The snowstorm that broke records and brought parts of the Rockies to a standstill had something else that was quite literally buried in the snow: a layer of brownish snow that fell in New Mexico and Colorado with dust that had traveled all the way from Mexico.
It was a tweet from the National Weather Service office in Albuquerque, New Mexico, that pointed out the phenomenon.
“The dust that was lofted this afternoon from the playas in Mexico … has now been transported all the way into Colorado!” it read.
“We had a low that was tracking across the state and it was bringing a lot of gusty winds from the southwest. You could see on the satellite imagery the dust being lofted,” said Sharon Sullivan, meteorologist at the NWS in Albuquerque.
The yellow on the NOAA satellite shows the dust being carried north with the winds. Using a filtered layer created by Colorado State University, the dust is easier to pick out in the imagery.
Dust even ended up in the snow as far north as Boulder, Colorado, according to the National Weather Service, which tweeted a picture of the brownish layer that fell outside its office.
“We don’t see it too often. Especially ending up as far north as Boulder,” said Sullivan. More often, she added, dust will be carried from White Sands National Park, which is in the southern part of the state, but to get it from Mexico is pretty rare.
How the Mexican dust was able to travel so far
The weather setup for this event was perfect. Northern New Mexico and parts of Colorado have had a red flag warning in place for the past several days, so winds were gusting out of the southwest at 60-70 mph at times. Those strong winds helped lift and carry the dust from Mexico.
“Some of these particles are very fine, so it only takes about 15-20 mph to have them lifted off the ground,” said Sullivan. So with winds gusting three times that, the dust was easily picked up and carried nearly 800 miles.
Similar to the way Saharan dust travels from Africa, across the Atlantic and ends up suspended over the Florida sky, this dust was picked up and carried north.
“The dust particles cling to the snowflake or water particle and falls with the snowflake to the ground,” said Sullivan. The result is a fresh coat of snow with a brown hue.
Sullivan said the same setup Tuesday could result in more dusty snow, which she says also reduces the snow’s albedo, or reflection power, causing it to melt more quickly and resulting in a reduced snowpack overall.
It has been a busy week for that region of the country. The National Weather Service office in Albuquerque had critical fire weather and winter weather advisories, and a tornado watch, at the same time — something that’s not unheard of for that region, but wild nonetheless.