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Observer Comments

18:14 Mon Nov 30, 2015

How Do Frost Heaves Form?

I’ve heard people ask questions, especially this time of the year, about frost heaves. Seemingly defying the laws of gravity, ice often pushes earth up with impressive force, lifting hundreds of pounds of material and potentially doing serious damage to structures in its path. How does this form?

A logical explanation to frost heaves is the expansion of water as it freezes. This would explain why ice is forced upward, however the 10% expansion in volume of frozen water does not account for the impressive distance the ice can force earth into the air.

Instead, the driving factor behind frost heaves is capillary action. If you dip the corner of a paper towel into water, you’ll see the water begin to travel up the paper. The main causes of capillary action are explained very well in this USGS article:

"Capillary action occurs because water is sticky, thanks to the forces of cohesion (water molecules like to stay close together) and adhesion (water molecules are attracted and stick to other substances). Adhesion of water to the walls of a vessel will cause an upward force on the liquid at the edges and result in a meniscus which turns upward. The surface tension acts to hold the surface intact. Capillary action occurs when the adhesion to the walls is stronger than the cohesive forces between the liquid molecules. The height to which capillary action will take water in a uniform circular tube is limited by surface tension and, of course, gravity."

So, that explains why capillary action occurs in test tubes and paper. It is very similar in soil-water travels upwards between porous particles. The temperature gradient within the soil also helps to pull moisture upward to the surface. 

Frost HeaveWater permeating through soil layers toward the surface causes frost heaves. Courtesy of Wikipedia-Open Source.

Capillary flow is strongest through semi-porous material. Therefore, clay would be too dense to promote capillary action and gravel too spread out to promote capillary water movement. A review released by Edwin Chamberlain of the Cold Regions Research and Engineering Laboratory indicated that materials with particles greater than 10% of the particles less than 0.075 mm in diameter supported frost formation. 

Do you have a weather question? Get it answered by the meteorologists here on the summit every Monday. Simply tag your question on social media with #mwometmonday!

Michael Dorfman, Weather Observer/IT Specialist

09:08 Sat Nov 28, 2015

What I am Thankful For
With Thanksgiving earlier this week, I have been thinking what I’m thankful for at the Observatory. The first thing I am thankful for is being selected to intern at Mount Washington Observatory. This internship is a dream come true for extreme weather enthusiasts like myself. Since beginning my internship in August I am thankful for the opportunity to learn about mountain weather through composing specialized forecasts for the higher summits of the White Mountains and helping with weather observations. I am thankful for the wonderful views from the summit when we are in the clear, such as the view depicted in the picture below taken at sunrise on Thanksgiving Day.
Thanksgiving Day sunriseThanksgiving Day sunrise
 I am also thankful that we had pleasant weather on Thanksgiving Day and I found time to go hiking with a fellow summit crew member. I am an avid outdoorsman and hiking is one of my favorite hobbies.
View of the Great GulfLooking into the Great Gulf on a Thanksgiving Day Hike
Most of all I am thankful for all the wonderful, knowledgeable people I work with on the summit and I am happy to call them my summit family. It was difficult spending Thanksgiving away from family and friends for the first time; however, I still had a great Thanksgiving with my summit family.

Andrew Henry, Summit Intern

22:17 Thu Nov 26, 2015

A Happy Thanksgiving On The Summit
Mount Washington Observatory is a manned weather station that operates 24 hours a day, 7 days a week, 365 days a year. We work in two crews for eight days at a time, swapping out every Wednesday (typically). This all means that regardless of holidays, one crew will be up here manning operations and observing the weather. This year’s crew, Kaitlyn, Mike D, Andrew, and myself had an enjoyable Thanksgiving. And while it is hard to be away from family and friends for the holidays, we always make the best of it with our summit equivalent of a family. We all chipped in and contributed a portion of tonight's meal all the while enjoying each others company. Here are some pictures documenting our Thanksgiving Dinner:
Thanksgiving table settingThe table setting for tonight's Thanksgiving Dinner
Mike Dorfman carving tonight's turkeyMike D carving tonight's turkey
Mike Dorfman, Kaitlyn, Andrew, and Ryan sitting down for Thanksgiving dinnerThe crew sitting down for dinner and sharing what they're thankful for
Mike Dorfman, Kaitlyn, and Andrew dishing up Thanksgiving dinnerThe crew passing around their contributions to tonight's Thanksgiving Dinner
Thanksgiving dinner on the summitThanksgiving Dinner
Thanksgiving desserts on the summitThanksgiving Dessert
We hope everyone had an enjoyable day and Happy Thanksgiving from the entire summit crew.

