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.

Using GOES-R Level 2 stability products to help nowcast the cessation of convective initiation

July 4th, 2020 |

GOES-16 Visible Imagery (0.64 µm), left, and Derived Stability estimates of Lifted Index (right), from 1001 to 1656 UTC on 4 July 2020 (click to animate)

The animation above shows GOES-16 visible imagery (Band 2, 0.64 µm) and stability indices. Initially an obvious gradient in stability is present where isolated convection is developing over southwestern Wisconsin. As the gradient relaxes, the convection dissipates even though instability is, in general increasing. A radar animation (clipped from RealEarth) is shown below.  The showers have largely dissipated over southwestern Wisconsin by 1700 UTC.

The absence of gradients in the derived stability product can often mean that convection will not initiate.  In this case, the relaxation of the gradient went hand-in-hand with the dissipation of convection.

MRMS Base Reflectivity, 1000 – 1700 UTC on 4 July 2020 (Click to enlarge)