A WRF model run that includes assimilated Low-Earth-Orbit (LEO) satellite sounder data (fused with ABI data) is being evaluated at the Hazardous Weather Testbed (Blog posts from forecasters at HWT are here). On 20 May 2024, the PHS model output included convective development over the eastern Plains of Colorado, as shown in the animation below of model Composite Reflectivity at hourly time-steps. The screenshots below are from AWIPS; model output is also available here.

The PHS model accurately predicted convective initiation, as shown in the (hourly) animation below of GOES-East visible imagery.

The three toggles below compare the forecasts of Composite Reflectivity and Visible Imagery at 2000, 2100 and 2200 UTC.

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Based on the forecast, a LightningCast monitoring point was created where the model forecast initiation (approximately 39.7^oN, 104.7^oW; National Weather Service forecasters have the ability to request monitoring points to supplement the airports/stadiums that are done routinely and are available at this website). That LightningCast probabilities are shown below for the point.

The animation below shows the Day Cloud Phase Distinction RGB and the LightningCast Probability contours over eastern CO (figure above and animation below courtesy John Cintineo, NSSL).

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While much of Kansas was under a “Particularly Dangerous Situation” Severe Thunderstorm Watch, 1-minute Mesoscale Domain Sector GOES-16 (GOES-East) Visible/Infrared Sandwich RGB images (above) showed thunderstorms that produced tornadoes, large hail (to 3.00 inches in diameter) and damaging winds (gusts of 90-100 mph) (SPC Storm Reports) across parts of Kansas on 19 May 2024. Some flash flooding was also reported, with water covering portions of Interstate 70 and other nearby roads. The discrete supercell thunderstorms that initially developed during the late afternoon hours eventually consolidated into a larger organized Mesoscale Convective System / squall line by about 0000 UTC on 20 May.

1-minute GOES-16 Visible/Infrared Sandwich RGB images combined with the Total Precpitable Water derived product (above) and the CAPE derived stability index (below) revealed a plume of moisture (TPW values to 1.6 in) and instability (CAPE values to 2200 J/kg) that was spreading northward along the I-35 corridor, feeding into the tornado/hail/wind/flash-flood-producing supercell thunderstorm that was propagating eastward along the I-70 corridor.

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Overlapping 1-minute Mesoscale Domain Sectors provided 30-second interval GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) — which showed thunderstorms that produced two EF1-rated tornadoes as well as damaging winds (resulting in some fatalities) across the Houston area (SPC Storm Reports) on 16 May 2024. Widespread structural damage occurred in downtown Houston — and there were also power outages across much of the area. The Infrared images revealed numerous pulses of thunderstorm overshooting tops that exhibited infrared brightness temperatures of -80ºC or colder (shades of violet embedded within brighter white regions).

Larger-scale views of 30-second GOES-16 Visible and Infrared images are shown below.

Taking a closer look at the Houston metro area, 30-second GOES-16 Visible images with/without an overlay of GLM Flash Extent Density (below) showed the lightning activity associated with these thunderstorms, which included a few brief lightning jumps.

Survey reports from severe storms 5/16:
– EF-1 tornado near Cypress (peak winds 110mph).
– Straight-line wind damage in downtown Houston. Winds peaked ~ 100mph.
– Widespread straight-line winds near Baytown/Galena Park area. Wind peaked 90-100mph.

More details to be shared later

— NWS Houston (@NWSHouston) May 17, 2024

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5-minute CONUS Sector GOES-16 (GOES-East) Ash RGB images (above) showed a pulse of blowing dust — lofted by thunderstorm outflow winds gusting as high as 70 kt (81 mph) — that was moving southward across West Texas late in the day on 16 May 2024. This dust reduced surface visibility to 1-1/4 mi at some sites as it made its way south across Interstates I-20 and I-10. In this particular case, the Ash RGB provided a better depiction of the blowing dust than the Dust RGB — for example, at 0001 UTC (both RGBs use the same spectral bands, but are scaled differently).

GOES-16 True Color RGB images from the CSPP GeoSphere site (below) provided a clearer view of the areal coverage of this blowing dust.

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