3:00 PM MST, Friday, January 11, 2019
Intermittent snow is likely into the evening today, mainly along the west and south side of metro Denver and the Palmer Divide. Although additional accumulation won’t be very large, nightfall and temperatures dropping below freezing may cause some accumulation and black ice on roads this evening.
The weekend should be dry and seasonably cold, but perhaps with some air stagnation along the urban corridor.
At 3PM at my home in South Boulder there has been 1.2 inches of snow and 0.54 inches of liquid. That’s a remarkable snow-to-liquid ratio for a January storm. About 0.15 inches of liquid fell as rain early this morning. It’s more like an April storm!
9:00 AM MST, Thursday, January 10, 2019
A weak but intensifying storm will move through the central Rockies on Friday bringing some snow. The snow is likely to be a little wetter than usual for January with a gradient ranging from very little in the plains of eastern Larimer and Weld County, to some moderate amounts (exceeding 6 inches) in the Palmer Divide and foothills.
The most likely accumulation
There is a lot of variability due to the timing of storm intensification and whether there might actually be a little rain at the start. The most likely accumulation is 4-8 inches for the foothills and Palmer Divide area, 2-4 inches for most of the Denver-Boulder metro, 0-2 inches in Longmont, Fort Collins, Cheyenne, and Colorado Springs. The timing is mainly during the day on Friday, possibly beginning by sunrise and continuing into the evening. This outcome has about a 60% chance of occurring.
The low end possibility
The GFS, a reliable U.S. based model, has been consistently showing that the storm won’t really get going until it’s east of Colorado and thus the snowfall should be rather minor. Amounts with this model should range from 3-6 inches in the foothills, mountains, and Palmer Divide regions, 1-2 inches in the Boulder-Denver area and little or nothing in Longmont, Fort Collins, Greeley, and Cheyenne. This outcome has about a 30% chance of occurring.
The high-end possibility
Some of the mesoscale models based on the WRF have been more likely to begin intensifying the storm as it moves east through the central Rockies and tapping some subtropical Pacific moisture as it intensifies. These solutions suggest a 6-10 inch snowfall in the Denver area south of I-70 and extending north along foothills to Broomfield and Boulder. The amounts trail off rapidly to just 1-3 inches for northeast Boulder County, Larimer, and Weld counties. The trend seems to be away from this so this outcome has about a 10% chance of occurring.
Dry weather with seasonable temperatures. The air may be somewhat stagnant, so some haze along the Front Range urban corridor is likely.
9:20 AM MST, Sunday, January 6, 2019
My forecast from yesterday morning hasn’t changed except that the chance for some strong gusty west-northwest wind has increased for the Front Range region and adjacent plains. Today through Monday are likely to see some gusty downslope winds, especially in and along the foothills. The best chance for gusts exceeding 60 mph is on Monday.
Other than that, you should still expect some snowy stretches in the mountains and western Colorado today. There may be a lull tonight and then some additional intervals of snow at the high elevations on Monday. Totals of 6-10 inches are likely at some of the high passes, much less in the valleys.
The Front Range foothills and plains should stay dry with some cloudy intervals and gusty winds. Some sprinkles or flurries will make it as far east as the foothills before evaporating. Despite slightly cooler weather, lower elevations are still likely to reach 50 degrees, which is above average for January.
9:30 AM MST, Saturday, January 5, 2019
A couple of fast moving Pacific storm systems will move across the Rockies Sunday and Monday bringing some snow to the mountains and West Slope areas, but probably nothing much more than some increased cloudiness and slightly cooler weather for the eastern foothills and plains.
The heaviest snow is likely in the higher mountains and west-facing slopes where 6-10 inches could fall mainly on Sunday, but some on Monday too.
Snow shouldn’t make it too far east of the continental divide, but some light accumulations are likely in places like Rocky Mountains Park and Brainard Lake. Although some clouds and cooler weather are likely in the lower foothills and plains, temperatures are likely to remain near or a bit above average. Very mild weather is likely to return by mid-week.
9:30 AM, Sunday, December 30, 2018
After a mild Sunday, Monday will bring very cold weather and some snow. The best chance for accumulation along the Front Range urban corridor will be south of a line from Lyons to Longmont to DIA. Although a big storm is not expected, you should be prepared for some winter driving conditions in the mountains and in the Denver-Boulder area on Monday.
0-1 inch: Fort Collins, Greeley, Longmont
1-3 inches: Cheyenne, northeast Denver & DIA, Colorado Springs
2-4 inches: Boulder, Broomfield, west and south sides of Denver, Castle Rock
3-6 inches foothills and Palmer Divide of Douglas, Jefferson, and Boulder counties
Mild, then very cold, then mild
Mild weather today will be replaced by temperatures on Monday that fail to make it to 20 degrees. It will probably be around zero in Denver-Boulder around the time that the new year arrives. By New Year’s morning temperatures are likely to range from 0 to -10 along the Front Range (coldest in areas that have snow cover). But then by the Thursday-Saturday period dry, unseasonably mild, and occasionally windy weather will be in place.
11:30 AM MST, Friday, December 28, 2018
The cold will let up a bit by Sunday ahead of another cold front Sunday night that should bring more cold weather New Year’s Eve and New Year’s Day. No major storms are expected to impact the Front Range Region during the weekend, but some light snow amounts may accompany the arrival of the next cold spell Sunday night or Monday.
December did not bring any temperature extremes (either warm or cold). Although tonight will probably be the coldest of the season so far for the Front Range and eastern plains, it won’t be anything remarkable for this time of year.
By Sunday we should see temperatures near or even a little above average (40s for most of the Front Range urban corridor). The the next cold air mass Sunday night should keep daytime temperatures no warmer than the 20s for New Year’s Eve and New Year’s Day, and New Year’s morning will probably see a range of 0-10 for most locations in the urban corridor.
A relatively weak storm system with the next cold front will probably bring some light snow amounts Sunday night or Monday for the mountains and the urban corridor. Right now it’s looking pretty minor. I will update on Sunday.
Warm spell ahead
Beginning on January 2nd it appears we may enter a multi-day stretch of dry and unseasonably mild weather. But as is often the case with warm weather in January, we will have to watch for the potential for some windy periods.
7 AM MST, Wednesday, December 26, 2018
Cold weather will be in place through Saturday, with temperatures even in the lower elevations likely to stay below freezing all day Thursday and Friday.
A storm system moving to the south of Colorado and then intensifying out on the Great Plains will mostly miss the Front Range and the urban corridor. The best chance for accumulating snow tonight and early Thursday will be in the south suburbs of Denver and the Palmer Divide region, but even here the amounts will likely be less than 2 inches where it does snow. From Denver northward, 0 to 1 inch will likely be the range, with 0 most likely in Longmont, Fort Collins, and Greeley.
Light snow amounts are likely today and tonight in the higher mountains.
The only area with significant winter weather is out on the high plains near the border with Kansas and Nebraska. Around 6-10 inches of snow and blowing snow may make travel difficult late tonight and early Thursday for people traveling west toward the Front Range on I-70, I-76, and I-80.
There is a small chance for flurries or areas of light snow Friday, but that is more likely along the southern Front Range (south of Pueblo).