At 7:19 a.m. on Saturday, the National Weather Service released an updated freezing fog advisory in effect until 9 a.m. for Northern El Paso County/Monument Ridge/Rampart Range below 7,500 ft, Colorado Springs Vicinity/Southern El Paso County/Rampart Range below 7,400 ft and Pueblo Vicinity/Pueblo County below 6,300 feet.

The NWS adds to anticipate, “Localized visibility one quarter mile or less in freezing fog. Visibility will rapidly improve through the morning.”

“Low visibility could make driving conditions hazardous with patchy slick conditions possible, especially near steam generation sources like power plants,” adds the NWS. “If driving, slow down, use your headlights, and leave plenty of distance ahead of you.”

Understanding freezing fog advisories

When a freezing fog advisory is in effect, it indicates that fog is developing while surface temperatures hover at or dip below the freezing point. In such conditions, the minuscule liquid droplets within the fog can instantaneously freeze upon contact with various surfaces, including vehicles and roadways. Freezing fog poses heightened risks for driving, boating, flying, and other modes of transportation. Typically, visibilities plummet to a mile or less.

What is a freezing fog?

Freezing fog, a close cousin to ice, forms the same way as regular fog. Both fog and freezing fog start when the skies are clear, heat radiates into space, and as a result, the Earth’s surface cools down. As this cooling progresses, the air’s capacity to retain moisture decreases, triggering the condensation of water vapor into minuscule liquid droplets — the essential components of fog. When this fog forms in sub-zero temperatures, its water droplets remain in liquid form, a phenomenon known as “Supercooling”. In essence, supercooling occurs when a liquid, despite being below its freezing point, remains in a liquid state due to the absence of a freezing surface.

When these supercooled droplets encounter surfaces, they undergo a remarkable transformation, crystallizing into delicate ice structures known as rime. This transformation is often visible on vertical surfaces exposed to prevailing winds, as well as on trees, plants, and other elements in the environment. In fact, rime can form on a variety of surfaces, including stairs, railings, sidewalks, roads, and even vehicles.

What is black ice?

Black ice, also known as clear ice, refers to a delicate, nearly invisible layer of glaze ice that forms on various surfaces, especially on roadways. Despite its name, the ice is not black, but possesses exceptional transparency, enabling the underlying black pavement of the road, to remain visible.

The formation of black ice is frequently attributed to freezing fog, which can swiftly coat roadways with this treacherous hazard. Its near-invisibility renders black ice exceptionally perilous, as it poses a significant challenge for road users to detect.

How to stay safe?

When freezing fog blankets your surroundings, the safest course of action may entail avoiding travel if at all possible. If venturing out becomes an inevitability, exercise utmost caution and heed these essential safety guidelines:

High vigilance:

Be vigilant, as freezing fog can give rise to the notorious black ice, which remains elusive and challenging to spot.

Moderate your speed:

Drive at a reduced pace, especially when icy conditions are suspected.

Visibility matters:

Ensure your vehicle is visible to others by using low-beam headlights, which automatically activate your taillights. Utilize fog lights if your vehicle is equipped with them.

Avoid high-beams:

Refrain from using high-beam lights, as they create glare, making it more difficult for you to see what’s ahead of you on the road.

Keep a safe distance:

Maintain a generous following distance to account for abrupt stops or shifting traffic patterns.

Stay in your lane:

Use the road’s lane markings as a guide to remaining in the correct lane.

For those taking to the skies, be aware that even a thin layer of ice can form on aircraft surfaces, posing significant flight safety risks. Ensure the aircraft is appropriately treated or equipped with effective de-icing systems before embarking on your journey.

In the realm of freezing fog, knowledge, and vigilance serve as your steadfast allies, empowering you to navigate these meteorological complexities with safety as your main priority.

Source: The National Weather Service