4:15 PM MDT, Sunday, August 30, 2020
A cold front should sweep from north to south through the Front Range region tonight making Monday and Tuesday cooler. There isn’t a lot of moisture to work with, and the best area of moisture will move through the area between Monday evening and Tuesday morning, so the best chance for some clouds and rain in Monday night and early Tuesday.
Overall a dry pattern will continue into at least the start of the Labor Day weekend. We will see warmer weather Wednesday, maybe a bit cooler again Thursday, and then warmer again going into at least the first part of the weekend. Despite the recent break in the smoke, fire danger remains high, especially west of the Front Range, so be careful with fire.
12:45 PM MDT, Wednesday, August 26, 2020
We have a couple more hot days and then a little less hot on Friday, and something we can really call cooler by Monday. But before then, Thursday may see near record hot temperatures (record highs in Denver and Boulder are 98 and 96 for Thursday).
Although most of us will not see any rain of consequence today or Thursday, there is a better chance today than there has been, so you can hope. Friday afternoon and night might bring the best coverage of showers/thunderstorms that we’ve seen in weeks, but even then, it probably won’t get everyone.
A cold front late Sunday or Sunday night is likely to bring a real change. It’s not record cool, but the last day of August (Monday) may be the only day this month when almost all Front Range stations observe below-average temperature. It is not a particularly moist air mass behind the cold front, but at this point I can’t rule out some clouds and rain with the cooler air mass.
10:30 AM MDT, Saturday, August 22, 2020
Some local spots received some rain during the last couple days, but most of us did not see any rain of consequence. The chance for rain today and Sunday is nearly zero. By Monday, the chance for afternoon thunderstorms goes up a little once more, but the chance for any substantial rain at any one location will remain quite small into mid week.
Daily high temperatures this weekend will be near record. The record highs today and Sunday are 97 and 98 in Boulder, 98 and 98 in Denver, 95 and 98 in Fort Collins, and 92 and 94 in Cheyenne. Although there may be some more afternoon clouds Monday-Wednesday, afternoon highs well into the 90s are likely to continue for the urban corridor.
For a couple weeks we have been seeing and feeling the effects of smoke from fires in Colorado. Smoke from California fires is now in the middle atmosphere over the entire central Rocky Mountain region. Although the severity of smoke may vary from day to day, expect the smoke haze to continue.
I’m watching eagerly for the possibility of more widespread showery rains later next week. It certainly is not a done deal yet, but worth watching.
12:50 PM MDT, Tuesday, August 18, 2020
There has been an increase in moisture in the middle part of the atmosphere, enough to result in the development of a few afternoon thunderstorms today, tomorrow, and Thursday, mainly in the mountains. Most of us will probably get by without any rainfall of consequence. A few isolated spots might get good and wet for a brief time.
Although it might seem the chance for rain is good given the fires, and it is, there is a down side. The lower atmosphere is dry and that can cause rain to evaporate before reaching the ground. The result is that some areas may get lightning and gusty winds, but little or no rain, resulting in new fires.
At this point it looks like the dry and hot pattern will continue through the weekend. Some of the longer range guidance from our weather models suggest a more substantial surge of moisture around 8-10 days from now. But that is far enough in the future that I wouldn’t bet on it just yet.
A few of you have asked about air quality websites. I do the same thing that most of you probably do, search the web. Look for official sites like Colorado.gov.
I also like to look at satellite because smoke conditions change fast. The RAMMB Slider (google it) offers a range of satellite options and you can zoom in. The afternoon and early evening is the best time to look because that’s when fires are most active. The satellite won’t necessarily tell you how bad it is at ground level, but you can see which smoke plumes are activity growing and where they are going.
10:30 AM MDT, Friday, August 14, 2020
A large upper level high centered over our region has kept it dry and hot. That upper high will strengthen but also shift westward a little so that it’s centered over Utah and Nevada. For the Front Range and eastern Colorado that means that some slightly less hot air may slip in from the northern plains every now and then over the next 5-7 days. In fact the first example of that is moving southward through eastern Colorado right now, and so today’s hot temperatures may top out early and then fall off a little this afternoon. But don’t expect any truly long-lived switch to cooler weather; we are still in a warm and dry pattern. If you are heading west for the weekend, record and near-record hot temperatures are likely over western Colorado, Utah, and the Southwest.
A slight increase in atmospheric moisture through the weekend may bring back the chance for some isolated late-day thunderstorms. But I expect most areas will not experience any rain of substance over at least the next five days. I hope I’m wrong.
Many parts of the Front Range have been experience terrible air quality due to wildfires in western Colorado. I have good news and bad news about that. The good news is that as the upper high strengthens to our west, our winds above the surface will switch from west to more northwest or north. So smoke from the western Colorado fires will not drift this way anymore. The bad news is that with high fire danger throughout Colorado and Wyoming, new fires locally or to the north could be a new source of smoke. In fact a fire west of Fort Collins this morning is expanding as I write.
Enjoy the weekend, and be very careful with fire!
12:45 PM MDT, Friday, August 7, 2020
If you are looking for a weekend with almost no chance for afternoon thunderstorms in Colorado, this may be your weekend. An anomalously dry air mass will be over the central Rockies region keeping the chance for afternoon thunderstorms at nearly zero. Lower elevation temperatures should get well into the 90s each day.
Monday will probably bring back some afternoon clouds and a small chance for rain. But in general, a warm and dry pattern will likely remain over us for at least a week.
Although some very localized parts of the Denver to Cheyenne corridor have benefitted from a good soaking at some point over the last 6 weeks, the pattern has been so dry that most areas have not. Denver’s official station at DIA has had less than 50% average rainfall in June and July and isn’t doing any better so far in August. Fort Collins had one of their driest Julys on record with a mere 0.15″ for the whole month. Boulder was about average in June, but measured only 0.34″ in July, or about 20% of average. Please use care with fire when you are out recreating!