Tag Archive for: Winter Forecast

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La Nina Is Here

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She Is Bringing Snow For Some. Find Out Who.

La Nina is has been lurking around the west coast of South America since August. That frosty little senorita brings cooler temperatures to the mid- and eastern Pacific waters which in turn impacts atmospheric circulation, which affects the shape of the Jet Stream across North America.  And that determines precipitation and temperatures across the entire continent, essentially shaping the severity of winter storms.

The Jet Stream is impacted by La Nina. Credit: Climate Prediction Center

The National Weather Service’s Climate Prediction Center foresees that the La Nina will hang around for the entire ski season into Spring 2021.

La Nina raises the potential for more hurricanes, which we are currently experiencing. As of this writing, we’re up to 28 named storms since the start of the hurricane season.

Classic La Nina weather patterns feature a wave-like jet stream flow across North America, which causes colder and stormier than average conditions across the northern tier and warmer and less stormier conditions across the south.  

That’s good snow news for Alaska, western Canada and the northern Rockies, northern California, Wyoming, and the Northwest. It’s probably drier and warmer for New Mexico, Arizona, and Southern California.  Utah and Colorado, and the Northeast as well as parts of the Midwest are in the uncertain zone. 

For an interesting discussion of the different impacts of El Nino and La Nina conditions, click here for seasonal correlations for resorts from Australia to South and North America.

Secret formula at The Farmer’s Almanac has different outcomes. Credit: Farmer’s Almanac

Compare the Climate Predication Center’s forecast with the 2020-21 prediction from the Farmer’s Almanac.  The venerable publication uses its own formula and data for weather prediction, and, as you can see, this year’s future picture is different than what we are hearing from NOAA.

Take your pick.

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What New La Nina May Bring To Snow Forecast

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The Latest Update Shows Impact Might Good for Some, Uncertain For Others.

La Nina impact how the jet stream bends over the Pacific. Here's NOAA's prediction as of end of Oct. Credit: NOAA NWS

La Nina impact how the jet stream bends over the Pacific. Here’s NOAA’s prediction as of end of Oct.
Credit: NOAA NWS

NOAA’s National Climate Predication Center announced that La Nina has returned. She’s weak but still might pack a sting for our winter weather.

La Nina means cooling of water in the eastern Pacific.  As remote as that may seem to North America, that coolness effects how weather masses form and move around the globe.  As we reported earlier, the Climate Prediction Center said that La Nina hadn’t developed as expected after a record El Nino (warming water) in 2015-16.  But just last month, a weak La Nina was detected.

What does that mean for snow forecast? Weather forecasting is about probabilities. A look at the temperature map below (right) reveals that temps are expected to be generally warmer across the lower US and cooler in the Pacific Northwest, Upper Midwest and Ontario.  The precipitation map says below normal precip across the southern US, continuing the drought situation there, and above average precip in the upper band across the US-Canada border.  This is pretty consistent with the snow forecast we reported on last month.  Confirming an La Nina just ups the odds.

So, good news for the Pacific NW and BC, Montana, Wyoming.  Uncertainty for just about everyone else.

Remember, these are probabilities and not definitive.  Variance will happen.  NOAA will update their forecast in a few days.  We’ll let you know.

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