Thanksgiving Travel Update: 'Bomb Cyclone' Forecast for Eastern Pacific, Increased Snow Storms in the West to Cause Severe Disruptions

A powerful 'bomb cyclone' is expected to develop over the eastern Pacific before reaching the West Coast while storm systems spreading to the lower states are expected to bring increased heavy snowfall, with damaging winds and a potential for several tornadoes in the South, causing severe travel disruption across the country over the Thanksgiving holiday travel period.

The weather is "becoming increasingly unsettled from the West Coast to the Midwest," the National Weather Service Weather Prediction Center (NWS WPC) warned in its latest forecast on Tuesday, with one major storm system intensifying from "the Colorado and Wyoming Rockies to the Upper Peninsula of Michigan where winter storm warnings are currently in effect."

"High wind warnings are in effect from eastern New Mexico to southern Kansas, where winds could gust in excess of 55 mph at times. High wind watches are in effect for portions of the Midwest and Ohio Valley as the storm approaches that region by Wednesday," the NWS notes.

An increased rate of snowfall at one inch per hour is possible in northeast Colorado, the southern Nebraska Panhandle region, northeast Nebraska as well as in northwest Kansas, the NWS Storm Prediction Centre warns (NWS SPC).

Snow levels are expected to reach total accumulations between 6 and 12 inches, with locally higher amounts, across the central U.S., the NWS WPC noted in a posted on its official Twitter account.

But a second "even stronger storm" will build over the eastern Pacific that "will likely undergo bombogenesis by late Tuesday afternoon, at which point it will likely become a sub-980 mb [millibars] low with hurricane force winds over the offshore waters," the NWS predicts.

A bombogenesis occurs when a low pressure system drops "at least 25 millibars over 24 hours. A millibar measures atmospheric pressure. This can happen when a cold air mass collides with a warm air mass, such as air over warm ocean waters. The formation of this rapidly strengthening weather system is a process called bombogenesis, which creates what is known as a bomb cyclone," the National Oceanic and Atmospheric Administration (NOAA) National Ocean Service explained.

The low pressure system may reach a record November low level, reaching the border between California and Oregon by Tuesday evening before it moves inland, the NWS WPC predicts.

"The mountains of southern Oregon and northern California are likely to get hammered with blizzard conditions, and battering surf and high winds for coastal areas.

Two powerful storm systems will move through the Lower 48 states this week. Storm 1 will bring heavy snow from the Rockies to the Upper Midwest Tuesday and Wednesday with strong winds south of it's track. Storm 2 arrives Tuesday into the West Coast with heavy mountain snow.

— National Weather Service (@NWS) November 26, 2019

"Winter storm watches and warnings are already in effect for many of these areas... Snowfall accumulations on the order of 1 to 3 feet appears likely for many of the California mountain ranges, and winter storm watches are in effect farther to the east to include northern Arizona," the NWS WPC adds.

A major winter storm is expected to impact northwest California and southwest Oregon Tuesday and Wednesday. This is not an ordinary storm! Significant impacts are expected, and weather should be factored into any holiday travel plans. #CAwx

— NWS Eureka (@NWSEureka) November 25, 2019

Travel over the Thanksgiving period in these regions may be "severely affected", while "travel before the #Thanksgiving holiday will be impacted, and driving may become difficult to impossible in some areas," the NWS WPC warned on its official Twitter account.

Wednesday is predicted to be the "the worst travel period nationally," according to a report by INRIX, a global transportation analytics company, "with trips taking as much at four times longer than normal in major metros."

In addition to the snows,, our storm system is also expected to bring severe weather to parts of the South tomorrow afternoon. Damaging winds are possible, along with the potential for a few tornadoes.

— National Weather Service (@NWS) November 25, 2019

Trevor Reed, transportation analyst at INRIX, added: "Although travel times will peak on Wednesday afternoon nationally, travelers should expect much heavier than normal congestion throughout the week."

More than 55 million people will be traveling for Thanksgiving this year—1.6 million more than last year—including 49.3 million by car, 4.45 million by plane and 1.49 million by train, bus or cruise ship, according to INRIX.

Boston airport bomb cyclone snow storm 2018
Snow removal at Logan International Airport following a "bomb cyclone" the previous day on January 5, 2018 in Boston. A bomb cyclone is forecast for the eastern Pacific this week. Getty Images