Sunday, February 2, 2020

Major All Elevations Storm on Tap Through Tomorrow

I'm working on a manuscript this morning and have only time for a quick post to look at the pending storm for tonight and tomorrow.

Perhaps the key points are:

1. This is a cold storm that will produce snow at all elevations
2. It will likely strongly impact the morning commute, so plan accordingly and monitor forecasts
3. It will provide a good refresh at upper elevations and a reset and enhancement of the snowpack for lower-elevation nordic skiing

Below is a series of downscaled snow accumulation estimates based on the NAM for the 6-hour periods ending at 0600 UTC 3 February (11 PM MST Sunday), 1200 UTC 3 February (5 AM MST Monday), and 1800 UTC 3 February (11 AM MST Monday).  These images illustrate how snow is expected to move over the Wasatch Front overnight and persist through most of the morning. 

The downscaled SREF forecasts for Salt Lake City International Airport show snow beginning overnight.  Most members continue producing snow through at least 1500 UTC (9 AM MDT) Monday 3 February.  The range by 1800 UTC (11 AM MDT) Monday (03/18Z on the graph below) is 4-12 inches, with a mean of about 7. 

The good news for the commute is that this event has been anticipated for some time and road crews are on alert.  How snarled things get will probably depend a lot on snowfall timing and intensity, whether or not people adjust schedules, and the accident rate. 

At Alta Collins, the range through 1800 UTC (11 AM MDT) Monday is 5 to 17 inches, although the latter is an outlier.  Most embers are between 5 and 12 inches, with a mean of about 8.  My impression is that the SREF is running low compared to the latest NAM and GFS runs, although I haven't had time to ponder whether or not that's and indication of the SREF being pessimistic or the NAM and GFS being optimistic.

Regardless, Tomorrow looks to be a free refill day. 

This is a one-day event.  The NAM time-height section shows winds transitioning to northeasterly Tuesday night, but also things drying out.

It's also quite cold with 700-mb (10,000 ft) temperature forecast to be -19˚C at 8 AM Tuesday morning.  For the valley, Tuesday morning will probably produce the coldest temperatures we've seen since that epic cold blast in late October.  For the mountains, be prepared for sub-zero temperatures with wind up high.  For backcountry travelers, that northeast flow and lots of fresh snow means wind loading is going to occur in unusual places. 

Bottom line: Monitor official forecasts from the National Weather Service and play it smart. 

No comments:

Post a Comment