Atmospheric speed bumps ahead

Spring in Minnesota is not a straight line.

Over time the warming trend is clear. But day to day, week to week spring weather is like a game of atmospheric bumper cars. Zoom toward the next warm up, crash into the next cold front.

Buckle up.

• 62 degrees high temps at Minneapolis-St. Paul International Airport Monday

• Six days above 60 degrees in the past week in the Twin Cities

After a record run of April and May temperature levels in mid-March we return to reality this week. Temps Tuesday in the mid 40s are about 25 degrees colder than Sunday's record highs in many Minnesota towns and cities.

Yes, the inbound air mass is 20 to 30 degrees colder.

Cold fronted 

You can feel the chill returning to the air in Minnesota as the cold front blows in from the north. A southerly wind blew for days. That changed Monday afternoon as wind turned into the north across the state. Here's a snapshot of the changing weather conditions at MSP Airport Monday afternoon as winds turned north.

The atmospheric trigger for our rapidly changing weather? A cold front more seasonable for March in Minnesota.

This week's front feels like March, but more like late March.

Highs still run a few degrees above average most of this week. A stray rain and snow showers zip through Wednesday night with a potentially fleeting coating on some grassy areas, but I still don't see any more typical big March snow events on the horizon.

The longer range outlook calls for a chilly weekend, followed by a warm-up next week. The models are spinning up a system by next Wednesday that could bring the hops for some much needed rainfall. Too early to be certain, but encouraging?

Frost coming out

Unseasonably warm weather of the past week has taken frost out of the ground to significant depth in southern Minnesota including the Twin Cities area.

Here's a look at soil temps at the University of Minnesota's Southern Research and Outreach Center in Waseca, south of the Twin Cities. Frost has left the ground down to a depth below 8 inches. A frost layer remains at 20-inch depth.

Can Pacific cyclones turbo boost El Niño?

This caught my eye. The position of two cyclones straddling the equator in the Pacific might be able to boost westerly winds, and send a bubble of warm water eastward across the equator toward the eastern Pacific.

Think of it as two giant atmospheric wheels turning a conveyor belt of westerly winds that drives warmer waters east.

Climate Central's Andrea Thompson elaborates on why these twin cyclones could boost a sputtering El Niño.

Where the two cyclones come in is the winds associated with an El Niño. Normally, the tropical Pacific features a pool of warm water in the west and cooler temperatures to the east, where cold waters well up from deep off the coast of South America. The prevailing easterly trade winds keep this temperature pattern in place. When an El Niño occurs, the winds slacken and can even reverse to blow from the west. That sends the warm waters spilling eastward, the hallmark of an El Niño. (When a La Niña occurs, the easterlies grow stronger and intensify the east-west temperature contrast.)

Bavi, because it is in the Northern Hemisphere, rotates counterclockwise, while Pam, rotates clockwise in the Southern Hemisphere. In the portions of the storms nearest the equator, the winds in both storms are from the west.

“We have an impressive westerly wind burst on the equator right now,” Michelle L’Heureux, an El Niño forecaster with the National Oceanic and Atmospheric Administration, said.

“The winds are certainly tied in with these twin cyclones straddling the equator.”