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 “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.

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.

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).

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.

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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.

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.

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.

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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.

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.

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

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The animation above (from the CSPP Geosphere site — click here for a direct link to the animation) shows True Color imagery (daytime) and Night Microphysics RGB (nighttime) from 2310 on 6 October through 0540 UTC on 7 October 2022 in 10-minute time-steps.

Convection developed over southwest Arizona after noon on 6 October, and the outflow boundary that developed generated a haboob that propagated from the Imperial and Coachella Valleys into San Diego County, California, and resulted in at least one Dust Storm Warning from the NWS in San Diego (The NWS San Diego Twitter Feed has plenty of surface-based images of the dust).   How well does the dust show up in the true-color imagery above?  Imagery before 0000 UTC on the 7^th suggest dust, and likely  even a linear feature at the leading edge of the dust, over the central part of extreme southern California, even though the background is about the same color as the dust cloud that is moving over it.  Zoomed in, however, below, the dust feature is indeed distinct!

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Did the GOES-West Dust RGB capture this wind event? Somewhat. The animation below shows the Dust RGB plotted with surface observations that testify to the vigor of the outflow boundary. Dust should show up as bright pink/magenta in the RGB, and there are some small regions where that color is apparent. Information on the Dust RGB is available here and here. For this case, True-color imagery better identifies the dust than does the Dust RGB.

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After sunset, the ability to track the dust (in the visible) is gone, and the dust RGB also loses its signal.  The focus of attention can then shift in the animation at the top of the blog post to the very interesting scouring of the low clouds along the northwest Mexican coast. Dry continental air moves over the ocean (in the form of an outflow boundary from decaying convection over the land). Mixing of this dry air with the marine boundary layer occurs, causing evaporation of clouds.  The bright cyan enhancement in the Night Microphysics depicts low clouds.  As the clouds evaporate, the purple enhancement that replaces cyan shows the underlying sea surface.  Notice also the ripples in the cyan enhancement showing gravity waves propagating along the top of the boundary layer stratus ahead of the outflow boundary! 

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