A trio of winter storms will trot across the continental US this week just in time to plague travel for turkey day. By the holiday week’s end, roughly one half of the lower-48 will have been blasted with heavy snow, accumulating to the order of feet in the hardest-hit areas. Powerful winds will accompany these storms, wrecking havoc on air travel even in places where it does not snow. The vast size and intense magnitude of these storms will snarl travel for millions of Americans all across the country. Below we use snapshots of our proprietary WeatherOptics Roads Conditions Index (RCI) and WeatherOptics Power Index from our soon-to-be launched Insight Portal to guide weary travelers through this week’s weather madness.
Direct impacts from these storms will be focused mainly west of the Mississippi River, where strong winds or heavy precipitation will affect travel everywhere, even in the Desert Southwest. The worst impacts from the snow and wind however, will be felt in the Sierra-Nevada Mountains, the Rocky Mountains, the Plains, and the Upper Midwest. The travel mayhem will begin Monday with the formation of low pressure in central Nevada with the haste approach of a vigorous Pacific jet stream that will spawn and intensify all three storms this week.
Scattered snow showers in the interior West and Great Basin Monday morning will conglomerate and intensify over Utah and the Rocky Mountains of Wyoming and Colorado Monday afternoon as low pressure intensifies. By Rush Hour Monday evening, the worst of the snow will be focused over southern Wyoming and higher elevations of central Utah. Our Roads Conditions Index (RCI) projects treacherous travel along the entire segment of I-80 from Cheyenne to Salt Lake City at 5pm MT (7pm EST), where values of up to 8 on our 10 point scale indicate “Slowdowns are inevitable,” and that “roads may begin to close.”
In a matter of hours, snow will spread south and east as Fort Collins, Boulder, and Denver become ensnared by intensifying, wind-wrapped snow bands. The wind will help reduce visibility to near zero at times. Travel will be next to impossible during these blizzard-like conditions.
The shield of snow will expand overnight to include the western half of Nebraska and southern South Dakota by sunrise Tuesday. A snapshot of the Roads Conditions Index suggests the I-80 Corridor from Laramie to Cheyenne will feature the most treacherous driving conditions by 7am MST (9am EST), where values of up to 9 of 10 warn of “Extreme Delays” with “High Danger to Life” on roadways. The advance of poor road conditions (RCI > 5) into Nebraska can also be noted at this time. Snow will continue to spread across the Central Plains toward the Upper Midwest through early evening, when snow will finally come to an end in the Central Rockies. Snow will accumulate 6-10″ in Denver with amounts incrementally increasing northward on I-25 through Cheyenne by this time, where amounts of one to two feet may accumulate, with even larger totals likely in higher elevations.
Snow will spread with the intensifying low pressure system across the Central Plains toward the Upper Midwest by Tuesday evening. By 5pm CST (6pm EST) near whiteout conditions will have overspread across much of Nebraska’s I-80 corridor, with the worst conditions just west of Lincoln, where widespread RCI values of 9 /10 can be noted, indicating “High Danger to Life” on roadways. Lincoln and Omaha, Nebraska’s two largest cities, lie closer to the path of the low pressure system and therefore closer to the warm air. These cities will undergo a transition from rain to snow Tuesday evening and will therefore be largely spared compared to areas north and west.
Overnight Tuesday into Wednesday the heavy snow will spread northeast into eastern South Dakota, northern Iowa, southern Minnesota, and northern Wisconsin. The worst travel conditions will overspread the Twin Cities overnight into Wednesday morning as the low pressure system reaches peak intensity over Wisconsin in its trek eastward toward Michigan and Ontario.
By 6am CST (7am EST) Wednesday, snow will have already begun to die down in Minneapolis while reaching peak intensity over northern Wisconsin, including near Eau Clair where the RCI is expected to reach 9 of 10 as demonstrated below.
Drivers will have to dig out of 6-10″ of snow in southern Minnesota and northern Iowa and up to a foot in central Nebraska by the time snow clears midday before they can embark on their pre-Thanksgiving travels on the busiest travel day of the year. Snow will likely continue in Wisconsin and across the Upper Peninsula of Michigan through early Wednesday night, accumulating locally up 18″ near Lake Superior. As of Monday afternoon, the low pressure system is expected to clear just north of Green Bay, which will likely avoid accumulating snow. But a slight shift south could make for a much messier travel day.
While it will be windy to be sure in the Central Rockies, Central Plains, and Upper Midwest, where wind gusts on the order of 40 mph are possible, extended blizzard conditions are not expected. The most powerful winds are actually expected in the dry warm sector Tuesday morning, south of the snow-impacted areas. The Pacific jet feeding energy into this weeks’ storms will nose just overhead the Southern Plains, which will consequentially be pounded hardest by the winds Tuesday. An extended period of sustained winds of 35-40 mph and gusts of 60-65 mph will impact these areas beneath the jet, including eastern New Mexico, western Texas, the Texas and Oklahoma Panhandles, southwestern Kansas, and southeastern Colorado. Most flights to and from cities in this region including El Paso, Lubbock, and Amarillo will likely be impacted in some way. Delays also possible to and from Santa Fe, Oklahoma City, and Wichita through early Thursday evening. Each of these cities reside along the outer fringes of the strong winds.
