Severe weather outbreak across eastern Texas and the Deep South

April 13th, 2019 |

GOES-16

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

An outbreak of severe weather began in eastern Texas on the morning of 13 April 2019, where thunderstorms produced hail up to 3.0 inches in diameter, tornadoes and damaging winds (SPC storm reports). 1-minute Mesoscale Domain Sector GOES-16 “Red” Visible (0.64 µm) images (above) showed the clusters of thunderstorms that developed as a surface low and associated frontal boundaries moved eastward (surface analyses). The corresponding GOES-16 “Clean” Infrared Window (10.3 µm) images (below) revealed numerous overshooting tops with infrared brightness temperatures as cold as -70 to -75ºC. In addition, the storm producing 3.0-inch hail and damaging winds at 1428 UTC exhibited an Above-Anvil Cirrus Plume (Visible/Infrared toggle).

GOES-16 "Clean" Infrared Window (10.3 µm) images, with SPC storm reports plotted in purple [click to play MP4 animation]

GOES-16 “Clean” Infrared Window (10.3 µm) images, with SPC storm reports plotted in purple [click to play MP4 animation]

A comparison of Terra MODIS Visible (0.65 µm) and Infrared Window (11.0 µm) images at 1650 UTC is shown below.

Terra MODIS Visible (0.65 µm) and Infrared Window (11.0 µm) images [click to enlarge]

Terra MODIS Visible (0.65 µm) and Infrared Window (11.0 µm) images [click to enlarge]

Later in the day, the thunderstorms continued to produce a variety of severe weather as they moved eastward across Louisiana and Mississippi, as shown by GOES-16 Visible and Infrared images (below).

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]

GOES-16 "Clean" Infrared Window (10.3 µm) images, with SPC storm reports plotted in cyan [click to play MP4 animation]

GOES-16 “Clean” Infrared Window (10.3 µm) images, with SPC storm reports plotted in cyan [click to play MP4 animation]

After sunset, the thunderstorms continued to move eastward, spreading more serve weather across Mississippi into Alabama and far southern Tennessee (below).

GOES-16 "Clean" Infrared Window (10.3 µm) images, with SPC storm reports plotted in cyan [click to play MP4 animation]

GOES-16 “Clean” Infrared Window (10.3 µm) images, with SPC storm reports plotted in cyan [click to play MP4 animation]

VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP (below) provided additional views of the storms as they were moving across Mississippi and Alabama. Several bright lightning streaks were evident on the Day/Night Band images. Note: the NOAA-20 image (downloaded and processed from the Direct Broadcast ground station at CIMSS) is incorrectly labeled as Suomi NPP.

VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images from Suomi NPP and NOAA-20 [click to enlarge]

VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images from NOAA-20 at 0645 UTC and Suomi NPP at 0734 UTC [click to enlarge]

On a NOAA-20 VIIRS Day/Night Band (0.7 µm) image at 0825 UTC (below), an impressively-long (~400 mile) dark “post-saturation recovery streak” extended southeastward from where the detector sensed an area of very intense/bright lightning activity northeast of Mobile, Alabama.

NOAA-20 VIIRS Day/Night Band (0.7 µm) image at 0825 UTC [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) image at 0825 UTC [click to enlarge]

Large hail in Texas

April 6th, 2019 |

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with GLM Groups plotted in cyan and 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 with plots of GLM Groups (above) showed a large and electrically-active Mesoscale Convective System (MCS) which produced hail up to 4.5 inches in diameter (SPC storm reports) in eastern Texas on 06 Aprill 2019. These severe thunderstorms intensified generally along and north of a quasi-stationary frontal boundary (surface analyses).

The corresponding GOES-16 “Clean” Infrared Window (10.3 µm) images (below) showed that cloud-top infrared brightness temperatures associated with the strongest overshooting tops were around -70ºC (dark black enhancement). Earlier that afternoon, a higher spatial resolution Suomi NPP VIIRS Infrared Window (11.45 µm) image at 1950 UTC showed brightness temperatures as cold as -77ºC just northeast of where 2.0-inch diameter hail was reported at Marquez — located approximately midway between station identifiers KLHB and KPSN — at 2015 UTC. Assuming the 00 UTC Lake Charles sounding was representative of the air mass these storms were developing in, the -77ºC temperature would be at an altitude over 1 km higher than the Most Unstable parcel’s Equilibrium Level.

GOES-16 "Clean" Infrared Window (10.3 µm) images, with GLM Groups plotted in beige and SPC storm reports plotted in cyan [click to play animation | MP4]

GOES-16 “Clean” Infrared Window (10.3 µm) images, with GLM Groups plotted in beige and SPC storm reports plotted in cyan [click to play animation | MP4]

With better cloud-top shadow contrast, GOES-16 Near-Infrared “Snow/Ice” (1.61 µm) images (below) were helpful to locate the presence of Above-Anvil Cirrus Plume (AACP) features with the 2 strongest cells — and a comparison with 10.3 µm Infrared images indicated slightly warmer brightness temperatures with these AACPs (for example, at 2244 UTC and  0005 UTC).

