Flooding in South Dakota, Nebraska and Iowa

March 15th, 2019 |

GOES-16 Near-Infrared

GOES-16 Near-Infrared “Vegetation” (0.86 µm) and “Snow/Ice” (1.61 µm) images [click to play animation | MP4]

GOES-16 (GOES-East) Near-Infrared “Vegetation” (0.86 µm) and “Snow/Ice” (1.61 µm) images (above) revealed widespread river flooding (in the wake of rapid snow melt and heavy rainfall) across parts of southeastern South Dakota, eastern Nebraska and western/central Iowa on 15 March 2019. Water and flooded land appear as darkest shades of gray to black on both sets of images —  remaining snow cover also appeared as darker shades on the 1.61 µm imagery. Additional information regarding the flooding is available from NWS Sioux Falls

In a toggle between Suomi NPP VIIRS Visible (0.64 µm) and “Snow/Ice” (1.61 µm) images at 1821 UTC (below),1.61 µm imagery showed the darker shades of flooding over a north/south portion of Interstate 29 that was closed from State Highway 34 (west of Glenwood, Iowa) to the Iowa/Missouri border (south of Hamburg, Iowa).

Suomi NPP VIIRS Near-Infrared "Vegetation" (0.86 µm) and "Snow/Ice" (1.61 µm) images [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) and “Snow/Ice” (1.61 µm) images; Interstate Highways are plotted in red, while State Highways are plotted in gray [click to enlarge]

Comparisons of Terra MODIS True Color and False Color Red-Green-Blue (RGB) images at 1720 UTC viewed using RealEarth are shown below. In the False color imagery, snow cover appears as lighter shades of cyan, while water appears as darker shades of blue.

Terra MODIS True Color and False Color RGB images [click to enlarge]

Terra MODIS True Color and False Color RGB images, centered over eastern Nebraska [click to enlarge]

Terra MODIS True Color and False Color RGB images, centered near Vermillion, South Dakota [click to enlarge]

Terra MODIS True Color and False Color RGB images, centered near Vermillion, South Dakota [click to enlarge]

Terra MODIS True Color and False Color RGB images, centered near Ames, Iowa [click to enlarge]

Terra MODIS True Color and False Color RGB images, centered near Ames, Iowa [click to enlarge]

===== 16 March Update =====

Landsat-8 False Color image. centered to the east of Sioux City, Iowa [click to enlarge]

Landsat-8 False Color image centered to the east of Sioux City, Iowa [click to enlarge]

An overpass of the Landsat-8 satellite at 1706 UTC on 16 March provided 30-meter resolution False Color imagery — 2 sections of the swath are shown above and below. The RealEarth link to interactively view the image is here.

Landsat-8 False Color image. centered to the south of Omaha, Nebraska [click to enlarge]

Landsat-8 False Color image centered to the south of Omaha, Nebraska [click to enlarge]

Closer views centered at the NWS Omaha forecast office — which had to be evacuated due to flooding — and just west of Offutt Air Force Base are shown below.

Landsat-8 False Color image. centered at the NWS forecast office in Valley, Nebraska [click to enlarge]

Landsat-8 False Color image centered at the NWS forecast office in Valley, Nebraska [click to enlarge]

Landsat-8 False Color image. centered near Offutt Air Force Base, Nebraska [click to enlarge]

Landsat-8 False Color image centered just west of Offutt Air Force Base, Nebraska [click to enlarge]

Cyclone Idai makes landfall in Mozambique

March 14th, 2019 |

Meteosat-8 Infrared (10.8 µm) and DMSP-17 SSMIS Microwave (85 GHz) images of Cyclone Idai at 1630 UTC [click to enlarge]

Meteosat-8 Infrared Window (10.8 µm) and DMSP-17 SSMIS Microwave (85 GHz) images of Cyclone Idai at 1630 UTC [click to enlarge]

Cyclone Idai — which had been slowly intensifying over warm water within the Mozambique Channel since 09 March — made landfall as a Category 2 storm along the coast of Mozambique on 14 March 2019. A toggle between Meteosat-8 Infrared Window (10.8 µm) and DMSP-17 SSMIS Microwave (85 GHz) images from the CIMSS Tropical Cyclones site (above) revealed a large and well-defined eye and eyewall structure at 1630 UTC. Idai had been rated at Category 3 intensity during 3 periods of time during its life cycle, most recently at 12 UTC on the day of landfall.

At 1911 UTC, Metop-A ASCAT winds in excess of 60  knots were sampled just west of the eyewall region (below).

Meteosat-8 Infrared Window (10.8 µm) image, with plots of Metop-A ASCAT winds at 1911 UTC [click to enlarge]

Meteosat-8 Infrared Window (10.8 µm) image, with plots of Metop-A ASCAT winds at 1911 UTC [click to enlarge]

A comparison of VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP, visualized using RealEarth, is shown below.

