Severe thunderstorms in South Dakota

August 30th, 2020 |

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

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

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images — with and without an overlay of GLM Flash Extent Density (above) showed the rapid development of thunderstorms along a cold front across eastern South Dakota on 30 August 2020. One particularly well-defined and long-lived Enhanced-V signature with an Above-Anvil Cirrus Plume (reference | VISIT training) was seen in the Visible and Infrared imagery, which extended northeastward from the core of a thunderstorm where large hail and tornadoes were occurring.

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

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

1-minute GOES-16 Visible images with time-matched plots of SPC Storm Reports are displayed above, with the corresponding Infrared images below.

GOES-16 “Clean” Infrared Window (10.35 µm) images, with time-matched 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]

There were some overshooting tops which exhibited infrared brightness temperatures as cold as -72ºC — a plot of 00 UTC rawinsonde data from Aberdeen, South Dakota (below) indicated that this was about 7ºC colder than the tropopause temperature of -66.1ºC.

Plot of 00 UTC rawinsonde data from Aberdeen, South Dakota [click to enlarge]

Plot of 00 UTC rawinsonde data from Aberdeen, South Dakota [click to enlarge]

Category 4 Hurricane Laura makes landfall in Louisiana

August 27th, 2020 |

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

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

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images — with and without an overlay of GLM Flash Extent Density (above) showed Category 4 Hurricane Laura as it made landfall near Cameron, Louisiana around 0600 UTC on 27 August 2020. The GLM data showed intermittent lightning activity along the inner eyewall region of the hurricane.

Strong outer convective bands ahead of Laura’s landfall produced isolated tornadoes as it moved onshore (SPC Storm Reports). Peak wind gusts included 116 knots or 133 mph at Lake Charles at 0642 UTC (in addition, Lake Charles reported another peak wind gust of 113 knots or 130 mph at 0703 UTC). Strong winds associated with the northern portion of the eyewall destroyed the Lake Charles radar (YouTube video) — the final reflectivity and velocity images at 0553 UTC (12:53 am CDT) are shown here (the 0.5-degree inbound and outbound radial velocity values were as high as 160-162 mph).


Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0751 UTC (credit William Straka, CIMSS) [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0751 UTC (credit William Straka, CIMSS) [click to enlarge]

A toggle between Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 0751 UTC (above) revealed the nighttime glow of lights from Lake Charles (since that city was near the inside edge of the eye of Hurricane Laura at that time) — in other locations across Louisiana and far eastern Texas, the signature of city lights was muted to varying degrees by the storm’s dense cloud cover and precipitation.

The corresponding Suomi NPP ATMS Microwave (88.2 GHz) and MiRS Rainfall Rate images at 0751 UTC (below) depicted the pattern of precipitation that was spreading inland.

Suomi NPP ATMS Microwave (88.2 GHz) and MiRS Rainfall Rate images at 0751 UTC (credit William Straka, CIMSS) [click to enlarge]

Suomi NPP ATMS Microwave (88.2 GHz) and MiRS Rainfall Rate images at 0751 UTC (credit William Straka, CIMSS) [click to enlarge]

DMSP-17 and GMI Microwave (85 GHz) images from the CIMSS Tropical Cyclones site (below) showed the structure of Laura several hours before landfall.

DMSP-17 SSMI Microwave (85 GHz) image at 0054 UTC [click to enlarge]

DMSP-17 SSMI Microwave (85 GHz) image at 0054 UTC [click to enlarge]

GMI Microwave (85 GHz) image at 0255 UTC [click to enlarge]

GMI Microwave (85 GHz) image at 0255 UTC [click to enlarge]

An animation of the MIMIC-TC product during the 26-27 August period (below) showed the deterioration of the eyewall structure after landfall.

MIMIC-TC product during the 26-27 August period [click to enlarge]

MIMIC-TC product during the 26-27 August period [click to enlarge]

Prior to making landfall, Laura had been moving across the warm waters of the Gulf of Mexico — however, it began to encounter an environment characterized by increasingly unfavorable deep-layer wind shear as it approached the Gulf Coast (below) which likely prevented further intensification.

GOES-16 Infrared Window (11.2 µm) images, with an overlay of deep-layer wind shear [click to enlarge]

GOES-16 Infrared Window (11.2 µm) images, with an overlay of deep-layer wind shear [click to enlarge]

Laura becomes a hurricane in the Gulf of Mexico

August 25th, 2020 |

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

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

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed Laura during the the 12-hour period after it intensified from a Tropical Storm to a Hurricane in the southern Gulf of Mexico at 1215 UTC on 25 August 2020. Numerous convective overshooting tops were observed, some exhibiting cloud-top infrared brightness temperatures as cold as -87ºC.

A comparison of NOAA-20 MiRS Microwave (88 GHz), GOES-16 “Red” Visible (0.64 µm) and GOES-16 “Clean” Infrared Window (10.35 µm) images at 1851 UTC (below) revealed a curved convective band wrapping around the eye of Laura.

