In late March 2003, a slow moving closed low starting to the south of us and slowly moving east caused a three-day storm that dumped 30-40” in Denver, 40-50” in Golden, and 60-80” in our patrol zone.  For the last 18 years we haven’t had a storm that one could even begin to compare to that wonderful monstrosity of a storm.  Until, maybe, possibly, potentially, perhaps, now?

So, will we see something comparable?  Spoiler alert for this forecast.  I have no idea.  It’ll be a big storm for the foothills and plains – but no idea yet if it will truly be epic, and if epic, if it will be as great (or greater) in our patrol zone than at my house.  As discussed more below, the American Model is calling for almost 10 times more snow in our patrol zone than the Canadian Model.  And, the models are in no closer agreement today than they were when I put out a Monday morning forecast.  So, with the spoiler out of the way, let’s dive into the forecast.

There is a powerful low pressure system currently just off the California coast.  Per the American Model, it will likely be centered over the Four Corners by Friday night, and slowly meander eastwards along the southern part of Colorado until Sunday afternoon when its center will pass into Kansas.  This will mean both key ingredients for lots of snow will be present, i.e., (i) lots of moisture, and (ii) strong winds from the eastern side of the compass that cause the biggest snow storms for our patrol zone (and the front range).  And the American Model is bullish, predicting over 5 feet of snow for our patrol zone as a result.  But, other models disagree both on the location of the low, the shape of the low, and the strength of the upslope winds.   

Here are the current model snow forecasts for our patrol zone from Thursday at noon (the very beginning of the storm) through Monday at noon (the very end of the storm):

American Model: 61”

UKMet Model: 37”

European Model: 15”

Canadian Model: 7”

And, for those who are curious, here are the same model forecasts for my house in Golden – UK Met Model: 48”, American Model: 46”, Canadian Model: 21”, and European Model: 20”.  Notice how a key question for our patrol zone will be whether the upslope will be strong enough to truly dump in our patrol zone?  The Canadian Model is calling for 14” more snow at my house than at Bryan Mountain, while the American Model is calling for 15” more snow at Bryan Mountain than at my house. 

I’ll try to update this forecast again when the full storm is in the forecast range of the shorter term regional models (i.e., the NAM, WRF, and RDPS Models) as well.  Until then, we’ll just keep holding our breath and hoping that the American Model is calling this one right.

Four big picture thoughts.  First, if this storm comes in on the big end, travel will be mostly impossible for potentially several days.  Second, avalanche danger could be through the roof (no pun intended) from this storm.  Third, per the American Model, winds during the height of the storm on Saturday will be from the northeast at 10 mph with gusts to 30 mph.  If the storm comes in as predicted by the American Model (or even the UKMet Model), it will have been nearly two decades since we’ve gotten snow anything like this with winds from the opposite direction as most days.  This will create bizarre loading patterns none of us are used to.  While travel in the backcountry would likely not be prudent, if travel is necessary, this is a time to concentrate on slope angles that you’re on and above you.  Non-traditional avalanche paths are as likely (or perhaps even more likely to slide) than the traditional avalanche paths, so be extra cautious.  Fourth, we’re likely to see heavier snow than we normally do in our patrol zone, owing to the type of storm.  This may mean all numbers above are too optimistic for total snow, but not for moisture.

Thanks, and forgive me for not even looking at the comparatively small snows predicted now through Thursday, and the interesting storm that may come in next Tuesday-ish.  Fingers’ crossed for the better snow outcomes.  Cheers.

-Jordan (Wednesday 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.