Strong northerly winds on the backside of a broad central US low pressure system resulted in widespread dense blowing dust across the southern high plains on 15 Jan 2021. Wind gusts of 45-65 knots initiated blowing dust across eastern Colorado during the mid-late morning, which expanded south-southeast into southwest Kansas and the OK/TX panhandles by late morning into the early afternoon. The blowing dust resulted in widespread and prolonged visibility reductions to less than 2 miles, with temporary reductions to near-zero captured on video. These reduced visibilities prompted the issuance of multiple NWS Dust Storm and Blowing Dust warnings, as well as road closures.
Some images from within the dust plume:
A GOES-East 1-min mesoscale sector was available over the region of blowing dust, thanks to a request the previous evening by NWS Norman for Fire Weather. The initiation of blowing dust in the morning across southeast Colorado is observed and tracked efficiently by GOES-East 1-min VIS-SWD combo, a procedure which can be created in AWIPS (Fig 1). The combo uses a semi-transparent SWD overlay with a range centered around that of the dust signal, allowing areas of potential dust to “pop”. The animation depicts the issuance of Dust Storm Warnings in relation to the dust evolution.
According to a NWS Pueblo forecaster, the GOES imagery aided in determining where and where not significant blowing dust was occurring, and was used in combination with surface obs and webcams to issue the warning. See text below for one of the warnings issued by NWS Pueblo (Fig 2).
Panning out and observing the daytime evolution using GOES-East Geocolor, we see the location of the blowing dust in relation to the larger cyclone centered over Missouri/Illinois (Fig 3). The dust, in this case, is easy to diagnose in Geocolor, especially later in the day as forward scattering increases for GOES-East. Note, GOES-West provided slightly better detection of the dust in the reflectance bands and products during the morning (more forward scattering), but was only available at 10-min resolution, vs 5-min and 1-min from GOES-East.
The DEBRA-Dust product, available on the CIRA Slider, can similarly be used in combination with Geocolor imagery to highlight areas of blowing dust. With this event, the algorithm performed very well in capturing the blowing dust with no apparent false alarm, from both GOES-East (Fig 4a) and GOES-West (Fig 4b).
Given the strong dust signal, the Dust RGB also captured the dust signal quite well as red (Fig 5).
Finally, blowing dust was easily detectable in the Dust-Fire RGB (relatively bright green), along with periodic wildfire hot spots (red pixels) within and near the dust (Fig 6). This RGB is a useful situational awareness tool for tracking both the evolution of blowing dust and new wildfire starts, phenomena which occur under similar environmental conditions.
The NWS Aviation Weather Center issued multiple IFR SIGMETS due to the blowing dust, utilizing satellite imagery and surface obs (Fig 7). An AWC forecaster noted their increasing use of the Dust RGB in operations, and that it was utilized today to assist in product issuance.
VIIRS imagery provided a high resolution view of of the dust plume during the early afternoon. The Day Land Cloud RGB, created using the 1.6 um, 0.86 um, and 0.64 um I band channels for the RGB components, respectively, provides us with a 375 m RGB effective at highlighting lofted dust and distinguishing it from other features (Fig 8a and 8b). Blowing dust appears as relatively bright brown to tan, while liquid cloud tops are white/gray, ice cloud tops are cyan, and snow cover an even brighter cyan.
Even higher resolution imagery, 10 m true color, from Sentinel-2 was available over the blowing dust during the late morning when the event was well underway (Fig 9a and 9b). The zoomed in view captures areas of both transparent and opaque dust advancing across HWY 50 between Lamar and Holly in southeast Colorado.
NWS offices experiencing the blowing dust were active on social media sharing GOES imagery of the event as part of their Decision Support Services.
To close, the full daytime evolution of the blowing dust viewed in the GOES-East 5-min Geocolor/SWD image combo, with Dust Storm Warning polygons overlaid (Fig 10).
The blowing dust would continue to travel southeast through the night, reaching the Gulf of Mexico by the next morning. GOES-East IR-based multispectral products were effective in continuing to track the lofted dust through the evening. Shown is a modified version of the Dust RGB, with lofted dust appearing as a dark blue relative to surrounding areas (Fig 11). The CIRA geocolor product is appended to the start and end of the loop to capture the daytime reflectance view of the dust on either end.
Bill Line, NESDIS and CIRA, Steve Hodanish (NWS PUB), Declan Cannon (NWS AWC)