A sequence of Suomi-NPP VIIRS Visible (0.64 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images at 2149 UTC and 2332 UTC (above) showed “before” and “after” views of a  pyrocumulonimbus (pyroCb) cloud that developed south of McGrath, Alaska late in the day on 11 June 2022. The coldest cloud-top infrared brightness temperature of the pyroCb cloud on the 2332 image was -48C.

A couple of hours later, preliminary / non-operational GOES-18 “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.35 µm) images (below) showed that the Little Hog Butte Fire — located southwest of Lake Minchumina (PAMH) — produced a larger and more long-lived pyroCb cloud, which then drifted east-northeastward from the fire source region. The coldest cloud-top infrared brightness temperature of that pyroCb cloud was around -48C. Smoke from this fire was reducing the surface visibility to 2 miles at times at Lake Minchumina. Particularly noteworthy was the fact that this was the first documented pyroCb over Alaska in 2 years.

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GOES-18 images in this blog post are preliminary and non-operational

Overlapping 1-minute Mesoscale Sectors provided GOES-18 imagery at 30-second intervals — and “Red” Visible (0.64 µm) images (above) showed the development of showers and thunderstorms across western New Mexico and far eastern Arizona on 11 June 2022.

In northeastern New Mexico, another feature of interest was the bright reflection of sunlight from large solar panel arrays at a facility located just west of Interstate 25 in northeastern New Mexico (below). Similar to a 2019 example observed with GOES-17 in California, long vertical “stripes” emanating from the bright reflection signature — extending both northward and southward from the solar farm — were likely related to saturated ABI detector column amplifiers, due to an excess charge induced by intense sunlight reflection off the large solar panels.

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A weak line of showers moved through southern Wisconsin late in the afternoon of 10 June 2022, as depicted in the 2001 UTC toggle above of NEXRAD Composite Reflectivity and GOES-16 Day Cloud Phase Distinction RGB. What satellite-based products could be used to anticipate that line?

NOAA-20 orbits over the Midwestern United States on 10 June (shown here, from this site) were configured such that NUCAPS profiles over Wisconsin were derived from two consecutive passes. The toggle below shows derived Total Precipitable Water at ca. 1730 and 1930 UTC. Dry air over northeastern Wisconsin is abutted by greater values of total precipitable water over the southern part of the state.

Data from NUCAPS profiles can also be used to compute various stability indices, including the Total Totals index, which is shown below from the two passes. Note in particular the gradient in the index over southern Wisconsin at 1930 UTC: a corridor of instability is present, and it is focused in that location mostly because of dryer air to the northeast (click here to view 850-mb Mixing Ratio from gridded NUCAPS at 1730 and 1930 UTC). In addition, diagnosed mid-level Lapse Rates (in this case, 700-500 mb) at 1930 UTC (shown below) show values between 7 and 8 ^oC/km. (Note to AWIPS Users: Gridded NUCAPS Total Totals index values can be accessed via the Product Browser, under ‘Grids’)

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ProbSevere LightningCast (link) is a forecast aid created to diagnose (from ABI imagery) the probability that a GLM Lightning observation will occur in the next 60 minutes. It can also alert a forecaster to developing convection, because the satellite signatures that suggest lightning might occur in the next 60 minutes often occur before radar observations of convection. The animation below shows LightningCast at 15-minute time steps, from 1800 to 2000 UTC on 10 June. Note how LightningCast keys on the developing line of cumulus long before showers develop (and more than 30 minutes before lightning occurs!)

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The animation below shows GOES-16 Day Cloud Phase Distinction overlain with Geostationary Lightning Mapper (GLM) Minimum Flash Area (MFA) observations, from 2001 – 2316 UTC. Consider the smallest MFA values (in yellow) to represent vigorous, new updrafts. Larger MFA (green) are more likely in the anvil.

NUCAPS and ProbSevere LightningCast added to Situational Awareness for this event.

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Some imagery in this Blog Post was created using the NOAA/TOWR-S AWIPS Cloud Instance. Thank you!

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The second week of the Hazardous Weather Testbed (here is the blog site) ran 6-10 June 2022, and this blog post will discuss one or two of the events that happened this week. I was away from the Testbed on the first two days, and day #4 was not an active day for severe weather during the Testbed hours. The daily maps that summarize the short-term forecasts and the observed severe weather (courtesy Bill Smith, Sr) are shown below. On all days, the STP forecasts and analyses overlapped the region of severe weather.

Wednesday’s STP example over southeast Indiana was one of the better predictions of the week (and it’s also discussed in this HWT blog post). The ProbSevere objects contours are surrounding maxima in the STP field. As during week 1, there were many examples that showed ProbSevere signals along the perimeter of large MUCAPE values (Most Unstable Convective Available Potential Energy; that is — in the MUCAPE gradient). Here’s an example from 2000 UTC on 8 June 2022 (the same time as the image below).

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As with Week 1, forecasters found great utility in using PHSnABI model output in anticipating where convection might form; that is, it was most useful in the pre-convective environment, and forecasters found 0-4h forecasts most useful.

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