visible in Day Night Band Imagery from VIIRS at 0722 UTC (from NOAA-20) on 24 March 2018.  It is also apparent in the shortwave Infrared imagery from both GOES-16 (very subtly) and from VIIRS (which offers better spatial resolution).

The icebreaking track was also apparent on 250-meter resolution Terra MODIS True-color and False-color Red-Green-Blue (RGB) images from the MODIS Today site (below). In the False-color image, ice and snow (in areas of sparse vegetation) show up 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]