Severe thunderstorms in Argentina

January 25th, 2019 |

GOES-16

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

On 25 January 2019 a GOES-16 (GOES-East) Mesoscale Domain Sector was positioned over Argentina in support of the RELAMPAGO-CACTI field experiment, providing imagery at 1-minute intervals. “Red” Visible (0.64 µm) images (above) showed thunderstorms that developed and moved northward over the Córdoba (SACO) area — surface observations there (plot | list) showed a sharp drop in temperatures along with wind gusts to 37 knots during the thunderstorm, which also produced hail and heavy rainfall. Two important features were revealed in the imagery: (1) an outflow boundary (from the decay of a large and long-lived Mesoscale Convective System to the southeast) which was moving slowly northward between between Rio Cuarto (SAOC) and Córdoba, likely helping to enhance boundary layer convergence and lift, and (2) a southward/southwestward flow of moist, unstable air — indicated by a plume of agitated cumulus clouds — approaching Córdoba. Toward the end of the day, the presence of an Above-Anvil Cirrus Plume also became evident in the Visible imagery.

The corresponding GOES-16 “Clean” Infrared Window (10.3 µm) images (below) showed that infrared brightness temperatures of the pulsing thunderstorm overshooting tops were frequently -90ºC or colder (yellow pixels embedded within darker purple). This indicates a significant overshoot of the tropopause, which had an air temperature of -72.1ºC at an altitude of 15.2 km on 12 UTC rawinsonde data. Also note the development of a pronounced cold/warm thermal couplet over the core region of the storm, as an enhanced-V storm top signature formed.

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 side-by-side comparison of GOES-16 Visible and Infrared images is displayed below.

GOES-16 "Red" Visible (0.64 µm, left) and "Clean" Infrared Window (10.3 µm, right) images [click to play MP4 animation]

GOES-16 “Red” Visible (0.64 µm, left) and “Clean” Infrared Window (10.3 µm, right) images [click to play MP4 animation]

A toggle between NOAA-20 VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images at 1734 UTC as viewed using RealEarth (below) showed the early stage of convective development south of Córdoba, as well as the large decaying MCS to the southeast. Cloud-top infrared brightness temperatures with the developing storms were already -80–C and colder (violet enhancement), about 10ºC colder than what was observed using lower-resolution GOES-16 imagery at that same time.

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

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images at 1734 UTC [click to enlarge]



Tornadoes in Ohio and Pennsylvania

January 8th, 2019 |

GOES-16

GOES-16 “Red” Visible (0.64 µm, left) and “Clean” Infrared Window (10.3 µm, right) images [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) showed an isolated thunderstorm which produced an EF-1 tornado in northeastern Ohio and 1.0-inch diameter hail in northwestern Pennsylvania during the morning hours on 08 January 2019 (SPC storm reports). (09 January update: a storm survey conducted by NWS Pittsburgh also confirmed an EF-1 tornado with the same storm that earlier produced the 1.0-inch diameter hail)

GOES-16 Mid-level Water Vapor (6.9 µm) images (below) revealed the broad cyclonic flow associated with a trough of low pressure aloft over the Great Lakes, and RAP40 model fields showed an elongated lobe of 500 hPa vorticity pivoting across Ohio and Pennsylvania. After the initial tornado/hail-producing thunderstorms during the late morning hours, a second round of storms produced additional hail in the afternoon.

GOES-16 Mid-level Water Vapor (6.9 µm) images, with overlays of surface fronts and NAM40 geopotential height and vorticity [click to play animation | MP4]

GOES-16 Mid-level Water Vapor (6.9 µm) images, with overlays of surface fronts and NAM40 model 500 hPa geopotential height and vorticity [click to play animation | MP4]



Rare December tornado in Washington

December 18th, 2018 |


GOES-17 “Red” Visible (0.64 µm) images, with plots of hourly surface reports and SPC storm reports [click to play animation | MP4]

* GOES-17 images shown here are preliminary and non-operational *

A rare December tornado occurred in Port Orchard, Washington on 18 December 2018. GOES-17 “Red” Visible (0.64 µm) images (above) and “Clean” Infrared Window (10.3 µm) images (below) showed the thunderstorms that moved eastward across the area in the wake of the passage of an occluded front earlier in the day.

