5:45 AM MDT, Friday July 30, 2021
A plume of moisture associated with the southwest monsoon has been immediately to our west and is expected to move over the Front Range region later today and into the weekend. In addition, a cold front by this evening should result in some easterly or northeasterly upslope flow in the low levels. All of that means that the chance for showers and thunderstorms ramps up later today. There is a chance for showers to redevelop in parts of the area into the late night or early morning.
Over the weekend expect cooler temperatures than recent days with a better chance than the usual 20%-30% climatology for showers and thunderstorms.
6:45 AM MDT, Wednesday, July 28, 2021
Temperatures in many low-elevation areas are likely to reach the 95-100 range this afternoon and Thursday afternoon. Friday will likely continue the heat wave, but with a small chance of afternoon thunderstorms re-entering the scene, and slightly less hot temperatures. The weekend is expected to bring cooler weather with a much better chance for showers and thunderstorms across the Front Range region.
What is the monsoon?
The Southwest monsoon (sometimes called the North American monsoon or the Mexican monsoon) is not responsible for all summer rain, but it can have a major influence during mid summer. It occurs when numerous thunderstorms along the Mexican Sierra pump lots of tropical Pacific moisture into the atmosphere. By mid July some of the moisture works its way into the American Southwest where it enhances the chances for showers and thunderstorms. In some years that moisture brings one or more periods of enhanced shower/thunderstorm activity to Colorado and Wyoming.
The monsoon has been active in the Southwest (including southern Colorado) this month. This weekend we may see it expand through Colorado and into Wyoming, at least for a day or two. Although there are exceptions, monsoon thunderstorms are not typically known for severe hail or tornadoes. But under certain conditions they can produce heavy rain.
6 AM MDT, Friday, July 23, 2021
It has been a while since I’ve posted, and that’ s because we have been in a typical (and not very interesting) July pattern with a small percentage of the Front Range receiving a late day thundershower and low elevation temperatures reaching into the 90s.
I don’t have any big changes to report, but there is a small change today and Saturday that may increase the chance for a late day thunderstorm, and the extra clouds will probably keep some portions of the Front Range a little below 90. The flash flood watch currently in the foothills is mostly to keep us aware that if a thunderstorm moves across an area recently burned by wildfire, there could be very rapid and dangerous runoff. Thunderstorms are likely to become more scarce again by Monday, along with low elevation temperatures rising back into the 90s.
You may have noticed that smoke haze from western fires is mostly gone. Don’t get too used to that. The fires are still there, it’s just that the wind direction is steering it more to the north of the Front Range region. I’m dreading its return sometime next week.
1PM MDT, Thursday, July 1, 2021
There is plenty of moisture in the atmosphere today, so numerous showers and thunderstorms this afternoon means that just about everyone will hear thunder and get at least a sprinkle. A few locations are likely to experience heavy rain for an hour or two. Be alert for local flooding.
The weekend looks warm with a scattering of afternoon thunderstorms. The chance for rain is less than today, but it might still be good to have a plan B for your outdoor activity.
In the longer range, we may be heading for a hotter, drier period by the middle of next week.