GOES-16 Near-Infrared "Snow/Ice" (1.61 µm) images, with SPC storm reports plotted in red [click to play animation | MP4]

GOES-16 Near-Infrared “Snow/Ice” (1.61 µm) images, with SPC storm reports plotted in red [click to play animation | MP4]

GOES-16 All Sky Total Precipitable Water (TPW) and Convective Available Potential Energy (CAPE) products (below) showed the areal coverage and trends in moisture and instability across the region on that day.

GOES-16 All Sky Total Precipitable Water (TPW) images [click to play animation]

GOES-16 All Sky Total Precipitable Water (TPW) product [click to play animation]

 

GOES-16 All Sky Convective Available Potential Energy (CAPE) product [click to play animation]

GOES-16 All Sky Convective Available Potential Energy (CAPE) product [click to play animation]

Severe Thunderstorms with Above-Anvil Cirrus Plumes over Texas

March 22nd, 2019 |

GOES-16 "Clean" Infrared Window (10.3 µm) images, with SPC storm replorts plotted in cyan [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm, left) and “Clean” Infrared Window (10.3 µm, right) images, with SPC storm reports plotted in red/cyan [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images before sunset (above) and Infrared images after sunset (below) revealed Above-Anvil Cirrus Plume (AACP) features associated with severe thunderstorms that were producing large hail (SPC storm reports) over the Texas Panhandle on 22 March 2019.

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images, with SPC storm reports plotted in cyan [click to play animation | MP4]

A plot of 00 UTC rawinsonde data from Amarillo, Texas (below) showed that the Equilibrium Level (EL) and the tropopause was around 11 km — where the air temperature was near -60ºC, which is highlighted by a red enhancement on the Infrared imagery.  The calculated Maximum Parcel Level was around 13 km — where the air temperature was near -50ºC, which is highlighted by a yellow enhancement on the Infrared imagery; the MPL was the likely altitude of the AACP. Note on the 0245 UTC and 0258 UTC images that two of the hail reports were located near the colder (darker red to black) pixels of overshooting tops, which were close to the southern end of the warmer (brighter yellow) pixels of the AACP.

Plot of 00 UTC rawinsonde data from Amarillo, Texas [click to enlarge]

Plot of 00 UTC rawinsonde data from Amarillo, Texas [click to enlarge]

As pointed out on the Satellite Liaison Blog, some of the accumulating hail remained on the ground during the overnight hours — and the next morning, a hail swath signature was evident on GOES-16 Visible and Near-Infrared “Snow/Ice” (1.61 µm) imagery (below); the longest swath stretched for a distance of about 40 miles. The hail appeared as shades of white in the Visible imagery, and as darker shades of black in the Snow/Ice imagery (since ice is a strong absorber of radiation at the 1.61 µm wavelength). Note how the darker signature of wet soil (water is also a strong absorber at 1.61 µm) persisted on Near-Infrared  imagery even after the brighter signature of the melting hail swath disappeared on Visible imagery. Accumulating hail occurred over portions of Interstate 27 between Amarillo and Canyon, and Interstate 40 between Wildorado and Bushland; one trained storm spotter reported that the hail was several inches deep just northwest of Amarillo (Local Storm Reports).

GOES-16 "Red" Visible (0.64 µm) and Near-infrared "Snow/Ice" (1.61 µm) imagery [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) and Near-infrared “Snow/Ice” (1.61 µm) imagery [click to play animation | MP4]

As the morning sun was beginning to warm the soil, GOES-16 Land Surface Temperature images at 1402 and 1502 UTC or 9:02 and 10:02 AM local time (below) depicted temperatures up to 10ºF cooler within the hail swath compared to adjacent bare ground.

GOES-16 Land Surface Temperature product at 1402 and 1502 UTC [click to enlarge]

GOES-16 Land Surface Temperature product at 1402 and 1502 UTC [click to enlarge]

With ample illumination from the Moon (in the Waning Gibbous phase, at 92% of Full) a “visible image at night” was provided by the Suomi NPP VIIRS Day/Night Band (0.7 µm), which showed the hall swath at 0748 UTC or 2:48 AM local time — a toggle between that Day/Night Band image and an early morning GOES-16 Visible image is shown bellow.

Suomi NPP VIIRS Day/Night Band (0.7 µm) image at 0748 UTC and GOES-16 "Red" Visible (0.64 µm) image at 1427 UTC [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) image at 0748 UTC and GOES-16 “Red” Visible (0.64 µm) image at 1427 UTC [click to enlarge]

Intense central US midlatitude cyclone

March 13th, 2019 |

GOES-16 Air Mass RGB images [click to play animation | MP4]

GOES-16 Air Mass RGB images [click to play animation | MP4]

An unusually deep midlatitude cyclone — which easily met the criteria of a “bomb cyclone”, with its central pressure dropping 25 hPa in only 12 hours (surface analyses) — developed over the central US on 13 March 2019 (WPC storm summary). GOES-16 (GOES-East) Air Mass RGB images from the AOS site (above) showed the large size of the cloud shield — and the deeper red hues over the High Plains indicated the presence of ozone-rich air (from the stratosphere) within the atmospheric column as the tropopause descended. A preliminary new all-time low surface pressure of 975.1 hPa occurred at Pueblo, Colorado just after 13 UTC; to the east of Pueblo, a 970.4 hPa minimum pressure recorded at Lamar (plot) possibly set a new state record for Colorado.

