Warmth will build over the Eastern United States, while chilly air and episodes of mountain snow will begin to frequent the West during the first half of November and perhaps much of the month, due in a large part to El Niño.
While the pattern will feature some fleeting bursts of chilly air from the northern Plains to the Great Lakes and the Northeast, the number of calendar days (days and nights) with above-normal temperatures will exceed the number of calendar days with below-average temperatures.
It is possible that any chilly episodes in the Midwest and Northeast will fall short of the outbreak of Oct. 16-19, when daytime temperatures were held to the 30s and 40s F in some locations. If not, then any cold outbreak with lake-effect snow will be short-lived.
Normal temperatures trend downward by approximately a degree every two to three days during November. With this in mind, temperature departures on some calendar days will range from 10 to 20 degrees above normal in portions of the East during the first half of the month.
In the West, temperatures on a number of calendar days will range from 5 to 10 degrees below normal during the first two weeks of November.
AccuWeather meteorologists look at a number of factors in determining the forecast for a month or season in advance, including prior years where the pattern was similar. The vast majority of Novembers during a strong El Niño were mild in the East and chilly in the West.
According to AccuWeather Long-Range Meteorologist Ben Noll, "The first half of November looks a great deal like November of 1982."
That month brought warmth to the East and chill to the West.
"An El Niño was in progress during November of 1982 and resulted in a mean temperature average of 1-3 degrees above normal for the month in the eastern third of the nation," Noll said. "In the West, a mean temperature average of 1-3 degrees below normal occurred."
An exception to this typical pattern across the U.S. occurred in November of 1997 when the opposite occurred, and there was notably more chill in the Southern states and Plains.
"Based on what we are seeing now, this November looks a lot less like 1997," Noll said.
The pattern will bring a few episodes of rain to the Plains, Midwest, Northeast and South. Any snowfall will be brief and generally limited to parts of the northern Plains, Upper Great Lakes and the highest elevations of the central Appalachians and northern New England.
In the West, snow levels will lower a bit faster than average for early November. This could catch some motorists by surprise traversing the higher passes along Interstate 70, I-80 and I-90 to name a few.
During the second half of the month, temperatures may tend to even out a bit, when compared to the first half of the month with an active storm track in the Deep South, according to Noll.
"The storm track could lead to severe weather outbreaks, while the Gulf of Mexico and the western Atlantic basin in general will have to be watched for tropical development," Noll said.