2019-03-08 13:39:57.000 – Chloe Boehm, Summit Intern
My last shift, the summit experienced the highest winds in over 30 years and a record-setting wind speed for the month of February at 171 mph. The shift before that, the summit saw, at the time, the highest winds in over a decade at 148 mph. Now looking at the upcoming system this weekend, the summit is poised to see winds gusting over 100 mph, which would be the highest winds since the 171 mph storm. So for the past three shifts, we experienced one high wind event amidst many relatively calm days. This peaked my interest and I decided to delve a little deeper into it. I pulled up some historical surface weather maps and my interest only grew.
First I looked at the 148 mph storm about a month ago that occurred from Thursday to Saturday with the peak winds occurring Saturday morning. Below is the surface weather map for Friday morning.
Surface weather map for the morning of February 8th, 2019. Courtesy of NOAA.
Looking at this map, the first thing to notice is the two low pressure systems straddling New England. When the storm presents this way, it is called a double-barrel low pressure system, due to the two low pressure areas. These low pressures eventually moved north and joined together, creating a stronger single low-pressure. This strong low-pressure then created a steep pressure gradient with an incoming high pressure which resulted in the 148 mph winds. It is also interesting to note that the stronger of the initial two lows, the left one on the map originated from the Great Lakes region. This set up is unlike the typical nor’easters that New England is known which will originate in the mid-Atlantic region.
Next I looked at the surface weather maps from the more impressive 171 mph storm two weeks ago. This storm affected New England from Sunday-Tuesday with the peak wind gust occurring Monday evening.
Surface weather map for the morning of February 25th, 2019. Courtesy of NOAA.
This storm was also a double-barrel low pressure system. You can see the two lows straddling New England, just like the previous storm. The lows followed a similar trajectory, combining in the Canadian Maritimes and producing a very tight pressure gradient. The lows in this case were stronger than the 148 mph storm, which resulted in higher winds. In addition, there was a very strong temperature inversion just above the summit, serving to cause further amplification of already very strong winds by the terrain of the Presidential Range.
Now, when looking at the upcoming weekend, I see a similar pattern emerging in models.
Surface weather forecast for the morning of March 11th, 2019. Courtesy of Tropical Tidbits.
Once again, it seems like a double barreled system is headed our way. I added red arrows to point out the lows as it is a bit tougher to see on this map. It is clear that especially the secondary low to the south does not look quite as strong as in the previous two storms which will means we will probably not see winds anywhere near as high. However, the distinctive double barrel shape is present once again. Considering this storm looks like it will affect the region Sunday-Monday and the setup of the lows, it certainly feels a bit like deja-vu from the most recent storm. For the past few shifts, we have seen strong double-barreled storm spaced out almost exactly two weeks apart and this trend seems to be continuing this week. As I previously mentioned this type of storm is not the typical nor’easter that New England sees which makes the current frequency particularly interesting.
Lastly, I just want to briefly mention the setup of the record-breaking 231 mph storm back in 1934. Although technology was not quite good enough to say for certain what the setup of the storm was, based on surface weather maps that were produced once a day back then, it looks like there is a very high probability that the storm was once again a double-barreled system.
Historical surface weather map of April 12th, 1934, the day of the 231 mph wind gusts. Courtesy of the U.S. Department of Agriculture, Weather Bureau.
The more I look at setups of some of the largest wind storms in the Mount Washington Observatory’s history, the more it seems like this particular setup is most favorable. The frequency and timing of these storms for the past month is fascinating to me, and is contributing to a higher than average wind speed this winter. We will see how this upcoming storm pans out, but as it stands right now, the next few days will be pretty interesting and should continue this captivating trend!
Chloe Boehm, Summit Intern