11 AM, Friday, September 22, 2017
Autumn begins at 2:02 PM MDT today and will be accompanied by warm weather. But the first autumn weekend will turn much cooler and may also be wet at times.
A cold front will sweep from north to south through the Front Range region late tonight and Saturday. In fact there may be an initial front Saturday morning and then a stronger push of cool air Saturday evening. Temperatures Saturday should hover in the 60s in the lower elevations of the Front Range and possibly start falling later in the day. Sunday and Monday will probably get no warmer than the 50s in lower elevations.
Although it’s not a great setup for a soaking rain and mountain snow, it is the best chance we have had in a while for widespread measurable rain. Showery rain (and maybe a few thundershowers) are likely to affect some areas Saturday. By Saturday evening the chance for a multi-hour period of low clouds, drizzle, or rain increases. That possibility stays with us through early Monday, but I think there will also be some dry stretches and breaks in the overcast on Sunday. And yes, there will probably be some wet snow above treeline and maybe some flakes down into the upper foothills.
6:00 AM, Friday, September 15, 2016
A cold front today will result in a significant change in temperature but not a big increase in the chance for rain. It may not reach the Denver area until late afternoon, so it should still be a warm day until then. But the cooler air will probably sweep into the northern Front Range (including Cheyenne) a bit sooner. Cooler weather over the weekend won’t be too bad, and afternoons may be quite pleasant.
This system will bring some much needed rain and snow to parts of Montana and northern Wyoming. For the Front Range there is a slightly increased chance for clouds and a few showers late today through Saturday morning, but for the most part the overall dry spell has a good chance of continuing.
Warmer weather should return early next week ahead of another cold front around in the Tuesday-Wednesday time frame.
9:30 AM, Sunday, September 3, 2017
Today, Sunday, should be the hottest day of the Labor Day weekend. Temperatures should be around record levels. The record in Denver is 95 (from 1985) and in Boulder it is 94 (from 2013). Monday will continue the very warm weather, but a cold front sweeping in from the north Monday evening will make it 20-30 degrees cooler on Tuesday, It’s possible that the temperatures will start to cool off by late afternoon Monday along the northern Front Range.
A widespread rain is not expected with the upslope flow behind the front. But there may be a period of low clouds and some patchy drizzle Monday night or Tuesday morning. Fire danger will remain elevated, especially north of I-70 where the summer monsoon was not as generous.
Beyond that the weather in Colorado will not be too exciting (other than the fire danger), and average to above average temperatures are likely to return later in the week. But weather may be making national news again by next weekend as Hurricane Irma approaches the eastern seaboard, an extreme fire danger continue the plague parts of the West.