The North American monsoon

12:35 PM, Wednesday, July 19, 2017

The North American monsoon, sometimes called the Southwest monsoon or the Mexican monsoon, is a seasonal weather pattern that in some years can bring enhanced rainfall across the southwestern U.S., including the Front Range region. The impacts for the Front Range are seen in the climate record from mid July through the late summer.  In a nutshell, showers and thunderstorms erupt daily along the Mexican Sierras as the tropical Pacific heats up and that pumps lots of moisture into the atmosphere. Some of that moisture makes its way north into the southwestern United States. In the Front Range region not every year sees the effects, and the surges of moisture can be intermittent.

 

The 2017 monsoon has arrived, but for the most part the moisture has been in the upper levels of the atmosphere and so rainfall has been sparse despite afternoon clouds (there has been more moisture and areas of rain from Colorado Springs southward). Over the next two or three days a moderate plume of moisture (mainly middle and upper levels) should result in some afternoon and evening showers and thunderstorms. It’s not a highly anomalous amount of moisture, but it’s the best we have seen in a while. The best chance for rain is over the mountains of western Colorado, but I am holding out some hope for the Front Range too.

 

A little better chance for rain

3:35 PM, Monday, July 10, 2017

There hasn’t been much to write about lately, unless you want to worry about the increasing dryness of the local forests.

 

This week is bringing the best chance for afternoon/evening showers and thunderstorms. It’s not a guarantee, and some areas will get by with some clouds, maybe thunder, but little or no rain. But a bigger portion of the Front Range region may see rain  this evening or one of the next few days. A few local spots may even get a soaking downpour.

 

With the greater amount of afternoon clouds temperatures should be less hot, but still quite warm.

 

 

Brief cool-down Friday, then warm holiday weekend

12:40 PM, Thursday, June 29, 2017

A cool air mass will slide down the Front Range later today and tonight and bring a cooler-than-average day on Friday. The cooler weather won’t extend to the West Slope, so hot weather with high fire danger will continue there.

 

Very warm weather is likely to return for the holiday weekend. There is some indication that the mid to late part of next week can see extreme heat. There is uncertainty about exactly which part of the West will be affected, but the Front Range region might be in for a heat wave.

 

This evening and tonight will bring the best chance of rain for the Front Range, but that’s not saying much. Moisture is limited and heavy thunderstorm rain is likely to be isolated with the best chance on the eastern plains. Later tonight or early Friday we may see some areas of low clouds and possibly light rain as the cool air mass pushes in. But it’s possible that much of the region will get through the next 24 hours with little or no rain. The chance for rain over the weekend is looking very small.

 

Although a few local spots may have received a good downpour this month, the official recording stations in Colorado Springs, Denver, Boulder, and Cheyenne (and I think Fort Collins too) are much below average. Both Denver and Boulder could see one of the driest 5 Junes (but not the driest) if it doesn’t rain tonight.  Be careful with fire this weekend!

Cool spell coming

5:45 AM, Thursday, June 22, 2017

 

After a couple days of record or near-record heat, today will be a little less hot. Then it will be much cooler Friday-Sunday. In fact daytime highs in the urban corridor may only reach the 70s Friday and Saturday, and nighttimes could drop into the 40s in some areas. If you are traveling west of the continental divide this weekend  the cool air mass won’t make as much impact in western Colorado.

 

Rain? We could sure use some along the Front Range. The best chance for showers or thunderstorms in and along the Front Range is late this afternoon and tonight. In fact, there could be a few local areas that experience a strong thunderstorm with hail. Even late tonight or early Friday there could be some redevelopment of showers as the cold Front pushes through. For areas that don’t get much tonight, that chance for rain becomes quite small again after Friday morning.

Very warm, slightly cooler, then warmer again

5:40 AM, Friday, June 16, 2017

Expect a very warm summer day today with little or no chance for rain and temperatures  in the lower elevations reaching around 90. A cool front on Saturday may arrive by early afternoon, but it is more likely to hold off until evening, so Saturday  is likely to be another very warm day. There may be a few thunderstorms around Saturday afternoon and evening, but there will be areas that get by with little or no rain.

 

After a slightly cooler but still warm Sunday, hot and mainly dry weather is likely to be the rule next week. The summer solstice is on Wednesday at 10:24 PM MDT, and the weather will feel like summer.

Slight Cool-down and Windy Tue-Wed

5:55 AM, Monday, June 12, 2017

Hot weather will be in place today and again later in the week, with a milder period Tuesday and Wednesday when low-elevation temperatures may hold to the upper 70s and low 80s. Those milder temperatures may be accompanied by a period of gusty west-northwest winds late Tuesday into early Wednesday. The best chance of those gusty winds is up near the Colorado-Wyoming border and in the Cheyenne area, but a period of gusty winds is possible along the Front Range and northeastern plains of Colorado too.

 

It will be generally dry other than a chance for a few thunderstorms around today.

Holiday Weekend Weather

11:55 AM, Friday, May 26, 2017

 

In a nutshell, not bad. Saturday will be the coolest of the three days with temperatures running a little below average. Saturday will also bring a chance for some showers or a thundershower, especially after noon. Sunday and Monday should be sunnier with near average temperatures for this time of year and very little chance for rain. Have a nice weekend.