Mesoscale vortices in Oregon and Idaho

December 7th, 2018 |

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

As noted by NWS Boise, a pair of mesoscale vortices were apparent over far southeastern Oregon and far southwestern Idaho on 07 December 2018. A comparison of GOES-17 and GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (below) showed that even with the larger GOES-16 viewing angle (or satellite zenith angle), the features could still be seen rather well.

GOES-17 and GOES-16

GOES-17 and GOES-16 “Red” Visible (0.64 µm) images [click to play animation | MP4]

Topography in feet [click to enlarge]

Topography in feet [click to enlarge]

A look at the local topography (above) indicated that the low altitude quasi-stationary Oregon vortex was located within the Owyhee River valley, just northeast of the Rome airport KREO. With high pressure centered over the Idaho/Montana border (surface analyses), the low-level southerly/southeasterly flow seen in a plot of 12 UTC rawinsonde data from Boise, Idaho (below) was being channeled between the higher terrain surrounding the valley; interactions with that terrain likely caused the Oregon vortex to form. The Idaho vortex was moving toward the northeast — Boise rawindsonde data showed southwest winds at 727 hPa or an altitude of 2700 feet. The 2 vortices wre quite small, having a diameter of only

12 UTC rawinsonde data from Boise, Idaho [click to enlarge]

12 UTC rawinsonde data from Boise, Idaho [click to enlarge]

The pair of vortices likely formed just before or right around sunrise, since there was no signature seen in earlier nighttime MODIS or VIIRS “Fog/stratus” infrared Brightness Temperature Difference (BTD) images {below).

MODIS and VIIRS

MODIS and VIIRS “Fog/stratus” infrared BTD images [click to enlarge]

Industrial and ship plumes in supercooled clouds

December 4th, 2018 |

MODIS and VIIRS

MODIS and VIIRS “Fog/stratus” BTD images [click to enlarge]

A sequence of nighttime MODIS and VIIRS “Fog/stratus” infrared Brightness Temperature Difference (BTD) images (above) revealed long plumes (darker shades of red) streaming southwestward for over 200 miles from their industrial point sources in the Mesabi Range of northeastern Minnesota on 03 December 2018.

During the subsequent daytime hours, a comparison of GOES-16 (GOES-East) “Red” Visible (0.64 µm), Near-Infrared “Snow/Ice” (1.61 µm), Near-Infrared “Cloud Particle Size” (2.24 µm) and Shortwave Infrared (3.9 µm) images (below) showed signatures of these Mesabi Range plumes along with others emanating from industrial or power plant sources. A few ship tracks were also apparent across Lake Superior.

Particles emitted from the exhaust stacks at power plants and industrial sites (as well as ships) can act as efficient cloud condensation nuclei, which causes the formation of large numbers of supercooled water droplets having a smaller diameter than those found within the adjacent unperturbed supercooled clouds — and these smaller supercooled cloud droplets are better reflectors of incoming solar radiation, thereby appearing brighter in the Near-Infrared and warmer (darker gray) in the Shortwave Infrared images.

GOES-16

GOES-16 “Red” Visible (0.64 µm), Near-Infrared “Snow/Ice” (1.61 µm), Near-Infrared “Cloud Particle Size” (2.24 µm) and Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

On the following night, another sequence of MODIS and VIIRS “Fog/stratus” infrared Brightness Temperature Difference (BTD) images (below) highlighted a number of industrial and power plant plumes across Minnesota, northern Wisconsin and the Upper Peninsula of Michigan. The curved shape of many of these plumes resulted from boundary layer winds shifting from northerly to westerly as the night progressed.

MODIS and VIIRS "Fog/stratus" BTD images [click to enlarge]

MODIS and VIIRS “Fog/stratus” BTD images [click to enlarge]

During the following daytime hours on 04 December, a comparison of VIIRS Visible (0.64 µm), Near-Infrared “Snow/Ice” (1.61 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images (below) showed 2 plume types across eastern Nebraska. There were several of the brighter/warmer plumes similar to those noted on the previous day across Minnesota/Wisconsin/Michigan — but one large plume originating from industrial sites just east of Norfolk (KOFK) had the effect of eroding the supercooled cloud deck via glaciation (initiated by the emission of particles that acted as efficient ice nuclei) and subsequent snowfall. This is similar to the process that creates aircraft “distrails” or “fall streak clouds” as documented here, here and here.

VIIRS Visible (0.64 µm), Near-Infrared

VIIRS Visible (0.64 µm), Near-Infrared “Snow/Ice” (1.61 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images [click to enlarge]


Farther to the east over Ohio and Pennsylvania, another example of the 2 plume types was seen (below) — one plume originating from an industrial site near Cleveland was glaciating/eroding the supercooled cloud and producing snowfall, while another bright/warm supercooled droplet plume was moving southeastward from a point source located west of Indiana County Airport KIDI.

The Cleveland plume was captured by an overpass of the Landsat-8 satellite, with a False Color Red-Green-Blue (RGB) image viewed using RealEarth providing great detail with 30-meter resolution (below). A small “overshooting top” can even be seen above the industrial site southeast of Cleveland, with the swath of glaciated and eroding cloud extending downwind (to the southeast) from that point.

Landsat-8 False Color RGB image [click to enlarge]

Landsat-8 False Color RGB image [click to enlarge]

Coincidentally, Landsat-8 also captured another example of a glaciating cloud plume downwind of the Flint Hills Oil Refinery south of St. Paul, Minnesota on 03 December (below). The erosion/glaciation of supercooled cloud extended as far south as Albert Lea, Minnesota. Similar to the Cleveland example, a small “overshooting top” was seen directly over the plume point source.

Landsat-8 False Color RGB image [click to enlarge]

Landsat-8 False Color RGB image [click to enlarge]

===== 08 December Update =====

The effect of this industrial plume glaciating and eroding the supercooled water droplet clouds over northern Indiana was also seen in a comparison of Terra MODIS Visible (0.65 µm), Near-Infrared “Snow/Ice” (1.61 µm) and Infrared Window (11.0 µm) images (below).

Terra MODIS Visible (0.65 µm), Near-Infrared

Terra MODIS Visible (0.65 µm), Near-Infrared “Snow/Ice” (1.61 µm) and Infrared Window (11.0 µm) images [click to enlarge]

===== 09 December Update =====



During the following daytime hours, GOES-16 “Red” Visible (0.64 µm), Near-Infrared “Snow/Ice” (1.61 µm), Near-Infrared “Cloud Particle Size” (2.24 µm), Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.3 µm) images (below) showed a number of plumes from industrial sites (many of which were likely refineries) streaming southeastward and eastward over the Gulf of Mexico on 09 December. Note the lack of a plume signature in the 10.3 µm imagery.
GOES-16 "Red" Visible (0.64 µm), Near-Infrared "Snow/Ice" (1.61 µm), Near-Infrared "Cloud Particle Size" (2.24 µm), Shortwave Infrared (3.9 µm) and "Clean" Infrared Window (10.3 µm) images [click to play MP4 animation]

GOES-16 “Red” Visible (0.64 µm), Near-Infrared “Snow/Ice” (1.61 µm), Near-Infrared “Cloud Particle Size” (2.24 µm), Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.3 µm) images [click to play MP4 animation]

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]