Tuesday, December 2, 2014

Stuck in the Middle with You

As I looked at the computer model forecasts for the next several days, the Stealers Wheel song Stuck in the Middle with You came to mind.  Although we're going to get some scraps of moisture into Utah late tonight and tomorrow, for the most part we are stuck between two streams of moisture, one penetrating inland north of the High Sierra and one penetrating inland south of the High Sierra, as illustrated by the GEFS ensemble mean integrated water vapor transport forecast for 0000 UTC Thursday (1800 MST Wednesday).

Source: NWS
Thus, we get a little bit of moisture and precipitation in here late tonight and early tomorrow (valley rain, mountain snow), but beyond that, we're stuck in the middle of the two juiciest airstreams.  Check out the GFS forecast for 0000 UTC Friday (1800 MST Thursday).  Precip to the north and precip to the south, but we're left high and dry.  Clowns to the left of me, jokers to the right, here I am stuck in the middle with you!

Just to further emphasize how we are stuck in the middle, here's the GFS total precipitation forecast through 0600 UTC 5 December.  Note how we are in an area of lower precipitation between an arm of high precipitation extending across Idaho and an arm of higher precipitation extending across Arizona.

Finally, here's an ensemble of our 22 experimental downscaled forecasts for Alta–Collins from the North American Ensemble Forecast System (NAEFS) for the next week.  There are a few members of the Canadian modeling system that are going for big totals for the event late tonight and tomorrow, but this is highly unlikely and we've seen outlier forecasts produced by some of their ensemble members before.  Most are generating 5" or less of snow through tomorrow night.  Some as little as 2".

Based on this, I'd go for probably go for 2–4" at upper elevations in the Cottonwoods, but even that might be optimistic.  I'd call it dust on crust, but it's going to be more like crud on crust since it's going to be a warm storm.  Beyond that, we have to hope for some scraps to sneak in here as there are no direct hits projected for the next week.

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