A series of shortwave troughs brought strong winds and a pair of widespread blowing dust events to E NM and W TX on Dec 13 and Dec 15, 2020. The first event saw the lofted dust begin in E NM, and expanding east into W TX during the day in response to a compact and quick moving shortwave trough digging across the region per 6.2 um water vapor imagery (Fig 1). Imagery for the Dec 13 case comes from the CIRA Slider, while Dec 15 imagery comes from AWIPS and CIRA Slider.
The blowing dust was captured well in GOES Geocolor imagery, and as has been discussed in previous blog posts, diagnosis in the western US is better in GOES-West imagery during the early day, and GOES-East imagery during the late day (Fig 2-3).
A product not discussed much on this blog, but is available on the CIRA Slider, and upon request, in NWS offices AWIPS, is the DEBRA Dust product from CIRA (Fig 4). The product is effective in drawing attention to regions of potential blowing dust, prompting further interrogation.
The next blowing dust event occurred, primarily across W TX, after another shortwave and associated jet streak tracked across the area, captured again in WV imagery and also analyzed in RAP 500 mb height field and 250 mb wind field (Fig 5). Dry descending air is observed and an intensifying 120+ knot jet max analyzed across W TX during the time of strong surface winds and blowing dust.
The following GOES-East imagery has been discussed in numerous dust posts on this blog, and includes Geocolor (Fig 6), DEBRA Dust (Fig 7), SWD-IR Combo (Fig 8), and Dust-Fire RGB (Fig 9). Each of these displays has proven effective in reliable blowing dust detection. While Geocolor provides high resolution daytime detection option and DEBRA-Dust a high resolution day/night option (but with some false alarm), SWD-IR combo and Dust-Fire RGB (which incorporates the SWD), provide day/night dust detection (at slightly lower spatial resolution), along with cloud classification. The Dust-Fire RGB has the added benefit of incorporating wildfire hot spot detection, which often develop during such high wind events. This particular SWD-IR procedure includes the SWD as the gray scale bottom layer, Clear Sky Mask as the middle layer, and cold IR BTs as the color top layer, in order to isolate the blowing dust feature (darkest gray) from clouds, while also including cloud temperature information. All methods require the forecaster to do some degree of analysis and interpretation in order to make a determination on whether the feature is dust.
Exemplifying the multiple dust detection methods available to and used by operational forecasters, NWS offices across the region shared various imagery on social media during the events:
Bill Line, NESDIS and CIRA