Inter-mountain West is wetter for some and warmer
For the Inter-mountain West’s five states of Arizona, Colorado, New Mexico, Utah and Wyoming, it’s the south versus the north regarding climatic conditions during the first half of 2024. Much of the southern states in the Inter-mountain West region have had a wetter and warmer-than-normal first half of 2024, while northern states in the region didn’t reap the benefits of much moisture climatologists said during the latest Inter-mountain West Climate Outlook webinar on Tuesday, July 23. In the webinar hosted by the National Oceanic and Atmospheric Administration, the National Integrated Drought Information System, the U.S. Department of Agriculture and other partners, regional climate and drought conditions were highlighted.
Colorado had its 11th warmest and 40th wettest January to June period. Colorado has had 9.77 inches of precipitation which is 0.71 inches above normal. For Colorado, the moisture really cranked up in February, which was its 15th wettest February, calculated from 130 years of records.
March was Colorado’s 29th wettest March. February and March were wet with snowfall. In June, rain and thunderstorm activity added to its wetness.
Arizona had its 23rd warmest January to June, and its 26th wettest six-month period.
“So, that’s all really good. When we look at managing the water supply, it starts in October, and it was hot in October. But, January — our El Nino winter came back, which is statistically wetter,” said Erinanne Saffell, Ph.D., Arizona State Climatologist and a key speaker on the webinar. Arizona’s monsoon season came in June and the resulting thunderstorm activity helped out, Saffell said. The monsoon weather pattern is caused by a seasonal wind shift or reversal, occurring from June 15 to Sept. 30.
In addition to Colorado and Arizona faring well with moisture the past six months, New Mexico had its 46th wettest first half of the year, Utah had its 49th wettest, but, conversely Wyoming had its 43rd driest January to June with 8.33 inches (which is -0.77 inches below normal).
“Some locations have received above average precipitation so far this water year, like southern Arizona, central New Mexico, northern Utah, central Colorado, and small areas in northern and southern Wyoming,” Saffell noted.
WARM TEMPERATURES
Overall, the water year has been warmer than normal for Arizona, Colorado, New Mexico, Utah and Wyoming. So far it’s been the fifth warmest October to June in the Rockies and westward region. Colorado’s average temperature of 43 degrees ranked it their 11th warmest, the temperature averaged over all those months was 2.9 degrees above normal. Wyoming has had its 12th warmest six month period, with an average temperature of 38.8 degrees, which was 3 degrees above normal. Arizona had its 23rd warmest January to June, New Mexico had their eighth warmest, Utah had its 10th warmest, and Wyoming had its 12th warmest January to June.
Some areas in Colorado, New Mexico and Wyoming recently had below-normal July temperatures, which was attributed to thunderstorm activity, with locations in central Arizona, central New Mexico, eastern Navajo Nation, eastern Colorado, and northern Wyoming getting above average amounts of precipitation so far this July, Saffell said.
The Pacific Ocean is still in El Nino neutral conditions, but La Nina has a 70% chance of developing from August-October, and persisting through January 2025. Therefore, a dry winter in the southern tier of the U.S. is expected as La Nina develops, with possibly a wetter winter in the northern tier of the U.S.
Seventy-five percent of the West has been without drought, with some abnormally dry areas from January to June, however, by the end of July, a few areas of drought moved into the region; including north central Colorado. Wyoming has seen drought areas in the eastern and western third of the state as of July 27.
Seasonal outlooks expect warmer and drier conditions August to October.
FORESTS AND WILDFIRES
Another topic on the webinar was “Understanding Forest Health and Wildfire Risk in a Changing Climate” and the impacts of the weather conditions on wildfires, floods, disruption to water supply and ecosystems, as well as impacts to affected industries like agriculture, tourism and public health.
Although the practice of helping naturally restore forests by planting tree seedlings helps trees re-grow and forests flourish again following wildfires, however, the current status of restoring forests is experiencing a few snags.
“Post-fire reforestation seedling survival rates are low because of increased heat and drought stress. We can increase survival by identifying landscape positions that buffer the seedling from extreme heat or drought,” said Matthew Hurteau, a professor in the Biology Department at the University of New Mexico, speaking on the webinar.
Landscape positions that increase survival are any place that decreases the amount of sunlight that the seedling experiences and any place that tends to “collect” water. For example, a slight depression on a north-facing slope increases the chance of survival, Hurteau said. Tree seedlings are typically planted following stand-replacing wildfire to help with reforestation.
Scientists can predict the probability of planted seedling survival with 63% accuracy, using high resolution topographic data.
Hurteau co-authored a report with colleagues about how wildfires in the southwestern U.S. have continued causing large areas of tree mortality, while removing the seed sources needed to naturally regenerate these forest landscapes. Planting tree seedlings helps increase reforestation, although survival of these seedlings has been a challenge in the semi-arid climate in the southwest U.S.
For more information, go to droughtmonitor.unl.edu/.
