13:27 Fri Mar 24, 2023
Re-Tracing February’s Arctic Air Mass and Record Cold
It took 89 years, but as the headlines have reported, on Feb. 4 Mount Washington Observatory managed to tie its all-time record low air temperature of -47 °F, originally set in January 1934. Observer Karl Philipoff documented the harrowing and historic day in a previous observer comment
, and while I will probably think about my experiences that day for the rest of my life, my aim with this post is to take a look at the meteorology behind this event.
To start, we need to look up, way up, to the top of the troposphere, or more specifically, the tropopause. The tropopause is the boundary between the stable stratosphere and the lower, more turbulent troposphere. During the warmer months, and in tropical latitudes, the tropopause is much higher due to the atmosphere being much warmer. In the tropics, the tropopause may be as high as 11 miles.
Meanwhile, at the frigid poles, the tropopause is much closer to the surface at a height of around six miles. I mention all of this because it helps to establish some context. Below is a map of the continental U.S. with an overlay of something called the 2 PVU surface. In short, the height of the 2 PVU surface is more or less the height of the tropopause.
Meteorology is a bit like golf, where the lower your pressure value is, the higher in the atmosphere you are. In this image you can see tropopause height values that range from 30 milibars (mb) in the tropics to 690 mb over the White Mountain region. For reference, the summit is located at 6,288 feet or around 800 mb. In essence, this map shows us that the tropopause was located 110 mb or about 4,000 feet above the summit on Feb. 4. To get the troposphere that low, it has to be very cold.
The next image shows just how cold temperatures were around 850 mb (5,000 feet). Those fuchsia colors may look beautiful, but they represent temperatures lower than -40 °C. Cold of that magnitude is typically found high in the Arctic where the polar vortex usually spends its winters before breaking down in the spring.
Feb. 3 and 4, however, were not ordinary days for both the summit staff and the polar vortex. On this day, the vortex was a long way from its typical home and was displaced southward into the middle latitudes. More accurately, this cold air outbreak was the result of a piece of a much larger vortex breaking off and being pushed south due to a warmer Arctic and weaker jet stream.
Fortunately, we are able to trace the journey of this exceptional airmass. By using what’s known as a reverse trajectory, we can see where air masses originate. The following map tells an interesting origin story for the air that brought us our record cold.
By running the model back four days, we can see that the nursery for the airmass was none other than the high Canadian Arctic. Over the course of four days, the airmass traveled from Salisbury Island to New England. This translated to a 1,300-mile cross country journey. The half-loop path that the air took was the result of a powerful storm system that helped to dislodge cold air to the south, and eventually over the Northeast and the White Mountain higher summits.
Francis Tarasiewicz, Weather Observer & Education Specialist
While we can definitely confirm that we tied our record low temperature, there is still a lingering question that we have gotten from hundreds of people. Did the summit make it into the stratosphere during the Feb. 3-4 storm? Did we as observers smell Ozone when we went outside in the grueling conditions?
The short answer is no. For starters, the stratosphere contains the highest ozone concentrations of any layer of the atmosphere. If we were indeed in the stratosphere, then we would have noted an increase in the gas. Fortunately for us, the New Hampshire Department of Environmental Services (DES) maintains an ozone monitoring site on the summit. Their data for the time period in question shows something surprising.
During the coldest part of the two-day cold snap, Ozone levels actually decreased. This dealt a critical blow to hopes that we were briefly in the second layer of Earth’s atmosphere.
A weather balloon launched by the National Weather Service in Gray, ME (about 80 miles southeast of the summit) showed that the tropopause was located around 795 mb while the summit was at 777 mb. So, maybe there was a chance after all, right?
Well the story is a bit more complicated than that. The higher summits of the White Mountains do a lot to stretch and uplift air as it flows up and over the terrain. On this day, winds were blowing from the northwest, and up and over the summits. We suspect that this lift may have pushed the tropopause higher over the immediate summit area. From here, it quickly fell in elevation with air sinking on the leeward side of the Whites.
From record-setting cold to exceptionally low tropopause heights, this event has reshaped me as a forecaster and a person. I will never forget the dedication of my humble team and their willingness to go above and beyond when weather was at its most extreme. Our work up here is humbling, rewarding, and rarely easy, but I feel lucky to have a front row seat to nature’s extremes. If you enjoy sharing this ride with us, please consider supporting the Observatory.
16:33 Thu Mar 16, 2023
Red Sky at Morning, Hikers Take Warning
Having grown up along the coast of Maine, there was a saying instilled in me by my parents every time I was planning to go outside for an extended period of time: “Red sky at morning, sailors take warning. Red sky at night, sailors’ delight.”
This got me in the habit of looking out at the sunrise and sunset every day with the phrase repeating in the back of my mind. It was my parents’ way of getting me to pay attention to the weather when I was going out, and to take appropriate clothing or be home before a storm might roll in.
Working for Mount Washington Observatory, I have heard a similar phrase repeated to me by hikers that I have encountered on the summit while out taking weather observations. It however switches out the "sailors" for "hikers" in the rhyme.
Sunrise over undercast on Feb. 14, 2022.
Hayden Pearson, Weather Observer & Research Specialist
While many have undoubtedly heard a variation of this rhyme before, where does it come from? And is there any scientific backing to this phenomenon? The history of this phrase dates back to at least the 1st century AD, and it was cited in the New Testament showing prevailing knowledge of the seafaring people of the time. Shakespeare also used it in his play Venus and Adonis. It has been rewritten and adapted countless times since then.
