6:30 AM, Monday, April 3, 2017
The storm system moving through southern Colorado tonight is somewhat limited in moisture and will go through its major intensification after it is east of our region. The result should be a relatively minor snowfall, from little or nothing in low elevations north and east of Denver to about 6-10″ in the mountains south of I-70. The timing should be late evening through early Tuesday, with some intermittent showery precipitation possible during the day on Tuesday. Hard freezes should be widespread at all elevations Wednesday morning followed by springlike weather for the remainder of the week.
6-10 inches: mountains and foothills south of I-70
3-7 inches: mountains and foothills north of I-70 and the Palmer Divide region
1-3 inches: along foothills from Boulder County south (Boulder, Broomfield, west & south sides of metro Denver, Colorado Springs
0-1 inch: DIA, Longmont, Fort Collins, Cheyenne
12:15 PM, Sunday, April 2, 2017
A storm system heading our way will likely bring rain and snow to the region late Monday into Tuesday. Some guidance is suggesting somewhat heavy amounts in and along the foothills. It’s hard to get too excited given the storm predictions that did not verify Friday night. But the previous storm, although quite large, was weakening when it was in New Mexico at its closest approach to us. The next storm is a little different. It is likely to be in its intensification stage and may move through southern Colorado Monday night.
The potential exists for 6-10 inches in and immediate along the foothills, less further away from the foothills. That’s not a confident forecast at this point, and I will update tomorrow.
The official climate stations in both Boulder and Denver made it through March with no measurable snow. Only a trace (less than 0.1 inch) was recorded in both places. This had happened only twice before in Denver’s record (2012 and 1995). No measurable snow had happened four times previously in Boulder (2012, 1918, 1911, and 1910). I should note that the Boulder snowfall records a century ago were not of the best accuracy.
12:15 PM, Friday, March 31, 2017
Changes from my forecast yesterday are that I’m a little more inclined to go with the lower end of the snowfall forecasts that I gave yesterday. The heaviest snow reports are likely to come in from the southern Front Range (west of Pueblo down through the east slopes of the Sangre de Cristos). But you should still be prepared for significant wet snow this evening and tonight along the mountains and foothills from Colorado Springs northward.
The storm system in the four corners region this morning was at peak intensity and will be weakening as it moves across northern New Mexico through Saturday. The current observations (satellite and radar) suggest that the most likely period for some heavy precipitation is between late afternoon and about midnight, with more intermittent precipitation and dry intervals late tonight and Saturday.
Changeover to snow in the lower foothills and plains
Some pockets of heavier convective precipitation may speed up the changeover to snow late this afternoon, but most areas probably won’t change over until after dark. The result will be highly variable accumulation potential. Snow may accumulate rapidly including some on the roads during brief periods of heavier snow this evening, while other nearby areas may stay wet with very little snow.
Most likely snowfall
Above 7000 feet: 7-15 inches
6000- 7000 feet: 5-10 inches
Below 6000 feet: 0-6 inches
- Cheyenne, Boulder, Broomfield, Castle Rock, Colorado Springs, and Denver’s west and south sides are a little more likely to be in the 3-6 inch range.
- DIA, Longmont, Fort Collins are a little more likely to be under 3 inches.
Update at 2:55PM Friday:
The heavy bands do not appear to be coming together as expected. Will probably see the lower end of the snowfall ranges listed above.
Again late Monday?
The next storm in the series is due to begin late Monday. It’s looking snowy all the way down to the plains, but keep in mind that the last couple storms evolved a bit differently than the 3-4 day model guidance suggested.
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.
12:15 PM, Tuesday, March 28, 2017
The storm currently moving through will continue to produce periods of mainly rain below 6000 feet, mainly snow above 7000 feet, and some slushy snow between 6000 and 7000 feet.
Denver-Boulder-Fort Collins-Colorado Springs: intermittent rain into tonight. The rain may mix or change to snow toward morning, but little or no accumulation is expected (0-2 inches). If there is accumulation the chances are a little better toward the south side of Denver and the north side of Colorado Springs.
Foothills and mountains: Rain should change to snow in the lower foothills tonight, with mainly snow continuing above 7000 feet. Accumulations are likely to range from a few inches in the lower foothills to between 6 and 12 inches higher up. There may be some localized areas greater than 12 inches, especially southwest of Denver and in the Pikes Peak region. Watch for accumulating snow in the Palmer Divide region as well.
Next storm Friday and Saturday
Another storm late Friday and Saturday is looking like it could be a slow moving 4-corners type system that has the potential to be quite wet along the Front Range. Early indications are that is may also be a few degrees cooler which could bring significant wet snow into the lower elevations.
4:30 PM, Monday, March 27, 2016
Two storms with mainly rain in the lower elevations and wet snow above 7000 feet are likely tomorrow afternoon and early Wednesday and again Friday afternoon into Saturday.
I will need to update tomorrow but here are the highlights for the Tuesday-Wednesday morning storm:
Heavy wet snow in the foothills and Palmer Divide region. Probably 6-18″ (the higher amounts as you go up in elevation). This storm is likely to have heavier amounts than last Friday’s storm.
Rain (maybe some thunder late Tuesday) for the lower foothills and urban corridor. It is likely to be mainly rain, with a changeover to wet snow in some areas by Wednesday morning. This is the part that I will update tomorrow. With heavier precipitation expected this time around a changeover to wet snow could accumulate quickly.
6:20 AM, Friday, March 24, 2017
If you are just getting started this Friday morning, the worst of the storm for the Front Range is over. For many areas north of Denver the precipitation came to an end before the changeover to snow. There are some major impacts south and east of Denver. A stretch of I-25 is closed between Denver and Colorado Springs, and a portion of I-70 is closed well east of Denver, and wintry conditions will continue out east through the morning.
Active storm track
We are in a more active storm track for Colorado now. The next period with precipitation likely in Colorado/Wyoming is Sunday, but that will likely be very minor along the Front Range. Another chance comes in around Tuesday, and probably another storm toward the end of next week.