Lightning and Rainbows

Twilight lightning over Kendrick Park. The north flanks of Kendrick Peak are illuminated by the bolt.


We are in the midst of the “Transition Season” where the summer monsoon pattern fades away and the mid-latitude westerlies and low pressure systems move across the area. Another of these events is in progress as a weak closed-low moves across the southwest bringing showers and thunderstorms to the area.

Thunderstorms begin to develop over the San Francisco Peaks.
Thunderstorms begin to develop over the San Francisco Peaks.

Saturday afternoon we set out for the north side of the San Francisco Peaks hoping that thunderstorms would form over the higher terrain and then move northwestward across Kendrick Park. A few storms did form over the peaks and some of them were briefly photogenic but there was very little in the way of lightning. Eventually, approaching rain chased us from Kendrick Park to the northwest where we set up near Slate Mountain in a large meadow with good views of the peaks.

Distant lightning under the rainbow.
Distant lightning under the rainbow.
A multi-pronged lightning strike under the rainbow.
A multi-pronged lightning strike under the rainbow.
Twilight lightning over Kendrick Park.
Twilight lightning over Kendrick Park.
Twilight lightning over Kendrick Park. The north flanks of Kendrick Peak are illuminated by the bolt.
Twilight lightning over Kendrick Park. The north flanks of Kendrick Peak are illuminated by the bolt.
Twilight lightning over Kendrick Park. The north flanks of Kendrick Peak are illuminated by the bolt.
Twilight lightning over Kendrick Park. The north flanks of Kendrick Peak are illuminated by the bolt.

These slow-moving storms continued to move towards the northwest and this time we got lightning and rainbows—and rainbows with lightning. As the sun dropped lower in the west the rainbow quickly faded and rain was again approaching our location. We retreated back to Kendrick Park—this time with the thunderstorms located to our northwest with light from the setting sun still illuminating some clouds. Lightning stikes were frequent and close enough to fill the field of view of the 17-mm focal length lens. Several of these lightning bolts struck the northern flanks of Kendrick Peak. About a half-hour after sunset it was over and the storms quickly dissipated.

Another fun day of storms and lightning.

250-mb height/winds at 0000 UTC 26 September 2021.
250-mb height/winds at 0000 UTC 26 September 2021.
24-hour lightning plot with a lightning cluster near the San Francisco Peaks.
24-hour lightning plot with a lightning cluster near the San Francisco Peaks.

Is the Monsoon Over Already?

An early-season trough of low pressure moved across the west on Wednesday and Thursday disrupting the winds associated with the North American Monsoon. As the trough moved across the area, copious amounts of sub-tropical moisture surged northward across Arizona and surrounding areas. Widespread rain with embedded thunderstorms occurred across the area with areas of heavy rainfall and localized flash flooding.

Water vapor satellite imagery for 0210 UTC 20 August 2021.
Water vapor satellite imagery for 0210 UTC 20 August 2021.
500-mb analysis for 0000 UTC 20 August 2021 (image courtesty NCAR/RAL).
500-mb analysis for 0000 UTC 20 August 2021 (image courtesty NCAR/RAL).

But now the trough has moved northeastward across the Rocky Mountains and into the northern Plains states. The moisture across the southwest has been swept away. This can be seen in the water vapor satellite image. The warm colors are associated with a drier air mass and this has overspread the southwest.

Medium range models such as the GFS (Global Forecast System) suggest that moisture and showers will not return to the area before the end of the month leaving us with an extended break in rainfall.

Hurricane Grace at 1800 UTC 20 August 2021. (Image courtesy TropicalTidbits.com)
Hurricane Grace at 1800 UTC 20 August 2021.
72-h forecast for the remnants of tropical cyclone Grace.
72-h forecast for the remnants of tropical cyclone Grace. (Image courtesy TropicalTidbits.com)

But there are always some features that can result in different outcomes. For example, Hurricane Grace is moving westward across the Gulf of Mexico and is expected to make landfall in Mexico. The remnants of this tropical cyclone will continue to move to the west and may emerge in the Pacific south of the Gulf of California. If this happens, there might be a surge of moisture moving northward toward Arizona that could bring a return of showers and thunderstorms sooner than models currently suggest.

The 2020 nonsoon-Monsoon

A thin band of clouds partially blocks the sun and creates an array of crepuscular rays of light.

This is the second year in a row in which the North American Monsoon has failed to deliver its normal weather to Arizona. The monsoon had a late start in July with only a few isolated rain events early in the month and the main event starting around the third week of July. But even that faltered after a week and the final week of July was dry.

August was even worse with no measurable precipitation until after mid-month and even then the amounts were light. The National Weather Service in Flagstaff has posted some climate data for the area for August. It was the hottest August and the 2nd driest on record in Flagstaff and most of the west experienced similar conditions (Figure 1; Figure 2; Figure 3).

Photographing summer monsoon storms has been a challenge this year because there were so many dry periods. Even so, there are always interesting weather events and clouds that make it worthwhile. So here is a collection of the most interesting weather photographs from this summer.

Convection

Early stages of convection over the San Francisco Peaks as viewed from Marshall Lake.
Early stages of convection over the San Francisco Peaks as viewed from Marshall Lake.

A time-lapse movie shows that the ducks are more interesting than the convection.

Developing Cb's over the San Francisco Peaks.
Developing Cb’s over the San Francisco Peaks.
Small cumulus clouds over the Painted Desert.
Small cumulus clouds over the Painted Desert.
A weak thunderstorm near Two Guns, Arizona.
A weak thunderstorm near Two Guns, Arizona.
A well-developed thunderstorm over the Mogollon Rim viewed from Sedona.
A well-developed thunderstorm over the Mogollon Rim viewed from Sedona.

