1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) with/without an overlay of GLM Flash Extent Density (above) showed the development of a thunderstorm that produced the fatal EF3-rated tornado that moved through Perryton, Texas (located about 4 miles southwest of airport identifier KPYX) from 2206-2217 UTC on 15 June 2023. A modest amount of lightning activity was associated with these storms. Prior to convective initiation in the far northern Texas Panhandle, orphan anvil pulses were evident south of Perryton (indicating that convective inhibition was diminishing across that area).

The corresponding GOES-16 “Clean” Infrared Window (10.3 µm) and Cloud Top Temperature derived product images are shown below; just prior to the tornado, the coldest 10.3 µm infrared brightness temperature and Cloud Top Temperature values were -73.41ºC and -76.92ºC, respectively, at 2158 UTC (note that the coldest temperature for this infrared color enhancement was adjusted to be -95ºC).

In a toggle between GOES-16 Visible and Infrared images at 2158 UTC (below), the apparent location of the thunderstorm’s cold overshooting top was over the Oklahoma Panhandle — but taking parallax into account, the actual location of that overshooting top would have been about 20 km (12 miles) to the southeast (closer to Perryton).

GOES-16 Lifted Index (LI) and Convective Available Potential Energy (CAPE) derived products (below) showed that the thunderstorms were approaching a N-S oriented corridor of instability (as was also discussed in this blog post). The most unstable LI values within that corridor were around -10ºC, with CAPE values around 2500 J/kg.

GOES-16 Total Precipitable Water (TPW) derived product images (below) indicated that an axis of moisture was also in place within the corridor of instability. Peak TPW values were around 1.3 inches.

GOES-16 Visible and Infrared images (below) include time-matched (+/- 3 minutes) plots of SPC Storm Reports.

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The Storm Prediction Center predicted a moderate risk of severe weather (link) over the southern Plains of the US on 15 June 2023. The animation above shows surface-based CAPE derived from 4-km WRF model output. This model incorporates information from Polar Hyperspectral Soundings via the Fusion process. Model CAPE fields are overlain by NOAA/CIMSS ProbSevere (version 3) polygons from 1700-2000 UTC. There is good agreement for those times between the gradient of the CAPE fields and the location of the ProbSevere polygons that show were severe weather is most likely. The 2100 UTC image of surface-based CAPE is also shown. Where do you think the polygons will be at 2100 UTC? That is shown below. These model fields can help with situational awareness in the near-term. (Model output is available at this link).

A particular benefit of the PHS model output fields shown above is that they are high-resolution, that information is available in cloudy and clear regions and that the forecast provides short-term (that is, 0-9 hour) guidance. Other satellite-based stability products are available of course. The two-panel below shows PHS output and GOES-16 Derived Stability Index estimates of CAPE. The character and gradients of the fields are very similar — but the Level-2 GOES estimate is created only in regions of clear skies. A direct (toggled) comparison of the fields at 1900 UTC is here. The comparison between the real-time GOES estimates and the 5-h model field suggests that the model evolution is just a bit slow.

NOAA-20 overflew the eastern part of this domain at around 1900 UTC, and gridded NUCAPS fields of temperature and moisture were used to diagnose the stability. That is shown below. As with the PHS-enhanced WRF model output, NUCAPS fields give information in clear and cloudy regions. The horizontal resolution of NUCAPS data, however, is around 50 km; the display of tight gradients is a challenge.

The toggle below shows Sounding Availability points (Green Points: infrared retrieval converged to a solution; Yellow Points: microwave retrieval converged to a solution; Red Points: neither infrared nor microwave retrieval converged), the Total Totals index, and the lapse rate from 700-500 mb. The Total Totals index suggests the strongest instability over western Oklahoma, a region with steep 700-500 mb lapse rates.

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The PHSnMWnABI model output (and Probsevere Version 3) were both evaluated at SPC’s Hazardous Weather Testbed within the past month. Blog Posts from the forecasters that describe how these products can be used are here. SPC storm reports for this day are shown below. They do align with satellite estimates of CAPE.

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1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) images with time-matched (+/- 3 minutes) plots of SPC Storm Reports (above) showed thunderstorms that produced several tornadoes, hail as large as 5.00 inches in diameter, and damaging winds to 82 mph across parts of Mississippi, Alabama, Georgia and Florida on 14 June 2023. Pulses of overshooting tops exhibited infrared brightness temperatures in the -70ºC to -80ºC range.

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1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) images with time-matched (+/- 3 minutes) plots of SPC Storm Reports (above) showed thunderstorms that produced hail as large as 4.50 inches in diameter, damaging winds to 71 mph and a tornado across parts of New Mexico, Texas and Oklahoma from the late afternoon into the subsequent nighttime hours on 11 June 2023.

In a closer look at 1-minute GOES-16 Infrared images over the Dallas-Fort Worth, Texas area (rawinsonde site KFWD) from 0000-0200 UTC on 12 June (below), several overshooting top pulses became surrounded by brief “warm trench” signatures — a likely indication of compensating subsidence around the periphery of these vigorous updrafts as they rapidly ascended past the local equilibrium level and/or tropopause. The coldest overshooting top exhibited an infrared brightness temperature of -87.6ºC at 0115 UTC.

Comparisons of GOES-16 Infrared image, CLAVR-x Cloud Top Height and Operational Cloud Top Height for overshooting tops with surrounding “warm trench” signatures in Tarrant County and Denton County at 0106 UTC, 0116 UTC and 0121 UTC are shown below —  note how the full-resolution (nominal 2-km) CLAVR-x Cloud Top Height products (created at CIMSS) more accurately depicted the overshooting top and surrounding warm trench features, which were not as apparent in the 10-km resolution Operational Cloud Top Height products that are currently distributed to AWIPS users.

When comparing cursor-sampled values of Cloud Top Height for the coldest portion of overshooting tops in Tarrant and Denton County (below), the CLAVR-x values were always significantly higher (14.9 kft to 16.8 kft higher) — since the CLAVR-x higher spatial resolution more accurately depicted the size and location of the overshooting tops (as seen in the Infrared images).

However, cursor-sampled Cloud Top Height values within the corresponding warm trench features were generally similar (below), although the CLAVR-x values were usually several hundred feet lower than the Operational values.

The largest CLAVR-x Cloud Top Height difference between an overshooting top and its surrounding warm trench was 19,431 feet (over Tarrant County at 0116 UTC, shown below) — the corresponding lower spatial resolution Operational Cloud Top Height difference was only 2973 feet!

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