AccuWeather reportsthe chilliest air of the season so far will settle over much of the NortheastThursdayintoFridayand will bring the threat for frost to a much larger area as compared to earlier in the week.The pattern through this week will bring cooler-than-average temperatures to the region.A reinforcing push of cool air is forecast to settle inThursdayintoFriday.
Where skies become clear and winds diminishThursdaynight over the interior, the stage will be set for a frost and even a freeze in the coldest locations.
According to Canada Weather Expert Brett Anderson, "The air mass moving in late this week has originated from the Arctic and record lows will be challenged from Ottawa to Montreal and Quebec City."
While record lows are not likely to fall along the I-95 corridor from Boston to New York City and Washington, D.C., temperatures may dip to their lowest levels since the spring and surpass the chill from a few days earlier. Record lows during the middle of September in the I-95 Northeast are typically in the lower to middle 40s F.
In portions of northwestern New England, upstate New York and northern Pennsylvania, the growing season may come to an end. Low temperatures in the lower 30s are forecast for much of this area, with the coldest rural areas, away from lakes and rivers, likely to dip into the 20s.
Official temperatures are measured at and forecasts are made for a height of about 6 feet off the ground. In clear and calm conditions, temperatures can be several degrees lower at ground level, hence the concern for a frost or freeze in this situation.
A scattered light frost is possible in some of the rural areas surrounding the northern and western suburbs of New York City, Philadelphia and Baltimore. Frost is likely within the northern and western suburbs of Boston.
Nearest the inland waterways, especially in the valleys, dense fog may form and could impact theFridaymorning commute from northern Virginia to New England and part of the Midwest.
The area of high pressure responsible for the chill will slowly moderate this weekend into early next week. High temperatures will trend upward through the 70s along much of I-95 and in much of the central Appalachians. Some people heading to afternoon high school, college and NFL football games this weekend will be able to shed jackets and sweatshirts for a few hours.
In addition to the temperature rebound, many days of rain-free weather is in store.
While the weather pattern will bring typical challenges for agriculture in terms of frost in northern areas, the rain-free conditions will offer nearly ideal weather for harvest and cutting and drying hay.
The only potential damp areas will be over the St. Lawrence Valley, where spotty showers are possibleon Thursdayand along the mid-Atlantic coast from Virginia to New Jersey, where spotty showers and some drizzle may occur late this week.
For those braving the cool air and seeking the relatively warm waters of the Atlantic this week, there is a risk of strong rip currents and rough surf. Edouard, which is a couple of thousand miles offshore in the Atlantic, became a Category 3 hurricaneon Wednesdayand has already sent swells outward.
Source: AccuWeather Global Weather Center --17 September 2014