Pine Gulch Fire, Western Colorado

What would have become the largest fire in Colorado history was only topped by the East Troublesome and Cameron Peak Fires which also occurred in 2020. The initial fire growth would be minimal, considering its location, but dry windy conditions would allow the fire to grow each day. A thunderstorm on August 18th would cause the fire to grow nearly 40,000 acres in 24 hours.

Let's look at the weather conditions that occurred from May 1st through July 31st in Grand Junction, CO.

• High Temperature Average - 89.0º ( + 3.3º )
• Low Temperature Average - 57.1º ( + 1.6º )
• Precipitation - 0.66" ( - 1.29" )

As you can see, temperatures were above normal along with much below normal precipitation. Since the fire started 18 miles north of Grand Junction, this is a good indication that the monsoon moisture that western Colorado can get was almost non existent. The forests would dry out from lack of precipitation. This would cause western Colorado into an Extreme Drought.

Conditions for western Colorado for the date of the fire did not warrant a Red Flag Warning but conditions would still be dry and breezy. Hunter Creek RAWS (Remote Automatic Weather Stations), which is near the start of the fire, reported gusts up to 25 mph and humidities as low as 10%. The fire would only grow to 280 acres within the first 24 hours.

On August 18th, a thunderstorm moved through the fire bringing gusty, erratic winds to 40 mph. Firefighters were forced to evacuate the area around the fire. Due to the lack of ability to fight the fire, it would grow 37,791 in the next 24 hours. Terrain played a role along with the dry conditions.

Another new fire was found at roughly 5:15 PM MDT on July 31st. The cause of the fire was lightning.

Let's look at pyrocumulus clouds for a minute. NASA wrote a blog going into depth explaining what they are and how they occur.

Pyrocumulus clouds—sometimes called “fire clouds”—are tall, cauliflower-shaped, and appear as opaque white patches hovering over darker smoke in satellite imagery. Pyrocumulus clouds are similar to cumulus clouds, but the heat that forces the air to rise (which leads to cooling and condensation of water vapor) comes from fire instead of sun-warmed ground. Under certain circumstances, pyrocumulus clouds can produce full-fledged thunderstorms, making them pyrocumulonimbus clouds." - NASA

For more information, you can view the rest of the blog  here .

The fire remained under control overnight with fire growing only growing to 280 acres by morning.

Winds would blow smoke directly into Grand Junction and the surrounding areas. But winds were set to change directions on August 3 from Grand Junctions to Aspen and Rifle.

Air quality continued to deteriorate in western Colorado on August 3rd, leaving a Air Quality Advisory for the next 24 hours.

As the fire changes directions from the wind, homes were threatened though no one was forced to evacuate yet.

On August 3rd, an IMET (Incident Meteorologist) from NWS Boulder was on his way to the Pine Gulch Fire to provide onsite support to the firefighters. This also helped relieve some of the duties that NWS Grand Junction was doing for the last several days.

Windy condition caused the fire to quickly expand to 3,600 acres.

After the growth on August 4th, the fire didn't grow much on the 5th. But windy, dry conditions returned causing the fire to grow to 12,000 acres, but still no evacuations had been made.

Weather patterns like this can make forecasters sound like a broken record. Dry, windy conditions returned on the 7th with the fire growing to 20,000 acres. Despite the growth, no evacuations had been issued at this time.

Hot, dry, windy conditions continued yet again with 3 straight days of Red Flag Warnings. Temperatures soared into the 90s to low 100s with winds gusting up to 30 mph.

As of Thursday morning, the fire lines along County Road 204 had held the blaze from moving forward, according to the incident management team. - thedenverchannel.com

A thunderstorm moved through the fire on August 8th, bringing gusty, erratic winds to 40 mph. Firefighters were forced to evacuate the area around the fire. Due to the lack of ability to fight the fire, it would grow 37,791 in the next 24 hours.

On September 1st, all evacuation orders were lifted and people were allowed back to their properties to see what damage may have occurred. With this fire only one building was destroyed with no fatalities.

On September 15th, the fire was 100% contained at 139,007 acres with the loss of only one building.