Midwest Derecho

August 10th, 2020 |

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

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

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed the eastward progression of a Mesoscale Convective System (MCS) that produced a long swath of damaging winds (SPC Storm Reports) or derecho from eastern Nebraska to Indiana on 10 August 2020. The highest measured wind gust was 112 mph in eastern Iowa at 1755 UTC.

The corresponding GOES-16 “Clean” Infrared Window (10.35 µm) images are shown below.

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

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

In a comparison of Infrared Window images from Suomi NPP (11.45 µm) and GOES-16 (10.35 µm) at 1931 UTC (below), the higher spatial resolution of the VIIRS instrument detected infrared brightness temperatures as cold as -84ºC, compared to -76ºC with GOES-16 (the same color enhancement is applied to both images). The northwest parallax offset associated with GOES-16 imagery at this location was also evident.

Comparison of Infrared Window images from Suomi NPP (11.45 µm) and GOES-16 (10.35 µm) at 1931 UTC [click to enlarge]

Comparison of Infrared Window images from Suomi NPP (11.45 µm) and GOES-16 (10.35 µm) at 1931 UTC [click to enlarge]

GOES-16 Visible/Infrared Sandwich Red-Green-Blue (RGB) and “Clean” Infrared Window (10.35 µm) images, with “probability of intense convection” contours and SPC Storm Reports, is shown below. The probability contours are produced from a deep-learning algorithm used to identify patterns in ABI and GLM imagery that correspond to intense convection. It is trained to highlight strong convection as humans would identify it. Work is ongoing to incorporate this storm-top information into NOAA/CIMSS ProbSevere.

GOES-16 Visible/Infrared Sandwich RGB and “Clean” Infrared Window (10.35 µm) images, with “probability of intense convection” contours and SPC Storm Reports (credit: John Cintineo, CIMSS) [click to play animation | MP4]

GOES-16 Visible/Infrared Sandwich RGB and “Clean” Infrared Window (10.35 µm) images, with “probability of intense convection” contours and SPC Storm Reports (credit: John Cintineo, CIMSS) [click to play animation | MP4]

A comparison of Terra MODIS True Color RGB images (source) from before (28 July) and after (11 August) the derecho (below) revealed very large swaths of wind-damaged crops (lighter shades of green) across Iowa. It is estimated that around 10 million acres of corn and soybean crops were flattened by the strong winds.

Comparison of before (28 July) / after (11 August) Terra MODIS True Color RGB images centered over Iowa [click to enlarge]

Comparison of before (28 July) / after (11 August) Terra MODIS True Color RGB images centered over Iowa [click to enlarge]

A toggle between VIIRS True Color RGB images from Suomi NPP and NOAA-20 visualized using RealEarth (below) also displayed the crop damage swath.

VIIRS True Color RGB images from Suomi NPP and NOAA-20 -- with and without map labels [click to enlarge]

VIIRS True Color RGB images from Suomi NPP and NOAA-20 — with and without map labels [click to enlarge]

Shown below is a before/after (28 July/11 August) comparison of VIIRS Day/Night Band (DNB) imagery (source), where many of the areas across Iowa that suffered significant power outages — appearing darker (due to a lack of city lights) on the nighttime DNB images — corresponded to the large swaths of crop damage seen on the 11 August MODIS True Color image. Around 550,000 households lost power across the state.

VIIRS Day/Night Band (0.7 µm) images on 28 July and 11 August, along with a MODIS True Color RGB image on 11 August [click to enlarge]

VIIRS Day/Night Band (0.7 µm) images on 28 July and 11 August, along with a MODIS True Color RGB image on 11 August [click to enlarge]

Even 2 days later (on 12 August), many customers remained without power across Iowa (below), especially in Marshall County (where peak winds of 106 mph were recorded), Tama County (where peak winds of 90 mph were recorded) and Linn County (where peak winds of 112 mph were recorded).

Iowa counties with power outages on 12 August [click to enlarge]

Iowa counties with power outages on 12 August [click to enlarge]


Derecho in South Dakota

June 7th, 2020 |


GOES-16 ABI Band 13 (10.3 µm) infrared imagery, 1901 6 June 2020 – 0656 7 June 2020 (Click to play mp4 animation)

 

Portions of the High Plains and intermountain states experienced a climatologically rare Derecho event oni 6-7 June 2020. (Here is a preliminary write-up on this event from the National Weather Service in Rapid City SD;  the forecast office in Boulder discussed the event here.). The GOES-16 Clean window infrared (10.3 µm) animation, above, (Click here for the same animation as an animated gif) shows rapid development over western South Dakota late in the afternoon of 6 June. The swath of wind reports is shown in this graphic from the Storm Prediction Center.