GOES-17 "Clean" Infrared Window (10.3 µm) images, with plots of hourly surface reports and SPC storm reports [click to play animation | MP4]

GOES-17 “Clean” Infrared Window (10.3 µm) images, with plots of hourly surface reports and SPC storm reports [click to play animation | MP4]

Due to the relatively large GOES-17 satellite viewing angle (or zenith angle) of 56.38 degrees, there was a modest amount of parallax error in terms of the actual location of cloud-top features associated with the tornado-producing storm. A toggle between GOES-17 Visible and Infrared images at 2147 UTC with SPC tornado reports plotted at their actual and “parallax-corrected” locations (assuming a mean storm-top height of 8 km) are shown below — note how the parallax-corrected tornado plot location more closely aligns with top the parent thunderstorm.

GOES-17 "Red" Visible (0.64 µm) image at 2147 UTC, with SPC tornado report plots at their actual and "parallax-corrected" locations [click to enlarge]

GOES-17 “Red” Visible (0.64 µm) image at 2147 UTC, with SPC tornado report plots at their actual and “parallax-corrected” locations [click to enlarge]

GOES-17 "Clean" Infrared Window (10.3 µm) image at 2147 UTC, with SPC tornado report plots at their actual and "parallax-corrected" locations [click to enlarge]

GOES-17 “Clean” Infrared Window (10.3 µm) image at 2147 UTC, with SPC tornado report plots at their actual and “parallax-corrected” locations [click to enlarge]

A comparison of VIIRS Infrared Window (11.45 µm) images from Suomi NPP (Washington overpass time: 2042 UTC) and NOAA-20 (Washington overpass time: 2132 UTC) is shown below. The coldest cloud-top infrared brightness temperatures on the VIIRS images were -42ºC (bright green enhancement), which corresponded to altitudes of 7-8 km on 00 UTC rawinsonde data from Quillayute, Washington (plot).

VIIRS Infrared Window (11.45 µm) images from Suomi NPP (overpass time 2042 UTC) and NOAA-20 (overpass time 2132 UTC) [click to enlarge]

VIIRS Infrared Window (11.45 µm) images from Suomi NPP (overpass time 2042 UTC) and NOAA-20 (overpass time 2132 UTC), with the location of the SPC tornado report plotted in red [click to enlarge]

A toggle between NOAA-20 VIIRS Infrared Window (11.45 µm) images at the local overpass times of 1952 UTC and 2132 UTC, viewed using RealEarth (below), provided a closer view of the convection.

NOAA-20 VIIRS Infrared Window (11.45 µm) images at 1952 UTC and 2032 UTC [click to enlarge]

NOAA-20 VIIRS Infrared Window (11.45 µm) images at 1952 UTC and 2032 UTC [click to enlarge]

Severe thunderstorms in Argentina

December 10th, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm, top) and “Clean” Infrared Window (10.3 µm, bottom) images [click to play MP4 animation]

A comparison of GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) showed the development of thunderstorms well ahead of a cold front (surface analyses) that was moving northward across central Argentina on 10 December 2018. A Mesoscale Domain Sector had been positioned over that region in support of the RELAMPAGO-CACTI field experiment IOP15, providing imagery at 1-minute intervals. The northernmost storm (of a cluster of 3) featured a very pronounced overshooting top that was seen for several hours, briefly exhibiting infrared brightness temperatures as cold as -80ºC (violet enhancement) at 2133 UTC and 2134 UTC. Also noteworthy was the long-lived “warm trench” (arc of yellow enhancement) immediately downwind of the persistent cold overshooting top.

Plots of GOES-16 GLM Groups on the Visible and Infrared images (below) showed a good deal of lightning activity with this convection — especially in the leading anvil region east of the storm core. However, it is interesting to point out that there was a general lack of satellite-detected lightning directly over the large and persistent overshooting top. The GLM Groups were plotted with the default parallax correction removed, so the optical emissions of the lightning aligned with cloud-top features as seen on the ABI imagery.

