La Niña could bring another wet and snowy winter to the Northwest

We have come out of one of the most torrid summers in Pacific Northwest history following one of the wettest winters, and in this back-and-forth battle between weather patterns it appears La Niña could once again play a role.

Skiers would love for that to happen again, though the predicted overall impacts of a La Niña or it's "brother" El Niño are never a guarantee.




La Niña watch continues

The official agency which monitors these larger-scale weather patterns -- NOAA's Climate Prediction Center -- issued a La Niña Watch last month, signaling that the waters along the equatorial Pacific coast of South America are cooler than normal and expected to remain so.

On Thursday, they released their newest report with little change.

This band of cool La Niña water extending westward off the South American coast has a big effect on the overall jet stream patterns in the upper atmosphere.  Those jet stream winds and direction, in turn, steer weather systems.

If we get the jet stream to be above our region more often during the winter, we're more likely to get lowland rain and heavy mountain snow!

Right now, the anticipated La Niña is expected to be on the weak side, but that still could be enough to "tip the scales" toward a cooler and wetter winter overall.

Again, it is NOT a guarantee.  Nor should this past winter's weak La Niña be taken as meaning this year will be a repeat.   The chances for a repeat of last winter are very small.  It was truly a remarkable season.

Possible effects vary by elevation and aren't guaranteed

Still, we'll be looking for a better shot at above-average mountain snow with a weak La Niña, a bit better chance than a typical year for windstorms and about normal amounts of wintertime rain in the lowlands.

Lowland snow really is such a fickle thing too -- having a La Niña or El Niño in place isn't cause for celebration by schoolkids who want snow days just yet.  There's just too much that has to come together perfectly for a big lowland snow.   Stay tuned.

But, with a weak La Niña predicted, there's nothing I can see that points to a "bad" year for mountain snow.

The wild card in a La Niña would be an atmospheric river -- a fast-moving flow of very rich moisture which can bring very heavy rains to our mountains and subsequent flooding in the lowlands.   This, again, is a wild card that we'll just have to watch for.

We'll just watch and wait... and wax our skis and boards!   And the kids wanting a snow day can keep a close look at the forecast on KIRO 7 as we head into 2018.

The effect of La Niña are more likely to be evident in the months of December, January and February.

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