While many residents in the central and eastern United States are expected to endure a cold latter half of October, a pattern flip is in the forecast for November, which could bring milder temperatures back to those who are shivering now.
Warmer-than-average temperatures are forecast in November from the West Coast to the northern Plains and much of the Midwest, with below-average temperatures likely in the southern Plains, according to the latest outlook from The Weather Company, an IBM Business. The warmest temperatures relative to average should be found in the northern Rockies, northern Plains and upper Midwest.
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A swath from the Southwest to the central Plains, mid-Mississippi Valley, Ohio Valley and Northeast is expected to see near- or slightly above-average temperatures during November. Meanwhile, near- or slightly below-average temperatures are forecast from the southern Plains to the Appalachians, Southeast and mid-Atlantic region.
"We’ve reduced forecast temperatures a bit in the eastern U.S. for November and have increased them across the northern Rockies and Plains, given the expected Arctic Oscillation trends later in the month and the contrarian ECMWF (European model) guidance," said
Dr. Todd Crawford, chief meteorologist with The Weather Company.
Crawford said the positive phase of the North Atlantic Oscillation (NAO) – and positive phase of the Arctic Oscillation – which has prevailed through most of 2018, may finally be fading away. One consequence of this could be an increased chance of colder air reaching parts of the eastern states.
A positive NAO means an upper-level trough of low pressure is in place near Greenland and typically correlates with warmer temperatures in the eastern United States. When the NAO trends negative, high pressure builds near Greenland, and cold air can be drawn southward into the eastern U.S.
"Given the evidence discussed, along with the cooler (and historically more reliable) ECMWF ideas for November, we have reduced forecast temperatures across the eastern U.S. and increased them across the northern Plains," Crawford said.
This overall weather pattern of milder temperatures toward the north and colder temperatures toward the south is currently expected to continue into the start of winter.
December
Winter is expected to start out mild for much of the northwestern and north-central states.
Far above-average temperatures are expected in the Northwest, with warmer-than-average temperatures also anticipated from northern California to the northern Plains, upper Midwest and northern Great Lakes.
Near- or slightly above-average temperatures are forecast from Southern California and the Southwest to the central Plains, Midwest and Northeast.