16:44 Mon Jan 11, 2021
2020 By The Numbers
As we flipped the calendar to read 2021, it was time to look back and summarize the year that was (2020 in this case). If I were to use adjectives to summarize 2020 they would be - warm, dry, snowy, foggy, and windy. To figure out why those words were chosen, let's look back at some of the stats that made up 2020:
Our average temperature for 2020 was 29.6°F (-1.3°C) which is 2.3°F above the 1981-2010 30-year normal for our station. This would make the annual average temperatures of 2020 the fourth highest in our dataset, which started in 1932. Our warmest temperature recorded in 2020 was 68°F (20°C) which occurred on June 18th and on July 9th. Our coldest temperature recorded in 2020 was 18°F below (-18°F/-27.8°C) which occurred on January 17th.
In terms of precipitation from January to December of 2020, the summit of Mt Washington received 81.21 inches which was 15.66 inches below the 1981-2010 30-year normal for our location. From January to December of 2020, the summit of Mt Washington received 281.6 inches of snow which was 0.4 inches above the 1981-2010 30-year normal for our location.
In terms of winds, for 2020 our average was 37.0 mph which was 2.0 mph above 1981-2010 30-year normal for our location. Our highest gust recorded for 2020 was 147 mph which occurred on August 4th. This August gust set a new August peak gust record surpassing the previous August record of 142 mph set on August 31, 1954. From January to December, we had 171 days which had gusts of 73 mph or greater and of those days, 49 days had gusts that were 100 mph or greater.
As for our weather during 2020, we averaged 34% of the possible sunshine. The summit had 16 days that were noted as clear or mostly clear, there were 72 partly sunny days, with the remaining 278 days were filed under mostly cloudy, cloudy, or obscured (fog) (2020 had 366 days as it was a leap year). We had 320 days with at least some fog recorded during a 24-hour period. We had 136 days with rain and 141 days with snow.
Ryan Knapp, Observer/Staff Meteorologist
15:31 Sun Jan 10, 2021
Joining the "Watchers on the Wall"
Hi everyone, my name is Jackie Bellefontaine and I am the new Mount Washington Observatory winter intern! I grew up outside of Boston in Malden, Massachusetts but recently moved to Meredith, New Hampshire. I have always loved the New Hampshire Lakes Region and the White Mountains! I graduated from the University of Maine in 2020 with a B.S. in Earth and Climate Sciences. During my undergraduate career, I became very interested in and excited by the Earth’s climate system and extreme environments. So, interning at the Mount Washington Observatory is like a dream! I am very happy to be here and excited to share my intern experience with you all.
Tower at Sunset
My first day started with a snow-cat ride up the Auto Road to the summit. I had never seen a snow-cat before and was impressed by the sheer size of the vehicle as it rounded the corner to pick up our shift. Our ride up to the summit was gorgeous, we had clear views of the summits of Mt. Clay, Mt. Jefferson, Mt. Adams and Mt. Madison. Additionally, there was an awesome undercast to the west of the Mt. Washington summit. It looked like a sea of clouds and made for a beautiful sunset! I spent the rest of the afternoon exploring the Sherman Adams building, familiarizing myself with daily summit operations and getting to know the awesome summit team.
Jackie Bellefontaine, Intern
View of Northern Presidentials from the Snowcat
My First Summit Sunset-Pretty Spectacular!
On Thursday, I began to shadow observers Nicole and Sam. I accompanied them on their daily observations out on the summit deck and got to experience the strongest winds I had ever felt--70 mph winds and an 86 mph gust! It made the hourly observations a fun challenge when trying to cross the deck back into the building. Also, the summit was in the clear and we had 130-mile visibility! I was amazed by just how far we could see from the summit--from the ocean off the coast of Portland, ME to Whiteface Mountain, NY!
I very much enjoyed my first week at the summit and am looking forward to experiencing and learning more about the Home of the World’s Worst Weather! Also, a special thank you to observers Nicole, Sam, and night observer Ryan for welcoming me to the observatory and helping me adjust quickly to life on the summit!
12:17 Mon Jan 04, 2021
Terms Used In Forecasting: Advection
It has been a while since I have written anything in this space so here is something I have been meaning to share. I plan to discuss several topics in our forecasts, specifically, the terms we use and why we use them. We generally try to use basic language in our forecast discussions, but I realize that is not always the case. Understanding these many terms and processes can be useful as they are used in forecasts by us here at the Observatory, the National Weather Service (NWS), and by other third party organizations such as your local news station, or a phone app.
These posts will provide a quick explanation of some of the terms used in forecasts so that you can better understand and prepare for whatever reason you require the information. Today’s topic will be ADVECTION. I am going to define it scientifically and then break it down in a much more conceptual and ‘real’ way. It should be noted that advection is one of many other processes that causes the temperature to change in a region.
Advection is defined by the American Meteorological Society as the “The process of transport of an atmospheric property solely by the mass motion (velocity field) of the atmosphere; also, the rate of change of the value of the advected property at a given point.” That was copied from their online glossary and there is a fancy calculation along with it, but let’s think about it conceptually so we can apply the concept. First off, an example of an atmospheric property that we will discuss and is arguably the most used in forecasting is temperature. Secondly, the “solely by the mass motion (velocity field)” means that the temperature is being moved by the flow of the mass of the substance (the air) and not by heating from the sun or convection. Advection differs from convection in the sense that advection is a movement of temperature from the speed and direction of the air, its velocity, whereas convection is the movement of air usually due to a density gradient or difference. Therefore, to simplify, for forecasting reasons, advection is the movement of temperature by the wind.
There are two types of advection, Cold and Warm Air Advection (CAA and WAA respectively). The way advection is measured is explained in the second part of the AMS definition; “also, the rate of change of the value of the advected property at a given point.” To apply this to temperature advection is to say the change in temperature at a certain point over a certain amount of time. To apply it even more directly to our forecasts, I would say something like this. “Cold air advection will bring falling temperatures into the evening as northwesterly flow sets up behind the cold front.” OR I would say, “Warm air advection behind the warm front will bring rising temperatures and an increase in moisture to the region.” What forecasters mean when they write or say the first statement is that the temperature will drop because colder air from the north is moving south from the north WITH the wind where it is colder. The temperature is not dropping because it is nighttime and there are no clouds around. This is more evident during the day when it is sunny but temperatures are dropping. The second statement means that warmer temperatures are moving north from the south WITH the wind so temperatures will rise because of the flow of the wind and not because of daytime heating or latent heat release.
Lastly, to pull this all together, look at the chart below. The shaded blue is CAA and the shaded red is WAA and is expressed as the change in temperature in Kelvin/hr. A higher number of WAA or CAA could mean a number of things. It could mean that there is a higher flow of air or that there is high pressure or temperature gradients as well. Forecasters use advection to infer and/or to lead to other factors that influence the state of the atmosphere. It is also an encompassing term to explain a process, which is why it used so often.
Jay Broccolo, Weather Observer and Meteorologist
Temperature advection (K/hr, shaded) at 850hPa with contours and wind barbs from the NAM3K model. Note the darker red and blue shading. These areas are higher temperature changes from wind flow per hour. Chart from www.tropicaltidbits.com.
I hope this post was helpful. Look for more of these in the future.