The VIIRS Today website (link) contains daily imagery from the Day Night Bands on both Suomi NPP and on NOAA-20. For example, here are three images from Suomi-NPP on 12 August over the Pacific Northwest and northern California: 2-km resolution, 1-km resolution, and 250-km resolution. The animation below shows Day Night Band imagery over northern California, showing the development of the Dixie Fire (14 July) and its expansion and motion over the subsequent weeks. The animation was derived from 1-km resolution imagery.

Smoke from the fire is occasionally obvious in the imagery (for example on 2 August), depending on the amount of lunar illumination. Clouds also cover the fire at times, but the light emanated from the fire shines through. A fire to the east that is in progress when the Dixie fire starts is contained during the first week of the animation. Other fires are apparent as well, but the Dixie Fire is the longest-lasting one in the animation. The Dixie Fire has occasionally burned hot enough to product pyrocumulonimbus clouds, as shown here.

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The GOES-14 satellite was brought out of storage on 11 August 2021, for its annual checkout activities (NOAA bulletin). Shortwave Infrared (3.9 µm) images (above) provided a 4-GOES view of the thermal anomalies (or hot pixels, darker black enhancement) exhibited by the Richard Spring Fire in southeastern Montana. On that day the fire had burned over 149,000 acres, and was only 15% contained. The 4 panels of images are displayed in the native projection of each satellite.

The GOES-14 Imager has the same 5 spectral bands (above) as GOES-15 (below).

A sequence of Infrared images from EWS-G1 (formerly GOES-13), GOES-17, GOES-15, GOES-14 and GOES-16 — between 1345 UTC and 1500 UTC on 13 August — is shown below. Full-resolution data from all 5 of the GOES were received by satellite antennas operated by SSEC Satellite Data Services.

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Potential Tropical Cyclone 6 was upgraded to Tropical Storm Fred at 03 UTC on 11 August 2021, just south of Puerto Rico — and 1–minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed Fred as it made landfall along the southern coast of the Dominican Republic around 18 UTC.

Fred was moving through an environment characterized by relatively low values of deep-layer wind shear, according to an analysis from the CIMSS Tropical Cyclones site (below).

 

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The Storm Prediction Center has placed much of southern Wisconsin in an Enhanced Risk (below; click here to view the image at the SPC website). 

By 1800 UTC, below, surface dewpoints in southern WI/eastern Iowa were at torrid levels, and mid-level lapse rates were steep as depicted in the SPC Mesoanalysis below.

NOAA-20’s orbits on 10 August (as shown below, and here, from this site) suggest that, perhaps, sequential NUCAPS profiles (as discussed here) will be available over parts of southern WI on 10 August. (Update: YES! It happened!)

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Gridded NUCAPS lapse rates from the ~1800 UTC NOAA-20 overpass are shown below. The most unstable mid-level air is over central WI, and these values were derived from retrievals that did converge properly to a solution. The Total Totals index, below, showed the most unstable air more isolated in central Wisconsin

Moisture values from NUCAPS show a pronounced maximum oriented southwest-to-northeast over central Wisconsin.

What do individual soundings look like over western Wisconsin? Let’s look at the one just south of the Total Totals maximum in central WI, at 43.5N, 89.9 W. The sounding is shown below. Note that the surface T/Td in the profile is 28.6 and 17.1, in a region where the dewpoint analysis shows values in the mid-70s! Thus, this sounding should be adjusted to better match near-surface conditions.

The modified sounding is shown below. (Note that Gridded NUCAPS fields do not use modified soundings). The LCL and EL levels have both changed, and the amount of CAPE has jumped! NSharp-computed Surface-based CAPE/LI has changed from 1018/-4 in the original sounding to almost 5000/-12 in the modified; ML 100 CAPE/LI has changed from 1442/-5 to 3800/-10.

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SPC has issued a mesoscale discussion #1465 suggesting watch issuance will occur by 2100 UTC.

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The second NUCAPS pass did provide overlapping points over southern Wisconsin. The 700-500 Lapse Rate, Total Totals index, and 850-mb Mixing Ratio are shown below. As with the previous pass, gridded values over Wisconsin are derived from infrared retrievals that converged to a solution. Mid-level stability is very weak over Wisconsin; moisture and instability as measured by the Total Totals index is more widespread at 1933 UTC vs. the pronounced corridor 90 minutes earlier.

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What do the individual profiles from this NUCAPS pass look like? The one below is from near the location chosen from the previous pass, but this time at 43.45 N, 90.3 W. It shows abundant moisture and modest amounts of CAPE above the boundary layer. As in the sounding above, however, the boundary layer is far too dry.

The sounding above has a surface T/Td of 28.8 and 17.2 ; again, this sounding will be modified to more accurately match surface conditions (in particular, the sounding is far too dry at low levels), and the modification changed the computed Surface-based CAPE/LI from 1104/-4 to 5600/-13 and the ML 100 CAPE/LI from 1272/-2 to 5300/-12!

When convective activity is possible, remember that NUCAPS soundings give ample information about thermodynamics at a convenient time: halfway between regular synoptic soundings.

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Severe Thunderstorm Watch #420 was issued at 2045 UTC. See below.

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Storm Reports from SPC (above) show many incidents of wind damage in the southern part of the region of high instability diagnosed by NUCAPS. The mp4 animation (Click here for an animated gif) below shows the 1-minute mesoscale (Sector 2) GOES-16 “Red” Visible (0.64 µm), from 1900 UTC on 10 August through 0040 UTC 11 August 2021. Convection over Iowa moved into the unstable air over Wisconsin.

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