A previous post displayed photographs of storms and weather that occurred during July of this year’s North American Monsoon. Here are photographs from August (plus the first day of September).
Cumulus and Cumulonimbus
A search for wildflowers and thunderstorms brought me to Rogers Lake west of Flagstaff. It’s a lake only ephemerally during springs with heavy snow runoff. But it makes a grand place for photographs when a wide-open vista is desired. Earlier convective storms were pushing an outflow boundary southward with new convection developing on the boundary.
Outflow boundary and convection over Rogers Lake with the San Francisco Peaks in the distance.A distant cumulonimbus can be seen from the Doney Mountain Picnic Area near Wupatki National Monument.Thunderstorms move across Grand Canyon with low clouds clinging to the higher points and buttes.
There was just enough vertical wind shear on this day to allow some storms to briefly exhibit supercell characteristics and deviate to the right —which brought this thunderstorm near the edge of the North Rim of Grand Canyon.
A strong thunderstorm over the North Rim of Grand Canyon is reflected in a small pool of water.A weak, late afternoon thunderstorm is backlit by the setting sun.
Fog and Smoke
Sometimes the unexpected can be magical. When fog forms in Grand Canyon the visitors may be disappointed but there is the potential for amazing photographs.
A long-lived cluster of thunderstorms east of Grand Canyon pushed a cool, moist outflow into the canyon producing areas of fog near the South Rim.More fog in Grand Canyon.
Smoke from the Obi Fire on the North Rim creates a colorful sunset.Smoke from the Obi Fire fills Grand Canyon and reduces visibility.
Sunset and Full Moon
Sunset after the storms can be amazing. And if there is a nearly full moon, things can get very interersting.
A backlit thunderstorm at sunset over Grand Canyon.Post-sunset colors illuminate the underside of a dissipating shower.Dissipating cumulus clouds at sunset with O’Leary Peak in the distance.Dissipating showers are backlit by the setting sun.The nearly full moon illuminates the inner canyon as twilight fades behind a distant thunderstorm.A dissipating thunderstorm anvil cloud is seen above pueblo ruins in Wupatki National Monument at sunset.
Rainbows
A double rainbow above Cathedral Rock in Sedona.A rainbow, dissipating anvil, thunderstorm, and towering cumulus.
Lightning
And lightning…
An amazing anvil bolt…and too close!Lightning west of Sedona, Arizona.Anvil bolt over Cathedral Rock. (It’s out of focus—you try focusing in the dark!)Lightning illuminates Grand Canyon at night.Lightning strikes the Moenkopi Plateau (composite image).Several bolts strike behind Wukoki Pueblo in Wupatki National Monument.The setting sun lights up rain curtains as a brilliant lightning bolt strikes behind Wukoki Pueblo in Wupatki National Monument.
It’s early September and the summer monsoon pattern is beginning to fade away. Soon it will be time to start thinking about autumn colors on the peaks.
September 1 marks the first day of “meteorological autumn” and it started out with a severe weather event across portions of northern Arizona. Severe storms are more likely during what is often called the “transition season” as we make the switch from the North American Monsoon weather pattern into a fall pattern.
In the transition season the westerlies begin to push southward again as the large area of high pressure over the southwest weakens. Disturbances in the westerlies along with stronger jet-level winds can combine with copious amounts of residual tropical moisture to bring severe thunderstorms to the area.
250 mb pattern for 1200 UTC 01 September 2018. (Image from NOAA/Storm Prediction Center.)Upper air sounding for KFGZ at 1200 UTC 01 September 2018.
A short-wave trough and moderate jet stream were present across Arizona at 1200 UTC 01 September. Monsoon moisture was also present. The first hint that something was up was the development of thunderstorms—some severe—before sunrise. This patch of storms moved to the east and northeast and, in its wake, left a pool of cooler air across northeastern Arizona along with an outflow boundary. Outflow boundaries can often play an important role in subsequent convection with increased severity and rotation as the storm moves across the boundary. (Maddox et al. 1980; Rasmussen et al. 1998)
Afternoon runs of the HRRR model showed storms developing along an east-west line across northern Arizona and that some of these would interact with that boundary, become severe and turn to the right moving southeast. And that’s pretty much what happened. Score one for the HRRR model.
HRRR simulated radar forecast for the afternoon of 01 September. (Animated GIF courtesy of College of DuPage.)Reflectivity from KFSX radar at 1607 MST.
Other storms produced very large hail with a report of 2.75″ hail in Holbrook and another of 2.00″ near Tolani Lake.
View of rapidly developing convection east of Wupatki National Monument (Panorama from northeast through south).
I was watching and photographing these storms from the southern portions of Wupatki National Monument. There was explosive vertical growth in these storms along with some generally unorganized rotation. The storm also developed a rear-flank downdraft. And I was able to hear the “hail roar” (i.e., a roaring sound that originates in the storm cloud caused by large hailstones hitting the ground or colliding in mid-air). I’ve occasionally heard hail roar in High Plains storms but never in Arizona.
Low clouds, fog, and a K-H wave in the cold pool behind the storm.Cumulonimbus mammatus behind the storm.
