Forecast Summary:

Big snow on Thursday!  Pleasant weekend.  Possible storm early to middle of next week.

Forecast Discussion:

On Thursday, a powerful system descends on us from the north northwest.  There’s a strong jet streak component to this system, which means the models will undoubtedly struggle to put their fingers on how much snow we’ll get.

Unsurprisingly, the models disagree on timing and amount.  Let’s start with the optimistic ones.  The Canadian Model has it starting Wednesday afternoon and by Friday morning dumping a whopping 18” of snow.  The NAM Model has the same timing and is predicting 13” of snow.  The WRF Model is even more optimistic with the same timing, with a total of 30” of snow. 

Now let’s turn to the pessimistic models.  The American Model has it starting early Thursday morning, ending by midnight Thursday, and dumping 9.5” of snow.  The European Model has the storm coming in later and ending later, with a total of 8” by the end of the day Friday. 

Okay, so we know this is good when the pessimistic models are still predicting 8” or more.  And, when the range is 8”-30”, it’s hard to make predictions.  If you want my guess, I’d go for 12-18” as that seems to be the middle to upper range, the jet streak has been overperforming so far this winter, the National Weather Service discussion this morning was optimistic, but the WRF can tend to overpredict near the edge of its forecasting range.

For those of us stuck in the Golden / Boulder corridor – the four major models (European, NAM, American, and Canadian Models) are all calling for something in the range of 6-9” at my house in Golden on Thursday. 

We’ll have a break from the snow over the weekend.  Then, there’s a potential storm next Tuesday and Wednesday.  The European Model doesn’t see more than a dusting.  The Canadian Model sees 3”, and the American Model sees a wonderful 17”.  Let’s hope out in forecast fairyland that the American Model is the better judge of that system.

Retrospective Discussion:

Great snowfall on Easter Sunday / Monday.  Complex system as it was a combination of upsloping, jet streak, and a cold front.  The models overall did a nice job on forecasting this complicated storm in our patrol area, though they didn’t quite predict the crazy snow totals in the Boulder / Golden corridor. 

While the models predicted the snow almost all falling on Sunday, strong snow continued into Monday.  Without the Eldora Snowstake Webcam functioning, which is the most reliable indicator of actual snowfall, it continues to be a bit tough to estimate actual snowfall.  That said, the Lake Eldora Snotel reports a 1.0” increase in SWE on Sunday / Monday.  As a side note, in my experience SWE (i.e., Snow Water Equivalent) numbers are vaguely reliable from Snotel sites, but snowfall numbers from Snotel sites are almost worthless.  1.0” of SWE, considering the temperatures of the storm, probably translates to roughly 12” of snow.  The nearest NWS station report is 10.6” of snow just a hair north of Nederland.  So, the American Model and the WRF Model each did a decent job calling this storm.  The NAM Model was too low, and the European Model was even lower. 

K.B.O. everyone.

-Jordan (Tuesday morning)

Note: Unless otherwise noted, all forecasts are for 10,000’ in exposed areas.  References to American Model are the American (GFS) Model.  References to the Canadian Model are the Canadian (GDPS) Model.  References to the WRF Model are the CAIC WRF Hi-Res Model.  References to the European Model are the European (ECMWF) Model.