A Warm Spot But Not THE Warm Spot

2014-01-04 20:03:41.000 – Ryan Knapp,  Weather Observer/Meteorologist

Sunset and a sliver of the moon this afternoon.

When I looked at the various weather maps, soundings, models and current conditions on Friday afternoon, everything was pointing towards a strong inversion setting up over the state of NH for the overnight hours. For those wondering what an inversion is, let me briefly explain. Normally, as you move up in the atmosphere, the temperature will typically decrease with height. With an inversion, the temperature may start off decreasing with height but at some point, it will actually start warming before once again cooling. If you were to simplify this and draw the two on a simple x/y axis, a “normal” profile would look more or less like a single slanted line whereas an inversion might look more like a sideways “z” or a crude lightning bolt. In the case of last night, cold northern air along with minimal daytime heating, low winds, and clear skies allowed for cold air to pool at the surface while aloft, a weak return flow was allowing less dense and warmer air to move in over this cold air.

This isn’t anything unusual, especially around the summit in the winter time. There are numerous times each winter where locations like Berlin, Whitefield, Fryeburg, or Conway will be colder than we are during the overnight hours as warm air moves in aloft. I can reference you back to an Observer Comment that our intern at the time, Brent Antkowiak, wrote which pointed out one such occurrence he observed between us and Berlin, NH to our north. You can also see it occurring on any given night by using our Auto Road Vertical Profile. So, an inversion is semi-normal for here. However, what made last night’s inversion particularly exciting is the fact that models were showing us as being not only the warmest location in the North Country, but the entire state – something I have never witnessed in my 8+ years up here. So, I continuously monitored the stations about the state through the night. By the time I went to bed at 6am, we were close to reaching this lofty goal, but a few holdouts kept us from being the warmest location; most of them situated between the Great Bay and the Atlantic Ocean. So, while we weren’t THE warmest location last night, it was still fun to witness us briefly become one of the few “hot” spots in the entire state of New Hampshire.

Ryan Knapp,  Weather Observer/Meteorologist