Tornado outbreak in Illinois

December 1st, 2018 |

GOES-16

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

The largest December tornado outbreak on record for the state of Illinois occurred on 01 December 2018 (NWS St. Louis | NWS Lincoln | NWS Quad Cities). 1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed the development of supercell convection which spawned the severe weather. in addition to the tornadoes, SPC Storm reports included hail as large as 1.75 inch in diameter and wind gusts of 75 mph.

GOES-16 “Clean” Infrared Window (10.3 µm) images (below) showed that cloud-top infrared brightness temperatures were as cold as -55ºC (darker shades of orange) with the more vigorous thunderstorm overshooting tops.

GOES-16

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

Plots of 18 UTC and 00 UTC rawinsonde data from Lincoln, Illinois (below) indicated that the coldest overshooting top brightness temperature of -55ºC seen in GOES-16 Infrared imagery was representative of a height just above the calculated air parcel Most Unstabe (MU) Equilibrium Level (EL).

Plot of 00 UTC Lincoln, Illinois rawinsonde data [click to enlarge]

Plots of 18 UTC and 00 UTC rawinsonde data from Lincoln, Illinois [click to enlarge]

A sequence of MODIS (from Terra and Aqua) and VIIRS (from Suomi NPP and NOAA-20) Visible and Infrared images (below) provided 2 higher-resolution views of the pre-storm environment, plus 3 views during/following convective initiation. Unfortunately, the thunderstorms in Illinois were located along the far eastern edge of the instrument scans in the final 2 images.

Terra/Aqua MODIS and Suomi NPP/NOAA-20 VIIRS Visible and Infrared images [click to enlarge]

Terra/Aqua MODIS and Suomi NPP/NOAA-20 VIIRS Visible and Infrared images [click to enlarge]

Even though the convection in western Illinois was near the limb of NOAA-20 (mis-labelled as Suomi NPP) VIIRS swath at 2007 UTC — degrading the spatial resolution and introducing some parallax error — the coldest detected Infrared brightness temperature (-52C) was still several degrees colder than that detected by GOES-16 (below). The two images are displayed in different projections, but the enhancements use the same color-vs-temperature breakpoints.

Comparison of GOES-16 ABI and NOAA-20 VIIRS Infrared Window images at 2007 UTC [click to enlarge]

Comparison of GOES-16 ABI and NOAA-20 VIIRS Infrared Window images at 2007 UTC [click to enlarge]

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]

GOES-17 / GOES-16 True Color Composite

November 26th, 2018 |
GOES-17 / GOES-16 True Color RGB composite [click to enlarge]

GOES-17 / GOES-16 True Color RGB composite [click to enlarge]

* GOES-17 imagery posted here is preliminary and non-operational *

A composite of GOES-17 and GOES-16 True Color Red-Green-Blue (RGB) imagery (above) was created by blending a total of 59 north-south swaths — each swath within +/- 23 minutes of “local Noon” (for example, the blue swaths using GOES-16) — during the period beginning at 1115 UTC on 26 November (over the eastern Atlantic Ocean and far western Africa, using GOES-16) and ending at 0200 UTC on 27 November 2018 (over the western Pacific Ocean, using GOES-17). Since the GOES-16/17 ABI does not have a true “Green” (0.51 µm) spectral band, that component of the RGB image is simulated using other Near-Infrared bands.

For perspective, the GOES-17/GOES-16 True Color composite is overlaid on a global “Blue Marble” background (below), which helps to emphasize the total areal coverage provided by the GOES-R constellation.

GOES-17 / GOES-16 True Color RGB composite [click to enlarge]

GOES-17 / GOES-16 True Color RGB composite [click to enlarge]

Notable Northern Hemisphere features seen in the imagery include (1) a pair of strong mid-latitude cyclones in the North Atlantic, (2) a large storm in the Gulf of Alaska with a trailing cold front moving inland along the west coast of North America, (3) two storms in the West Pacific, and (4) convective cloud bands along the Intertropical Convergence Zone (ITCZ) in the tropical Atlantic and Pacific basins (below).

Surface analyses from 12 UTC on 26 November to 00 UTC on 27 November [click to enlarge]

Surface analyses from 12 UTC on 26 November to 00 UTC on 27 November [click to enlarge]

Kudos to Rick Kohrs (SSEC) for masterfully perfecting the blending technique to create these composite GOES images.

Eruption of Volcán de Fuego in Guatemala

November 19th, 2018 |

GOES-16 Upper-level (6.2 µm, top), Mid-level (6.9 µm, center) and Low-level (7.3 µm, bottom) Water Vapor images [click to play animation | MP4]

GOES-16 Upper-level (6.2 µm, top), Mid-level (6.9 µm, center) and Low-level (7.3 µm, bottom) Water Vapor images [click to play animation | MP4]

Following several days of unrest, there was a moderate eruption of Volcán de Fuego in Guatemala beginning around 0630 UTC on 19 November 2018. GOES-16 (GOES-East) Upper-level (6.2 µm), Mid-level (6.9 µm) and Low-level (7.3 µm) Water Vapor images (above) displayed a signature of the volcanic plume, which drifted slowly northward and eastward for several hours. Since the 7.3 µm spectral band is also affected by SO2 absorption, the longer-lasting signal in the Low-level Water Vapor imagery suggests the plume contained SO2 as well as ash (since the 7.3 µm band is also sensitive to SO2 absorption).

A GOES-16 multiispectral Ash/Dust Cloud Height product from the NOAA/CIMSS Volcanic Cloud Monitoring site (below) indicated that the ash reached a maximum height of 7-8 km in the general vicinity of the summit between 1100-1200 UTC. A low-altitude plume of ash was seen drifting westward at heights of 1-5 km.

GOES-16 Ash Height product [click to play animation | MP4]

GOES-16 Ash/Dust Cloud Height product [click to play animation | MP4]

Along the southern coast of Guatemala, a 1400 UTC METAR from San Jose (MGSJ) reported a surface visibility of 5 statute miles with Volcanic Ash in the vicinity (VCVA) as the current weather type (below). At that time, the GOES-16 Split Window (10.3-12.3 µm) Brightness Temperature Difference was highlighting  concentrations of middle-tropospheric volcanic ash (yellow enhancement) farther inland closer to the volcano.

GOES-16 Split Window difference (10.3-12.3 µm) image, with METAR surface reports [click to enlarge]

GOES-16 Split Window difference (10.3-12.3 µm) image, with METAR surface reports [click to enlarge]