Hazardous Weather Testbed Satellite Proving Ground: Week 3 Downburst Prediction
Disclosure: this article includes text generated with the assistance of an AI writing program.
During Week 3 of the 2026 NOAA Hazardous Weather Testbed (HWT) Satellite Proving Ground, downburst prediction and diagnosis activities focused on leveraging multi-sensor satellite capabilities across the Northern High Plains and Rocky Mountain Front Range. Evaluated products included next-generation geostationary and polar-orbiting datasets: GOES-19 sounding retrievals, NOAA-21/METOP-C NUCAPS profiles, machine-learning guidance (LightningCast), and experimental multi-channel risk products. These activities underscored a crucial balance in operational forecasting: matching high-fidelity thermodynamic and microphysical diagnostics with a forecaster’s need for rapid data acquisition to maximize lead times for short-fuse warnings and impact-based decision support.
Daily Meteorological Review
Day 1 (June 1, 2026): Orographic Forcing & Inverted-V Profiles (SE Wyoming)
Strong, orographically-forced, high-based thunderstorms initiated early in the afternoon along the Rocky Mountain Front Range in southeastern Wyoming. As cells advected east-northeastward, they underwent rapid intensification characterized by cooling ice-phase cloud tops and a sharp rise in LightningCast flash rates. Pre-convective environmental monitoring via a comparison of 1800 UTC GOES-19 sounding retrievals and the RAP model sounding over Cheyenne, WY, revealed a classic “hourglass-inverted-V” profile. This deeply mixed, dry sub-cloud boundary layer yielded an associated Wind Gust Potential (WGP) of 39.2 to 44.5 knots. A 1647 UTC ACARS sounding profile from Denver International Airport demonstrated strong synoptic agreement across the Front Range boundary layer, confirming high Downdraft CAPE (DCAPE) values of 826 to 1027 J/kg and optimal wet-bulb zero heights for evaporative downdraft acceleration.
The thermodynamic setup culminated in a severe 52-knot downburst wind gust recorded at Bordeaux, WY, at 1958 UTC.
Focus Day (June 2, 2026): Persistent Severe MCS & Passive Microwave Diagnostics (SW South Dakota)
Convective activity over Fall River County, SD, quickly evolved into a persistent, severe mesoscale convective system (MCS) that tracked east-northeastward. By 2030 UTC, the system intensified into a complex of two distinct bow echoes, each characterized by prominent rear-flank dry-air notches denoting active mid-level dry air entrainment. The pre-convective air mass was evaluated using an 1800 UTC Rapid City, SD (KUNR) radiosonde observation (WGP: 40.8 knots; MU-CAPE: 1014 J/kg) and a GOES-19 sounding retrieval taken 90 km SSE of Rapid City (WGP: 46.7 knots; MU-CAPE: 1584 J/kg). Regional validity was confirmed by a 1919 UTC NOAA-21 NUCAPS sounding 150 km SE of Rapid City showing an absolutely unstable boundary layer with significantly increasing CAPE (WGP: 64.0 knots; MU-CAPE: 2837 J/kg).
In the wake of this event, passive microwave data added a vital structural layer to the analysis. The Advanced Microwave Scanning Radiometer-2 (AMSR2) onboard the GCOM-W1 satellite, currently regarded as one of the highest -resolution (5 km) global operational microwave radiometers, captured the bow echo complex at 1935 UTC in Figure 1. The polarization corrected temperature (PCT) comparison for A- and B-scan retrievals at 1935 UTC identified a prominent brightness temperature (“TB”) depression within the convective core of the bow echo complex accompanied by TB values lowering to near 160K, well below the previously-identified threshold for deep convective storms (Ferraro et al. 2015). This physical attribute signifies a large volume of ice-phase precipitation aloft — including graupel, small hail, and ice aggregates. As this frozen mass falls, melts, and evaporates, it drives negative buoyancy to force intense thunderstorm downdrafts and severe surface downbursts.
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Successive imagery from the GOES-19 3-channel microburst risk product in Figure 2 inferred a localized wind gust potential of 40 to 50 knots across southwestern South Dakota. This risk product corresponded with the deeply mixed sub-cloud layer observed in the GOES-19 sounding profile 90 km SSE of Rapid City.
The satellite-derived gust potential was operationally validated by multiple measured surface downburst wind gusts ranging from 43 to 55 knots across southwestern South Dakota, including a peak downburst wind gust of 55 knots at Cactus Flats, SD, at 2043 UTC.
Day 3 (June 3, 2026): Miller Type 1 Soundings & Frontal Forcing (NE South Dakota)
An eastward-advancing cold front and a lingering outflow boundary from an earlier MCS served as the focal boundaries for convective development in the Aberdeen, SD area. Pre-frontal cumulus streets were tracked prior to glaciation using the GOES-19 SZA Day Cloud Phase Distinction product, presenting as blue-shaded liquid-water cloud features. The 1800 UTC KABR radiosonde and GOES-19 sounding retrievals revealed a prominent “narrow hourglass” structure. This matched a classic Miller Type 1 profile, featuring a moist boundary layer with a prominent overlying mid-to-upper tropospheric unsaturated air layer. This thermodynamic setup yielded an inferred WGP of 43 to 45 knots derived from the MWPI product. The 1900 UTC NOAA-21 NUCAPS sounding retrieved 40 km NW of Aberdeen confirmed excellent spatial uniformity, with both profiles placing optimal wet-bulb zero heights between the 650-700-mb levels for severe downburst generation. Convection accelerated rapidly as the cold front impinged on the capped air mass, verifying with at least five severe wind reports between 52 and 84 mph (45–73 knots).
Day 4 (June 4, 2026): Squall Line Microphysics & Joint Sounding Signatures (MT/SD Border)
An upper-level disturbance and surface cold front forced a linear convective system along the Montana/South Dakota border, developing into an organized broken-line squall line and bow echo complex across Carter County, MT, and northwestern SD. Satellite observations revealed a tight spatial correlation between bright yellow cores in geostationary imagery and high MRMS radar reflectivity. This signature tracked an intensifying storm line with high ice-phase precipitation content aloft, signaling severe downburst potential through sub-cloud melting and evaporation. A regional environmental review compared a 1700 UTC METOP-C NUCAPS sounding (135 km NW of Rapid City) with the 1800 UTC UNR radiosonde. Both profiles showed good structural agreement, exhibiting a combined hourglass and inverted-V signature with favorable wet-bulb zero heights near 700 mb and a severe convective WGP approaching 50 knots.
In conclusion, Week 3 activities demonstrated that while high-fidelity vertical soundings (such as NUCAPS and GOES retrievals) provide indispensable diagnostic value for identifying macroscale environments like the Miller Type 1 or inverted-V profiles, the fast-paced nature of severe weather operations requires rapid data ingestion. A successful forecasting approach for navigating short-fuse warning environments should include pairing intensive thermodynamic analysis with scannable multi-channel risk maps and high-resolution passive microwave hydrometeor imagery. This hybrid approach allows operational meteorologists to anticipate significant microburst and downburst hazards before severe straight-line winds reach the surface.
References
Google. (2026). Gemini [Large language model]. https://gemini.google.com
Ferraro, R., Beauchamp, J., Cecil, D., Heymsfield, G., 2015. A prototype hail detection algorithm and hail climatology developed with the advanced
microwave sounding unit (AMSU). Atmos. Res. 163, 24–35.
