Thunderstorms to mark start of North American monsoon in Southwest
By
Alex Sosnowski, AccuWeather senior meteorologist
Published Jun. 14, 2022 3:06 PM EDT
|
Updated Jun. 15, 2022 10:06 AM EDT
Temperatures could drop as much as 40 degrees Fahrenheit early this week across the southwestern United States, replacing the record-setting heat over the region.
A surge of moisture will arrive in the southwestern United States later this week, and the pattern change will be enough to trigger the onset of the North American monsoon, AccuWeather meteorologists say.
A tropical breeze will help initiate the annual event for the Southwest that helps produce an increase in showers and thunderstorms. The change in wind direction from dry west to northwest winds to a moist southerly flow will allow the first spotty showers and thunderstorms to erupt in the pattern starting Thursday and Friday in parts of New Mexico. The storms will then spread westward into part of Arizona and northward to portions of Colorado and Utah over the weekend and into early next week.
This year's monsoon will start earlier than average, as AccuWeather's long-range forecast team indicated it could in the 2022 U.S. summer forecast.
The average start date for the North American monsoon in southern New Mexico and Arizona is July 3, according to the National Weather Service. However, the monsoon season is similar to other wet seasons and times of the year.
The monsoon season stretches from June 15 to Sept. 30. Last year, the monsoon began during the week of June 15, but then retreated as the weather got hot and dry for a time from late June to the start of July. In 2020, the monsoon was practically a no-show due to a persistent area of high pressure that blocked moisture from flowing northward into the Southwest.
"Since the atmosphere will be transitioning from dry to moist very gradually, the first storms may struggle to bring much rain," AccuWeather Lead Long-Range Meteorologist Paul Pastelok said. "In fact, many of the first storms from location to location may bring little or no rain, but rather gusty winds and lightning strikes that could initiate wildfires and kick up dust."
As the monsoon pattern evolves, it could get rather moist and help produce beneficial rainfall for some areas in the coming weeks. However, forecasters warn that severe weather and localized flooding could also occur.
The Southwest is only days removed from some of the hottest weather in the region so far this year. Death Valley, California, recorded a high of 123 F Friday, June 10, while Phoenix hit 113 F last Friday and then 114 Saturday.
An unusually sharp southward dip in the jet stream will reach the Pacific coast with cool air this weekend then lift northward, according to AccuWeather Senior Storm Warning Meteorologist Joe Bauer.
"This jet stream action, when combined with high pressure that pumps moisture northward can set the stage for thunderstorms packing high winds, hail and isolated tornadoes this weekend to early next week over portions of the interior West," Bauer said.
"It's possible some areas in the Four Corners region could experience flooding, especially in areas where there are recent burn scars," Bauer said. Mudslides and debris flows can occur in these areas.
"There is a chance that downpours related to the monsoon reach northwestern Wyoming and southern Montana, but the storms should not be widespread enough to significantly aggravate flooding that developed in Yellowstone National Park early this week," Pastelok said. Downpours from a storm that arrived from the Pacific Ocean triggered flash flooding that washed away bridges and forced officials to close the park. Several days of dry weather or limited shower activity are in store prior to the return of downpours to the region and may be enough to allow streams to recede.
Any downpours would be extremely beneficial due to the extensive and long-term drought in the region, as long as they don't result in severe flooding, meteorologists say. Every state in the West was experiencing some form of drought, according to the United States Drought Monitor. All with the exception of Washington had extensive areas where the drought was severe to extreme and exceptional as of Tuesday.
It is possible that some tropical moisture along the coast of Central America and southern Mexico could be drawn northward for a time next week. However, perhaps similar to last year, moisture and thunderstorms related to the monsoon may retreat southward later in June.
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"A significant amount of showers and thunderstorms related to the monsoon are in store for the interior West this summer," Pastelok said. "However, it is not likely to be quite as wet as last year."
Tucson, Arizona, received more than double its average rain for June through September in 2021 when 12.79 inches poured down. Phoenix picked up 4.20 inches of rain, compared to an average of 2.43 inches, while less rain fell in Las Vegas which received 0.65 of an inch. The normal rainfall total for Sin City during the four-month period is only 1.06 inches.
