International Space Station transits

A few weeks ago we had a couple of nights in which the International Space Station (ISS) made some evening twilight transits that were visible across northern Arizona. The first night the ISS transited from the northwest across the sky to the east. As it swung across the evening sky it passed near Mizar in Ursa Major then near Polaris in Ursa Minor. The following night it traveled from west to southeast and passed near the Moon and Jupiter before it entered into the Earth’s shadow.

International Space Station transiting the skies across northern Arizona.
International Space Station transiting the skies across northern Arizona.

Both of these final images are composites. Each was shot with a 16mm ultra-wide angle lens at f/4.0, ISO 800, and 10s exposure. For the photograph above, 16 images were composited. For the photograph below, seven images were used. In Photoshop, images are assembled as layers then blended using Lighten mode. This allows the streak of light from the ISS to show through all layers. The advantage to this method — compared to a single image of longer duration — is that the sky does not become overexposed. Instead the result is a dark background upon which the ISS flies.

International Space Station transiting the skies across northern Arizona.
International Space Station transiting the skies across northern Arizona.

Both images were taken at the Kachina Wetlands located a few miles to the south of Flagstaff, Arizona. This location provides wide open skies for viewing objects low on the horizon and offers ponds of water that produce wonderful reflections of the stars.

To find out when the ISS will fly across your area, visit either of these sites:

SpaceWeather.com

Heavens-Above

White Sands Reflected in Pools of Water

We recently took a trip to White Sands National Monument in New Mexico. The weather forecast that day called for increasing clouds and a chance of thunderstorms — some possibly severe — by late afternoon. Normally, this would be a deterrent to those wishing to visit this wonderful place but since I enjoy photographing thunderstorms and severe weather this was an opportunity not to be missed.

Rainbow over White Sands National Monument.
Rainbow over White Sands National Monument.

We arrived at WSNM in mid-afternoon and the clouds were beginning to fill the sky. We were soon rewarded with a rainbow stretching across the parabolic dunes on the edge of the dune fields. As that first storm moved away, other storms began to develop back to the west. I set up the camera to take lightning photographs and was rewarded with a couple of pretty good shots.

Late afternoon cloud-to-ground lightning over White Sands National Monument.
Late afternoon cloud-to-ground lightning over White Sands National Monument.

But the really wonderful part came the next morning. Those afternoon thunderstorms continued through the evening and into the night and produced about one and a half inches of rain across the sands. And in the bright blue sky of the following morning we found shallow lakes of up to a few inches deep scattered across the sands as a result of the heavy rainfall. The reflections of the sand dunes and other vegetation in these ephemeral lakes was simply delightful.

Reflections in the shallow lakes produced by heavy rainfall across White Sands National Monument.
Reflections in the shallow lakes produced by heavy rainfall across White Sands National Monument.

Autumn colors in West Fork Oak Creek Canyon

Autumn has brought wonderful colors to the flora in West Fork Oak Creek Canyon this year. The mouth of this canyon, located between Flagstaff and Sedona, lies at an elevation of about 5400 feet. With its narrow width and high walls, sunlight is strongly filtered before reaching the canyon floor. This produces a micro climate that is much cooler than would otherwise be expected for a location at this elevation.

Autumn colors found in West Fork Oak Creek Canyon in northern Arizona.
Autumn colors found in West Fork Oak Creek Canyon in northern Arizona.
Autumn colors reflected in the waters of West Fork Oak Creek in northern Arizona.
Autumn colors reflected in the waters of West Fork Oak Creek in northern Arizona.
Fallen leaves lie beside rushing waters in West Fork Oak Creek in northern Arizona.
Fallen leaves lie beside rushing waters in West Fork Oak Creek in northern Arizona.

The result is that there is large variety of flora in this canyon dominated by pine, maple, oak, and sycamore. And when the shorter and cooler days of autumn arrive the colors on these trees can be magnificent.

Mountain biking at 38 degrees

Thirty-eight degrees. Temperature — not latitude.

