Saturday, February 4, 2017

Stormy Week Ahead

With the inversion thankfully behind us, we are now staring directly down the barrel of what will likely prove to be a stormy week for the Wasatch Range.

The stage was set by last night's teaser, which brought a few inches to the Wasatch Range and provided a sparkly white coat when the sun breaks came at times today.

While we might se some snow showers tonight and tomorrow, things really get rolling Sunday night.  The NAM-derived upper-Cottonwoods forecast meteogram below shows strong winds (middle left) through the end of the model run at 11 PM Tuesday.   Model water equivalent reaches 2.5 inches (lower left).

Capping this off will be an atmospheric river that should reach Utah late Tuesday.  As shown in the GEFS ensemble mean (top) and GFS (bottom) forecast for 1200 UTC (5 AM MST) Wednesday, a broad river extends northward over the eastern Pacific and then curves anticyclonically (clockwise) across the state.

Thus, it looks like another really busy period for the snow-safety staffs at the resorts and along the highways.  Batten down the hatches.


  1. Is there a "season" for atmospheric river events, when do they typically begin to build and when do they end during a calendar year? Also, is there data that shows that atmospheric river events are increasing or decreasing?

    1. The seasonality and the strength of the seasonailty varies geographically over the western US. See Figure 6 of Over northern Utah, the seasonal variability is relatively weak, although there is a slight minimum in February.

      With regards to trends, that's something I'll need to look in to. The answer likely varies geographically.