Blowing dust across the High Plains (Part 2)

January 15th, 2021 |

GOES-16 Dust RGB images, with and without hourly surface reports [click to play animation | MP4]

GOES-16 Dust RGB images, with and without hourly surface reports [click to play animation | MP4]

As discussed in this blog post, GOES-16 (GOES-East) Dust RGB images (above) displayed the distinct signature of a large blowing dust plume (brighter shades magenta/pink) that initially developed over drought-stricken areas of eastern Colorado and far western Kansas on 15 January 2021. Surface wind gusts in excess of 60 knots were seen in eastern Colorado near the source of the dust plume, with a peak gust of 63 knots or 72 mph — in fact, the anomalously-strong 925 hPa wind speeds were 5-6 sigma above the climatological mean (source). Pilot reports near the edges of the plume indicated visibility restrictions due to dust at altitudes of 5,000 feet over southwestern Kansas and 10,000 feet over northeastern New Mexico.

GOES-16 True Color RGB and Dust RGB images (created using Geo2Grid) are shown below.

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

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

Due to the presence of very dry throughout the lower/middle troposphere (Amarillo, Texas rawinsonde data), a signature of the dust plume was also evident in GOES-16 Near-Infrared “Cirrus” (1.37 µm) images (below).

GOES-16 Dust RGB and Near-Infrared

GOES-16 Dust RGB and Near-Infrared “Cirrus” (1.37 µm) images, with plots of Ceiling and Visibility [click to play animation | MP4]

After sunset, the plume signature persisted in GOES-16 Dust RGB images (below) as the blowing dust continued to move southeastward across Texas.

GOES-16 Dust RGB images, with and without hourly surface reports [click to play animation | MP4]

GOES-16 Dust RGB images, with and without hourly surface reports [click to play animation | MP4]

===== 16 January Update =====

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

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

On the following day, the dust plume began to flow off the Texas coast and over the Gulf of Mexico by 06 UTC — and although the plume signature began to diminish in the GOES-16 Dust RGB images after sunrise, it was very apparent in True Color RGB imagery (above). Note that the True Color images revealed some recirculation of dust which began to move inland toward the end of the day, as surface winds near the coast shifted to southeasterly (surface analyses).

GOES-16 Natural Color RGB images with plots of Ceiling and Visibility (below) showed that the dust reduced the visibility to 2.5 miles at a site located just off the Texas coast at 14 UTC, and to 5 miles at a site located about 100 miles offshore at 15 UTC.

GOES-16 Natural Color RGB images, with plots of Ceiling and Visibility [click to play animation| MP4]

GOES-16 Natural Color RGB images, with plots of Ceiling and Visibility [click to play animation| MP4]

In a toggle between VIIRS True Color and False Color RGB images from Suomi NPP (below), the dust plume was very evident over the Gulf of Mexico (where its lighter appearance stood out against the dark background of the water).

VIIRS True Color and False Color RGB images from Suomi NPP [click to enlarge]

VIIRS True Color and False Color RGB images from Suomi NPP [click to enlarge]

Winter storm affecting the southern Plains and Lower Mississippi Valley

January 10th, 2021 |

GOES-16 Mid-level Water Vapor (6.9 µm) images, with hourly surface weather type plotted in yellow [click to play animation | MP4]

GOES-16 Mid-level Water Vapor (6.9 µm) images, with hourly surface weather type plotted in yellow [click to play animation | MP4]

GOES-16 (GOES-East) Mid-level Water Vapor (6.9 µm) images (above) showed widespread precipitation that was developing across the southern High Plains and Lower Mississippi Valley on 10 January 2021. A closed middle-tropospheric low was providing forcing for ascent as it moved eastward across the region — and its cyclonic circulation was evident in the Water Vapor imagery. Storm total snowfall accumulations were as high as 11 inches in Texas, 8 inches in New Mexico, 6.5 inches in Louisiana and 4.5 inches in Mississippi.

GOES-16 Day Cloud Phase Distinction RGB images (below) revealed pockets of banded convection, whose glaciated cloud tops appeared as shades of green to yellow.

