Severe thunderstorms exhibiting Above-Anvil Cirrus Plumes over the Dakotas

July 4th, 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 two severe thunderstorms along the North Dakota / South Dakota border region, which exhibited Above-Anvil Cirrus Plumes  (reference | VISIT training).

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]

A longer animation of GOES-16 Visible images with plots of time-matched SPC Storm Reports is shown above, with GOES-16 Infrared images shown 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]

Pulsing overshooting tops were seen whose cloud-top infrared brightness temperatures were in the -70 to -78ºC range — according to a plot of 00 UTC rawinsonde data from Aberdeen, South Dakota (below), this represented a 1-2 km overshoot of the Most Unstable (MU) air parcel’s Equilibrium Level (EL).

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]

Several hours later, another thunderstorm that produced damaging winds in southwestern North Dakota exhibited a residual Above-Anvil Cirrus Plume in central North Dakota as the storm was dissipating, seen in Suomi NPP VIIRS Infrared Window (11.45 µm) and Day/Night Band (0.7 µm) images at 0915 UTC (below). Coldest cloud-top infrared brightness temperatures in the overshooting top region were in the -60 to -66ºC range, while within the warmer AACP feature extending eastward they were in the -52 to -55ºC range.

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

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

Blowing dust in southern Bolivia

July 4th, 2020 |

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

GOES-16 True Color RGB images (credit: Tim Schmit, ASPB/CIMSS) [click to play animation | MP4]

GOES-16 (GOES-East) True Color Red-Green-Blue (RGB) images created using Geo2Grid (above) showed plumes of blowing dust originating from dry river beds along portions of the Río Grande O Guapay and Río Parapetí in southern Bolivia on 04 July 2020. Strong northerly winds developed across that region, just east of the axis of a deepening trough of low pressure.

VIIRS True Color RGB images from Suomi NPP and NOAA-20 as visualized using RealEarth (below) provided a more detailed view at the blowing dust plumes.

VIIRS True Color RGB images from Suomi NPP and NOAA-20 [click to enlarge]

VIIRS True Color RGB images from Suomi NPP and NOAA-20 [click to enlarge]

A plot of surface report data from Viro Viru International Airport, Santa Cruz de la Sierra — located not far to the north of the blowing dust plumes — showed northerly winds gusting as high as 36 knots (41 mph) at 20 UTC (below).

Plot of surface report data from Viro Viru International Airport [click to enlarge]

Plot of surface report data from Viro Viru International Airport [click to enlarge]

Thanks to Santiago Gassó for pointing out these dust features.

Actinoform clouds near Hawai’i

June 30th, 2020 |

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

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

GOES-17 (GOES-West) “Red” Visible (0.64 µm) images (above) revealed 3 cyclonically-rotating actinoform cloud structures that were moving west-southwestward toward the Hawaiian Islands on 30 June 2020 (surface analyses).

A closer look at the northernmost actinoform feature showed it moving over Buoy 51000 (located northeast of Hawai’i) around 04 UTC on 01 July — there was somewhat of an increase in 1-minute wind speeds and wind gusts as it approached, but no obvious perturbation was seen in the air pressure (it appeared to have arrived during the typical ~12-hourly drop in pressure).

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

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

A sequence of 3 hourly (at 0010, 0110 and 0210 UTC) panoramic camera views from Buoy 51000 (below) suggested that there were rain showers reaching the ocean surface beneath one of the actinoform’s radial arms at 0210 UTC (GOES-17 Visible image).

Sequence of 3 hourly (at 0010, 0110 and 0210 UTC) panoramic camera views from Buoy 51000 [click to enlarge]

Sequence of 3 hourly panoramic camera views from Buoy 51000, at 0010, 0110 and 0210 UTC [click to enlarge]

True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) VIIRS images from NOAA-20 and Suomi NPP as visualized using RealEarth (below) provided a detailed view of 2 of the actinoform clouds. The radial arms that comprised the cloud features remained within the marine boundary layer, so they exhibited fairly warm cloud-top infrared brightness temperatures.