Fall has arrived in northern Arizona and the leave are turning colors and, in some cases, have already fallen. We went on a mountain bike ride on one of our favorite section of the Arizona Trail the other day so that we could view the aspen trees in their autumn glory. A cold front had passed through a day earlier and it was quite cold that morning with temperatures only in the upper 30s. So we bundled up with a few extra layers, caps and gloves, and off we went.

Riding the Arizona Trail at 8000 feet elevation and 38 degrees Fahrenheit. All you have to do is bundle up!
Riding the Arizona Trail at 8000 feet elevation and 38 degrees Fahrenheit. All you have to do is bundle up!
Riding an easy stretch of the Arizona Trail. The aspen leaves have fallen and left a carpet of color on the trail.
Riding an easy stretch of the Arizona Trail. The aspen leaves have fallen and left a carpet of color on the trail.

The only problem was that the rain from a few days earlier had left the trails pretty muddy and with the cool weather they had not dried yet. Suddenly we found our tires and bikes caked with mud. Eventually it became too difficult to ride as the mud accumulated on the tires, in the brakes, derailleurs, and anywhere else mud can collect. And that’s a lot of places!

A grove of aspen trees in full autumn color on the San Francisco Peaks.
A grove of aspen trees in full autumn color on the San Francisco Peaks.

New snow on the higher elevations of the San Francisco Peaks stands in contrast to a grove of aspen in full autumn color.
New snow on the higher elevations of the San Francisco Peaks stands in contrast to a grove of aspen in full autumn color.

So we abandoned the ride to return another day. Still, it was a pleasant enough day with plenty of color to view in the aspen trees in Flagstaff at 8000 feet and 38 degrees — especially with the new snow on the San Francisco Peaks.

Tornado outbreak in northern Arizona

While tornadoes are not as common in Arizona as in, say, the mid-western United States, neither are they rare. In an average year, about six tornadoes are reported in Arizona. It’s a near certainty that this number is an undercount of the actual number of tornadoes that occur. Because much of Arizona is sparsely populated, it’s possible — likely, even — that many tornadoes are not seen and thus, not reported.

So, while it may seem like the tornado outbreak in northern Arizona that occurred on October 6, 2010, was an extreme event, we can not be certain that it was. We can only be certain that it was one of the most extreme “reported” events.

At least eight tornadoes have been confirmed. Based on a review of the Doppler weather radar data there is a reasonable probability that additional tornadoes occurred in the vast Ponderosa forests of northern Arizona and the damage paths have not yet been noted and surveyed. While conducting a formal damage survey on October 7 and 8 for two of the already confirmed tornadoes, we found additional tornado damage paths that had not yet been previously identified.

Recent research has identified a repeatable weather pattern that is responsible for a significant fraction of tornadoes in northern Arizona. As that weather pattern began to develop, warning forecasters began to carefully monitor Doppler radar looking for signatures of severe thunderstorms. And when these signatures appeared, they quickly issued Tornado Warnings. It is almost certain that these warnings minimized injuries in the paths of these tornadoes.

Damages homes from the Bellemont, Arizona, tornadoes on October 6, 2010.
Damaged homes from the Bellemont, Arizona, tornadoes on October 6, 2010.

Flattened forest of Ponderosa Pine in northern Arizona from the tornadoes on October 6, 2010.
Flattened forest of Ponderosa Pine in northern Arizona from the tornadoes on October 6, 2010.
Forest Service crews quickly cleared treefall from Forest roads.
Forest Service crews quickly cleared treefall from Forest roads.

Some of the research on tornadoes in northern Arizona can be found at these links sponsored by the American Meteorological Society:

Blanchard, D.O., 2006: A cool season severe weather episode in northern Arizona. Preprints 23nd Conference on Severe Local Storms, St. Louis, MO., Amer. Meteor. Soc.

Blanchard, D.O., 2008: Synoptic environments associated with tornadoes in northern Arizona. Preprints 24th Conference on Severe Local Storms, Savannah, GA., Amer. Meteor. Soc.

Blanchard, D.O, 2010: Forest damage associated with tornadoes in northern Arizona. Preprint 25th Conference on Severe Local Storms, Denver, CO, Amer. Meteor. Soc.