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Tropical Storm Karl in the Gulf of Mexico

By Scott Bachmeier •

The intensity of Tropical Storm Karl had recently peaked late in the day on 12 October — however, 1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) images on 13 October 2022 (above) showed that a large, long-lived convective burst developed southeast of Karl’s center around 11 UTC. Within this larger-scale... Read More

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

The intensity of Tropical Storm Karl had recently peaked late in the day on 12 October — however, 1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) images on 13 October 2022 (above) showed that a large, long-lived convective burst developed southeast of Karl’s center around 11 UTC. Within this larger-scale convective burst, periodic small-scale “hot towers” exhibited cloud-top infrared brightness temperatures of -90ºC and colder (yellow pixels embedded within areas of darker purple enhancement).

The center of Karl passed very close to Buoy 42055 around 12 UTC — as shown in a plot of wind speed and air pressure (below).

Plot of Buoy 42055 Wind Speed (blue), Wind Gust (red) and Air Pressure (green)

GOES-16 “Red” Visible (0.64 µm) iages [click to play animated GIF | MP4]

1-minute GOES-16 “Red” Visible (0.64 µm) images after sunrise (above) showed the detailed cloud-top shadowing and texture associated with Karl’s convective features. Later in the day, a portion of the tropical cyclone’s low-level circulation became partially exposed, due to northwesterly wind shear across that region.

GOES-16 Infrared Window (11.2 µm) images (below) include contours of deep-layer wind shear valid at 2200 UTC from the CIMSS Tropical Cyclones site — which displayed the shear that was affecting Karl and helping to partially expose its low-level circulation.

GOES-16 Infrared Window (11.2 µm) images, with contours of deep-layer wind shear valid at 2200 UTC [click to enlarge]

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Tornadoes and damaging winds along a cold front across southeast Wisconsin

By Scott Bachmeier •

GOES-16 (GOES-East) Mid-level Water Vapor (6.9 µm) images shown above were centered over southeast Wisconsin during a period when tornadoes and damaging winds (NWS Milwaukee summary) occurred on 12 October 2022. Of note in the Water Vapor imagery was a narrow southwest-to-northeast oriented “warm/dry” (darker shades of blue) feature that appeared to align with the... Read More

GOES-16 Mid-level Water Vapor (6.9 µm) images with plots of NWS Warning Polygons, Local Storm Reports and Surface Fronts [click to play animated GIF | MP4]

GOES-16 (GOES-East) Mid-level Water Vapor (6.9 µm) images shown above were centered over southeast Wisconsin during a period when tornadoes and damaging winds (NWS Milwaukee summary) occurred on 12 October 2022. Of note in the Water Vapor imagery was a narrow southwest-to-northeast oriented “warm/dry” (darker shades of blue) feature that appeared to align with the progression of the surface cold front — and many of the tornado and damaging wind reports also occurred in close proximity to the location of this Water Vapor feature as it moved southeastward across the area.

The corresponding GOES-16 “Red” Visible (0.64 µm) images (below) include overlays of GLM Flash Extent Density — no satellite-detected lightning activity was seen in this area during the time of the tornado and damaging wind reports.

GOES-16 “Red” Visible (0.64 µm) images, with overlays of GLM Flash Extent Density [click to play animated GIF | MP4]

GOES-16 “Clean” Infrared Window (10.3 µm) images (below) revealed that cloud-top infrared brightness temperatures were not particularly cold in the vicinity of the tornado and wind reports — generally within the -25 to -30ºC range.

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

In fact, the GOES-16 Cloud Top Phase derived product (below) classified most of the clouds near the tornado/wind reports as Mixed Phase (darker shades of green), since they were not cold enough to ensure complete glaciation.

GOES-16 Cloud Top Phase derived product [click to play animated GIF | MP4]

Given that these were relatively warm and mostly non-glaciated clouds, GOES-16 Cloud Top Height values near the storm reports were generally fairly low, in the 22,000-26,000 feet range (below).

GOES-16 Cloud Top Height derived product [click to play animated GIF | MP4]

Finally, GOES-16 Day Cloud Phase Distinction RGB images (below) did not display a strong signature of fully-glaciated clouds (darker shades of green) in the direct vicinity of most of the tornado and damaging wind reports.