As for scientific backing, the phrase does explain in some basic terms phenomena that we observe with the weather both at sea and in the White Mountains. To understand how this lore can be used to predict the weather, we must first look at colors in the sky and the prevailing winds.
The Tip Top House is shown with newly fallen snow at sunset on June 19, 2022.
In the mid-latitudes, the prevailing winds are Westerlies, meaning the wind is from the west and storm systems move west to east. A storm system typically has high atmospheric moisture and dust content, which can scatter light coming in from the sun. During the sunrise and sunset, the light is projected through the troposphere, which is the densest part of the atmosphere. This is additionally where all of the Earth’s weather is confined.
A deep red sunrise or sunset suggests that the atmospheric particles are concentrated enough that they are scattering shorter wavelengths of light and only permitting the longest wavelengths, red, to pass through. As areas of low pressure deepen, they tend to collect more particles, leading to the development of clouds and storms, whereas building high pressure leads to fair-weather skies and clearing weather patterns.
Sunset from the observation deck on Aug. 13, 2022.
So how does this apply to the rhyme? In a general sense, in order to see a sunrise or sunset, the region is typically under the influence of high pressure as the skies are clear enough to see the sun. Knowing that, let’s look at the first part – red sky at morning, hikers take warning. We know that the red color is caused by the scattering of light as it passes through the atmosphere, as the sun rises from the east. This light is scattered off the approaching clouds and the increasing suspended particles as low pressure and storm systems move in.
Now for the second part – red sky at night, hikers’ delight. The same principles of light diffraction apply. However, since the sun is setting in the west, the departing clouds are now illuminated, signaling high pressure to follow.
While this does provide a natural warning, if you are planning on hiking in the White Mountains, it is still always best to check out our Higher Summits Forecast
ahead of your trip.
Nimbus looking out at sunset on Aug. 14, 2022.
17:31 Sat Mar 04, 2023
Traditional Mount Washington Rockpile Crunch Recipe
Winter on top of Mount Washington means high winds, snow, and of course, lots of rime ice! Rime ice is a phenomenon that occurs when supercooled water droplets freeze on contact with any surface they come into contact with. When foggy conditions occur concurrently with high winds, rime ice can accumulate pretty quickly. Unlike glaze ice, which is clear and dense, rime ice is opaque, light, and fluffy. These qualities make it the perfect ingredient for ice cream!
Rime ice cream (also known as Rockpile Crunch or R’ice cream) is a Mount Washington Observatory tradition that dates back before many generations of weather observers. Eric Pinder, a former observer, wrote about the unique dessert in his book Life at the Top first published in 1997. Life at the Top, “describes the joys and terrors of living in the clouds and explains Mount Washington’s geology and weather”. Also included in the book is a, “one-of-a-kind cookbook made up of recipes contributed by the Observatory staff”. If you are interested in seeing more MWOBS recipes and reading stories about observer life on Mount Washington, Pinder’s book is available at the MWOBS online shop or on Pinder’s website. All proceeds from the purchase of this book are donated to the observatory to support research and educational outreach.
Ira Seskin, a long-time summit volunteer, contributed this particular recipe for the book. I had the pleasure of working with Ira during his most recent shift volunteering where he told me all about the development of the recipe. According to Ira, the recipe was derived from the classic maple syrup snow, but using sweetened condensed milk gives a more creamy texture. When it comes to mix-ins, Ira says, “there are no rules, I would just use whatever they had up here (on the summit)”. He says for the base, “you can use rime ice or fresh snow,” then jokingly, “just don’t use yellow snow”. Although it has been many years since Ira came up with his recipe for rime ice cream, he still enjoys making it. His preferred mix-ins to use currently are strawberries and blueberries.
I happened upon the recipe for Rime Ice cream when planning for a Winter Storms EduTrip in December of 2022 and thought that it would make the perfect activity to include in the curriculum. After teaching participants about the many different types of ice and their formation processes, we went outside and collected rime ice. We then quickly went inside to gather ingredients and began the process of making the rime ice cream. To make traditional Rockpile Crunch, ingredients include rime ice or snow, sweetened condensed milk, chocolate chips, M&M’s Reese’s Pieces, chopped nuts, and raisins.
The EduTrip participants were so excited to watch the process unfold while I stirred and fellow weather Observer Hayden Pearson slowly poured in the sweetened condensed milk. It took quite some time and a lot of stirring, but eventually the EduTrip participants’ suspicions about the possibility of such a dessert were refuted. Everyone really enjoyed the sweet treat, one even commenting, “It tastes like a New England winter day”. See below for the full recipe as it appears in Life at the Top.
Alexandra Branton, Weather Observer & Education Specialist
Rime Ice Cream (Contributed by Ira Seskin)
“This wintertime camping favorite, also known as “Rockpile Crunch,” tastes best with a fresh crop of Mount Washington rime ice. If none is available, plain snow will do just fine. (Caution: In the good old days, all fresh snow was white and clean. Unfortunately, pollutants and acidity in the atmosphere now make it unwise to eat snow in many areas. If that’s the case where you live, save this recipe for better days, when the air is clean again.)
- 2 quarts rime ice
- 14-oz can sweetened condensed milk
- Chocoloate chips
- M&M candies
- Reese’s Pieces
- Chopped Nuts
Place a 2-quart mixing bowl outdoors prior to a predicted snowfall (or fill it with existing rime ice). Carefully fold in the condensed milk until the mixture is slightly granular. If the milk is added too quickly, mix with a fork to correct the consistency. Fold in all remaining ingredients until it looks and tastes right. The mixture should be soft and creamy−like soft ice cream. Use ice pellets for an extra crunchy texture” (Life at the Top, Eric Pinder).