Thursday, November 15, 2018

Looking ahead to winter ... What does a Mild El Nino really mean for SW/Central Idaho?

Courtesy National Weather Service 
Previous El Nino winters since 1950 in terms of precipitation. 1976-77 was my freshman year at the University of Montana, and it was absolutely one of the worst drought winters in the 1900s ... Montana Snow Bowl in Missoula never opened! 
Hi all,

I went to an early-season meeting with water and weather experts last week to learn more detail about what a mild El Nino winter really means, and what's expected?

The bad news is that if the experts are right, the El Nino winter will bring warmer-than-normal temperatures and drier-than-normal precipitation at least in the first half of the winter. The jet stream with storms is expected to set up to move across the southern tier of the United States, and more High Pressure weather patterns are expected to set up off the Pacific Coast.

That's the pattern we have right now affecting Southwest Idaho ... we've had High Pressure systems dominating the region, with cold and clear nights, cold mornings, and warmer afternoons suitable for hiking, biking and running.

This weather is expected to persist until the end of next week, when there's a chance of storms moving in on Thanksgiving and Black Friday. The official 6- to 10-day forecast calls for above-normal temperatures and above-normal precipitation for this region ... guess we'll see if the above-normal precipitation kicks in over Thanksgiving weekend.

So for the short term, if you're excited to see some snow fall in SW Idaho, you'll have to wait until then. And if you want to go skiing, you'll need to look for opportunities where resorts are making snow. Sun Valley always comes through with at least some limited skiing/riding available with its world-class snowmaking system. Brundage Mountain will be making snow on the bunny hill and at the Activity Barn, the tubing hill and xc area south of McCall. Bogus Basin also is firing up its snow-making system to provide some early-season skiing.

Going back to El Nino winter predictions, Troy Lindquist with the National Weather Service indicated that "not all El Nino events are the same." They printed a series of maps of El Nino winters to show how things really play out. "You see a lot of variabilities in there."

Long-term precipitation trends also may not be as dry as predicted, Lindquist said. "With the precipitation index, there is not as strong of an indicator one way or the other," he said.

Looking at the latest 30-day and 90-day forecasts, Lindquist is right ... all of the long-term forecasts are predicting above-normal temperatures, but as you look at the 30-day and 90-day forecasts, the chance of precipitation is showing more like "Equal Chances" (which is good) or even "Above Normal."

What this means is that depending on how many degrees above-normal temperatures we get, the snow level may rise higher than we'd like ... the base area of most ski resorts in Idaho is at about 6,000 feet. If the freezing level is more like 7,000 feet, you know what that means ... pretty soggy conditions at the base area ... and poor snow quality. 

Here's a series of maps showing their precipitation predictions:

8-14 day outlook shows a good chance of above-normal precipitation ... 

30-day outlook calls for Equal Chances or above-normal precipitation in E. Idaho 
90-day outlook calls for Equal Chances of precipitation. That's good! 
The bottom line is you should hope for a cold and snowy winter and hope the weather people are WRONG! Grow a beard! Women could grow hairy legs. Do a snow dance. Do whatever you think will bring snowy conditions!

This is what we're hoping for! Big *pow*! 
Every El Nino winter is different!
- SS

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