The strong winds are also likely to result in scattered to widespread power outages, which could disrupt Thanksgiving meal-prepping. Our WeatherOptics Power Index suggests that areas in east-central New Mexico and in the Texas Panhandle near Amarillo are at highest risk for power outages Tuesday morning, maintaining ratings of 4 out of 5, indicating an 80% chance of a power outage within 10 mi of a point. Away from these areas, the Power Index is generally rated at most a 2, suggesting a 20% chance of a power outage within 10 mi of a point.
These winds will have overspread the Mississippi and Ohio Valleys Wednesday as the storm pulls further northeastward. As suggested by our Power Outage Index suggest some areas of northern Illinois and Western Ohio are at high risk for power outages. Localized areas here are rated a 3 or 4, indicating a 60% or 80% chance of a power outage within 10 mi of a point.
A second and much stronger storm will make landfall on the coast of Northern California near Eureka Tuesday evening while snow from the first Pacific storm falls over parts of the Midwest. Torrential rain will pelt coastal Oregon and northern California driven by dangerous wind gusts of 65-80 mph. Some of the most exposed coastline may undergo more violent hurricane-force wind gusts of 80-100 mph. Widespread power outages are expected in populated areas. Heavy rain accompanied by weaker winds will spread down the coast all the way to San Francisco Tuesday evening and to San Diego by Wednesday morning. Winds may be strong enough to disrupt air travel as far south as Los Angeles.
Conditions just inland from the coast will be much whiter–and much more dangerous–Tuesday evening in southern Oregon and Northern California. Travelers planning to drive along I-5 between Redding, CA and Medford, OR will likely find the highway closed or impassible at certain points, including a long stretch through the southern Cascades near Weed and Mt. Shasta, where the RCI is projected to reach its maximum value of 10 by 7pm PST (10pm EST) as in the image below, indicating that “Roads will not be passable” and that “widespread closures are likely.” Similar conditions will persist for drivers passing between California and Nevada across the Sierra Mountains via I-80, where Donner Pass may close for a time.
Heavy snow will fall at rates of 2″ or more per hour in the areas shaded red in the above plot of RCI. Coupled with wind gusts as high as 65 mph, the resulting white-out conditions will make travel life-threatening if not impossible at times, especially Tuesday evening into the early overnight hours. Snow chains will be required if traveling across mountain passes along I-5 and I-80. If travel is an absolute necessity, be sure to bring food, water, a flash flight, abundant blankets, and a fully charged cell phone.
Power Outages are likely essentially everywhere near the coast and in the mountains of southern Oregon and northern California. Our Power Index is rated as a 3 or 4 in many of the problem areas, but south of Sisikiyou Pass on I-5 in northern California near the Oregon Border, it is rated a 5, suggesting that there is a greater than 80% chance of a power outage. This makes sense because winds typically increase with altitude and the elevation here is some of the highest along I-5.
Snow will clear the West Coast by Wednesday afternoon except for some elevations above 4000 feet. Total snow accumulations in elevations above 2500 feet will generally range from 1-2 feet, with higher totals of 2-4 feet likely above 4000 feet. Accumulating snow may fall as low as 1500 feet in Northern California and Southern Oregon at peak storm intensity Tuesday night, giving Medford, OR and some suburbs of Redding, CA a rare November snowfall.
From the West Coast the snow will migrate into the Great Basin, with higher elevations of Nevada and Utah expected to pick up an additional 6-12″ of snow Wednesday into Thursday. The upper-level vortex driving the storm responsible for Tuesday night and Wednesday’s treacherous travel will drive yet another storm into the California Coast. This third Pacific storm will be much weaker than the second, but it will produce unusual weather in areas that typically do not receive it.
Heavy rain will besiege the Mojave and Sonoran deserts of Southern California and Arizona as it rotates southeast about the upper-level vortex responsible for this week’s messy weather. Even Death Valley will be unable to hold back the onslaught of rain Thursday evening. Travel conditions will be the worst in Arizona, where drivers on I-10 near Phoenix will encounter periods of downpours that could result in flash flooding.
Perhaps the worst Thanksgiving Day weather in the contiguous US will be north of Phoenix, where the holiday will be white rather than wet. Heavy snow will snarl all travel along I-17 and I-40, especially near Flagstaff, where snow is expected to begin Wednesday night and continue through at least Friday evening. White-out conditions are possible Thanksgiving Day in Flagstaff and elsewhere in northern Arizona and parts of Utah, making travel treacherous if not impossible at times.
While heavy rain and snow inundate the Southwestern US Wednesday night and Thursday, another wave of low pressure with Pacific origins will redevelop over central Texas. Enriched by the Gulf of Mexico, heavy rain will overspread northern Texas and Oklahoma. Deep cold air will be drawn from the Rocky Mountains into the Southern Plains, triggering an accumulating snowfall event from northern New Mexico to Nebraska Wednesday night into Thursday. The snow will generally be light, on the order of 2-5″ except in some higher elevations.
As the third Pacific storm crosses the Rocky Mountains Thursday night, the jet stream driving it will interact with this wave of low pressure over the Plains to produce another intense winter storm over the Central US Friday into Saturday. It is still too soon to nail down the details, but the same areas impacted by heavy snow earlier this week from Storm 1 may receive another heavy snowfall. Additional areas may receive heavy rainfall including Arklatex and the Mississippi Valley.
All travelers in the Midwest and Inter-mountain West impacted by the dangerous wintry conditions produced by these three storms are encouraged to make alternate travel plans, either by driving around the impacted areas, or by delaying or advancing travel. If long-distance driving through these storms is absolutely necessary, be prepared for extended travel delays. Bring a flash flight, necessary medications, and abundant food, water, and blankets.