Ryan Knapp, Weather Observer/Staff Meteorologist

18:22 Wed Nov 25, 2015

Tech Women | Tech Girls - A Week of STEMspiration!
The NH High Tech Council (NHHTC) Tech Women | Tech Girls launched its first ever Tech Women Ambassadors week-long program, beginning Monday November 16 and concluding Friday November 20. Several workshops took place at various venues, encouraging young women across the state to consider a STEM-based career. I was lucky enough to visit with a great group of 9th grade girls at the White Mountain Community College in Berlin, NH last Friday to share my own experiences about pursuing a career in meteorology.
Students examining rime iceA piece of rime ice from the summit was passed around the classroom. Photo courtesy of NH Division of Economic Development
I thoroughly enjoyed telling my story and talking about all of the awesome and exciting weather events I get to experience working on the summit of Mount Washington. It’s so important to encourage young women to consider a career path that they may have never thought about before, or simply assumed would be impossible to pursue. Choosing a challenging career is never easy, but it’s certainly very rewarding. The opportunities are endless!
I look forward to future programs offered by Tech Women | Tech Girls!

Kaitlyn O'Brien, Co-Director of Summit Operations

16:36 Sat Nov 21, 2015

Where's the Snow?

After a brief warm spell with over an inch of rain falling on the summit Thursday and Friday, temperatures have fallen back below freezing atop Mount Washington. But where’s the snow? So far for the month of November the summit has only picked up 7.1 inches of snow, well below our monthly average of 37.8 inches. Temperatures have been on the mild side as well, with an average temperature for this month of 28 degrees resulting in about half of our precipitation falling as rain and not snow.

Looking at the weather patterns over the week ahead, there will be some snow in the forecast. A cold front crossing the summit tomorrow will bring snow showers to the higher summits, with a light accumulation possible in the trace to 2-inch range. Very cold air will be in place behind this system, with temperatures bottoming out just shy of 0 degrees Fahrenheit Tuesday. Off and on snow showers will continue through Thursday, hopefully adding to the thin snowpack in place. The next significant storm looks to affect the northeast and Mount Washington over the weekend, with potentially more substantial snow if the track of the storm remains the same in the coming days. Either way, we’re all looking forward to getting into the heart of the winter season on the summit!

Mount Washington and the Presidential Range from the Omni Mount Washington Hotel earlier this month.

Tom Padham, Weather Observer/Meteorologist

20:22 Thu Nov 19, 2015

Back at the Summit

Greetings from the summit! After a 10 day off week, it is good to be back up on the mountain. I was a little disappointed at the lack of snow. With how white the summit was looking from the valley I expected there to be quite a bit more but everything is covered in rime ice so it makes for nice scenery. Currently we have gone back into the fog and with the temperature just above freezing, all the water vapor in the fog is condensing to the snow and rime accelerating the melting process. I am worried that all the snow and rime will melt before we fall back below freezing tonight! It also looks like we could also get quite a bit of rain tonight which will melt the snow even faster. I am hoping that we will be able to fall below freezing before the precipitation completely exits the region so there would at least be a little bit of fresh snow to fall to keep the summit white.


The summit is also much more quite now that Kyle has started his new job with only 3 people up this week. It will take some time to get used to not having Kyle up here, but I am sure he will be back to visit!  