Behind the storm, cold outflow dominated and low clouds and fog quickly developed across the low hills of Wupatki National Monument. A broad area of mammatus clouds was also present.
Lightning behind Wukoki Pueblo in Wupatki National Monument.( Single exposure of 1/4 second.)
And the lightning was impressive.
Lightning map for 01 September 2018. (Courtesy of WeatherBell.)
The North American Monsoon arrived in northern Arizona during the first week of July—which is an average start date. Within just a few days, we quickly transitioned from Extreme Fire Danger to High—and within a week or two—to Moderate.
Summer monsoon season is my second storm chase season—the first is in late spring across the High Plains. Second season is more about lightning, clouds with dramatic scenery, and colors at sunset. This July has been a bit more challenging than other seasons but still successful.
Here are some photographs of storms and storm-related activity during July 2018.
Early stage Cumulonimbus
A pair of developing cumulonimbus as seen from Kachina Wetlands.
Cumulonimbus over Hart Prairie.
Outflow boundaries and arcus clouds
Gust front and arcus clouds advance across Wupatki National Monument.Gust front and arcus clouds continue to advance across Wupatki National Monument.
This complex of storms was moving westward across Wupatki National Monument. I had originally planned to photograph the system from the Doney Mtn. Picnic Area but the system arrived at that location before I did. So I retreated back to US-89 and the entrance to the Monument. Both of these images are panoramas that span the northeast through south. The San Francisco Peaks can be seen at the far right of both images.
Rainbows (and maybe a tornado?)
A rainbow (and possible vortex).
As convection approached a rainbow developed and I was busy trying to reset the camera to capture the full bow. Only later, when examing the images, did I notice what might be a vortex bisecting the rainbow. Because I did not see it in real time I cannot say whether there was any rotation. It may just be a random bit of cloud debris.
Lightning
The best part of the thunderstorm season is trying to capture lightning. It’s more than just getting a photograph of lightning—it’s important to get lightning in an interesting location.
Lightning visibile from South Rim of Grand Canyon with Desert Tower in the distance.Lightning over the Painted Desert as seen from South Rim of Grand Canyon.Lightning over the Painted Desert.A composite of four images showing multiple lightning strikes on the San Francisco Peaks. These storms dropped almost 6 inches of rain in under 3 hours.
Menacing thunderstorms
Sometimes I chase storms—other times they chase me. We were mountain biking on Observatory Mesa when this thunderstorm developed and enveloped the San Francisco Peaks. It was definitely time to turn around.
A thunderstorms envelopes the San Francisco Peaks.
Sunset after the storm
And, of course, sunset after the storms can be pretty amazing,
Sunset over Grand Canyon as seen from Lipan Point.A distant thunderstorm is backlit by the setting sun at Grand Canyon.Late afternoon sun briefly lights up Cathedral Rock in Sedona.Dark skies behind Cathedral Rock.The setting sun lights up the clouds as shadows race up the face of Cathedral Rock.
Reflections
Reflections in pools of water can produce interesting images. Several days of heavy rain resulted in ponds of water at Crescent Moon Picnic Area.
The setting sun illuminates Cathedral Rock which is reflected in a small pond.
Rainfall amounts
As is typical, rainfall amounts can vary widely over even just a few miles. Here is a map showing the rain gauge amounts for July on the east side of the San Francisco Peaks southward through Flagstaff and beyond. Amounts range from 2.5 to 14.5 inches.
Rain gauge totals for July 2018.
August continues to bring thunderstorms, lightning, and flooding to northern Arizona.
We left Flagstaff yesterday and spent the night in Albuquerque and today we will drive the rest of the way to Denver. We will be spending two weeks in Denver visiting family and friends—and will do a bit of storm chasing if the right conditions present themselves.
We had dinner last night at the Owl Cafe—a Route 66-style diner. We’ve been here before and like the decor. The food isn’t too bad, either.
The drive from Albuquerque to Denver was interesting as we were in a post-frontal airmass and the clouds had these abstract undulations. We stopped a few times for photos along US 84 in eastern New Mexico.
Owl Cafe interior.Owl Cafe interior.Windmill and clouds in eastern New Mexico.Gate and clouds in eastern New Mexico.
And so it begins. The North American Monsoon has begun with many thunderstorms but not much rain. As a result, lightning-sparked wildfires are a possibility.
Just by chance, I was heading out towards Mormon Lake this morning to capture images of the building thunderstorms over the San Francisco Peaks. I had noticed that the early buildups had some interesting structure—a combination of convective vertical growth as well as some laminar wave clouds.
As I drove towards Upper Lake Mary I saw a small plume of smoke from a wildfire. Moments later, I spotted a helicopter dropping water on the fire.
Fortunately, the fire was a very short distance from the lake allowing multiple passes in quick succession.
Helicopter lifting water bucket from Lake Mary.Helicopter approaching Lake Mary to refill bucket.
The recent increase in moisture and a slight cooling of temperatures that we’ve experienced over the past few days will result in good chances of quickly containing this wildfire.
Ligntning map for 07 July 2018.
The lightning map for 07 July 2018 shows plenty of lightning across the higher terrain—so it’s likely this fire was caused by lightning.
