15:38 Mon Jun 04, 2018
Winter Weather Returns to Mount Washington
One of the reasons I was so excited to start my internship up here on the Northeast’s highest summit was for the chance to see snow in the summer. There hasn’t been any snow today, although plenty of freezing rain has been falling. While I’m still waiting for my first June snowfall, I’m just as happy with the ice that’s been falling.
I was lucky enough to get a chance to deice some of the weather instruments; apparently I think it’s more fun to deice with subfreezing temperatures and 30mph winds than my coworkers do!
So, why is there freezing rain at the summit as opposed to snow? The mechanism at play is called a temperature inversion, where the temperature increases with altitude. We can see this occurring by taking a look at a model sounding of the atmosphere valid at 9am.
The x-axis is shows the temperature, and the y-axis shows pressure, which can be used to approximate altitude. The red line is the temperature, the solid blue line is the freezing point, and the solid black line is about where the summit surface is. The temperature just above the summit is well above freezing, allowing all the precipitation to melt to just rain. At the summit, however, the temperature is right around freezing. The actual temperature at the summit at 9am was 28 degrees Fahrenheit – around 5 degrees colder than what this model projected! Then, below about 5,000 feet temperatures climb back to above freezing, so just plain rain is falling at the low elevations. This put Mount Washington in a goldilocks zone for ice today. Temperatures above and below the summit are above freezing, but Mount Washington itself is struggling to get above 31 degrees. As of 2pm, around half an inch of ice accrued on exposed surfaces (making this one of the largest ice storms I’ve experienced in my life – in June no less).
While the summit has yet to experience any measurable snowfall since May 1st, there is a chance precipitation changes to snow both tonight and again tomorrow night. The summit averages around 1 inch of snow in June, and just last year Mount Washington got 5.4 inches, and in 2016, 6.9 inches fell. Needless to say, I have high hopes that I’ll still get to experience some snow here at the summit of Mount Washington. In the meantime, you can probably find me outside taking pictures of the ice.
State Park sign covered in ice.
Icicles hang beneath a sign outside the Sherman Adams building.
Simon Wachholz, Summit Intern