Thunderstorms to spread northward in the West this week

Yahoo

2 days ago

The Southwest is typically dry this time of year. The monsoon, or the shift in winds that brings moisture into the area, does not usually begin until July. However, AccuWeather meteorologists say a former tropical storm along with a separate feature in the atmosphere will conspire to bring early-season rainfall.
"A low pressure area tapping into moisture from the Gulf of California and, additionally, moisture from the eastern Pacific being brought north by former Tropical Storm Alvin will cause thunderstorms in the Desert Southwest through Tuesday," explained AccuWeather Meteorologist Jacob Hinson.
Overall, the rain will be beneficial. Much of the region has been entrenched in an extreme to exceptional drought.
"The drought means the ground is dry and, counterintuitively, less able to absorb water, "said Hinson.
This occurs because rain is more likely to cause runoff on the hardened ground. Over time, water will eventually be able to penetrate into the ground and soil as the surface becomes more moist.
Of course, thunderstorms will also produce lightning. For anyone with outdoor plans, lightning strikes will be a prominent danger.
Even outside of thunderstorms, there will be an overall uptick in humidity. Therefore, anyone who must work outside will want to stay hydrated. That said, the clouds and rain will keep temperatures lower than what they otherwise would be with sunshine.
In some locations, thunderstorms may contain little or no rainfall. Gusty winds caused by the thunderstorms could then present another hazard: blowing dust. That can be very hazardous as visibility can be suddenly and severely reduced. Motorists traveling at highway speed may need to slow down very quickly, which can be dangerous to other motorists. Nevada, Arizona, New Mexico, southwestern Colorado and the eastern part of Southern California would be the most likely areas to experience blowing dust.
Where too much rain falls, flooding can be a concern.
"Flash flooding can occur in arroyos (dry stream beds), small streams and canyons, as these areas may rapidly fill with water, even with thunderstorms that are miles upstream," warned AccuWeather Senior Meteorologist Alex Sosnowski.Have the app? Unlock AccuWeather Alerts™ with Premium+
"The atmosphere will be holding onto about 1.50 to 1.75 inches of water, which is about how much rain could potentially fall from any particularly strong thunderstorm," cautioned Hinson.
The Four Corners and Southeastern California will be the focus of the showers and thunderstorms through Tuesday.
While the intensity of the showers and thunderstorms may subside a bit after Tuesday, the coverage area is likely to expand.
"As moisture expands over the next few days, thunderstorms can extend as far north as Idaho and southern Montana. These thunderstorms will not be as strong but can certainly prompt flash flooding, especially across area that have had very little in the way of rain this year," said Hinson.
Showers and thunderstorms should finally come to an end in Arizona and New Mexico by Friday, as moisture becomes focused farther to the north. Thunderstorms will become less numerous elsewhere, but could continue right into the weekend.
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