12:15 PM, Thursday, March 30, 2017
A storm system will be near peak intensity in the four corners region Friday and then slowly weaken as it moves east across northern New Mexico on Saturday. Deep easterly flow into the mountains should help generate wet weather, especially late Friday, with snow levels falling low enough to impact the Front Range urban corridor.
The biggest uncertainties
- The changeover to snow in lower elevations is likely to occur around the time of the most steady and heavy precipitation late Friday afternoon and evening. A small shift by a few hours can have a big impact on snow amounts.
- Convection: there is likely to be some short-term bands of intense convective precipitation (maybe even some thunder), possibly after the changeover to snow. This can increase localized snowfall rates for a few hours late Friday.
- The longest period of steady rain and snow may shift to the south of Colorado Springs Friday night. Although all of eastern Colorado should get significant precipitation, the timing of the shift will determine if the northern Front Range or the southern Front Range get the biggest totals (more on that tomorrow).
Most likely amounts (with greater uncertainty than usual)
- above 7500 feet: 10-20 inches. There will probably be some portion of the Front Range that gets over two feet, but it’s too early to tell if it will be in the northern or southern Front Range.
- foothills and Palmer Divide: 7-15 inches, with the greatest uncertainty in the lower foothills.
- lower elevations along the foothills (Colorado Springs, west and south sides of metro Denver, Broomfield, Boulder): 4-8 inches
- high plains and to the north (DIA, Longmont, Fort Collins, Cheyenne): 1-5 inches
I plan to update tomorrow. However, if this afternoon’s data trends toward the snowier potential for the Denver-Boulder area, you may notice a winter storm watch issued by the NWS for lower elevations.
Could it be a snowless March?
Official records in both Denver and Boulder show only a trace of snow has occurred so far this month, a rather unusual occurrence for March. In Boulder there have been 4 Marches with no measurable snow (1910, 1911, 1918, and 2012). Denver (DIA) will likely have measurable snow before midnight on March 31st. But in Boulder the climate day ends at 6PM. So if there is measurable snow in March 2017 it will be in the final hours or minutes leading up to 6PM Friday. Anything after 6PM counts in April 1st totals.