A few days of tropical moisture—remnants of Tropical Depression Nora—brought widespread rainfall to much of northern Arizona. As the moisture was replaced by drier air in the middle- and upper-levels but was unchanged in the near-surface layer, we were left with a situation in which fog might form in the early morning hours.
So, up before dawn to drive out to Mormon Lake and the surrounding basin. And there was fog—at least in one corner of the basin. Here is a 30-minute time lapse compressed down to 17 seconds showing the movement of the fog as it sloshes back and forth.
Sunrise through morning fog.
As this was taking place, the sun rose through a shallow layer of fog.
Sunset at Grand Canyon.
Bonus: on the previous evening the sun was setting through layers of smoke from the western wildfires.
We have been in a “monsoon break” in northern Arizona for a week or so, but there can still be some convection during these periods. A few days ago, some isolated showers and thunderstorms developed to the north of the San Francisco Peak in the late afternoon and early evening.
Lightning reflected in the ponds of the Kachina Wetlands.Lightning reflected in the ponds of the Kachina Wetlands.
This was a good opportunity to capture images of thunderstorms and lightning with reflections in the ponds of the Kachina Wetlands.
Radar image of storms north of the San Francisco Peaks.
Above is an image showing the thunderstorms and lightning north of the peaks.
One more thing: the mosquitos were pretty intense—but it was worth it.
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 2021.500-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 2021.72-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.
It was a pleasant evening in Sedona watching thunderstorms as the sun sank lower in the western sky. It was mostly clear in that direction allowing sunlight to illuminate storms in the east. This is one of my favorite setups: clear in the west and stormy in the east.
Early evening sunlight illuminates thunderstorms and Cathedral Rock in Sedona.Early evening sunlight illuminates thunderstorms.Lightning from a distant storm after sunset.Lightning from a distant storm after sunset.
The setting sun produced wonderful pastel colors on the clouds and occasionally illuminated the rock spires and buttresses in the middle distance. And after sunset, distant storms showed large anvils along with occasional bolts of lightning.
