Fresh snow cover and strong winds resulted in a stretch of blowing snow across the US Northern Plains during the period of 10-15 Jan 2024. GOES and JPSS Imagery provided helpful details regarding the state of the snowpack, and detection of blowing snow.
Starting with snowpack, recent snowfall and very cold temperatures allowed for a blowable snowpack. The VIIRS Snowmelt RGB has been discussed on this blog previously, and is a useful tool for assessing the blowability of a snowpack. Darker shades of blue represent older/crusted over/wet snow cover (coarse grain) which may have melted and re-frozen, and therefore is unlikely to blow, while lighter blues represent fresher snow cover (smaller grain) that may still be loose and blowable. An animation of daily Snowmelt RGB imagery from the 10th to the 16th captures a consistently blowable snowpack across most of the northern US plains with little in the way of change (Fig 1).
On Jan 10, northwesterly winds gusting over 30 knots across the fresh North Dakota snowpack resulted in a stretch of horizontal convective roles (HCRs) and associated blowing snow from northwest to southeast central North Dakota. Within the HCRs and associated blowing snow on the 10th, numerous sites reported blowing snow (or haze/light snow) with reduced visibility. The experimental GOES Blowing Snow RGB helps to highlight these features as a relative orange color against the background snow cover of red, bare ground of green, low/liquid clouds of bright blue/cyan, and higher/ice clouds of bright red/magenta (Fig 2). The shadows that develop as the HCRs deepen and sun sets also help to highlight these unique features. This RGB is similar to the Day Snow-Fog RGB, but replaces the ch03 red component with the high resolution ch02, in addition to some other more minor tweaks of the recipe.
NWS Bismark, SD leveraged satellite imagery to track the blowing snow, as mentioned in their afternoon 1/10 AFD: “Satellite imagery and webcams confirm the presence of blowing snow being lofted in horizontal convective rolls this afternoon. Surface observations within the blowing snow have been consistently reporting visibility around 2 to 4 miles.”
For comparison, visible imagery of the same scene is shown in Figure 3. While one can still diagnose the convective rolls, particularly due to the development of the shadows, the single band imagery is not as effective in isolating the features given a lack of coloration.
A direct comparison between the single band imagery and RGB imagery for a single time period is shown in Fig 4.
A similar Blowing Snow RGB can be produced from VIIRS I bands, making the product available at 375-m spatial resolution for 4-6 passes over a given northern plains location during the daytime. The higher resolution allows for better discernment of individual HCRs, and therefore determination of where the most considerable blowing snow conditions may be present. A 5 image VIIRS animation (leveraging VIIRS from N20, N21, and NPP) is shown in Fig 5, while a comparison of the ABI and VIIRS imagery is shown in Fig 6.
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Gusty winds and cold weather continued into the 11th, resulting in another day of blowing snow across North Dakota, albeit slightly further east, as depicted in the GOES Blowing Snow RGB and surface obs (Fig 7). Lake effect snow bands are also apparent as bright blue developing southeast off of Lake Sakakawea in the west-central portion of the scene. Again, from the afternoon (on 1/11) NWS Bismark, ND AFD: “Satellite imagery and surface observations show horizontal convective rolls lofting blowing snow from north central North Dakota into the northern James River Valley. Additionally, lake effect snow has been persistent over areas to the south and east of Lake Sakakawea, primarily northern Mercer County.”
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Blowing snow re-developed again in North Dakota on the 12th, also expanding to include South Dakota. In North Dakota, the HCR plumes were observable in the imagery, especially later in the day, in central/north-central part of the state, despite the presence of persistent high clouds (Fig 8).
In South Dakota, the blowing snow features become apparent during the afternoon in the south-central and southeast part of the state (Fig 9). For this day, I captured webcam footage from within the areas of blowing snow, revealing the reduced visibility across the region (Fig 10).
Figure 10: Webcam views from the afternoon of 12 Jan 2024 at locations in southeast South Dakota. From SDDOT.
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On the 13th, more widespread and intense blowing snow conditions developed across eastern South Dakota, where blizzard warnings were in place for ground blizzard conditions. The signature is obvious in the GOES-East Blowing Snow RGB imagery, with perhaps some enhancement of the HCRs apparent southeast off of Lake Oahe (Fig 11). The surface obs indicate locations within the plumes experiencing viability dropping below 1 mile.
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With weaker winds on the 14th, only spotty and minor blowing snow was present across the region.
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On the 15th, gusty winds again developed across the plains, and with persistent cold weather throughout the period limiting snow melt, significant blowing snow would again develop, particularly across South Dakota. The GOES-East Blowing Snow RGB revealed blowing snow in the southern part of the Aberdeen, SD NWS forecast area, and across much of the Sioux Falls, SD forecast area (Fig 12). These two offices leveraged satellite imagery in their forecast and analysis of the blowing snow event:
From the NWS Aberdeen, SD 1/15 PM AFD: ”The Blowing Snow RGB satellite imagery has been helpful this afternoon to view the lake enhanced/river enhanced clouds near Pierre with a band all the way down to far southeastern SD, blowing snow over much of eastern SD, and rolls of clouds over west central SD this afternoon.”
From the NWS Sioux Falls, SD 1/15 PM AFD: “As a lobe of positive vorticity advection passes over the area, satellite imagery shows some blowing snow plumes streaming across the area. While snowpack has been settling and becoming more dense, there remains enough blowable snow for breezy winds along with some weak instability and steeping low-level lapse rates to loft the snow, with scattered locations reporting visibilities below one half mile.”
VIIRS Blowing Snow RGB Imagery of this event is shown in Figure 13, and another comparison between ABI and VIIRS in Figure 14.
Both the VIIRS and ABI Blowing Snow RGBs can be accessed online on CIRA SLIDER. Additionally, the GOES Blowing Snow RGB can be installed in AWIPS.
Bill Line, NESDIS/STAR