GOES-16 Day Cloud Phase Distinction RGB images [click to play animated GIF | MP4]

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Pyrocumulonimbus clouds in Canada’s Northwest Territories

By Scott Bachmeier •

GOES-17 (GOES-West) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm), “Clean” Infrared Window (10.35 µm) and Fire Temperature RGB images (above) showed a wildfire just southeast of Fort Simpson in Canada’s Northwest Territories (just north of the border with British Columbia), which produced a pair of pyrocumulonimbus (pyroCb) clouds late in the day on 10 October 2022. Surface winds gusting... Read More

GOES-17 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), “Clean” Infrared Window (10.3 µm, bottom left) and Fire Temperature RGB (bottom right) images [click to play animated GIF | MP4]

GOES-17 (GOES-West) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm), “Clean” Infrared Window (10.35 µm) and Fire Temperature RGB images (above) showed a wildfire just southeast of Fort Simpson in Canada’s Northwest Territories (just north of the border with British Columbia), which produced a pair of pyrocumulonimbus (pyroCb) clouds late in the day on 10 October 2022. Surface winds gusting as high as 28 knots (32 mph) at Fort Simpson — in the wake of a cold frontal passage (surface analyses) — likely played a role in helping to intensify the fire enough to produce the 2 pyroCb clouds. The hottest 3.9 µm infrared brightness temperature sampled in the 10-minute imagery was 121.19ºC at 2000 UTC — with the pyroCb clouds developing around 2200 and 2330 UTC.

A toggle between Suomi-NPP VIIRS Visible (0.64 µm) images at 1903 and 2042 UTC (below) displayed the large smoke plume that drifted southeastward as far as northern Saskatchewan. About 200 miles southeast of the wildfire source region, this smoke reduced the surface visibility to 3 miles or less at Hay River NT around 21 UTC.

Suomi-NPP VIIRS Visible (0.64 µm) images at 1903 and 2042 UTC [click to enlarge]

During the subsequent nighttime hours, a toggle between Suomi-NPP VIIRS Shortwave Infrared (3.74 µm) and Day/Night Band (0.7 µm) images at 1211 UTC (below) revealed the thermal signatures and visible glow of individual active fires around the periphery of the fire complex.

Suomi-NPP VIIRS Shortwave Infrared (3.74 µm) and Day/Night Band (0.7 µm) images at 1211 UTC [click to enlarge]

GOES-17 and GOES-16 (GOES-East) True Color RGB images from the CSPP GeoSphere site (below) showed the hazy smoke plume as it drifted southeastward — along with the pyrocumulus and pyroCb clouds that developed over the wind-driven fire complex.

GOES-17 True Color RGB images [click to play MP4 animation]


GOES-16 True Color RGB images [click to play MP4 animation]

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Hurricane Julia makes landfall in Nicaragua

By Scott Bachmeier •

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) images (above) showed that Hurricane Julia made landfall as a Category 1 intensity storm along the east coast of Nicaragua around 0715 UTC on 09 October 2022. A notable increase in the areal coverage of deep convection was seen around the center... Read More

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

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) images (above) showed that Hurricane Julia made landfall as a Category 1 intensity storm along the east coast of Nicaragua around 0715 UTC on 09 October 2022. A notable increase in the areal coverage of deep convection was seen around the center of Julia as it approached the coast, suggesting a trend of further intensification just prior to landfall.

Julia was upgraded from a Tropical Storm to a Hurricane at 2300 UTC on 08 October — an analysis of deep-layer wind shear at that time from the CIMSS Tropical Cyclones site (below) indicated that Julia was moving through an environment of very low shear (which favored further intensification). The tropical cyclone was also traversing warm water with Sea Surface Temperature values around 29ºC.

GOES-16 Infrared Window (11.2 µm) images, with contours of deep-layer wind shear valid at 2300 UTC [click to enlarge]

A DMSP-17 SSMIS Microwave (85 GHz) image at 2353 UTC (below) showed that a closed eyewall was beginning to develop, but still remained open to the west-southwest.

DMSP-17 SSMIS Microwave (85 GHz) image at 2353 UTC [click to enlarge]

However, an animation of the MIMIC-TC product (below) showed that a closed eyewall did form around the time of landfall.

MIMIC-TC morphed microwave product [click to enlarge]

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