GOES-16 Day Cloud Phase Distinction RGB images [click to play animation | MP4]

GOES-16 Day Cloud Phase Distinction RGB images [click to play animation | MP4]

===== 11 January Update =====

GOES-16 Day Cloud Phase Distinction RGB and Day Snow-Fog RGB images [click to play animation | MP4]

GOES-16 Day Cloud Phase Distinction RGB and Day Snow-Fog RGB images [click to play animation | MP4]

On the following day, gaps in low-level cloud cover allowed the areal extent of resulting snow cover to be seen in GOES-16 Day Cloud Phase Distinction (snow = brighter shades of green) and Day Snow-Fog (snow = darker shades of red) RGB images (above).

A toggle between VIIRS True Color and False Color RGB images from Suomi NPP at 1936 UTC (below) provided another example of a RGB variant that is useful for the discrimination of low cloud vs. snow — snow cover appeared as shades of cyan in the False Color image.

VIIRS True Color and False Color RGB images from Suomi NPP [click to enlarge]

VIIRS True Color and False Color RGB images from Suomi NPP [click to enlarge]

Cold air advection in the Bering Sea

January 5th, 2021 |

GOES-17

GOES-17 “Red” Visible (0.64 µm) images [click to play animation | MP4]

GOES-17 (GOES-West) “Red” Visible (0.64 µm) images (above) displayed cloud streets across the Bering Sea — cloud features that frequently occur in areas with a strong flow of cold air over warmer water. This northerly flow of cold air across the Bering Sea was due to a strong pressure gradient between high pressure over Siberia and broad low pressure centered over the Gulf of Alaska (surface analyses).

In a GOES-17 Visible image with plots of ASCAT scatterometer surface winds from Metop-A (below), ASCAT sampled winds with speeds as high as 33 knots (although the instrument did not adequately sample the western portion of the Bering Sea, where the strongest winds likely existed).

GOES-17 "Red" Visible (0.64 µm) image, with plots of Metop-A ASCAT winds [click to enlarge]

GOES-17 “Red” Visible (0.64 µm) image, with plots of ASCAT winds from Metop-A [click to enlarge]

A sequence of Suomi NPP VIIRS Day/Night Band (0.7 µm) images (below) provided higher-resolution views of the cold air advection cloud streets.

Suomi NPP VIIRS Day/Night Band (0.7 µm) images [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) images [click to enlarge]

A toggle between Suomi NPP VIIRS Day/Night Band (DNB) and GOES-17 Visible images around 2320 UTC (below) highlighted the advantage of  VIIRS DNB imagery at high latitudes, particularly during low-light periods of the winter season.

Suomi NPP VIIRS Day/Night Band (0.7 µm) and GOES-17

Suomi NPP VIIRS Day/Night Band (0.7 µm) and GOES-17 “Red” Visible (0.64 µm) images [click to enlarge]

Tornadoes in Northern California

January 4th, 2021 |

GOES-16 “Red” Visible (0.64 µm, left) and “Clean” Infrared Window (10.35 µm, right) images, with SPC Storm Reports plotted in red [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm, left) and “Clean” Infrared Window (10.35 µm, right) images, with SPC Storm Reports plotted in red [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed thunderstorms moving eastward across Northern California on 04 January 2021, which produced 2 tornadoes (SPC Storm Reports) in the Sacramento Valley south and southeast of Red Bluff (KRBL). Vertical wind shear was evident in the Visible imagery, with low clouds moving northwestward and mid/upper-level clouds moving eastward.

A toggle between Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images at 2148 UTC (below) showed the storm that produced a tornado in Corning approximately 8 minutes earlier. The coldest cloud-top infrared brightness temperatures were around -38ºC (darker shades of yellow).

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images [click to enlarge]

MIMIC Total Precipitable Water images during the 02-04 January time period (below) showed a long ribbon of moisture (a necessary ingredient for convection) impinging upon Northern California — and a mid-tropospheric trough (500 hPa analysis) along with a cold front that was moving inland (surface analyses) provided forcing for ascent to further enhance convective development.

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

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