NOAA-20 and Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]

NOAA-20 and Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]

Idai had been moving through an environment of very low deep-layer wind shear — a favorable factor for maintaining its intensity — as shown in an animation of Meteosat-8 Infrared Window (10.8 µm) images (below).

Meteosat-8 Infrared Window (10.8 µm) images with contours of satellite-derived Deep-Layer Wind Shear valid at 18 UTC [click to enlarge]

Meteosat-8 Infrared Window (10.8 µm) images with contours of satellite-derived Deep-Layer Wind Shear valid at 18 UTC [click to enlarge]

The MIMIC TC product (below) suggested that Idai might have been in the early stage of an eyewall replacement cycle (ERC) just prior to making landfall. This, after completing a separate ERC during the preceding 48 hours.

MIMIC TC morphed microwave imagery [click to enlarge]

MIMIC TC morphed microwave image product [click to enlarge]

The eye of Idal was becoming cloud-filled as it approached the Mozambique coast, as seen on EUMETSAT Meteosat-8 High Resolution Visible (0.8 µm) images (below).

Meteosat-8 High Resolution Visible (0.8 µm) images [click to play animation]

Meteosat-8 High Resolution Visible (0.8 µm) images [click to play animation]

A time series of surface data from the port city of Beira FQBR (below) showed deteriorating conditions before observations ceased at 15 UTC.

Surface observation data from Beira, Mozambique [click to enlarge]

Surface observation data from Beira, Mozambique [click to enlarge]


Incidentally, an overpass of the Landsat-8 satellite on 11 March provided a 30-meter resolution view of the eye (below), soon after Idai’s first period of rapid intensification to Category 3 strength (SATCON). Surface mesovortices were apparent within the eye.

Landsat-8 False Color image of the eye of Idai on 11 March [click to play a zooming animation]

Landsat-8 False Color image of the eye of Idai on 11 March [click to play a zooming animation]

Tehuano wind event

March 5th, 2019 |

GOES-17 (left) and GOES-16 (right)

GOES-17 (left) and GOES-16 (right) “Red” Visible (0.64 µm) images, with plots of surface wind barbs (speed in knots) [click to play animation | MP4]

After a strong arctic cold front plunged southward across the US, the Gulf of Mexico, and then southern Mexico during the previous two days (surface analyses), GOES-17 (GOES-West) and GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) revealed the hazy plume of dust-laden Tehuano gap wind flow as it emerged from the southern coast of Mexico and spread southwestward across the Gulf of Tehuantepec and the Pacific Ocean on 05 March 2019. An image of the topography of southeastern Mexico shows the location of Chivela Pass, through which these gap winds flow. Along the Gulf of Mexico coast, surface winds gusted to 30 knots and higher after the cold front moved through Minatitlán/Coatzacoalcos International Airport (station identifier MMMT); off the Pacific coast, a ship in the Gulf of Tehuantepec reported a sustained wind speed of 30 knots at 12 UTC.

The GOES-16 Aerosol Optical Depth product (below) showed lightly enhanced AOD values toward the outer edges of the swath of Tehuano winds. Note the gap in the product during the afternoon hours, when large amounts of sun glint were present.

GOES-16 Aerosol Optical Depth product [click to play animation | MP4]

GOES-16 Aerosol Optical Depth product [click to play animation | MP4]

The GOES-16 Dust Detection product (below) did portray Low to Medium-Confidence areas of dust within the gap wind flow.

GOES-16 Dust Detection product [click to play animation | MP4]

GOES-16 Dust Detection product [click to play animation | MP4]

An overpass of the Suomi NPP satellite after 19 UTC provided numerous NUCAPS sounding profiles both within and outside of the perimeter of the Tehuano winds (below).

GOES-16 Aerosol Optical Depth product, with plots of available NUCAPS sounding profiles [click to enlarge]

GOES-16 Aerosol Optical Depth product, with plots of available NUCAPS sounding profiles [click to enlarge]

A comparison between a dry NUCAPS sounding (Point D) where the gap winds were first exiting the coast over the Gulf of Tehuantepec and a more “undisturbed” moist sounding (Point M) northwest of the gap wind flow is shown below. The dry air of the Tehuano wind flow was very shallow, but its presence could be seen in differences between the marine boundary layer dew point profile and the resulting height of the Lifting Condensation Level (LCL).

Comparison of Dry (D) and Moist (M) NUCAPS soundings [click to enlarge]

Comparison of Dry (D) and Moist (M) NUCAPS soundings [click to enlarge]

A NOAA-20 VIIRS True Color Red-Green-Blue (RGB) image viewed using RealEarth (below) also showed the hazy signature of dust-laden air.

