What a change! After accumulating snow atop Mount Washington on Thursday, July 1, deep heat is en route to New England.
The setup for summit snow came as cold air poured into New England a few thousand feet above the ground. For most of us, the result of this stark contrast between sub-freezing temperatures aloft and highs in the 70s on our valley floors was a picturesque display of bubbling "cumulus" clouds - puffy, fair-weather clouds that grew tall enough to yield a few rain showers in Northern New England. But on the mountain summits - enveloped in cold air - rain showers came down as snow, and the Mount Washington Observatory recorded a trace of snow, officially. This wasn't a lot of snow, but was sufficient to create sloppy conditions on the Mount Washington Auto Road and close the road for safety reasons from 12:45 to 2:45 PM. The following picture from the summit was taken by Mount Washington Observatory intern Kristin Raisanen.
Now, just one day later, we turn our attention to quick-moving heat that's moving east from the Northern Plains. This heat, producing a few clouds in Ontario and Quebec that slide through New England Saturday morning, has a history of producing high temperatures in the 90s, and as it arrives to New England, it's likely to warm further on a west wind, sloping down off of our mountains and hills, creating warming "downsloping" wind conditions. After a transition day in the 80s on Saturday, most New Englanders will see temperatures in the 90s on Sunday, and with the exception of localized sea breezes, this will continue through Thursday!
There are a few concerns the heat brings:
1) Elevated fire danger. With many considering private fireworks displays, keep in mind that the lack of humidity on Saturday, combined with the increasing heat, will drive up fire danger and make brush more susceptible to ignition.
2) Dehydration. The entire weekend requires drinking plenty of fluid, but Saturday actually may be the day on which dehydration can sneak up on us - more humid conditions allow sweat to linger on the skin, and we realize just how much water our bodies are losing. On drier days, like Saturday, sweat evaporates quickly, and it's easy to miss just how much water is drawn from the skin.
So, stay safe and enjoy the Holiday Heat!