A pair of intense storm systems may result in Thanksgiving travel disruptions for millions, unleashing heavy rain and snow, strong winds, and thunderstorms.
One storm will spin up late Monday in the Rockies before sweeping through the Great Plains Tuesday and the Great Lakes on Wednesday. Winter storm watches and warnings stretch from northeast Colorado to the Upper Peninsula of Michigan due to the potential for heavy snowfall and gusty winds.
The other storm, which the National Weather Service is predicting will be “historic” and “unprecedented” for southwest Oregon and northwest California, will pound the West Coast Tuesday through Thanksgiving with areas of damaging winds, heavy mountain snow and heavy rain at the coast.
The stormy duo will result in challenging if not impossible Thanksgiving travel conditions in some areas, with disruptions to air service in some spots almost certain. And signs point to another storm system potentially developing into the weekend.
Eastern Rockies, Plains, and Great Lakes
The weather disturbance that will manifest itself into a Great Plains rain/snowstorm is currently ejecting out of the Great Basin of Nevada, set to tiptoe through the Four Corners region into Colorado before blasting across the central/southern Plains on Tuesday.
First in line is Colorado. Winter storm warnings start near Denver, where 5 to 10 inches of snowfall are possible Monday night. The first bands of moderate to heavy snow may arrive late Monday afternoon. Anyone flying through Denver International Airport late Monday and Tuesday will want to closely monitor the system, and have backup plans in case the storm interferes with their travel.
“Travel will be difficult or impossible on Tuesday,” the Weather Service office serving Denver and Boulder warned. Some mountain locations are predicted to receive as much as 30 inches.
Meanwhile, winds sustained at 30 to 40 mph gusting to 60 mph at times are possible in the Texas and Oklahoma Panhandles as the system intensifies Tuesday before charging northeastward through the Corn Belt and Great Lakes.
In cities such as Kansas City, Omaha, Des Moines and Minneapolis, stormy conditions will arrive between Tuesday afternoon and night, while cities like Madison, Chicago, and Detroit will deal with their travel headache late Tuesday night into Wednesday.
On the warm side of the storm, roughly from Des Moines to Madison and to the south and east, a widespread 1 to 1.5 inches of rain is forecast.
North and west of the storm’s track, however, that water will come down as snow.
Omaha is expected to see rain change to up to several inches of wind-whipped snow with heavier amounts to the north.
Minneapolis is forecast to received 5 to 9 inches of snow with similar amounts projected for central northern Wisconsin, while the Upper Peninsula of Michigan could be plastered with near a foot.
A touch of snow is even possible late week in extreme northern New England as the system clips the U.S./Canada border.
The storm will exit northeast Wednesday evening into the first half of Thursday, but strong high pressure will quickly build in, steepening the pressure gradient and brewing a period of forceful winds even in the storm’s blue-sky wake. That could prolong disruptive travel into Thanksgiving itself.
For the East Coast, the storm largely looks like a miss to the north – with the exception of New England, where showers and mild weather are likely Wednesday.
Unseasonably mild weather is possible in the Mid-Atlantic Tuesday and Wednesday within the breezy southerly flow ahead of the system. Highs in Washington both days could flirt with 60 degrees.
Very windy weather is expected in the Northeast on Thanksgiving Day, with gusts to 40 mph possible.
A risk of severe thunderstorms will accompany the storm’s trailing cold front Tuesday for parts of the lower Mississippi Valley, including Arkansas, Louisiana, and the Golden Triangle region of the Texas Gulf Coast. While instability will be unimpressive, feisty wind dynamics in the upper atmosphere could favor a few isolated strong to locally severe storms popping up.
Tranquil weather returns across the South on Wednesday.
West Coast storm
An unseasonably cold and potent storm system will undergo “explosive cyclogenesis” off the coast of the Pacific Northwest Tuesday. This means the storm will be intensifying at a very fast clip, its air pressure dropping quickly enough to qualify it as a “meteorological bomb.”
The storm will pack ferocious winds at it arrives in northern California and southern Oregon late Tuesday night, meandering inland and weakening some Wednesday evening. It will also bring large waves, heavy rain at the coast, and substantial mountain snow.
The National Weather Service in Medford, Oregon, is calling this a “historically strong low pressure system.”
“We have seen 100 mph gusts at Cape Blanco with [similar conditions] in the past,” they wrote.
The Weather Prediction Center, meanwhile, is referring to it as “unprecedented” for the region it will impact, with the worst conditions expected Tuesday and Tuesday night.
As the system progresses east toward the Sierra Nevada, strong winds, cool temperatures, and mountain snow are possible off and on late Tuesday and continuing through Thanksgiving. Up to three feet of snow are expected, with snow levels in spots dropping to just 2,000 feet. Forty to 60 mph winds are possible in the higher elevations, while wind advisories are also in effect for many of the valleys.
In southern California, flash flood watches are up for Orange County and San Diego, stretching all the way down to the Mexican border Tuesday night through Thursday evening. Heavy rains in Los Angeles could also prove inclement for flights into/out of Los Angeles International Airport.
There’s even a shot at a few thunderstorms, a relative rarity in southern California. “With a very cold atmosphere aloft, the potential for strong thunderstorm is growing… on both Wednesday and Thursday,” wrote the National Weather Service in Hanford, California.
The system will move over the Desert Southwest Thursday and Friday, bringing windy conditions to the higher elevations and rain/snow showers as well.
Another storm in the offing?
There are early indications another strong storm system could develop across the nation’s midsection Friday and Saturday, though confidence on specific timing, details, and impacts remains very low.