Adam Gill, Summit Intern

20:31 Mon Nov 16, 2015

Another #MWOMetMonday is here!
Today, @gwhizkids asked a great question about what causes the extreme weather on the summit of Mount Washington.
Certainly Mount Washington is not the tallest peak on the East Coast (For one, Mt. Mitchell in North Carolina stands at 6,683 feet, topping us by 395 feet!). But, Mount Washington is the tallest peak north of North Carolina and east of the Mississippi River. In fact, the next tallest mountain west of here is Harney Peak in South Dakota with an elevation of 7,242 feet. So what does that have to do with our extreme weather?
On average throughout the year, Mount Washington sees winds predominantly out of the WNW direction. Looking at the terrain to our west, you can see there is a distinct funneling effect. As the air rushes toward the summit, not only is it funneled toward the mountain by the surrounding terrain, but it’s also forced to rise up and over the summit. When there is not much around for miles to inhibit this flow of air, it will cruise along until being forced and “molded” by the terrain.
What happens when you compress air or water? It accelerates! This is known as the Venturi Effect (which incorporates Bernoulli’s Principle). As the air is forced to rise over the summit, it is squeezed between a stable layer of air, known as the tropopause, and the mountain. As a result, the speed of the flow increases, and significantly accelerates the winds on the summit.
Venturi Effect diagram
 Mount Washington also lies in the center of 3 main storm tracks. A lot of the extreme weather we see simply has to do with our location. Below is a 10 year climatology of over 1,000 low pressure systems. As you can see, New England is the “tailpipe” of the United States, with areas of low pressure traversing the region all the time.
Storm tracks
Perhaps this is what makes Mount Washington so unique. It’s certainly not nearly as tall as peaks in the Western United States, but the ample access to moisture, location, prominence, and surrounding terrain forcings contribute to some of the most extreme weather conditions ever observed. Rime ice growth at rates of up to 10”+ per hour, high winds, low temperatures, and dense blowing snow are just a taste of the conditions that Mount Washington has to offer.  

Kaitlyn O'Brien, Co-Director of Summit Operations

20:38 Sat Nov 14, 2015

Comparing Wind Speed at Different Locations
The Mount Washington Observatory has a regional network of 19 different mountainous automated weather stations. This includes 6 sites every 1000 feet along the Mount Washington Auto Road from base to summit.  We’ve recently installed anemometers at our 4000 and 5300 foot sites in hopes to better record wind speeds above tree line on Mount Washington. Our 4000 foot site is located near an old Signal Corps foundation block, and is rumored to occasionally have wind speeds rivaling the summit. Our 5300’ site is our highest site in our network of stations and is exposed to some impressive weather as well!

I wanted to do a very brief analysis of the data we’ve recorded so far from these anemometers (they’ve been installed since September).  Don't consider this to be a thorough analysis of this data-it’s more of a sneak-peak with more to come.

First, let’s take a look at the average wind speed from various directions.  The following wind roses indicate the average wind speed from various directions.  Winds are named for where they come from, so the wedge pointing to the northwest indicates the average wind traveling from the northwest.

We can see that lower elevations see dramatically lower wind speeds.  As you travel further down the mountain, you are less exposed, lowering wind speeds.  In additions, the Venturi Effect, which is responsible for giving Mount Washington its famous winds, has less of an effect the further down the mountain you travel.  
Another big reason for these values is due to geography. Both 5300' and 4000' are surrounded by mountainous terrain, blocking and steering the air dependent on direction. Take a look at the map below to see the three sites along with their surrounding land features:

Another explanation for these values is the size of the sample set.  We’ve only had a few months of data from these sites, giving us a very good idea of prevailing wind directions (typically west and northwest on the summit), but not a very good sense of not-so-common directions.  Our previous world record wind speed of 231 mph came from the Southeast, a direction we haven’t seen too much of in the last few months.

One thing stands out to me, and that is the northwest wind direction at 4000 feet.  You can easily see wind speed from the northwest is over twice as strong as any other direction.  Let’s look a bit more into this.  So, while wind speed is from the northwest at 4000 feet, what direction is it on the summit?  The answer to this question will tell us the effect terrain has on steering the wind.

This shows that wind speed from the northwest at the 4000 foot site typically yields wind direction from the west on the summit.  When looking at the map above, you can see a ridge immediately to the west of the site.  It’s possible that the wind is steered around this ridge, approaching the site from a more northwesterly direction.  However, more research would be required to confidently say that this is the cause. 

