Thunderstorms over Argentina

November 29th, 2018 |

Suomi NPP VIIRS True Color RGB image at 1753 UTC [click to enlarge]

Suomi NPP VIIRS True Color RGB image at 1753 UTC [click to enlarge]

A Suomi NPP VIIRS True Color Red-Green-Blue (RGB) image viewed using RealEarth (above) showed numerous thunderstorms developing across the foothills of the Andes in western Argentina on 29 September 2018, in advance of a cold front that was moving northward.

Closer views of VIIRS True Color and Infrared Window (11.45 µm) images from Suomi NPP at 1753 UTC and NOAA-20 at 1843 UTC (below) depicted several cold overshooting tops (darker red enhancement) associated with the more vigorous thunderstorm updrafts.

Suomi NPP VIIRS True Color RGB and Infrared Windoe (11.45 µm) images at 1753 UTC [click to enlarge]

Suomi NPP VIIRS True Color RGB and Infrared Windoe (11.45 µm) images at 1753 UTC [click to enlarge]

NOAA-20 VIIRS True Color RGB and Infrared Windoe (11.45 µm) images at 1843 UTC [click to enlarge]

NOAA-20 VIIRS True Color RGB and Infrared Windoe (11.45 µm) images at 1843 UTC [click to enlarge]

In support of the RELAMPAGO-CACTI field experiment, a GOES-16 (GOES-East) Mesoscale Domain Sector had been positioned over the region, providing 1-minute imagery — animations of “Red” Visible (0.64 µm), Near-Infrared “Snow/Ice” (1.61 µm) and “Clean” Infrared Window (10.3 µm) imagery (below) showed the upscale development of the convection from 1300-2330 UTC. The largest storms were in the vicinity of and to the south of Mendoza (SAME) and Rio Cuarto (SAOC).

GOES-16

GOES-16 “Red” Visible (0.64 µm) images [click to play MP4 animation]

GOES-16 Near-Infrared "Snow/Ice" (1.61 µm) images [click to play MP4 animation]

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

GOES-16 "Clean" Infrared Window (10.3 µm) images [click to play MP4 animation]

GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play MP4 animation]

Toward the end of the day, a closer look at one storm along the southeastern end of the large convective complex (below) showed that it exhibited awell-defined enhanced-V signature around 20 UTC and shortly thereafter produced a long-lived Above-Anvil Cirrus Plume (AACP). Both are signatures of storms that often produce large hail, damaging winds or tornadoes.

GOES-16 "Red" Visible (0.64 µm, top), Near-Infrared :Snow/Ice" (1.61 µm, center) and "Clean" Infrared Window (10.3 µm, bottom) images [click to play MP4 animation]

GOES-16 “Red” Visible (0.64 µm, top), Near-Infrared :Snow/Ice” (1.61 µm, center) and “Clean” Infrared Window (10.3 µm, bottom) images [click to play MP4 animation]

The AACP exhibited a colder (around -55ºC, shades of orange) infrared brightness temperature than the anvil beneath it (-40 to -50ºC, green to yellow enhancement), due to the atmospheric temperature profile aloft as seen on 12 UTC rawinsonde data from nearby Santa Rosa (below). The sounding profile suggests that the AACP was at or perhaps above the tropopause.

Plot of 12 UTC Santa Rosa rawinsonde data [click to enlarge]

Plot of 12 UTC Santa Rosa rawinsonde data [click to enlarge]

Mesoscale Convective System in Argentina

November 13th, 2018 |

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images, with GLM Groups plotted in cyan/green [click to play MP4 animation]

In support of the RELAMPAGO-CACTI field experiment, GOES-16 (GOES-East) had a Mesoscale Domain Sector centered over northeastern Argentina on 13 November 2018 — and 1-minute “Clean” Infrared Window (10.3 µm) images with plots of GLM Groups (above) showed a large and long-lived Mesoscale Convective System moving eastward across far northeastern Argentina and expanding into southern Paraguay and southeastern Brazil. Note the large amount of lightning in the anvil region far southeast of the core of the convection.

The corresponding GOES-16 Infrared animation without lightning data is shown below. Minimum cloud-top infrared brightness temperatures often reached -90ºC and colder (yellow pixels embedded within darker violet regions).

GOES-16 "Clean" Infrared Window (10.3 µm) images [click to play MP4 animation]

GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play MP4 animation]

A comparison of NOAA-20 VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images using RealEarth (below) provided a very detailed view of the MCS at 1703 UTC. On the Infrared image, storm-top signatures often associated with severe thunderstorms included a well-defined enhanced-V (with a pronounced cold/warm couplet) situated over the Paraguay/Argentina border, and a “warm trench” surrounding the cold overshooting top at the vertex of the enhanced-V over extreme southern Paraguay.

NOAA-20 VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images at 1703 UTC [click to enlarge]

NOAA-20 VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images at 1703 UTC [click to enlarge]

The warm trench signature was also evident on 2-km resolution GOES-16 Infrared imagery at that same time (below), just west of Posadas, Argentina SARP. However, the warm trench surrounding the small overshooting top was only apparent from 1700 to 1705 UTC — so it was remarkable timing to have an overpass of the NOAA-20 satellite capture the brief signature in greater detail (at 375-meter resolution). A similar short-lived small overshooting top was seen at the vertex of the enhanced-V signature for the 6-minute period centered at 1652 UTC.

GOES-16 "Clean" Infrared Window (10.3 µm) image at 1703 UTC, with and without GLM Groups plotted in cyan/green [click to enlarge]

GOES-16 “Clean” Infrared Window (10.3 µm) image at 1703 UTC, with and without GLM Groups plotted in cyan/green [click to enlarge]

Severe thunderstorms in Pennsylvania

October 2nd, 2018 |

GOES-16

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

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed severe thunderstorms that moved across Pennsylvania on 02 October 2018, producing large hail, damaging winds and a few tornadoes (SPC storm reports). A parallax-corrected version of the animation — which shifts the location of SPC storm reports northwestward, to be more closely aligned with the storm-top features (assumed to be at a mean altitude of 12 km, based on 00 UTC Pittsburgh rawinsonde data) seen on satellite imagery — is available here.

The corresponding GOES-16 “Clean” Infrared Window (10.3 µm) images (below) indicated that the coldest cloud-top infrared brightness temperatures were in the -60 to -70ºC range (red to black enhancement).

GOES-16

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



Severe thunderstorms in Iowa and Minnesota

September 20th, 2018 |

GOES-16

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

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed thunderstorms that developed in the vicinity of a surface low and associated cold front (surface analyses) that was moving northeastward across the Upper Midwest during the afternoon and evening hours of 20 September 2018. These storms produced damaging winds and several tornadoes across northern Iowa and southern Minnesota (SPC storm reports | NWS FSD summary | NWS MPX summary). An animation of Visible images with hourly plots of surface reports is available here.

GOES-16 “Clean” Infrared Window (10.3 µm) images (below) showed cloud-top infrared brightness temperatures as cold as -70 to -75ºC (black to light gray enhancement) with the more vigorous overshooting tops. These thunderstorms continued moving eastward as a squall line, causing additional damaging winds across northern Wisconsin.

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play MP4 animation]