NOAA-20 VIIRS True Color Red-Green-Blue (RGB) image [click to enlarge]

NOAA-20 VIIRS True Color Red-Green-Blue (RGB) image [click to enlarge]

===== 06 March Update =====

GOES-16 Shortwave Infrared (3.9 µm) image, with Metop-A ASCAT winds [click to enlarge]

GOES-16 Shortwave Infrared (3.9 µm) image, with Metop-A ASCAT winds [click to enlarge]

GOES-16 Shortwave Infrared (3.9 µm) images with overlays of Metop-A ASCAT winds around 0338 UTC (above) and 1607 UTC (below) revealed a secondary surge of Tehuano winds on 06 March. The highest wind speed at 0338 UTC was 44 knots, with 38 knots being measured at 1607 UTC.

GOES-16 Shortwave Infrared (3.9 µm) image, with Metop-A ASCAT winds [click to enlarge]

GOES-16 Shortwave Infrared (3.9 µm) image, with Metop-A ASCAT winds [click to enlarge]

GOES-16 Shortwave Infrared images (below) were useful to monitor the spread of cooler water (shades of yellow) as the strong surface winds induced upwelling — especially since the resulting strong gradient in water temperatures was falsely interpreted as cloud by the GOES-16 Sea Surface Temperature product.

GOES-16 Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

GOES-16 Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

GOES-17 and GOES-16 Visible images (below) showed how the swath of Tehuano winds had spread out toward the south and southwest compared to the previous day.

GOES-17 (left) and GOES-16 (right) "Red" Visible (0.64 µm) images, with plots of surface wind barbs (speed in knots) [click to play animation | MP4]

GOES-17 (left) and GOES-16 (right) “Red” Visible (0.64 µm) images, with plots of surface wind barbs (speed in knots) [click to play animation | MP4]

In contrast to the previous day, the GOES-16 Dust Detection product (below) showed a larger coverage of dust on 06 March — with significantly more Medium Confidence areas.

GOES-16 "Red" Visible (0.64 µm) images + Dust Detection product [click to play animation | MP4]

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

A Suomi NPP VIIRS True Color RGB image at 1930 UTC (below) showed the hazy corridor of Tehuano winds bracketed by rope clouds.

Suomi NPP VIIRS True Color RGB image [click to enlarge]

Suomi NPP VIIRS True Color RGB image [click to enlarge]

Pyrocumulonimbus clouds in Western Australia

March 1st, 2019 |

Himawari-8

Himawari-8 “Red” Visible (0.64 µm) images [click to play animation | MP4]

Large bushfires burning in the southern portion of the state of Western Australia produced three pyroCumulonimbus (pyroCb) clouds on 01 March 2019. JMA Himawari-8 “Red” Visible (0.64 µm) images (above) showed that the pyroCb clouds drifted southeastward after formation.

Himawari-8 “Clean” Infrared Window (10.4 µm) images (below) further revealed the 3 distinct pyroCb pulses — 2 originating from the southernmost fire located near 29.5ºS / 124.4ºE, and a smaller one originating from a fire located farther to the northwest. Cloud-top infrared brightness temperatures cooled to the -59 to -63ºC range for the pair of larger pyroCbs (which was close to the tropopause temperature of -64ºC on Perth soundings: plot | data) with temperatures reaching -51ºC with the smaller northernmost pyroCb. Also apparent was a surge of cooler air moving northeastward behind a surface trough, whose arrival appeared to coincide with the pyroCb formation. A time series of surface data from Forrest (YFRT) clearly showed the arrival of the cool, moist air behind the trough.

Himawari-8 "Clean" Infrared Window (10.4 µm) images [click to play animation | MP4]

Himawari-8 “Clean” Infrared Window (10.4 µm) images [click to play animation | MP4]

Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images at 0537 UTC [click to enlarge]

Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images at 0537 UTC [click to enlarge]

As shown using RealEarth, an overpass of the Suomi NPP satellite provided a more detailed view of the first (and largest) pyroCb at 0537 UTC (above), with NOAA-20 capturing the second pyroCb cloud about an hour later at 0628 UTC (below). The coldest cloud-top infrared brightness temperature on the 0537 UTC Suomi NPP VIIRS image was -70ºC (darker black enhancement); in addition, there appeared to be an Above-Anvil Cirrus Plume associated with that pyroCb, extending southeastward from a subtle Enhanced-V signature at the upshear (northwestern) edge of the cloud (where the warmest temperature was -48ºC, green enhancement).

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images at 0628 UTC [click to enlarge]

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images at 0628 UTC [click to enlarge]

On Himawari-8 Shortwave Infrared (3.9 µm) images (below), the pyroCb clouds exhibited a warmer (darker gray) appearance compared to adjacent conventional cumulonimbus clouds — this is due to the fact that ice crystals ejected into the pyroCb anvils are smaller (due to their shorter residence time within the intense updrafts above the fires), and these smaller ice crystals are more effective reflectors of incoming solar radiation. The large flare-up of red-enhanced land during the day is due to highly reflective soils of the Great Victoria Desert that quickly become very hot.

Himawari-8 Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

Himawari-8 Shortwave Infrared (3.9 µm) images [click to play animation | MP4]