March forecast calls for heat dome, polar plunge, heavy flooding

Extreme swings expected across the U.S. in March

Meteorologists said the United States is facing a stretch of March weather extremes that could bring flooding rain in Hawaii, record heat in the Southwest, late-season snow in parts of the northern Great Lakes, and a return of Arctic chill in the Midwest and East. AP reported that nearly every part of the country was either already seeing unusual conditions or was expected to soon.

National Weather Service meteorologist Marc Chenard of the Weather Prediction Center said the pattern would affect broad areas even if some places did not experience the most extreme readings. “All of the country, even if you’re not necessarily seeing extremes, are going to see generally changing from cold to warm, or warm to cold to warm,” Chenard said.

Heat dome set for the Southwest and record risk in Phoenix

Forecasters said a heat dome would form early next week and park over the Southwest, pushing temperatures into triple digits in some locations. In Phoenix, some projections called for 98 degrees Fahrenheit on Tuesday, followed by 103 and 105, then two days of 107.

The weather service warned that this early-season heat would be more impactful than usual because people are not acclimated to it. It also said that in 137 years of record-keeping, Phoenix has never reached 100 degrees before March 26 and that the city usually sees its first 100-degree day in early May.

In Los Angeles, unusual 90-degree March weather was already underway, with at least one resident describing the discomfort and adjusting his routine. Shane Dixon, 40, said Thursday was difficult because of the heat; he also said, “The back of my neck was melting,” while preferring it to the cold and snow expected elsewhere.

Polar vortex forecast for Midwest and East, with teens and 20s in parts of the Northeast

As the Southwest heat builds, Maue said the polar vortex was forecast to send its chill deep into the Midwest and East, bordering parts of the Southeast. Minneapolis was expected to hover around zero (-18 C) for a low, and Chicago was forecast to be in the single digits on Tuesday.

Looking further east, Maue said “temperatures in the teens and 20s in the Northeast and 20s in the Mid-Atlantic.” He also said even Atlanta could drop to the 20s.

Back-to-back snowstorms on the northern tier and Great Lakes

AP reported that two storm systems were expected to move through in sequence—one Friday, then another Sunday into Monday—along the northern tier and the Great Lakes region. Meteorologists said the paired systems could drop 3 to 4 feet (0.91 to 1.22 meters) of snow in some places.

The larger second storm system was described as intensifying rapidly, with a sharp drop in barometric pressure and strengthening winds that would qualify it as a bomb cyclone. Jeff Masters of Yale Climate Connections said that just south of the part of Michigan expected to see the heaviest snow, there was potential for a significant ice storm.

High winds and wildfire risk stretching from the Plains into Texas and the Gulf

Masters said an area stretching from Kansas south through Oklahoma and into Texas, toward the Gulf of Mexico, was forecast to see high winds. He reported winds in the 60 mph range with stronger gusts Sunday night, including in the Austin and San Antonio region.

Masters also warned that wildfire risk could be heightened where there had not been much rain, because high winds and dry conditions can contribute to fire spread. AP reported that Nebraska Gov. Jim Pillen declared an emergency and mobilized the National Guard to help fight two dozen wildfires in the state.

The Nebraska Emergency Management Agency said the fires had burned more than 550 square miles (about 1,424 square kilometers) of range and grassland, and that no injuries had been reported at that point. It attributed the rapid fire activity to strong winds with gusts up to 60 mph and low humidity, saying the conditions made the fires difficult to contain.

Hawaii flooding threats and Oahu flash flood warning

In addition to heat and cold, forecasters said persistent heavy rain in Hawaii would raise flooding concerns. AP reported Maue said Hawaii was getting an atmospheric river with such persistent heavy rain that flooding would be a major issue, and that Oahu was under a flash flood warning.

Maue also said Alaska was expected to be about 30 degrees colder than usual.

Why the pattern is producing extremes near each other

Chenard said it was the time of year when unusual weather can happen, but that the outlook seemed anomalous compared with what is typically seen. He said, “It is ‘the time of year where we can see stuff like this,’” and added that some areas could be setting records for March temperatures.

Maue and Chenard tied the shift to a jet stream pattern that they described as unusually extreme: plunges followed by sharp rises, putting very different air masses next to each other. Maue said numerous studies have connected unusual jet stream and polar vortex activity to shrinking Arctic sea ice and human-caused climate change.

Even with the forecast risks, Maue pointed to the calendar as a turning point. “The first day of spring is 20th (of March), and then after that we get recovery,” he said.