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

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

Plots of rawinsonde data from Hilo, Hawai’i (below) indicated that the marine boundary layer was strongly capped by a temperature inversion at an altitude of 1.3-1.5 km (where the air temperature was around +15ºC — which was very close to the minimum cloud-top infrared brightness temperatures exhibited by the actinoform clouds).

Plots of rawinsonde data from Hilo, Hawai'i [click to enlarge]

Plots of rawinsonde data from Hilo, Hawai’i [click to enlarge]

Other examples of actinoform clouds have been shown in May 2019, March 2008, March 2007 and June 1997.

Exploring the effects of GOES-17 parallax over Alaska

June 27th, 2020 |

GOES-17 “Red” Visible (0.64 µm) and

Topography, GOES-17 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

GOES-17 (GOES-West) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (above) displayed the formation of an orographic rotor cloud downwind (north-northeast) of the Kigluaik and Bendeleben Mountains in the Seward Peninsula of Alaska on 27 June 2020. Even though the highest terrain in those mountain ranges was only 3700-4700 feet (1.1-1.4 km), the coldest cloud-top infrared brightness temperatures within the rotor cloud feature were around -50 to -51ºC.

A plot of rawinsonde data from Nome (below) showed the strong southwesterly winds that existed within most the troposphere on that day. The tropopause temperatures were around -51ºC at altitudes of 9.4-9.6 km — indicating that these high-altitude rotor clouds were forced by vertically-propagating waves initiated by interaction of the anomalously-strong southerly/southwesterly lower-tropospheric flow with the west-to-east oriented mountain ranges.

Plot of rawinsonde data from Nome, Alaska [click to enlarge]

Plot of rawinsonde data from Nome, Alaska [click to enlarge]

Comparisons of topography and Visible/Infrared images from Suomi NPP and GOES-17 around 1320 UTC and 2140 UTC are shown below. Since there is generally very little parallax offset associated with imagery from polar-orbiting satellites (such as Suomi NPP), the rotor cloud appeared closer to the topography that helped to force development of that cloud feature.

Topography, Suomi NPP VIIRS Visible (0.64 µm) and GOES-17 "Red" Visible (0.64 µm) images around 1320 UTC [click to enlarge]

Topography, Suomi NPP VIIRS Visible (0.64 µm) and GOES-17 “Red” Visible (0.64 µm) images around 1320 UTC [click to enlarge]

Topography, Suomi NPP VIIRS Infrared Window (11.45 µm) and GOES-17 "Clean" Infrared Window (10.35 µm) images around 1320 UTC [click to enlarge]

Topography, Suomi NPP VIIRS Infrared Window (11.45 µm) and GOES-17 “Clean” Infrared Window (10.35 µm) images around 1320 UTC [click to enlarge]

Topography, Suomi NPP VIIRS Visible (0.64 µm) and GOES-17 "Red" Visible (0.64 µm) images around 2140 UTC [click to enlarge]

Topography, Suomi NPP VIIRS Visible (0.64 µm) and GOES-17 “Red” Visible (0.64 µm) images around 2140 UTC [click to enlarge]

Topography, Suomi NPP VIIRS Infrared Window (11.45 µm) and GOES-17 "Clean" Infrared Window (10.35 µm) images around 2140 UTC [click to enlarge]

Topography, Suomi NPP VIIRS Infrared Window (11.45 µm) and GOES-17 “Clean” Infrared Window (10.35 µm) images around 2140 UTC [click to enlarge]

Plots of GOES-17 parallax correction vectors and displacements (in km) for a 30,00-feet (9.1 km) cloud feature at select points over the Alaska region (from this site) are shown below. For such a cloud feature over the Seward Peninsula, the parallax offset would be about 40 km (25 miles) — which closely corresponded to the offset seen between the GOES-17 and Suomi NPP images shown above.

Plots of GOES-17 parallax correction vectors and displacements (in km) for a 30,000-foot (9.1 km) cloud feature at select points over the Alaska region [click to enlarge]

Plots of GOES-17 parallax correction vectors and displacements (in km) for a 30,000-foot (9.1 km) cloud feature at select points over the Alaska region [click to enlarge]