Subtropical moisture associated with the North American Monsoon is impacting the Rockies on Monday with heavy rain producing thunderstorms developing from Montana to Colorado as of early afternoon. Storm development is also being aided by a disturbance in the upper atmosphere moving across Idaho and Wyoming.

As of early afternoon Monday, numerous thunderstorms were developing near Jackson Hole and across Eastern Idaho and Western Wyoming, producing locally heavy rains.

Farther north, a more organized wave of widespread rain showers has impacted the Gallatin, Beartooth, and Bighorn Ranges in Southern Montana and Northern Wyoming during the morning and early afternoon hours. This region will likely see additional rounds of thunderstorms later in the afternoon.

Farther south, thunderstorms were developing throughout the mountain ranges of Colorado as of early Monday afternoon from the Northern Front Range to the San Juans. 

Current Radar 

Forecast Radar

Due to the abundance of moisture and slow storm motions, heavy rain and flash flooding is a concern across Colorado. In fact, a Flash Flood Watch is in effect for portions of the Front Range, Sawatch Range, and Sangre de Christos and a few Flash Flood Warnings have already been issued as well.

Also, be sure to check out our Lightning Density Map to get an idea of the location and relative abundance of lightning strikes associated with thunderstorms.

Areas farther west are experiencing a drier weather pattern along with continued hot temperatures. Not surprisingly, the western-most states are where the majority of the current wildfires are located.

Large fires continue to burn in Northern California and British Columbia. Since our last post, new fires have also started in Southern California and along the eastern slopes of the Cascades in Washington.

Forecast Smoke (surface)

Forecast Smoke (sky)

Forecast for Monday, July 5th

Above-average warmth can be expected across the Pacific Northwest on Monday afternoon, while the Rockies and Southwest will see temperatures closer to average.

Widespread thunderstorms and locally heavy rains can be expected across the mountainous regions from Montana to New Mexico and Southeast Arizona, with more isolated coverage farther west in Utah and Central Idaho.

Forecast for Tuesday, July 6th

Generally speaking, warmer temperatures are expected west of the Continental Divide with cooler temperatures east of the Continental Divide. The Pacific Northwest along/east of the Cascades, in particular, will see well above average temperatures. 

The bulk of Tuesday's thunderstorms will shift to areas near and east of the Divide in Colorado and New Mexico, with more isolated activity along the eastern slopes of the Divide in Wyoming and Montana.

The greatest risk for flash flooding can be expected in New Mexico and Southern Colorado.

Forecast for Wednesday, July 7th

The core of the above-average warmth will shift into the Northern Rockies on Wednesday with a slight cooling trend across the Northwest and West Coast as a cold front arrives. New Mexico and Southeast Colorado will remain cooler than average as well.

Thunderstorm coverage will become more isolated across Colorado, with the most widespread activity expected in New Mexico and Southeast Arizona as monsoonal moisture becomes shunted farther south. 

The Northern Rockies could see some isolated dry thunderstorms ahead of an approaching disturbance, but any wetting rains are likely to remain north of the Canadian border.

Forecast for Thursday, July 8th

The Northern Rockies will see a slight cooling trend as a cold front arrives, but temperatures still be warmer than average and strong winds associated with the front will lead to elevated fire danger. Most other areas in the West will see warmer than average temperatures.

Thunderstorm coverage will be relatively isolated on Thursday, but there will still be at least a chance of storms throughout the Rockies from Montana to New Mexico with lesser chances the farther west you go from the Continental Divide.

Forecast for Friday, July 9th

The Far West will begin to heat back up again on Friday with well-above-average temperatures from Washington to California. The interior of the West will remain hot as well, with somewhat cooler temperatures in Montana and Wyoming behind Thursday's cold front.

Post-frontal upslope flow will lead to isolated thunderstorms east of the Divide in Montana and Wyoming. Farther south, a subtle uptick in moisture will result in better thunderstorm chances across Arizona, New Mexico, and Southern/Central Colorado.

Outlook for Sat, July 10 - Wed, July 14

A ridge of high pressure will shift west into California and Nevada this weekend and into early next week, resulting in hot temperatures across this region. Most of the West will continue to run warmer than average during this time, with near-average temperatures for Eastern Colorado and New Mexico.

Monsoonal moisture will continue to stay suppressed to the south during this time with the best chances of thunderstorms existing across Arizona, New Mexico, and perhaps Southern Utah and Southern Colorado.

Areas farther north including Northern Utah and Northern Colorado will see more isolated thunderstorm coverage and less rain potential, and the Northern Rockies may not see any rain.

Looking farther out, there are some signs that the monsoonal flow could shift northward again during the second half of July, which would eventually lead to better chances of thunderstorms and rain for the Central (and to some extent Northern) Rockies.

NEW: Proprietary Weather Forecast Data

Our goal is to create the most accurate weather forecast, period. 

On July 1, 2021, we began updating the forecasts on OpenSummit with a proprietary blend of global data from the GFS (American), GDPS (Canadian), and ICON (German) weather models, along with high-resolution data from the HRRR (American) and HRDPS (Canadian) weather models.

Previously, we used data from the National Weather Service (NOAA). While the NOAA data is great for cities and lowland environments, it limited our ability to adjust the data to create the best possible forecast for complex mountain environments with large changes in elevation.

Why is this new forecast data better than the old forecast data? The benefits include:

• Proprietary algorithm to improve the precipitation, lightning, temperature, and wind speed calculations for mountain environments.
• Provides the ability to create a forecast for any location (and elevation) to ensure that we are forecasting conditions on the mountain and not for a nearby town.
• Blending multiple global and high-resolution models increases accuracy and confidence in the forecast.

The data can be viewed as hourly forecasts for the next 5 days and includes:

• Daily High & Low Temperature
• Hourly Chance of Precipitation
• Hourly Lightning Potential
• Hourly Temperature
• Hourly Wind Speed, Gust, & Direction
• Hourly Cloud Cover %

This new blend of proprietary forecast data is updated every hour on OpenSummit for thousands of locations across the United States and we are adding new locations every day.

Here is an example of the OpenSummit 5-day hourly lightning potential forecast for Longs Peak, Colorado in Rocky Mountain National Park:

Use the links below to view the 5-day hourly weather forecast for popular locations across the United States:

Denali, Alaska

Grand Canyon, Arizona

Half Dome, California

Mt. Rose, Nevada

Mt. Rainer, Washington

Pikes Peak, Colorado

Fruita, Colorado

Grand Teton, Wyoming

Mt. Superior, Utah

Moab, Utah

Lone Mountain, Montana

McGown Peak, Idaho

Mt. Hood, Oregon

Mt. Washington, New Hampshire

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Explore Locations → OpenSummit.com

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