Very cold Arctic air will bring frigid temperatures to the US Northeast, possibly marking the region’s coldest Thanksgiving ever as well as the entire month of November. Meanwhile, a series of Pacific storms will deliver multiple rounds of heavy rain and mountain snow Wednesday, November 21 into the Thanksgiving holiday weekend. There is an elevated concern for flash flooding, mudslides and debris flows near wildfire burn scars in California. A weak storm system will cross the Great Lakes Wednesday with accumulating Lake Effect snow.
Parts of the Northeast can expect record low temperatures over the next couple of days as another blast of Arctic air hits the region. In some places, like Boston and Philadelphia for example, these temperatures will mark the coldest ever recorded not only on Thanksgiving but also in the entire month of November, according to Washington Posts’ Capital Weather Gang.
That would also be the coldest high temperature ever recorded during the entire Thanksgiving week of November 22 – 28, according to Peter Mullinax, a meteorologist with Planalytics.
“A front extending from the Lower Great Lakes to the Middle Mississippi Valley then northwestward into the Northern High Plains will move southeastward off the most of the Eastern Seaboard by Thanksgiving evening,” NWS forecaster Ziegenfelder notes November 21.
A stationary front will extend from the Southeast Coast northwestward to the Northern High Plains on Thanksgiving, producing snow over the Great Lakes into parts of Northern New England that will move off the Northeast Coast by Thanksgiving morning.
In the wake of the storm, very cold high pressure will southeastward from Western Ontario to the Northern Mid-Atlantic by Thanksgiving evening.
Temperatures will be 5 – 15 C (10 to 25 F) below average from the Great Lakes to the Northeast and Mid-Atlantic States from Thursday evening into Friday.
Meanwhile, upper-level energy over the New Mexico/Mexican border will move eastward to the Southeast by Thanksgiving evening. The energy will produce light rain over parts of the Western Gulf Coast that will expand eastward into parts of the Central Gulf Coast by Thanksgiving morning before ending over the Western/Central Gulf Coast by afternoon on Thanksgiving.
“An important story, a deep upper-level trough will move onshore over the West Coast on Wednesday moving inland to the Rockies overnight Thursday,” Ziegenfelder said.
Rain will begin to develop along the West Coast on Wednesday morning and move inland to the Northern/Central Rockies and the Great Basin by Thanksgiving evening.
The rain will be heavy over parts of Northern California into the Pacific Northwest Coast through Friday morning.
Heavy snow will develop over the higher elevations of the Sierras and the Cascades with heavy rain at the lowest elevations.
Due to the heavy precipitation, a marginal with embedded slight risk of excessive rainfall is issued over California from Wednesday morning into Friday morning.
Overnight Wednesday, rain and higher elevation snow will develop over parts of the Northern Intermountain Region and the Great Basin that will expand into the Northern/Central Rockies overnight Thursday.
Featured image credit: David Van Horn