April Snowstorm to Pound the Rockies, High Plains This Weekend (FORECAST)

Jon Erdman
Published: April 13,2016

The calendar may say April, but a major snowstorm will target parts of the Rockies and High Plains this weekend, with the potential of over a foot of snow and strong winds that could snarl travel and cause power outages.
The instigator for this is a classic upper-level low pressure system that eventually becomes cut off from the jet stream and parks itself over the Four Corners region for several days starting this weekend.

The atmospheric ingredients for the weekend Rockies snowstorm.

On the east side of that swirling, slow-moving low, deep moisture from the Gulf of Mexico will be pulled northwestward in what's called a "warm conveyor belt" into the High Plains and Front Range of the Rockies.
That moist air flowing up the slope of the High Plains will pass over a pool of cold air, the "cold conveyor belt", pulled southward down the Front Range and High Plains.
This will provide a soaking in lower elevations of the Plains. But as the precipitation gains elevation in the High Plains and Front Range of the Rockies, it will become a wet, heavy snowstorm.
(FORECAST: Flash Flood, Severe Threats in the Plains)
The big question is where that rain/snow transition occurs.
Here's what we know right now.

Timing

Before the upper low stalls and becomes cut off from the jet stream, it will sweep through the Pacific Northwest and northern Rockies, generating some modest mountain snow totals in the Cascades, Siskiyous through Friday.
(INTERACTIVE RADAR: Where the Snow is Now)
Here is a rough timeline of the potential snowstorm once it reaches the central Rockies and High Plains:

• Friday: Snow in the mountains of Colorado, Wyoming, Utah, northern Arizona, northern New Mexico, heavy in spots; mainly rain along/east of I-25.
• Saturday: Rain may change to snow, possibly heavy, in parts of the High Plains east of I-25 in southeast Wyoming, eastern Colorado, Nebraska panhandle; heavy snow in foothills/mountains.
• Sunday: Heavy, wet snow may continue in parts of the same areas of the High Plains as on Saturday; mountain snow continues in Wyoming, Colorado, northern New Mexico.
• Monday: Same as Sunday, with a slight lessening trend toward evening.

(FORECAST: 7-Day Rain/Snow National Maps)

Saturday Night's Forecast

Snowfall Outlook

Since some of these locations may see snow fall for two to three days, totals could become impressive, by April standards.
While it is still too soon to specify exact snowfall totals from this event, here is our latest thinking on the total snowfall potential.

• Highest confidence over 1 foot of snow: Foothills west and southwest of Denver, Palmer Divide between Denver and Colorado Springs, parts of southeast Wyoming, mountains of southwest Colorado
• At least 6 inches of snow possible: Plains of southern Wyoming, parts of the Nebraska panhandle, parts of the northeast Plains of Colorado.
• Very high uncertainty: Denver-Boulder-Ft. Collins I-25 Front Range corridor. Depending on the amount of near-surface cold air in place, the range of outcomes could be either a cold rain with a small amount of slushy, wet snow, to over a foot of heavy, wet snow.

(FORECAST: Denver | Cheyenne, Wyoming | Rapid City, South Dakota)

Snowfall Potential Through Early Next Week

Coupled with strong north to northeast winds occasionally gusting from 30-50 mph, this wet, heavy snow could lead to downed trees and power outages in these areas from this weekend into Monday.
To reiterate, the uncertainty between rain and heavy wet snow for lower elevations along the Front Range is high. Only a few degrees of difference in temperatures can make a difference between a cold rain and heavy, wet snow.
For now, if you have travel plans from Saturday into Monday in these areas, check back frequently for the latest forecasts and be prepared to alter your travel plans.
In this scenario, the following stretches of interstates may be closed for a period of time:

• Interstate 80 in southeast Wyoming, possibly into the Nebraska panhandle
• Interstate 25 in southeast Wyoming and also in the foothills south of Denver to Monument Hill.
• Interstate 70 both in the foothills west of Denver and also, possibly in parts of the Plains east of Denver
• Interstate 76 in parts of the Plains northeast of Denver

(INTERACTIVE: Your Commuter Forecast)

MORE: Winter Storm Selene (March 2016)