How do speeds on the summit compare to speeds at 4000 feet when coming from the northwest?  Does the ratio of summit-to-4000-foot speeds change depending on wind speed?  Let’s take a look:

For this specific direction, wind speed at 4000 feet is about one quarter that of the summit wind speed at low winds and around half the speed of the summit wind speed at higher wind speeds.  If we’re recording 48 mph from the Northwest at our 4000 foot site, we will, on average, record 105 mph on the summit.  While this is what we would see in theory, reality may be completely different.  We're looking forward to getting more data so we can come to more solid conclusions!

Michael Dorfman, Weather Observer/IT Specialist

17:41 Thu Nov 12, 2015

Calendars and Pictures
Looking at our 2015 calendar, it is weird to think 2016 is only ~49 days away (as of this writing). The year 2015 felt like it went by in a flash, at least for me. With 2015 coming to a close, that means our, and maybe your, wall calendars will soon be obsolete. Luckily, for the third year now, I have put together a few Mount Washington Observatory calendars to replace your soon-to-be obsolete calendar. This year we have not just two but three to choose from; all of them compiled from some of our most popular images we have posted to Facebook and elsewhere. If interested in checking them out head HERE. And if interested in buying one or two, our publisher is offering a 30% off coupon. Just enter NOVFLASH30 when checking out. Coupon codes are case sensitive and the offer ends November 12 at 11:59 PM EST. If we learn of any additional codes to pass along to you to save money, we will post them to our Facebook page.
While each of our calendars will provide you with a dozen or so images to admire, we also off our images individually with sizes varying from small to large (available HERE). I try to update our image portfolio every two weeks pulling from our most popular and interesting images posted on Facebook, Twitter, Instagram, or Observer Comments. While a lot make the cut, not all of them do. So if there is ever an image posted that you like that doesn’t make the cut in our updates, please just let us know and we would be more than willing to make it/them available. And addressing two of our most common questions: yes, the watermark is removed upon purchase and yes, panoramic images can be purchased in full. Instructions to do so are usually appended in the image's description section.
If you do decide to purchase a calendar or picture, let me say, "Thank you!" All purchases help fund our member supported Observatory.  

Ryan Knapp, Weather Observer/Staff Meteorologist

17:35 Tue Nov 10, 2015

Seasonal Changes On The Summit
As the seasons change on the summit, so do the number of visitors and staff. During the summer months, thousands of people visit the summit of Mount Washington via the Mount Washington Auto Road, the Mount Washington Cog Railway, and various hiking trails that lead to the summit. Many of these visitors stop in the Extreme Mount Washington Museum to learn about Mount Washington Observatory’s history. Members of the observatory frequently sign up for tours of the observatory weather station during the summer months. To accommodate for this increase in visitors, Mount Washington Observatory employs extra staff members during the summer months. The typical Observatory staff during the summer consists of three weather observers, two interns, a museum attendant, and two volunteers.
Partial rainbow and crepuscular rays at the end of summerPartial rainbow and crepuscular rays at the end of summer
As the weather becomes colder and snow/ice become more frequent during the fall, visitors to the summit become less numerous. As a result, only one intern is on the Observatory staff for the fall season. Typically in mid-October the Mount Washington Auto Road closes for the winter and the Cog Railway begins to run less frequently until it eventually closes for the season. With the two main modes of transportation to and from the summit closed, the number of visitors to the summit dwindles to almost none with only an occasional hiker here and there. The Extreme Mount Washington Museum closes for the season when Mount Washington State Park closes for the season, typically shortly after the closure of the Mount Washington Auto Road. Once the museum closes, the Observatory staff is down to the three observers, one intern, and two volunteers. The month of November is a relatively slow time of year for the Observatory with no planned day trips or overnight educational trips until the New Year approaches. As a result, the Observatory staff drops down to only the three weather observers and an intern for the month. This gives the Observatory staff a chance to bond with each other and develop a strong appreciation for all the hard work volunteers devote to the Observatory.
Lenticular cloud with fall foliage belowLenticular cloud with fall foliage below
Volunteers join the observatory staff again in December as the Observatory prepares for the winter trip season, which will bring a return of occasional small groups of visitors to the summit. The winter Observatory staff will consist of three observers, one intern, and two volunteers until mid-May when the Mt Washington Auto Road and Cog Railway reopen for the summer season, giving visitors easier access to the summit. As visitors to the summit increase, the Extreme Mount Washington exhibit will reopen for the season and the Observatory will return to its summer staff consisting once again of three weather observers, two interns, a museum attendant, and two volunteers.
Mount Washington with a fresh blanket of snow and rime iceMount Washington with a fresh blanket of snow and rime ice
Not only do the changing seasons bring changes in weather and the amount of staff at the Observatory, but I find my daily tasks have changed slightly as well. At the onset of my internship with the observatory in late August, I found myself working in the Extreme Mount Washington Museum and giving tours of the Observatory in addition to composing an afternoon forecast for the higher summits of the White Mountains and helping with observations when I could. Now that the museum is closed and there are no visitors to to provide tours to, I find I have much more time to focus on the meteorological aspects of my internship, such as becoming a better forecaster, and learning how to observe the weather. Additional tasks that the cold weather brings include deicing the instrumentation and shoveling snow away from our fire exits, both of which are tasks I thoroughly enjoy. I have always been an extreme weather enthusiast and nothing I have experienced gives quite the adrenaline rush of deicing the instrument tower in high winds, sub-freezing temperatures and visibilities near zero.
Sun setting into a sea of undercast with rime ice in the foregroundSun setting into a sea of undercast with rime ice in the foreground

