Arizona Braces for Thanksgiving After Unseasonal Hailstorm Disrupts Desert Landscape
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A rare November hailstorm transformed parts of Arizona into a winter wonderland, wiht scenes in Phoenix and Tucson resembling Flagstaff as a sheet of white covered roads and yards on Wednesday, November 19th. The unexpected weather event, fueled by a lingering cold-core low-pressure system, brought damaging winds, icy accumulations, and even a partial roof collapse at the Desert Sky mall in west Phoenix.
The unusual precipitation began as a burst of hail, with social media flooded with images and videos of the icy deluge. This fall has been remarkably wet across much of Arizona. The weather station at Sky Harbor International Airport recorded 0.29 inches of precipitation this month,following 2.26 inches in september and 3.26 inches in October – significantly above average. While the hail has since melted, meteorologists warn that more stormy weather is possible before conditions dry out in time for Thanksgiving.
Understanding the Hailstorm’s origins
The intense hail core developed rapidly over the West Valley as a low-pressure system originating off the California coast moved eastward. Initial storms formed around Avondale and Buckeye before strengthening over Glendale, where hail briefly accumulated on surfaces. “We had a bit more instability in the atmosphere yesterday that allowed for some more intense storms to develop,” explained a meteorologist with the National Weather Service in Phoenix.
Precipitation totals ranged from half to three-quarters of an inch across the Valley, with localized areas in Glendale and west Phoenix receiving between 1 and 1.25 inches of rain.The system’s cold-core low and cool surface temperatures prevented the hailstones from melting before reaching the ground. The slow movement of the storm, coupled with moisture levels running at nearly 200% of normal, allowed it to intensify and produce concentrated pockets of precipitation.
The Science Behind Hail Formation
Hail forms within thunderstorms when strong updrafts carry raindrops into freezing layers of the atmosphere. These droplets collide with supercooled water, growing in size with each interaction. Some freeze instantly, creating cloudy ice pellets, while others freeze slowly, forming clearer layers.Eventually, the hailstones become too heavy for the updraft to support, and they fall to earth.Their size is resolute by the strength of the updraft, the duration spent aloft, and the amount of melting that occurs during descent.
While not a frequent occurrence, arizona does experience hail annually, particularly during fall low-pressure systems characterized by cooler temperatures and increased wind shear. “Hail is not super common in Arizona because we see most of our storm activity in the monsoon,which isn’t often favorable for hail,” noted a climatologist at the University of Arizona. The monsoon season typically features hot, moisture-rich environments with weaker wind shear, leading to quick-collapsing storms and more frequent microbursts and dust storms.
Compared to the central Plains – where states like Colorado, Wyoming, and Nebraska see the most hail annually – Arizona experiences fewer hailstorms. However, recent conditions have created a more conducive environment for their formation. Flagstaff, already experiencing its first snowfall of the season, has recorded 3.65 inches of November precipitation, demonstrating the widespread increase in moisture across the state.
Looking Ahead: forecast for the Week
The low-pressure system responsible for this week’s hail is currently moving east, promising a period of clearer skies for the Valley on Thursday, November 20th. “This afternoon going into tonight, we are expecting a period of clearer skies,” said a national Weather Service meteorologist. “We’re not really expecting any activity to develop today.”
Though, another low-pressure system is already developing off the West Coast and is expected to move inland into Arizona on Friday, November 21st, bringing a 20 to 30% chance of rain to Phoenix by the afternoon. Higher elevation areas north and east of the Valley could see rain chances increase to 60 to 70% on Saturday evening. Temperatures will remain below normal through the week, with highs in the low to mid-60s. A warming trend is anticipated early next week as these systems move out of the region, with temperatures expected to return to the low 70s in time for the holiday.
