Denver needs snow, but there is not much expected from the cold front approaching Wednesday evening

DENVER - The overnight wintry weather system moved through the area too fast to make a dent in our snowfall deficit.

Like many other cold fronts that have passed through the city this season, this one will be too fast and too dry to bring any significant amount of snow.

With 25-inches of snow measured to date in Denver the city is 10-inches shy of its average.

The largest single snowfall this season in Denver brought only been 3.6 inches, but feet of snow have fallen in the mountains, foothills, and Flatirons of Boulder County.  The reason: our La Nina weather pattern.

This weather pattern favors a very fast flow of wind from the Pacific Northwest blowing over Colorado from west to east.  That weather pattern isn't helpful for Denver snowfall for a few reasons:

1) The Continental Divide traps the vast majority of moisture on its western side. Northwest Colorado usually gets well above normal snowfall as a result. 

2) The drier wind that survives the Divide comes downhill toward the Denver area and eastern plains.  During that fall, that air warms and gets even drier as a result.  

3) Very little moisture is left by the time the wind hits Interstate 25 and east; explaining why west metro cities and the mountains have far more snowfall than Denver and the plains.

4) This weather pattern also causes many more strong cold fronts to come through. Certainly that was the case this season, with two significant cold outbreaks so far. February is 7-degrees colder than its average through the 18th, and very dry obviously too.

In most cases, La Nina patterns don't support snow storms coming toward the state from Arizona. That southwest approach gives more humidity to the plains, and upslope (upping the snowfall) over Denver versus the downsloping (downing the snowfall) over the Denver area of our current pattern.