Strong winds on the western portion of a deep surface low in association with an exiting shortwave trough resulted in lofted/blowing dust from the IA/NE/MO/KS Missouri River Valley (MRV) southeast across central Missouri. This is a favorable region for winds to go unimpeded, and the lofted dust is likely due in part to sedimentation/silt left behind from the big spring flooding of 2019. Further, it is still early in the planting season, so fields are susceptible to having dirt erosion. Local media shared photos of blowing dust across I-29, which runs along the eastern side of the MRV (Fig 1).
The Omaha NWS office noted the blowing dust on social media in the nighttime microphysics RGB (Fig 2). This RGB is effective in detecting lofted dust due primarily to the inclusion of the 12.3-10.3 um split window difference (SWD), which has been shown to be an effective ABI channel combination for dust detection (see previous blog post).
Given the conditions, the NWS in Omaha issued a Special Weather Statement for “reduced visibility due to blowing dust” along I-29, and the NWS in Pleasant Hill mentioned, “reductions in visibility as a result of the blowing dust” in their Wind Advisory.
The SWD-IR combo procedure perhaps provides the best depiction from ABI of the blowing dust across the region for the duration of the event (Fig 3). The blowing dust appears as very dark gray to black (very low positive or negative difference values), while most clouds will appear as colors with the inclusion of cold brightness temperatures from the IR window channel. Small cumulus clouds will be lighter gray) The lofted dust is diagnosed to initiate near northwest Missouri in the presence of a tight surface pressure gradient and 40+ knot wind gusts. The lofted dust is carried southeast over I-29 and into central Missouri as it wraps around the southwest and southern portion of the surface low. The animation, lasting 10 hours, depicts the long duration of this event.
The blowing dust can also be diagnosed in the 500 m 0.64 um VIS channel. The color table used is modified to highlight lofted material (Fig 4). The blowing dust becomes most apparent near sunset, when forward scattering of dust particles toward the satellite is heightened.
Finally, a modified Dust RGB provides a great depiction of the blowing dust, while capturing cloud details as well (Fig 5). In this example, the dust appears as deep magenta, low/cumulus clouds dark blue, stratus or mid-level clouds as red, and cirrus clouds as black. The RGB recipe is shown in Fig 6.
SNPP and NOAA-20 consecutive overpasses provided higher resolution (750 m vs 2 km for GOES) VIIRS M-band SWD imagery near the beginning of the event, allowing for slightly more details (spatially) to be gleaned from the lofted dust. (Fig 7).
Bill Line (NESDIS and CIRA) and Andrew Ansorge (NWS DMX)