January Thaw Maxes Out

2013-01-14 15:16:01.000 – Mike Carmon,  Weather Observer/Meteorologist

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This year’s January thaw has given Mt. Washington a new high mark.

That mark is 48F–the highest temperature ever recorded in the month of January in the Mt. Washington Observatory’s 80 year history.

During the waning hours of my shift on Sunday morning (January 13th), all of our temperature devices were hovering right around 39F, as they had been throughout most of that night. The models were forecasting a serious jump in temperatures on that day, which looked likely to come when winds, which were blowing around 30-40 mph, began to relax.

Suddenly, around 4:30 AM or so, the summit inherited a much quieter tone, as winds abruptly dropped off. At that time, the mercury showed a dramatic spike. This phenomenon occurs because wind acts as a great ‘stirrer’ of the atmosphere. A steady breeze ensures that the air is sufficiently mixed, preventing any uneven heating and/or cooling, and thus, generally guarding against temperature spikes that appear to be anomalous or extraordinary (frontal passages are an exception to this rule, where a spike in winds is usually accompanied by a spike or stark drop in temperature).

During the 5AM – 6AM hour, all three observers kept our eyes glued to our temperature sensor display, as it soared from 40F inexplicably up to 47F, reaching its peak sometime around 5:45 AM. It was at this time that I ran out to our official maximum thermometer, located on our observation deck, to see what it had recorded. Sure enough, it was displaying a reading that day observers Brian Fitzgerald and Steve Welsh later recorded as 47.6F.

Due to our perpetual desire for accurate data, the situation didn’t end there. In an important matter such as a possible monthly record high, we want to ensure that this reading grabbed by our maximum thermometer was not a fluke. To do this, I later assembled all of the temperature data from each of our temperature-recording instruments, and compared, looking for inconsistencies.

Examining all of this data revealed that, before, during, and after the time of the temperature peak, all of our instruments were quite consistent with each other, right down to the recorded time of their respective maximum temperature readings. Knowing that, I made the decision that this 47.6F (rounded to 48F) reading was valid, and sent it to the record books as the all-time record for the month of January! The previous monthly record was 47F, set back on January 19, 1995.

It is always exciting as a scientist to see long-standing records broken, particularly extraordinary records such as this. It should be kept in mind, though, that this was a one-time event; a ‘snapshot’ in a long history of climate data. This event, by itself, cannot be used as evidence for or against any theories of climate currently circulating in the mainstream.

Mike Carmon,  Weather Observer/Meteorologist