Photo Lensworth         Fern Wall on the  Divide shouting “impending snow.”

Boulder’s fern walls and juncos (the bird) are our own Boulder harbingers of snow.

Photo Lensworth    Black-eyed Junco, predictor of snow, ground-feeder.

The Black-Eyed Junco has a dark top half and a light bottom half. Boulder welcomes them with open arms, since moisture is probably close on the heels of the bird. While we rarely see them “normally,” we see them in significant numbers a day or two before it snows. To show off, you must learn the Latin name of the Black-Eyed Junco. Junco hyemalis.

I’ve already confessed to being a fool based upon my public prediction of a hard winter in Boulder. We already know that in Boulder, only fools and visitors to the valley try to predict the weather. I’ve been here too long to claim a “visitor defense” leaving only the fool.

That being said, we are looking for snow on Christmas, to the delight of many. Some for the atmosphere, others for the atmosphere, and a couple for sleds, skis, photographs, snowshoes, cross country skiing, snow ball fights, and myriad other things. Boulder is athletic, smart, and fun-loving. Boulderites seem to have developed a tolerance for cold by wearing the proper clothing. I’m ignoring those who wear sleeveless “T” shirts and shorts when it is below zero.

When official weather reporters say it is going to snow, either they are right or they are wrong. Mostly wrong. Either it does not snow at all, or it dumps. And dumps. OR, it snows, but days before or days after predicted.

I personally believe that weather prediction took a big hit as climate change set in and accelerated. Weather prediction [links] has always been based on models. Those models, run on the fastest computers on Earth, were pretty good at predicting the weather. Boulder of course is at the heart of the weather, with NCAR and NOAA right here. That’s the National Oceanic and Atmospheric Administration and the National Center for Atmospheric Research, again for the show-offs.

National Center For Atmospheric Research NCAR

Keep in mind that to be fair to the weather prediction people, Boulder is tricky. We have the winds off the mountains, the front range wave, upslope storms that can slide around and until the last minute, maintain unpredictable onslaught locations. If a weather map has lines on it indicating any kind of front; hot, cold, occluded, or pressure lines (isobars), EVERY line goes through Boulder, generally just East of the downtown.

[heading III The bird clue is easy. Meteorologist look out!

I believe that the patterns, perhaps as a result of climate change, no longer apply. It’s like a bible verse made into a popular folk song. “A time to rain, a time to clear, a time to refrain from predicting…” That’s a typical  one hour weather report for Boulder. Prayer is generally a fine idea, in whatever form.

Animal sensitivity to weather seems to be far less reliant on past models, reacting more to what’s going on in the present. Notice that weather studios do not have windows, and the meteorologist who report the prediction, the weather people, can’t look outside. I’d think that would be an important part of the    weather prediction.

Boulder’s World-Famous Rare Fern Wall

First, what is a fern wall? In the picture first identify the ducks. Now ignore them, since they are not fern walls. Follow the pic into the distance, past the foothills, to the continental divide. That’s the top ridge of the mountains which towers over the City of Boulder [link] and is still in Boulder County! They look tall and rugged because they ARE tall and rugged. The highest points we see are over  meters, 14,000 feet , 4267 meters, and many are above 12,000 feet, 3.357

NOW, look behind the line of the divide. See the white dense cloud that sits like a long white cigar behind the divide? THAT is the long sought after fern wall.

photo Lensworth

Even our weather in Boulder is unique! Fern walls are quite uncommon and a real treat to see. It’s our own version of the Northern Lights.

All of that to say that when we see the fern wall, snow is likely in a day or so.

photo Lensworth

What are we looking at that I’m calling a fern wall? The mechanics are so interesting and unusual that we’ll take a look into it, in some depth. You’ll be able to impress your next winter visitor! It also allows us to use great words like “orographic” which is great fun to say out loud!.

A “fern wall” cloud is a unique and specific type of cloud formation that occurs in mountainous regions, particularly near the Continental Divide. This cloud formation is characterized by its cylindrical shape, extensive length, and typical positioning parallel to or just east of the Continental Divide. Recognized as a harbinger of snow, the fern wall cloud is a fascinating meteorological phenomenon.

This cloud formation is primarily influenced by the orographic effect, which occurs when an air mass is forced to rise over a mountain range. As the air rises, it cools and expands, leading to condensation and cloud formation. The specific conditions around the Continental Divide, which includes a series of mountain ranges that act as a climatic barrier, are conducive to the formation of these unique cloud structures. For the show-offs, here’s what you need to know:

1. Orographic Lifting: As moist air approaches the mountain range, it is lifted upwards due to the topography. This lifting mechanism is a key factor in cloud formation in mountainous areas.
2. Cylindrical Shape: The fern wall cloud’s cylindrical shape may be influenced by the wind patterns and the mountain range’s alignment. The air flows over the mountains and forms a cloud that aligns parallel to the range, creating the distinct, elongated shape.
3. Snow Prediction: The presence of fern wall clouds is often associated with impending snowfall. This is because the conditions that lead to their formation—such as moisture-laden air and temperature gradients—are also conducive to snow precipitation, especially in elevated and mountainous regions.
4. Local Weather Patterns: The specific meteorological conditions in the area of the Continental Divide, including temperature, humidity, wind patterns, and geographical features, contribute to the formation of these clouds. The fern wall cloud can be seen as a unique interaction between these local conditions and broader atmospheric dynamics.
5. Indicators of Weather Change: Such cloud formations are valuable for weather prediction in mountainous regions. Their appearance can help forecasters and locals anticipate changes in weather, particularly the likelihood of snowfall, which is crucial for both safety and planning in these areas.

Understanding fern wall clouds involves a blend of cloud physics, mountain meteorology, and local weather patterns. Their formation is a testament to the complex and beautiful interactions between the Earth’s surface and the atmosphere. All we have to do is look!