NOAA-20 MIRS Microwave (88 GHz), GOES16

NOAA-20 MiRS Microwave (88 GHz), GOES-16 “Red” Visible (0.64 µm) and GOES-16 “Clean” Infrared Window (10.35 µm) images at 1851 UTC [click to enlarge]

In a toggle between Infrared Window images from Suomi NPP (11.45 µm) and GOES-16 (10.35 µm) at 1943 UTC (below), the coldest cloud-top infrared brightness temperature was -91.9ºC in the Suomi NPP image (compared to -87.0ºC on the GOES-16 image). The northwestward parallax displacement associated with GOES-16 imagery over the southern Gulf of Mexico was also apparent.

Infrared Window images from Suomi NPP (11.45 µm) and GOES-16 (10.35 µm) images at 1943 UTC [click to enlarge]

Infrared Window images from Suomi NPP (11.45 µm) and GOES-16 (10.35 µm) at 1943 UTC [click to enlarge]

True-color imagery from the CIMSS Direct Broadcast site

August 25th, 2020 |

NOAA-20 VIIRS True-Color Image of Lake Ontario, 1709 UTC on 25 August 2020 (Click to enlarge)

The Cooperative Institute for Meteorological Satellite Studies (CIMSS) acquires data directly from polar-orbiting satellites such as Suomi-NPP and NOAA-20 through Direct Broadcast antennae that are on the UW-Madison Campus. Community Satellite Processing Package (CSPP) software takes the Direct Broadcast signal and creates data files and, with Polar2Grid, imagery that are easily accessible at this ftp site where users can find directories for Suomi-NPP (ftp://ftp.ssec.wisc.edu/pub/eosdb/npp/) and for NOAA-20 (ftp://ftp.ssec.wisc.edu/pub/eosdb/j01/). ATMS and CrIS data (used in numerical modeling) are processed first and usually are finished processing in about an hour.

Direct Broadcast data is the fastest way to acquire data from Polar Orbiting satellites.

VIIRS True Color imagery (that is then fed to the CIMSS VIIRS Today Website), with a 375-m resolution (at nadir) has spectacular detail. The image above, from NOAA-20, (here is a link to the entire image, a link that will become stale after about 10 days) shows color variability over Lake Ontario at 1709 UTC.  The image below shows the Suomi-NPP scene of the same region 50 minutes later, at 1759 UTC (cut from this entire image.) One could compare the images and estimate lake surface currents.

Suomi-NPP VIIRS True-Color Image of Lake Ontario, 1759 UTC on 25 August 2020 (Click to enlarge)

The blog post immediately below this one notes the extensive smoke from Western Fires over the Midwest United States. The 1709 UTC image, below, shows the smoke pall along the east coast — but mostly north of the mouth of Chesapeake Bay.

NOAA-20 VIIRS True-color imagery over the Mid-Atlantic States, 1709 UTC on 25 August 2020 (Click to enlarge)

Similarly, True-Color imagery at 1759 UTC on 25 August 2020 from Suomi-NPP shows thick smoke over much of the Midwest south of a frontal boundary over the western Great Lakes.

Suomi NPP True Color Imagery over the western Great Lakes and midwest, 1759 UTC on 25 August 2020 (Click to enlarge)

The Direct Broadcast Antenna in Madison can view acquire information from satellites that are over the northwest Caribbean, in northern Canada, and along the west coast of the United States, as shown by the dashed circle in this image (from this website). On 25 August, imagery of Hurricane Laura was available. The image below is the true-color image of Laura at 1759 UTC from Suomi NPP. Beneath that is the true-color image of Laura at 1849 UTC from NOAA-20. The two different satellites in similar orbits — 50 minutes apart — can be used to create high spatial resolution animations. This is easier to do when satellite data are re-projected onto a fixed grid, of course, as done for the VIIRS Today website. (NOAA-20 view or Laura today; Suomi-NPP view or Laura today, both from VIIRS Today.)

 

Suomi-NPP True-Color imagery over Hurricane Laura, 1759 UTC on 25 August 2020 (Click to enlarge)

NOAA-20 True-Color image of Hurricane Laura, 1849 UTC on 25 August 2020 (Click to enlarge)

Both the VIIRS Today Website and the direct broadcast FTP directories include True Color, False Color, and Day Night Band imagery. Direct Broadcast imagery extends farther south and especially farther north than imagery at VIIRS Today. The Direct Broadcast ftp directory also contains images of individual ATMS channels, individual VIIRS channels (including the Day Night Band), MIRS products such as Rain Rate, and CLAVR-X cloud products (Rain Rate, Cloud Mask, Cloud Phase, etc.).

For the latest information on Hurricane Laura in the Gulf, refer to the National Hurricane Center.