12:30 PM, Saturday, November 26, 2016
A large, slow moving storm system will likely bring some snowy travel to the high passes of Colorado and southern Wyoming and Sunday and Monday. The high elevations of Colorado are likely to get more snow than Wyoming, but both I-70 and I-80 may see winter conditions at the high elevations, and wet lower down during the day
Little or no accumulating snow is expected for the lower foothills and plains of the Front Range, but there may be a period of rain early Sunday, and some snow showers later on. It’s not the kind of storm that tends to bring much precipitation to the Front Range. The higher foothills (around Nederland and westward) will likely get some accumulation. The cool down on Sunday afternoon will usher in a multi-day period of colder than average weather, but not bitter cold.
9:50 AM, Wednesday, November 23, 2016
The Front Range foothills and plains should have a nice, seasonably cool Thanksgiving. Watch out for strong west-northwest wind gusts tonight and into Thanksgiving morning. If you are traveling west be prepared for some light-moderate snow and blowing snow at the higher passes tonight. It should be over by late morning on Thanksgiving. Some of the higher passes along and north of I-70 may see 3-6 inches.
After Thanksgiving day we are in for a mild and dry Friday and Saturday across Colorado and Wyoming. By Sunday the next storm system may be causing some areas of clouds and snow, mainly from the mountains westward. There is still uncertainty about that one so make sure you check on forecasts if you are traveling across Colorado and Wyoming on Sunday.
Beginning Sunday we may be in for a week or so where colder-than-average days may be more likely than mild days.
8:45 AM, Monday, November 21, 2016
There will be two fast-moving Pacific storms in Colorado/Wyoming this week, one this afternoon through early Tuesday, and another late Wednesday into early Thanksgiving morning. Both are likely to bring some snow to the high elevations and high passes, but only minor impacts for the foothills and plains of the Front Range region.
For today in the Front Range region, expect some showery rain this afternoon and evening, and maybe some snow showers later during the night. A few areas may get enough to whiten up the ground, while other areas probably won’t get accumulation. If you are traveling into the mountains, there may be about 6 inches in some of the high passes.
Again late Wednesday and early Thursday we will have a storm system move west-to-east across the state with little impact expected for the Front Range region other than some strong wind gusts out of the northwest. But if you are traveling west expect some light to moderate amounts of snow and wind at the high passes.
The start of the Thanksgiving weekend looks like it will bring nice weather to Colorado and Wyoming. But whether that dry and relatively mild weather will last the whole weekend is uncertain at this time. I’ll update later in the week.
3:40 PM, Wednesday, November 16, 2016
Denver tied its November heat record of 80 today, and Boulder also reached 80 early this afternoon breaking the record for the date and also topping the November record of 79 last set on November 4, 1952. It’s impressive to set a November monthly heat record in the second half of the month! The warmest it will be on Thursday will likely be before sunrise, with temperatures 40 degrees colder than today by afternoon. And yes, there is still a good chance for the season’s first snow, although minor amounts.
The storm is very strong but also somewhat fast moving and will lack a long period of deep upslope (east-northeasterly flow) into the Front Range. The storm will probably be accompanied by some local areas or narrow bands of heavy convective snow (or rain changing to snow), but most of us won’t experience that. The main chance for snow should end Thursday evening.
Most likely result
4-8 inches in the mountains, heaviest near and west of the continental divide.
1-4 inches in the Cheyenne area and the higher foothills (along and west of Peak to peak Hwy)
trace – 2 inches lower foothills and plains of the Front Range (best chances in Palmer Divide Region)
A real possibility, but less likely
Little of no snow along the Front Range from Fort Collins south, OR,
A brief period of deep northeasterly wind combined with atmospheric instability may result in a couple hours of heavy wet snow or snow pellets (this is unlikely, but if it does happen DIA has just as much chance for a heavy burst as the west suburbs).
12:30 PM, Tuesday, November 15, 2016
A strong storm system and accompanying cold front on Thursday will make for a dramatic change on after record warmth today and Wednesday. The storm will be a relative fast mover from west to east, but it is quite strong. Although it’s not the type of setup for big Front Range snows, there is a good chance for some accumulating snow along the Front Range and northeastern plains (after a little rain or graupel). We will be watching its development tomorrow since relatively small shifts may result in more or less snowfall potential.
