Severe weather in Minnesota and Wisconsin

July 19th, 2019 |

GOES-16 "Red" Visible (0.64 µm) images, with SPC Storm Reports plotted in red [click to play MP4 animation]

GOES-16 “Red” Visible (0.64 µm) images, with SPC Storm Reports plotted in red [click to play MP4 animation]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed the development and propagation of a Mesoscale Convective System (MCS) that produced hail up to 3.0 inches in diameter in Minnesota and wind gusts to 84 mph and a few tornadoes in Wisconsin (SPC Storm Reports | NWS Twin Cities | MN DNR | NWS Green Bay) on 19 July 2019. Numerous overshooting tops and widespread storm-top gravity waves were evident in the imagery, along with a few Above-Anvil Cirrus Plume features extending northeastward from some of the overshooting tops around sunset. Also notable were the inflow feeder bands that were streaming northward into the southern flank of the MCS across Minnesota.

A comparison of GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (below) revealed cloud-top infrared brightness temperatures as cold as -86ºC over northwestern Wisconsin.

GOES-16

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play MP4 animation]

As the MCS persisted into the subsequent nighttime hours, GOES-16 Infrared images (below) showed the large canopy of cold cloud tops, with infrared brightness temperatures of -80ºC or colder (violet pixels).  Some of the embedded storms exhibited well-defined Enhanced-V storm top signatures (for example, at 2219 UTC).

GOES-16

GOES-16 “Clean” Infrared Window (10.35 µm) images, with SPC Storm Reports plotted in cyan [click to play animation | MP4]

===== 22 July Update =====

Terra MODIS True Color RGB images, 11 July vs 22 July [click to enlarge]

Terra MODIS True Color RGB images, 11 July vs 22 July [click to enlarge]

A comparison of Terra MODIS True Color Red-Green-Blue (RGB) images from 11 July and 22 July (above) showed the subtle NW-SE oriented swath of downed trees across northeastern Wisconsin. A 14 July vs 22 July comparison as viewed using RealEarth is shown below — the swath extended from approximately Pickerel to Mountain.

14 July and 22 July Terra MODIS True Color RGB images [click to enlarge]

Terra MODIS True Color RGB images, 14 July vs 22 July [click to enlarge]

In 22 July Terra MODIS images displayed using AWIPS (below), the swath of downed trees was brighter (more reflective) in the Near-Infrared “Snow/Ice” (1.61 µm), warmer (darker shades of orange to red) in the Shortwave Infrared (3.7 µm) and Land Surface Temperature, and lighter shades of green in the Normalized Difference Vegetation Index.

Terra MODIS Visible (0.65 µm), Near-Infrared "Snow/Ice" (1.61 µm), Shortwave Infrared (3.7 µm), Land Surface Temperature and Normalized Difference Vegetation Index images on 22 July [click to enlarge]

Terra MODIS Visible (0.65 µm), Near-Infrared “Snow/Ice” (1.61 µm), Shortwave Infrared (3.7 µm), Land Surface Temperature and Normalized Difference Vegetation Index images on 22 July [click to enlarge]

The swath of downed trees was also seen in GOES-16 Normalized Difference Vegetation Index images (below), showing up as a darker shade of green with that product’s default enhancement.

GOES-16 Normalized Difference Vegetation Index images [click to play animation]

GOES-16 Normalized Difference Vegetation Index images on 22 July [click to play animation]

Eruption of the Ubinas volcano in southern Peru

July 19th, 2019 |

GOES-16 Ash, SO2 and CIMSS Natural Color RGB images [click to play animation | MP4]

GOES-16 Ash, SO2 and CIMSS Natural Color RGB images [click to play animation | MP4]

A sequence of GOES-16 (GOES-East) Ash, SO2 and CIMSS Natural Color Red-Green-Blue (RGB) images (above) showed the volcanic cloud following an eruption of Ubinas in southern Peru on 19 July 2019. The volcanic plume was rich in both ash and SO2.

A plot of surface data from La Paz, Bolivia (below) indicated that the visibility dropped to 3 miles around 16 UTC as the volcanic cloud was drifting over that area (located about 150 miles downwind of Ubinas).

Time series of surface data from La Paz, Bolivia [click to enlarge]

Time series of surface data from La Paz, Bolivia [click to enlarge]

Terra MODIS Ash Probability, Ash Loading, Ash Height and Ash Effective Radius from the NOAA/CIMSS Volcanic Cloud Monitoring site (below) confirmed the high amounts of ash loading (of generally small ash particles) — with maximum radiometrically-retrieved Ash Height values in the 18-20 km range.

Terra MODIS Ash Probability, Ash Loading, Ash Height and Ash Effective Radius at 1440 UTC [click to enlarge]

Terra MODIS Ash Probability, Ash Loading, Ash Height and Ash Effective Radius at 1440 UTC [click to enlarge]

GOES-16 retrieved Ash Height values (below) were in general agreement with those obtained using the higher-resolution MODIS data.

GOES-16 Ash Height images [click to play animation | MP4]

GOES-16 Ash Height images [click to play animation | MP4]

Elevated NO2 signatures over the Northeast US

July 19th, 2019 |

TROPOMI NO2 concentration [click to enlarge]

TROPOMI NO2 concentration, courtesy of Bob Carp, SSEC [click to enlarge]

High temperatures (along with high dewpoints) prompted the issuance of Excessive Heat Warnings across much of the Northeast US on 19 July 2019. Under such conditions, surface NO2 concentrations in densely-populated urban areas often become elevated (primarily driven by emissions from motor vehicle exhaust, along with secondary sources such as coal-fired power plants and manufacturing / food processing industrial sources) — the high temperatures accelerate chemical reactions that form pollutants. The TROPOMI instrument detected plumes of elevated NO2 extending downwind (to the northeast) of major cities such as Philadelphia, New York City and Boston (above). The data are displayed using McIDAS-V.

A closer view centered on New York City is shown below.

TROPOMI NO2 concentration [click to enlarge]

TROPOMI NO2 concentration, courtesy of Bob Carp, SSEC [click to enlarge]

The Aqua MODIS Land Surface Temperature product around that time (below) revealed LST values in the 100-110ºF range across the New York City and Boston areas, where the daily maximum surface air temperatures were 95ºF and 93ªF, respectively.

Aqua MODIS Land Surface Temperature, with plots of daily maximum surface air temperatures [click to enlarge]

Aqua MODIS Land Surface Temperature, with plots of daily maximum surface air temperatures [click to enlarge]