Still trying to comprehend the wild weather of the last few weeks, some meteorologists say an "El Nino-like" system is the culprit behind the Ohio River Valley's massive floods, California's deadly mudslides, and even the storm that laid a thick coat of ice on local communities.
That same wacky pattern, they say, is partially responsible for the dense fog that littered area highways with car crashes and unusually warm weather last week that caused some Ohioans to remove their coats in mid-January. It is also one explanation for the frigid temperatures that put the region in a deep freeze this weekend.
Weather experts say the storms and flooding plaguing northwest Ohio the last two weeks began in mid-December over the Indian Ocean. Tropical moisture from there quickened westward, picking up steam and more moisture over the warm South Pacific. The jet stream then pushed the unusual weather toward Southern California and eventually across the United States, with a stop in the Ohio River Valley.
Meteorologists call this a Madden-Julian Oscillation, or MJO, a weather pattern that is like an El Nino tropical disturbance dubbed by some meteorologists as the primary reason for the recent extreme precipitation and volatile temperatures. The pattern, which appears at 30- to 60-day intervals, is usually most active during a neutral or weak El Nino winter - which fits the current conditions, said Vernon Kousky, a research meteorologist with the Climate Prediction Center of the National Oceanic and Atmospheric Administration.
"When certain phases of the MJO get just right, it triggers circulation over the United States," Mr. Kousky said. "There are many factors involved, but it is one of the culprits."
While an MJO is different from an El Nino, it shares many common features with the notorious weather system. El Nino sets in after a warming of the equatorial waters in the Pacific Ocean, which unleashes a range of unusual weather on the west coast and throughout the U.S.
"It looks like El Nino with the way it has been acting for the last 10 days," Mr. Kousky said.
Henry Margusity, a meteorologist at AccuWeather Inc., a private forecasting service in State College, Pa., isn't ready to label the unruly weather as a product of a complex system - such as MJO.
"I call it a storm," Mr. Margusity said. "It is a series of storms and it keeps battering the area. Weather just gets into these patterns. Nowadays, with all the observations we have, we know more about the weather than we ever did. A lot of this stuff has happened before, but now it is captured on videotape."
Last week, the Climate Prediction Center said three systems were on pace to collide and trigger severe storms on the west coast and in the central United States. Mr. Kousky said the pattern of the storm was on target, but the intensity of the storms didn't reach the expectations.
Still, Mr. Kousky said, "The very wet conditions in Southern California did cause mudslides and you had your flooding too."
Flooding along the Ohio River Valley is unusual for the heart of the winter because those conditions usually arise when warm weather melts snow in spring or in early fall when hurricanes can push rain all the way north to Ohio, meteorologists said.
"It's a little unusual to see," Mr. Margusity said. "In the Ohio Valley, you expect the snow to melt during the spring, but not this time of year. But being so warm, it is almost like a spring time weather pattern."
Mr. Kousky said there's always a potential for flooding when snowfall is followed by a warm spell.
"This is an extreme event," he said. "I don't think I can remember anything like this in the last ten years or so. At this time of year, the area is usually locked in cold weather."
Martin Thompson, a hydrometeorological technician for the National Weather Service in Cleveland, said a northern swing in the jet stream is responsible for some of the odd weather. Pockets of warm air are embedded in the storms that have rolled eastward across the country - which have helped usher in usually high temperatures, floods, and ice storms.
"The variability of the jet stream kind of threw us for a loop here," said Mr. Thompson, adding the National Weather Service's outlook for January predicted below normal precipitation. "The periods of dry weather you can almost count on your hand.
While maintaining differing theories about what caused such unusual weather so far this month, the meteorologists are expecting more typical winter weather in northwest Ohio for the rest of the season.
AccuWeather is projecting a cold weather pattern to set in over the next several days.
"The weather this year really seems to be changing rapidly all over the place," Mr. Margusity said. "Any time you've got cold arctic air running around like we've had the last several weeks, everyone has to watch out."
Because the MJO is a slowly developing system, the Climate Predication Center said it is difficult to predict whether it will continue to impact the region beyond one or two weeks. And, it is also unknown whether it will return or influence other weather patterns.
The center, though, expects that "it'll feel more like winter" in the weeks and months ahead.
"They aren't forecasting extremes," Mr. Kousky said. "We don't see anything to indicate it will be wetter or drier or warmer or colder in your area.
"Mother nature does not tend to repeat herself from one season to the next."
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