Dec 12th, 2016 Weather Conditions

Ok, I’m back with regular updates.

So here we go. El Nino of the last two years is gone, meaning warm California Coastal waters have returned to an ENSO neutral or La Nina condition, By my estimation. Remember warm water evaporates better than cold, which gave us two nearly normal winters for snowfall in the San Juans – not above – as would be expected, just a return to norm.

This wreaked havoc on the fisheries from the Gulf of Alaska to L.A. But this blob of warm water did not affect the jet stream as expected, which petered out the anticipated banner snow year by February.

As for this year, we are ENSO neutral trending towards La Nina. This means sea surface temperatures (surface to 100M deep) are normal or cooler. When this happens the steering jets tend to stay to the North. This has been true so far with most early season storms tracking through Montana, Wyoming, and barely making it S to the I-70 corridor. Also, the Arctic Ocean is nearly 30 degrees F above normal. This means typical arctic clipper systems, that break out cold air down to the lower 48 are laden with moisture.

These large lows have barely made it S of I-70 and instead are flowing down the east side of the Continental Divide, across the plains and Great Lakes, and NE. When these outbreaks of cold air occur, we in the San Juans hope for a southern moisture laden jet to collide with the cold air, for a big dump.

In the near term, the polar jet remains north and east of us, but a southern weak fork of the jet is bringing weak dynamics and moisture our way for most of the week as orographics come into play. By Friday a good fetch of sub-tropical moisture will impact the 4 corners on this weak (70-100kt) jet which will be West to South-west favorable.

Should tis play out, a good dump, can be expected by Friday.


red mtn
red mtn