Andrew Henry, Summit Intern

21:08 Mon Nov 09, 2015

We received a great question from one of our fans for today’s #MWOMetMonday!
Sometimes under certain atmospheric conditions, we actually report a warmer temperature on the summit than the valley. Why does that happen?
That seems a little odd, considering that the relationship between temperature and pressure is directly proportional. (Yikes! What does that even mean?)
Let’s take a closer look at what’s known as the ideal gas law:
PV = nRT
 P = pressure, V= volume, n= amount of gas, R = gas constant, T = temperature
All that is necessary to take away from this is the fact that the P and the T are on opposite sides of the equation. If the pressure decreases, that means the temperature must decrease too. If the pressure increases, that means the temperature must increase. This is what’s known as a directly proportional relationship.
How does that relate to the air on the Rockpile versus the air in the valley?
If you start at the base of Mount Washington, and work your way up to the summit, the pressure will slowly decrease as you ascend the mountain. Under standard atmospheric conditions, the temperature will decrease as well, gradually becoming colder as you approach the summit.
But sometimes, we see temperature differences of 10 to 15 degrees warmer up top! When the temperature increases with height, that is an indication of an atmospheric inversion. Inversions are quite common and are easily spotted when looking at our Mount Washington Auto Road vertical temperature profile. In fact, there is an inversion present this evening:
Inversion seen along the Mt Washington Auto Road Vertical Temperature Profile
On the left hand side, we can see that at the 4000’ site earlier tonight, the temperature was 47.5°F while the base site (1600’) was way colder at 33°F!
But what causes inversions to form?
There are several different reasons why an atmospheric inversion could occur. One of the more popular “flavors” of inversions is nocturnal inversions. Nocturnal temperature inversions are strongest on calm, clear, and cool nights. They generally begin to set up after sunset and are a result of radiational cooling of Earth’s surface. As the ground releases the day’s built up energy in the form of heat (known as longwave radiation), the air just above Earth’s surface begins to cool rapidly. Because air is a poor conductor of heat, these cooler temperatures at the surface are not transferred to the higher areas of the atmosphere without wind. So with calm conditions in place, there is little to no mixing, thus allowing the atmosphere to become very striated or layered, with distinct temperature differences noted across each layer. As Earth’s surface continues to release more longwave radiation, the air just above the surface becomes colder, creating an even stronger temperature inversion.
Sometimes sunrise is a great visual aid to see the effects of a strong nocturnal inversion that has developed the night before. The image below, taken in August of 2014, shows what I call a “pancake sun”. The layer of warm air at the inversion level below the summit is distorting the view of the sun as it rises, causing it to appear as flat as a pancake!
Atmospheric inversion causes sun to look as flat as a pancake

Kaitlyn O'Brien, Co-Director of Summit Operations

15:37 Fri Nov 06, 2015

What I am Thankful For...

