A look at La Nina, and how it could affect our winter
NORTH PLATTE, Neb. (KNOP) - The topic of La Nina really does show how the global weather patterns can affect us locally.
In a La Nina pattern there’s Cool Wind off the west coast of South America, and then strong Trade Winds blow east to west. It takes cool air all the way across the Pacific Ocean out toward Australia.
Now for us that means that a large high pressure system develops north of Hawaii, and that upper-level high cannot move off to the South due to the trade winds. There’s a clockwise flow around high pressure systems, so the jet stream moves North, goes through Alaska, and then down into the continental United States.
Now this winter here’s what it looks like with a La Nina pattern: We have a moisture feed coming from the Pacific, so above normal moisture is expected into the Pacific Northwest and up to Southern Alaska. Wetter than average conditions are also expected from Southeastern Nebraska and points off to the South and East, including into most of the Midwest. It will be drier than average across the Deep South, from NM to FL. For us we’re going to be average to maybe slightly below average in terms of moisture we do have a strong northwesterly wind that really can’t produce a lot of moisture in our viewing area because the terrain does slope from a higher elevation to a lower elevation as you move off to the east.
As for the temperature, it looks like to our north it will be cooler than average, but a downsloping wind is also a warm flow for us, so we usually have many days over the winter we hit 50 to 60 degrees, and we think that’s going to be the case for us this winter. Really cold air looks to make its way into the Northern Plains and even in the into the Pacific Northwest. With all the sunshine they’re getting into the South and out toward Texas it looks like they will be warmer than average this winter.
With La Nina the jet stream does go right over us. It will wobble back and forth. When it moves off to the South cooler air filters in; and when it moves back off to the north, warmer air will work in. We think this is going to be the story through the entire winter.
The lows that track along the jet stream will determine temperature and moisture. When the low tracks to our North we have a strong northwesterly wind which is dry and Mild for us.
When the low tracks off to our South, we will have the possibility of some snow, as an easterly wind will give us cooler than average weather, and produces moisture. We think this winter will bring slightly less snow than average; and temperatures just slightly above average, but nothing out of the extreme.
This is the third winter in a row we will be in a La Nina pattern. he last time we had back-to-back-to-back La Ninas was the late ‘90s.
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