Rainbows

Full rainbows eluded me this year butI did manage to photograph a rainbow segment.

Rainbow segment over the North Rim of Grand Canyon.
Rainbow segment over the North Rim of Grand Canyon.

Lightning

As with rainbows, lightning was elusive this year. It was typically a case of being in the wrong place on the wrong day and at the wrong time. But I did get lucky with the following image.

Lightning illuminates the interior of Grand Canyon.
Lightning illuminates the interior of Grand Canyon.
In-cloud lightning illuminates a small Cb near the Grand Canyon. I was trying to photograph the comet so I got lucky with this storm.
In-cloud lightning illuminates a small Cb near the Grand Canyon. I was trying to photograph the comet so I got lucky with this storm.
Lightning at sunset over the Mogollon Rim viewed from Sedona.
Lightning at sunset over the Mogollon Rim viewed from Sedona.
Weak storms over the San Francisco Peaks produced these two bolts of lightning.
Weak storms over the San Francisco Peaks produced these two bolts of lightning.
In-cloud lightning partially illuminates Grand Canyon while the nearly-full Moon provides additional illumination.
In-cloud lightning partially illuminates Grand Canyon while the nearly-full Moon provides additional illumination.

Sunsets

And when there is no lightning and no rainbow, one can be content with the sunset.

A small rain shaft is illuminated by the setting sun.
A small rain shaft is illuminated by the setting sun.
Distant rain catches the last light of the sun and provides backlighting for the Cockscomb.
Distant rain catches the last light of the sun and provides backlighting for the Cockscomb.
A thin band of clouds partially blocks the sun and creates an array of crepuscular rays of light.
A thin band of clouds partially blocks the sun and creates an array of crepuscular rays of light.
The sun sets over ruins in Wupatki National Monument.
The sun sets over ruins in Wupatki National Monument.
The setting sun illuminates both Cathedral Rock and the clouds above.
The setting sun illuminates both Cathedral Rock and the clouds above.

Miscellaneous

Crepuscalar Rays—Wupatki National Monument.
Crepuscalar Rays—Wupatki National Monument.
Crepuscalar Rays—San Francisco Peaks.
Crepuscalar Rays—San Francisco Peaks.
Even thought it is supposed to be the wet and rainy season, we still managed to get cap clouds on the high peaks with stars above.
Even thought it is supposed to be the wet and rainy season, we still managed to get cap clouds on the high peaks with stars above.

Perhaps 2021 will be a normal monsoon year.

Lightning and the end of the Monsoon Season

The monsoon season officially ends in Arizona on September 30 but convective activity ended a week or two ago. But the monsoon provided a great “end-of-season” show.

Lightning near Mormon Mt. and reflected in Lake Mary.
Lightning near Mormon Mt. and reflected in Lake Mary.

Several clusters of thunderstorms were moving from the lower elevations up onto the Mogollon Rim on the evening of September 13. I haven’t been able to get any good shots of lighting reflected in water in recent years so I decided to try again—this time along the shores of upper Lake Mary.

I was not disappointed.

Lightning near Mormon Mt. and reflected in Lake Mary.
Lightning near Mormon Mt. and reflected in Lake Mary.

The early storms were distant to the west resulting in images with only small flashes. Another cluster of storms was to the southwest—moving to the northeast. Several flashes produced dramatic branches out the top of the storm and into the starry sky.

Lightning near Mormon Mt. and reflected in Lake Mary.
Lightning near Mormon Mt. and reflected in Lake Mary.

The storms were moving directly towards me and I had to quit when they got too close. My comfort zone on these storms was about 12 miles. Close enough.

Sunset and Lightning at Grand Canyon

The other day provided a good opportunity to photograph both lightning from thunderstorms and sunset at Grand Canyon. Satellite imagery from the new GOES-16 satellite indicated that skies remained clear across western Arizona as well as southern Nevada and California. This would allow the setting sun to appear below the cloud deck from the thunderstorms and—maybe—create a great sunset with the clouds glowing from below as the sun approached the horizon.

GOES-16 visible satellite imagery.
GOES-16 visible satellite imagery.

Close, but it didn’t quite happen that way. The clouds never took on that beautiful glow. On the other hand, an abundance of monsoon moisture in the lower atmosphere allowed the sun to create beams of light and shadow through the depths of the canyon. This was at its best when the sun was briefly obscured by some mid-level clouds creating some shadows at my location—but with sunlight streaming into the canyon below.

Beams of light and shadow play across Grand Canyon.
Beams of light and shadow play across Grand Canyon.

After the sun had dropped below the horizon the beams were gone, of course, but there was still color in the western sky.

Twilight colors at Grand Canyon.
Twilight colors at Grand Canyon.

The earlier thunderstorms over the area had dissipated but new storms developed about 50 km to my west. This distance meant the visible bolts were fairly small. I wanted big bolts dropping into the canyon near me. What we want and what we get…well, you know.

The radar image shows my location (circle) and the storms to the northwest.

Twilight thunderstorms and lightning over Grand Canyon.
Twilight thunderstorms and lightning over Grand Canyon.
Evening thunderstorms and lightning over Grand Canyon.
Evening thunderstorms and lightning over Grand Canyon.

The lightning images are composites of multiple photographs taken over a period of several minutes. The shutter was left open for 15s for each photograph. Some had multiple lightning bolts while others were dark. Even though it was almost 90 minutes after sunset the photographs were still able to pick up twilight colors on the western horizon.

All in all, an illuminating evening (bad pun intended).