With Thanksgiving only being a few weeks away, our Financial/Administrative Assistant, Mary Anne, challenged the rest of the staff to write one thing per day that we are thankful for until Thanksgiving Day. Since I am leaving the Observatory in a few days to pursue another job opportunity, I decided to take on Mary Anne’s challenge and create my list of 26 things I am thankful for, here and now.

I am thankful for…

  1. The days I have spent working and living on the summit at the Mount Washington Observatory.
  2. Good Vibes Coffee; it is the observers life blood here on the summit.
  3. Being able to see temperatures so cold that bubbles freeze in air.
  4. Seeing days so cold and windy that boiling water thrown into the air crystalizes instantly.
  5. Seeing more sunrises and sunsets than I can remember, that were so breathtaking that no picture does justice trying to replicating them.
  6. Taking weather observations at the “Home of the World’s Worst Weather”.
  7. The days with a complete undercast.
  8. The days of snowboarding in the eastern snowfield.
  9. The days the summit was encased in rime ice and surrounded by clear blue skies.
  10. De-icing our weather instrumentation in winds over 120MPH!
  11. Seeing the Aurora Borealis.
  12. The time I made it into the “Century Club”.
  13. The times I didn’t make it into the “Century Club”.
  14. My boss Mike C. who has let me crash at his place during my travels to and from NJ.
  15. All the interesting people I have met on the summit through the winter trips the Observatory offers all winter long.
  16. Being selected as a summit intern in the winter of 2013.
  17. Being hired as a Weather Observer/ IT Specialist.
  18. The volunteers who have come to the summit and worked alongside us over the years.
  19. The valley staff and the work they do to keep the Mount Washington Observatory flourishing through the years.
  20. The mentoring I received from the IT staff here at the Observatory.
  21. The sponsors of the Observatory, especially Eastern Mountain Sports and Vasque, who provide us observers with the gear that keeps us warm, dry, and safe.
  22. The Observatory’s summit crew. They are some of the brightest hardworking people around. It was truly an honor working with them, especially Mike C. and Tom.
  23. Being able to spend the coming holidays with my family this year.
  24. My family and friends and the support and assistance they have given me over the years.
  25. My fiancé Rachel, who has stayed with me over the years, even with a work schedule that took me away for a week at a time. Without her love and support I don’t know where I would be today.
  26. Last but not least, all of you! The members and supporters of the Mount Washington Observatory.


The Mount Washington Observatory owes everything we do to the members and supporters of this organization. If it was not for their generous support we would have dissolved a long time ago. I know I am planning to continue my support after my departure, and I hope all of you that are members continue to support the Observatory, and those of you who might not be a member already, join! I promise it is not a decision that you will regret.

Well Mary Anne, there is my list. Hope you didn’t think that I was going to short you on 26 days’ worth of things I am thankful for!


Michael Kyle, Weather Observer/IT Specialist

21:01 Wed Nov 04, 2015

Feeling the Force of Mount Washington's Winds

The beginning of this shift was exciting wind wise up on the summit. Shortly after arriving on Oct. 24th for shift change, a warm front approached us from the south and caused some snow to start falling. By the late afternoon, the snow had switched to freezing rain and was accumulating fast. Wind speeds also ramped up to being sustained over 70 mph. After dinner, all the people on the summit went outside with a sled to be blown across the ice covered deck just by the force of the wind alone. Shortly after we all went back inside to warm up and play some board games, the first gust over 100 mph of the winter season occurred gusting to 108 mph. Thursday we had a “break” from the winds even though we still had a few gust over 75 mph. Friday we were caught off guard by how strong the winds actually got. We were expecting the winds to be sustained in the upper 80s to low 90s with a few gust over 100 mph but right after sunrise, the winds ramped up and were gusting over 120 mph consistently with winds sustained over 100 for about 15 minutes. Kyle successfully completed his century club attempt and in my attempt, I got knocked down with the first strong wind gust.

