CIMSS Satellite Blog, CIMSS

Mid-latitude cyclone in the central US

By Scott Bachmeier • 22 January 2018

A large mid-latitude cyclone intensified over the central US on 22 January 2018, producing a wide variety of weather — in the cold sector, heavy snow and blizzard conditions across the Plains and Upper Midwest (WPC storm summary), and in the warm sector, severe weather (tornadoes, large hail and damaging winds: SPC storm reports) from Mississippi... Read More

5-minute GOES-16 Water Vapor (6.9 µm) images, with hourly precipitation type plotted in yellow [click to play MP4 animation]

A large mid-latitude cyclone intensified over the central US on 22 January 2018, producing a wide variety of weather — in the cold sector, heavy snow and blizzard conditions across the Plains and Upper Midwest (WPC storm summary), and in the warm sector, severe weather (tornadoes, large hail and damaging winds: SPC storm reports) from Mississippi to Illinois, Indiana, and Ohio. GOES-16 (GOES-East) Mid-level Water Vapor (6.9 µm) images (above) showed the large size of the storm circulation, which included a well-defined Warm Conveyor Belt (WCB) and a Trough of Warm Air Aloft (TROWAL) as identified here. More information on conveyor belts and TROWALs is available here.

A GOES-16 Mesoscale Sector provided 1-minute imagery over the Upper Midwest — “Red” Visible (0.64 µm) images (below) revealed some of the convective elements surrounding the surface low as it reached its occluded stage over Iowa. A small cluster of thunderstorms also developed over central Illinois around 19 UTC, producing 1.0-inch diameter hail.

1-minute GOES-16 Visible (0.64 µm) images, with hourly precipitation type plotted in yellow [click to play MP4 animation]

Taking a closer look at the eastern portion of the previous satellite scene, there was an overlap between the M1 and M2 Mesoscale Sectors — this allowed for images at 30-second intervals (below).

30-second GOES-16 Visible (0.64 µm) images, with hourly precipitation type plotted in yellow [click to play MP4 animation]

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Rope Cloud over the northwest Gulf of Mexico

By Scott Lindstrom • 22 January 2018

GOES-16 “Red Visible” 0.64 µm imagery from 1402-2142 UTC on 22 January 2018. (Click to animate)

Visible GOES-16 Satellite Imagery over the northeastern Gulf of Mexico on 22 January 2018 showed the development of a Rope Cloud. Such features have been discussed before on the CIMSS Blog — here, here, here and here! Rope Clouds are handy features in satellite analysis over the ocean because they indicate distinctly where the surface cold front exists. Note that the WPC surface analysis, shown here for 1500 UTC, has the front in the same location as the rope cloud, with convection noted out in advance of the surface cold front. The hourly animation below, showing surface observations and the GOES-16 Red Visible (0.64 µm) Imagery, confirms the windshifts that were observed when the Rope Cloud/Cold Front passed any station.

Hourly Surface Observations and GOES-16 “Red Visible” 0.64 µm imagery from 1400-2200 UTC on 22 January 2018. (Click to enlarge)

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Eruption of the Mayon Volcano in the Philippines

By Scott Bachmeier • 22 January 2018

The first in a renewed series of eruptions of the Mayon Volcano in the Philippines began around 0450 UTC on 22 January 2018. As seen in Himawari-8 False-color Red-Green-Blue (RGB) images from the NOAA/CIMSS Volcanic Cloud Monitoring site (above), the ash cloud was transported to the northwest.Multi-spectral retrievals of the Ash Cloud Height... Read More

Himawari-8 False-color RGB images [click to animate]

The first in a renewed series of eruptions of the Mayon Volcano in the Philippines began around 0450 UTC on 22 January 2018. As seen in Himawari-8 False-color Red-Green-Blue (RGB) images from the NOAA/CIMSS Volcanic Cloud Monitoring site (above), the ash cloud was transported to the northwest.

Multi-spectral retrievals of the Ash Cloud Height (below) indicated that the ash reached altitudes of at least 10 km (dark blue).

