Jet stream patterns accompany warm temperatures - WAOW - Newsline 9, Wausau News, Weather, Sports

Jet stream patterns accompany warm temperatures

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WAUSAU (WAOW)—At least seven new record high temperatures were recorded across Northcentral Wisconsin today, according to statistics released by the National Weather Service. 

As of 3:00 pm Wednesday the cities of Marshfield and Wausau reached daytime highs of 75 degrees. 

The temperature readings beat Marshfield's old record of 65 degrees observed in both 1990 and 1995.  Wausau's record-setting day broke the community's previous record of 67 degrees from 1995.  The city's average high on March 14th is 38 degrees.   

Wisconsin Rapids hit 77 degrees, topping the old record by five degrees.  The city's previous 72 degree high had stood since 1995. 

The unusually warm temperatures have been felt across much of the country.  According to the National Oceanic and Atmospheric Administration, this winter was the fourth warmest on record in the United States and the third warmest in Wausau, Wis. 

Snow cover is gone in most areas in Central Wisconsin, with only a few inches remaining in portions of the Northwoods.  Without snow on the ground, less energy from the sun is reflected back into space.  That allows for more energy to warm the surface and air temperatures. 

In addition, the Arctic and North Atlantic Oscillation patterns have both been in positive phases for most of the winter. 

A positive phase of Arctic Oscillation tends to keep cold air bottled up toward the North Pole behind the polar jet stream.  A negative phase allows colder air to spill southward toward the United States, allowing winter-like temperatures to move southward. 

A positive phase of the North Atlantic Oscillation pattern tends to keep the jet stream that steers storm systems over North America fairly flat.  That acts as an additional barrier for cold air to overcome from the north.  A negative phase allows for large ridges and troughs to develop permitting cold air to move more freely. 

The patterns have been in positive phase for most of the winter.  They can change, and doing so greatly could trigger a return to more normal seasonal conditions later in spring. 

Online Reporter Rob Duns (WAOW)  

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