GOES-16 "Red" Visible (0.64 µm, top) with GLM Groups and "Clean" Infrared Window (10.3 µm, bottom) images [click to play MP4 animation]

GOES-16 “Red” Visible (0.64 µm, top) with GLM Groups and “Clean” Infrared Window (10.3 µm, bottom) images [click to play MP4 animation]

A similar comparison of GOES-16 Visible and Near-Infrared “Snow/Ice” (1.61 µm) images (below) helped to highlight the formation of multiple Above-Anvil Cirrus Plume (AACP) features, which are signatures of thunderstorms that are producing (or could soon be producing) severe weather such as tornadoes, large hail or damaging winds. The appearance of gravity waves upshear (west) of the overshooting top was also very apparent.

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

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

Plot of severe weather reports [click to enlarge]

Plot of severe weather reports [click to enlarge]

There were several reports of hail with these particular thunderstorms (above), concentrated in the area between 35-36º S latitude and 62-65º W longitude. GOES-16 Visible images (below) showed this was the area under the path of the more northern storm with the prolonged overshooting top and the prominent AACP. This convection produced very large hail in Ingeniero Luiggi and General Villegas (located at 35.5º S, 64.5º W and 35º S, 63º W respectively) — see the tweets below for photos. On a side note, the large overshooting top began to take on an unusual darker gray appearance after 2230 UTC, possibly suggesting that boundary layer dust or particulate matter was being lofted to the cloud top by the very intense and long-lived updraft — the 18 UTC surface analysis showed that sites northwest of and south of the developing storms were reporting blowing dust.

GOES-16

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

Additional GOES-16 animations of these storms can be found on the Satellite Liaison Blog.

A zoom-in of NOAA-20 VIIRS True Color Red-Green-Blue (RGB) imagery at 1835 UTC viewed using RealEarth  (below) showed the 3 discrete thunderstorms in the vicinity of Santa Rosa.

NOAA-20 VIIRS True Color RGB image at 1835 UTC [click to enlarge]

NOAA-20 VIIRS True Color RGB image at 1835 UTC [click to enlarge]

A toggle between NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images at 1835 UTC (below) revealed the cold overshooting tops associated with each of the 3 thunderstorms. Also note the swath of wet soil in the wake of the southern storm, which appears darker in the True Color image and cooler (lighter shades of gray) in the Infrared image.

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images at 1835 UTC [click to enlarge]

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images at 1835 UTC [click to enlarge]

A toggle between NOAA-20 VIIRS Infrared Window (11.45 µm) images at 1835 UTC on 10 December and 0555 UTC on 11 December (below) showed the upscale growth into a large Mesoscale Convective System (MCS) that moved northeastward (eventually producing flooding in Rosario).

NOAA-20 VIIRS Infrared Window (11.45 µm) images at 1835 UTC on 10 December and 0555UTC on 11 December [click to enlarge]

NOAA-20 VIIRS Infrared Window (11.45 µm) images at 1835 UTC on 10 December and 0555 UTC on 11 December [click to enlarge]


===== 11 December Update =====

GOES-16

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

On the following day, GOES-16 Visible images (above) showed that additional severe thunderstorms developed across northern Argentina, in the general vicinity of a stationary front (surface analyses) east of Cordoba (SACO). Plots of GLM Groups (below) indicated that these storms produced a great deal of lightning.

GOES-16 "Red" Visible (0.64 µm) images, with GLM Groups plotted in red [click to play MP4 animation]

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

The corresponding GOES-16 Infrared images, with and without plots of GLM Groups, are shown below. The coldest cloud-top infrared brightness temperatures were frequently colder than -80ºC, even reaching -90ºC (yellow pixels embedded within darker purple areas) from 1946, 1947 and 1948 UTC.

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]

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

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

A NOAA-20 VIIRS True Color RGB image (below) showed the cluster of thunderstorms east of Cordoba at 1817 UTC.

NOAA-20 VIIRS True Color RGB image at 1817 UTC [click to enlarge]

NOAA-20 VIIRS True Color RGB image at 1817 UTC [click to enlarge]

A toggle between NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images at 1817 UTC (below) showed the easternmost storm which produced a tornado at Santa Elena.

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images at 1817 UTC [click to enlarge]

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images at 1817 UTC [click to enlarge]