Life after Death

Although there has been quite a bit of variation between the models concerning the details, especially timing, things appear to be coming together for what should be an exciting period this weekend.

As discussed in the previous post, the precipitation accompanying the Pacific cold front that made landfall along the Pacific coast overnight is expected to die off as the system moves inland.  This is, however, a case of life after death as the cold front will be rejuvenated once the pre-frontal southerly flow begins to move past the Sierra Nevada, enabling juicy air over the eastern Pacific and Gulf of California to push into the Intermountain West.

The GFS loop below, which shows the 700-mb (10,000 ft) temperatures, surface winds, and precipitable water (a measure of the total water vapor content of the atmosphere, color fill).  Note as the front pushes across California and Nevada that it eventually draws moist air up the lower Colorado River Valley and into Utah.  

1200 UTC 24 Sep 2014 GFS Forecast of 700-mb (10,000 ft) temperature, surface winds, and precipitable water (color fill) from 1200 UTC (0600 MDT) 24 Sep – 0000 UTC 28 Sep (1800 MDT 27 Sep). 

Some of the moisture increase reflects what meteorologists call moisture convergence along the front, but tapping into the juicy stuff to the south plays an important role.

The GFS is currently really excited for late Friday night and Saturday, with heavy precipitation along the front over Utah (apologies for the crappy color scale; Friday night and Saturday are near the end of the loop.

1200 UTC 24 Sep 2014 GFS Forecast of 700-mb (10,000 ft) temperature, surface winds, and 6-h accumulated precipitation (color fill) from 1200 UTC (0600 MDT) 24 Sep – 0000 UTC 28 Sep (1800 MDT 27 Sep). 

Here's a better image showing the 6-hour accumulated precipitation for the period ending 6 PM Saturday.  The GFS is putting out up to just over an inch of rain in portions of northern Utah.

Who gets what will ultimately depend on factors that are not reliably predictable this far in advance, but it does look like late Friday Night and Saturday could be pretty wet with some thunderstorms thrown in just for fun.

After that, things look showery and cooler for northern Utah, but as things stand now, I don't think we'll see much more than some light accumulations in the highest elevations.