On a map of NWS warnings/advisories valid at 14 UTC (below), Blizzard Warnings (red) extended from Colorado to the US/Canada border. South of the Blizzard Warnings, High Wind Warnings (brown) were in effect to the US/Mexico border.

Map of NWS warnings and advisories at 14 UTC [click to enlarge]

Map of NWS warnings and advisories at 14 UTC [click to enlarge]

GOES-16 Mid-level Water Vapor (6.9 µm) images (below) displayed a hook-like signature resembling that of a sting jet, which developed over the Texas/Oklahoma Panhandle area after 11 UTC. At 14 UTC an interesting burst of surface wind gusts occurred at 3 sites — Burlington CO, Goodland KS and Colby KS — which may have been related to the downward transfer of momentum along the leading edge of the sting jet flow. The corresponding 7.3 µm Low-level Water Vapor animations are also available: GIF | MP4.

GOES-16 Mid-level Water Vapor (6.9 µm) images [click to play animation | MP4]

GOES-16 Mid-level Water Vapor (6.9 µm) images [click to play animation | MP4]

The MIMIC Total Precipitable Water product (below) showed the northward surge of moisture from the Gulf of Mexico.

MIMIC Total Precipitable Water product [click to play animation | MP4]

MIMIC Total Precipitable Water product [click to play animation | MP4]

During the afternoon hours, the strong surface winds began to create plumes of blowing dust across parts of southeastern New Mexico and western Texas — a blowing dust signature first became apparent on GOES-16 Split Window Difference imagery as plumes of yellow, but then became more obvious on “Red” Visible (0.64 µm) images as the afternoon forward scattering angle increased (below). Blowing dust reduced the surface visibility to 1-2 miles at Snyder (KSNK) and Lubbock (KLBB).

GOES-16 "Red" Visible (0.64 µm) and Split Window Difference images [click to play animation | MP4]

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

The blowing dust signature (lighter shades of brown) was also easily seen in late-afternoon GOES-16 True Color RGB images (below) — the dust plume reached southwestern Oklahoma by the end of the daytime hours, restricting the visibility to 5 miles at Frederick (KFDR). The blowing dust was also evident in True Color imagery from GOES-17, as seen here.

GOES-16 True Color RGB images [click to play animation | MP4]

GOES-16 True Color RGB images [click to play animation | MP4]

Not long after the cyclone reached its lowest analyzed surface pressure of 968 hPa at 18 UTC, an overpass of the Suomi NPP satellite around 19 UTC provided a swath of NUCAPS soundings covering much of the storm (below). The air was very dry and stable near the near the center of the surface low in eastern Colorado (TPW=0.29″, CAPE=0 J/kg), in western Texas (TPW=0.31″, CAPE=0 J/kg) and near the frontal triple point in southeastern Nebraska (TPW=0.30″, CAPE=0 Jkg) — and out ahead of the warm front, the air was moist but stable behind a line of thunderstorms in northeastern Arkansas (TPW=1.09″, CAPE=0 J/kg) but both moist and unstable in western Mississippi (TPW=1.36″, CAPE=3506 J/kg).

Suomi NPP VIIRS Visible (0.64 µm) image, with overlays of the surface analysis and available NUCAPS soundings [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) image, with overlays of the surface analysis and available NUCAPS soundings [click to enlarge]

During the early stages of cyclone development, this system spawned severe thunderstorms that produced tornadoes, large hail and damaging winds across New Mexico and Texas (SPC storm reports) late in the day on 12 March. A GOES-17 (GOES-West) Mesoscale Domain Sector had been positioned over that region — which was helpful during a brief GOES-16 data outage — providing images at 1-minute intervals (below).

GOES-17

GOES-17 “Clean” Infrared Window (10.3 µm) images, with plots of SPC storm reports [click to play animation | MP4]

===== 14 March Update =====

GOES-16 Mid-level Water Vapor (6.9 µm) images, with hourly plots of surface winds and gusts in knots [click to play animation | MP4]

GOES-16 Mid-level Water Vapor (6.9 µm) images, with hourly plots of surface winds and gusts in knots [click to play animation | MP4]

GOES-16 Mid-level Water Vapor (6.9 µm) images (above) showed the storm moving slowly northeastward across Kansas, Nebraska and Iowa on 14 March — with strong winds continuing north and west of the surface low, blizzard conditions persisted across much of the Midwest.

Farther to the east, severe thunderstorms produced large hail, damaging winds and tornadoes as far north as northern Illinois/Indiana/Ohio and southern Lower Michigan (SPC storm reports | NWS Detroit) — as shown with 1-minute Mesoscale Domain Sector GOES-16 Visible images (below). The corresponding GOES-16 Infrared image animation is available here; the coldest cloud-top infrared brightness temperatures were only in the -30 to -40ºC range

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

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