Just for fun, I calculated how much force the wind was exerting on me, if I was to be standing in the strongest gust that occurred during my century club attempt. I used the formula  

F = A * ρ * v2

Where F is force, A is area, ρ is the atmospheric density, and v is wind velocity in meters per second. To find the area, I took my height if 5’ 7” and then did an average of my width at 1’ 6” which I converted to meters. I reduced the area a bit because people are not boxes so the reduction would be more realistic and not as much of an overestimation. I found the density by using the temperature, humidity, and the atmospheric pressure at the summit at the time of the gust. The strongest wind gust during my attempt was 122 mph which converted to approximately 55 m/s. Plugging in the numbers into the formula

F = .78m2 * 1.043kg/m3 * 552m/s

Calculating to a force of 2460.96N which converts to an incredible 553.24 pounds of force exerted on me, if I was to be standing strait up facing the wind. Now, it is nearly impossible to stand strait up in winds over 100 mph so the trick is to be as low to the ground as possible to reduce the amount of area that you are exposing to the wind. Taking it slow really helps out to and wait for lulls in the gust to make forward progress into the wind. Overall it was quite the experience to feel the power of winds over 100 mph and hope that we get many more days like this during the course of this winter.

Adam Gill, Summit Intern

19:01 Mon Nov 02, 2015

MWO Met Monday: Mount Washington's Winds

This week for #MWOMetMonday we had a question that has been asked by many people for as long as the mountain has been known to exist, and it leads to why Mount Washington is such a special place.

Mount Washington has several factors that lead to the high winds seen on the summit, and they have to do with the location of the mountain, elevation or height of the summit, and atmospheric physics.

Location: Mount Washington is situated in a very favorable area to see stormy weather and have the opportunity to see high winds.

The image above shows average storm tracks across the United States for low pressure systems. Mount Washington’s location in New England (top right of image) is at the confluence of three major storm tracks. This allows the summit to see plenty of opportunities for high winds, with low pressure systems crossing the area generally every 2-3 days.

Elevation: The summit of Mount Washington is at 6,288 feet (1917 meters). Winds in general increase with height through the lowest layer of the atmosphere, called the troposphere. This is due mostly to friction, with higher friction at the surface slowing down wind speeds and less friction in the atmosphere above allowing for higher wind speeds. Since Mount Washington is the tallest mountain around and has relatively low elevations surrounding it, the wind is much less interrupted.


Mount Washington and the surrounding terrain.

Atmospheric Physics: Our atmosphere, and the air that makes up the atmosphere, are a fluid. Since air is a fluid it flows across the earth and creates our weather in a way that can be described by the laws of physics and fluid dynamics. Bernoulli’s Principle explains how Mount Washington actually enhances the surrounding wind one would expect to see at 6,000 feet. From Bernoulli’s Principle, the pressure in a stream of fluid is reduced as the speed of the flow is increased. If air, which is a fluid, is compressed then the air is forced to accelerate and also creates a corresponding lower pressure. A simple analogy that helps to visualize Bernoulli’s Principle is when you put your thumb over the end of a garden hose. As your thumb compresses the water, it accelerates and comes out of the hose faster.

Looking at the above terrain map again you can see large scale areas surrounding Mount Washington where air would be forced to funnel towards the summit. As the air does this it is forced to accelerate, and the winds become higher on the summit than surrounding elevations away from Mount Washington. Prevailing winds are from the west-northwest on average for the summit, which is where the elevations drop off sharply to only about 1,000 feet and the surrounding White Mountains form a “V” or funnel shape pointed towards Mount Washington and the Presidential Range. This compression and acceleration of the wind happens in three dimensions, with a vertical compression also occurring between the top of the mountain and the top of the lowest layer of the atmosphere (called the tropopause).

Although regional enhancement of the wind due to Bernoulli’s Principle occurs worldwide, Mount Washington is unique in that it has the combination of location, elevation, and very favorable terrain for high winds. All of these factors make Mount Washington a fantastic spot to study extreme weather, and routinely make us one of the windiest places on Earth!

A weather observer leaning into high winds on the observation deck.

Tom Padham, Weather Observer/Meteorologist


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