Several satellite-based thermodynamic estimates keyed in on South Dakota as a region where instability was noteworthy. The GOES-16 All-Sky Convective Available Potential Energy (available here), shown below from 2026 UTC on 6 June when values were greatest, for example, showed a persistent corridor of instability across South Dakota.

GOES-16 ‘All-Sky’ estimates of Convective Available Potential Energy, 2026 UTC on 6 June 2020 (Click to enlarge)

NUCAPS estimates of 700-500 mb lapse rates, below (from this site), show pronounced instability upstream of South Dakota at 1945 UTC, when Suomi-NPP overflew the region. (Most of the soundings used to produce the lapse rate information were from successful infrared retrievals as shown in this graphic).

700-500 mb Lapse Rates derived from Suomi NPP NUCAPS soundings, 1945 UTC on 6 June 2020 (Click to enlarge)

Surface moisture had pooled over western South Dakota. That is shown in the plot below of surface dewpoints showing very unusual (for South Dakota) mid-60s dewpoints! Further evidence of the unusual moisture amounts over the high Plains (for early June) is in this sounding from Rapid City at 0000 UTC on 7 June (source); Precipitable Water is at 1.2″! This value is unusual for the location and time of year, as shown here (Source).

Surface Dewpoints, 2100 UTC on 6 June 2020 over South Dakota and surrounding states (Click to enlarge)

GOES-17 Full-Disk imagery (at 10-minute time-steps) captured an oblique view of the developing convection. (The ‘PACUS’ sector with 5-minute imagery terminates in west-central South Dakota so is not used here; A GOES-17 Mesoscale sector was not in place for this event, although a GOES-16 one was).

GOES-17 Visible Imagery (0.64 µm) on 7 June 2020, 0000 – 0220 UTC (Click to animate)

1-minute Mesoscale Domain Sector GOES-16 “Red” Visible images with time-matched plots of SPC Storm Reports are shown below.

GOES-16 “Red” Visible (0.64 µm) images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) images [click to play animation | MP4]

Derecho affecting Pennsylvania and New Jersey

June 3rd, 2020 |

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

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

GOES-16 (GOES-East) “Red” Visible (0.64 µm) images with time-matched plots of SPC Storm Reports (above) displayed a fast-moving derecho which moved southeastward across Pennsylvania and New Jersey on 03 June 2020. Winds gusted as high as 83 mph in Pennsylvania (at 1535 UTC)  and 93 mph in New Jersey (at 1719 UTC).

A sequence of GOES-16 Visible images – with and without an overlay of GLM Flash Extent Density – and “Clean” Infrared Window (10.35 µm) images (below) showed modest lightning activity and pulsing overshooting tops with cloud-top infrared brightness temperatures as cold as -75ºC (darker red enhancement).

GOES-16

GOES-16 “Red” Visible (0.64 µm) – with and without an overlay of GLM Flash Extent Density – and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

Derecho causing severe weather from the Midwest to the Mid-South

May 3rd, 2020 |

GOES-16

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

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed a long-lived Mesoscale Convective System (MCS) or derecho that produced a swath of large hail and damaging winds (SPC Storm Reports | NWS Nashville) from eastern Kansas to central Tennessee, northern Mississippi and northern Alabama on 03 May 2020.

The corresponding GOES-16 “Clean” Infrared Window (10.35 µm) images are shown below. Pulsing overshooting tops exhibited cloud-top infrared brightness temperatures around -70ºC (black enhancement).

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

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

NOAA-20 VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images, with plots of available NUCAPS sounding points [click to enlarge]

NOAA-20 VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images, with plots of available NUCAPS sounding points [click to enlarge]

A toggle between NOAA-20 VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images (above) included plots of available NUCAPS sounding points. The temperature and dew point profiles for the green sounding point south-southeast of Jackson, Tennessee (station identifier KMKL) revealed a very unstable air mass in the pre-convective environment just ahead of the approaching MCS (below).

Temperature and dew point profiles for the NUCAPS sounding point south-southeast of Jackson,Tennessee [click to enlarge]

Temperature and dew point profiles for the NUCAPS sounding point south-southeast of Jackson,Tennessee [click to enlarge]