
A deep freeze is pushing its way into the eastern United States, plunging forecast temperatures tonight in the Northeast and Mid Atlantic to the lowest readings of the year. With temperatures dropping well below the freezing mark, the National Weather Service has issued Freeze Warnings for a large area where the growing season will draw to a close tonight.
The cold air will be rushing in via stiff northwest winds, which will also produce the lowest wind chill values across the northeastern United States tonight of the season. The Wind Chill is the perceived decrase in air temperature felt by the body on exposed skin due to the wind. The faster the wind speed, the more readily the surface temperature of a living being cools. The effect of wind chill is to increase the rate of heat loss and reduce any warmer objects to the ambient temperature more quickly. Dry air cannot, however, reduce the temperature of these objects below the ambient temperature, no matter how great the wind velocity. For most biological organisms, the physiological response is to generate more heat in order to maintain a surface temperature in an acceptable range. The attempt to maintain a given surface temperature in an environment of faster heat loss results in both the perception of lower temperatures and an actual greater heat loss. In other words, the air ‘feels’ colder than it is because of the chilling effect of the wind on the skin.
Freeze Warnings have also been issued for coastal Virginia, where Orbital ATK is planning to launch a rocket from NASA Wallops Flight Facility on Saturday morning. That mission cannot occur if the ambient air temperature drops below 20; temperatures there are forecast to remain above that threshold. In the latest weatherboy.com forecast, a morning temperature of 26 is expected.
Here’s a sample of low temperature forecasts for Saturday morning from weatherboy.com:
Boston, MA: 18
Albany, NY: 12
Hartford, CT: 16
New York City, NY: 18
Philadelphia, PA: 23
Scranton, PA: 13
Atlantic City, NJ: 20
Trenton, NJ: 19
Wilmington, DE: 21
Baltimore, MD: 29
Norfolk, VA: 32
Wallops Island, VA: 26
Richmond, VA: 24