Front Range Region
A lack of easterly component to the flow on Thursday may limit the snow accumulation in and near the foothills. The northerly flow should be enough for accumulation in the Cheyenne area and the north side of the Palmer Divide (including the south part of metro Denver). For the rest of the region there a a couple things to watch for:
- A short period of northeastlies may develop Thursday and contribute to a period of rain changing to accumulating wet snow all along the Front Range.
- Some atmospheric instability may result in a few local spots receiving convective snow that won’t last long but may come down hard for an hour or two.
Near the continental divide there will likely be moderate amounts, probably on the order of 6 inches at some of the high passes. The west-facing slopes appear to be a little more favored in this situation.
12:30 PM, Monday, November 14, 2016
The temperature will take quite a ride this week. Record or near record warmth Tuesday and Wednesday will be replaced by much cooler Thursday and Friday, and then probably warmer again by the weekend.
The record high temperatures in Denver are 78 on Tuesday (from 1942) and 77 on Wednesday (from 1941). In Boulder the record highs are 75 on Tuesday (from 1953) and 74 on Wednesday (from 1999). Up and down the Front Range (Cheyenne to Colorado Springs) we are likely to be close or even set new records. With the exceptional dryness in the area, fire danger will be elevated.
The cold front
A strong Pacific cold front should sweep through the Front Range region Wednesday night and early Thursday. Although the temperatures are not likely to be nearly as cold as it could sometimes get in mid November, we may very well see our first below-average temperatures since October 19th! For the mountains and west-facing slopes, some accumulating snow is likely (maybe rain at first in the valleys). There may even be enough to make for winter driving conditions at some of the central and northern passes like Rabbit Ears and Loveland Pass.
Front Range snow??
The storm is coming in mainly from the west, so low level winds are likely to be mainly from the north and northwest, not the from the northeast direction that we prefer for snow and rain in and along the foothills. But there are two things to watch for over the next couple days. 1) There may be a brief period of northeasterly flow on Thursday that would support a period of rain changing to snow. 2) North facing sides of the Palmer Divide and Cheyenne Ridge have a better chance for snow in these setups.
Bottom line: I think there is less than a 50-50 chance for the first 0.1 inch of snow in Fort Collins, Boulder, Longmont, Broomfield and Denver, and only a very small chance in Colorado Springs. But, there appears to be a slightly better than 50-50 chance that the ground will get whitened in Cheyenne and the far south and southwest suburbs of Denver.
As the storm cranks up, there is a better chance for some wet snow accumulation on the northeastern plains of Colorado late Thursday, mainly east of DIA and north of I-70.
12:00 noon, Friday, November 11, 2016
Another warm and dry weekend is in store for all of Colorado. In fact, above average temperatures should continue through Wednesday. It is appearing likely that a cold front on Thursday will bring more seasonably cool weather as a Pacific storm system passes mainly to the north. The good news is that there may be some snow in the mountains and west-facing slopes. The bad news is that the current projection of the storm will not favor precipitation for the Front Range region. So the prolonged dry spell may continue.
How dry? As mentioned in an earlier blog, both Denver and Boulder have seen less than 1/3 the average precipitation since July 1st, and nothing is expected through at least the November 16th. For the period July 1st through November 15th, Denver will have only 1.83″ (compared to an average of 6.14), and Boulder will have only 2.50″ (compared to the 1986-2015 average of 8.07 for that period). Except for August, each month beginning in June has had above average temperature, with October and the beginning of November being exceptionally warm.
Snow? The latest Denver has gone without its first snow is November 21, 1934. In Boulder there have been several years since the 1948 that made it to November 15th, most recently in 2005. There are several years in the 1900-1947 period when Boulder went longer than November 15th (November 29, 1927 is the latest first snow). But during that period snow in Boulder was typically measured once per day at 5PM, so an early season snowfall could have occurred but melted before it was measured. It appears that both Denver and Boulder will make it to at least November 17th this year, and maybe longer.