Tuesday, April 13, 2021

Dirty Harry Forecast

Yes, I know the wind is blowing, but my time this week is limited and I'm more interested in whether or not I can have another powder day this season.  

The forecasts through 1200 UTC (6 AM MDT) Thursday vary tremendously depending on what model you look at.  Some promise dust on crust for Thursday, others a deep-powder day.  

Below is the 1200 UTC initialized GFS total accumulated precipitation over the 48-hour ending at that time.  For the mountains of northern Utah, this is a wet forecast with over an inch of water equivalent for the Alta area.  

Source: Tropical Tidbits

The 0600 UTC GFS was even wetter.  Below is the meteogram for Alta from that run showing heavy precipitation starting tomorrow and continuing tomorrow night, with over 2" of water and 25 inches of snow by Thursday afternoon.  Whoot whoot!

On the other hand, the 1200 UTC HRRR is much drier.  Our area appears to be in a dry slot with the heaviest precipitation to the north.  Water totals at Alta through 1200 UTC (6 AM MDT) Thursday are less than a half inch.  Dust on crust.  

The majority of downscaled SREF members lean towards the HRRR-like solution and produce about 0.5" or less of precipitation, although there are 3 that go for bigger amounts of an inch or greater.  

On the other hand, most of the NAEFS members are wetter like the GFS and suggestive of deep powder.  

With model guidance like this, you must ask yourself one question...


  1. Feeling lucky enough to go up the canyons tomorrow if the AM snow report shows >3” AND if dry slot is overdone with decent precip is ongoing. With SSE flow at 700 mb might consider going to Brighton,

  2. Please inform Clint that "Feeling Lucky" paid off. Intended on going to Brighton, but roads (BCC) deteriorated rapidly above 6K ft so got off at Solitude instead around noon, where there was about 10-12" in the parking lot. Snowed heavily till about 130 with another 1-2", then the dry slot worked in briefly, followed by steadier snow returning as the lifts closed. Seems a blend of the drier HRRR and the GFS produced the best forecast...as did the 4km WRF model run by DRI. Despite hitting some frozen moguls on occasion, it was definitely a powder day worthy of taking a day off. :)