Himawari-8 Ash Cloud Height product [click to animate]

A plot of rawinsonde data from nearby Legaspi at 00 UTC on 22 January (below) indicated that the 10 km altitude corresponded to a pressure of 285 hPa.

Plot of rawinsonde data from Legaspi, Philippines [click to enlarge]

A Suomi NPP VIIRS True-color RGB image from RealEarth (below) revealed some of the lower-altitude ash (shades of tan to brown) drifting toward the west at the satellite overpass time of 0507 UTC. Thermal anomalies — signatures of hot lava flows — are indicated by red dots.

Suomi NPP VIIRS True-color RGB image [click to enlarge]

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Blowing dust in Texas and Oklahoma

By Scott Bachmeier • 21 January 2018

Strong winds in the wake of a cold frontal passage created large areas of blowing dust across the Panhandle Plains of northwestern Texas after 16 UTC on 21 January 2018. GOES-16 “Moisture” or “split-window difference” (10.3 µm – 12.3 µm) images (above) showed that the leading edge of this airborne dust moved over far southwestern Oklahoma after... Read More

GOES-16 “Moisture” Infrared brightness temperature difference (10.3-12.3 µm) images, with hourly surface reports plotted in cyan [click to play animation]

Strong winds in the wake of a cold frontal passage created large areas of blowing dust across the Panhandle Plains of northwestern Texas after 16 UTC on 21 January 2018. GOES-16 “Moisture” or “split-window difference” (10.3 µm – 12.3 µm) images (above) showed that the leading edge of this airborne dust moved over far southwestern Oklahoma after 20 UTC. (Note to AWIPS users: the default enhancement for this GOES-16 “Moisture” Channel Difference product was changed to “Grid/lowrange enhanced” to better highlight the dust with shades of yellow)

GOES-16 “Red” Visible (0.64 µm) and Near-Infrared “Cirrus” (1.37 µm) images (below) also displayed blowing dust signatures; the surface visibility was restricted to 2-3 miles at some locations, with Big Spring briefly reporting only 1/4 mile from 20-21 UTC. The dust signature was apparent on the Cirrus imagery because this spectral band can be used to detect any airborne particles that are effective scatterers of light (such as cirrus ice crystals, volcanic ash, dust/sand or haze).

GOES-16 “Red” Visible (0.64 µm) images, with hourly reports of surface weather plotted in red and surface visibility (miles) plotted in red [click to play animation]

GOES-16 Near-Infrared “Cirrus” (1.37 µm) images, with hourly reports of surface weather plotted in red and surface visibility (miles) plotted in red [click to play animation]

A Cirrus band is also available with the MODIS instrument on the Terra and Aqua satellites (as well as the VIIRS instrument on Suomi NPP and NOAA-20) — a comparison of Visible (0.65 µm), Cirrus (1.37 µm), Shortwave Infrared (3.7 µm) and Infrared Window (11.0 µm) images from Terra and Aqua (below) highlighted the differing appearance of the blowing dust features as sensed by each of those spectral bands. The airborne dust exhibited a darker signature in the Shortwave Infrared images since the small dust particles were efficient reflectors of incoming solar radiation, thus appearing warmer at 3.7 µm.

Terra MODIS Visible (0.65 µm), Cirrus (1.37 µm), Shortwave Infrared (3.7 µm) and Infrared Window (11.0 µm) images, with surface reports plotted in cyan [click to enlarge]

Aqua MODIS Visible (0.65 µm), Cirrus (1.37 µm), Shortwave Infrared (3.7 µm) and Infrared Window (11.0 µm) images, with surface reports plotted in cyan [click to enlarge]

Pilot reports within 20-45 minutes after the Terra overpass time (below) revealed Moderate to Severe turbulence at an elevation of 8000 feet, just southeast of the most dense dust plume feature (highlighted by the cooler, lighter gray infrared brightness temperatures) — this was likely due to strong wind shear in the vicinity of the rapidly-advancing cold front. Farther to the southwest, another pilot report indicated that the top of the blowing dust was at 7000 feet, with a flight-level visibility of 3 miles at 10,000 feet.