"The overall weather pattern is very similar to that of 2012, which many of our forecasts have been based upon for this summer," Pastelok said. "The timing of the extreme heat and busy nature of derechos in the Central states is similar to 10 years ago."
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News / Weather Forecasts
Thunderstorms to mark start of North American monsoon in Southwest
By Alex Sosnowski, AccuWeather senior meteorologist
Published Jun. 14, 2022 3:06 PM EDT | Updated Jun. 15, 2022 10:06 AM EDT
Temperatures could drop as much as 40 degrees Fahrenheit early this week across the southwestern United States, replacing the record-setting heat over the region.
A surge of moisture will arrive in the southwestern United States later this week, and the pattern change will be enough to trigger the onset of the North American monsoon, AccuWeather meteorologists say.
A tropical breeze will help initiate the annual event for the Southwest that helps produce an increase in showers and thunderstorms. The change in wind direction from dry west to northwest winds to a moist southerly flow will allow the first spotty showers and thunderstorms to erupt in the pattern starting Thursday and Friday in parts of New Mexico. The storms will then spread westward into part of Arizona and northward to portions of Colorado and Utah over the weekend and into early next week.
This year's monsoon will start earlier than average, as AccuWeather's long-range forecast team indicated it could in the 2022 U.S. summer forecast.
The average start date for the North American monsoon in southern New Mexico and Arizona is July 3, according to the National Weather Service. However, the monsoon season is similar to other wet seasons and times of the year.
The monsoon season stretches from June 15 to Sept. 30. Last year, the monsoon began during the week of June 15, but then retreated as the weather got hot and dry for a time from late June to the start of July. In 2020, the monsoon was practically a no-show due to a persistent area of high pressure that blocked moisture from flowing northward into the Southwest.
"Since the atmosphere will be transitioning from dry to moist very gradually, the first storms may struggle to bring much rain," AccuWeather Lead Long-Range Meteorologist Paul Pastelok said. "In fact, many of the first storms from location to location may bring little or no rain, but rather gusty winds and lightning strikes that could initiate wildfires and kick up dust."
As the monsoon pattern evolves, it could get rather moist and help produce beneficial rainfall for some areas in the coming weeks. However, forecasters warn that severe weather and localized flooding could also occur.
The Southwest is only days removed from some of the hottest weather in the region so far this year. Death Valley, California, recorded a high of 123 F Friday, June 10, while Phoenix hit 113 F last Friday and then 114 Saturday.
An unusually sharp southward dip in the jet stream will reach the Pacific coast with cool air this weekend then lift northward, according to AccuWeather Senior Storm Warning Meteorologist Joe Bauer.
"This jet stream action, when combined with high pressure that pumps moisture northward can set the stage for thunderstorms packing high winds, hail and isolated tornadoes this weekend to early next week over portions of the interior West," Bauer said.
"It's possible some areas in the Four Corners region could experience flooding, especially in areas where there are recent burn scars," Bauer said. Mudslides and debris flows can occur in these areas.
"There is a chance that downpours related to the monsoon reach northwestern Wyoming and southern Montana, but the storms should not be widespread enough to significantly aggravate flooding that developed in Yellowstone National Park early this week," Pastelok said. Downpours from a storm that arrived from the Pacific Ocean triggered flash flooding that washed away bridges and forced officials to close the park. Several days of dry weather or limited shower activity are in store prior to the return of downpours to the region and may be enough to allow streams to recede.
Any downpours would be extremely beneficial due to the extensive and long-term drought in the region, as long as they don't result in severe flooding, meteorologists say. Every state in the West was experiencing some form of drought, according to the United States Drought Monitor. All with the exception of Washington had extensive areas where the drought was severe to extreme and exceptional as of Tuesday.
It is possible that some tropical moisture along the coast of Central America and southern Mexico could be drawn northward for a time next week. However, perhaps similar to last year, moisture and thunderstorms related to the monsoon may retreat southward later in June.
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Have the app? Unlock AccuWeather Alerts™ with Premium+
"A significant amount of showers and thunderstorms related to the monsoon are in store for the interior West this summer," Pastelok said. "However, it is not likely to be quite as wet as last year."
Tucson, Arizona, received more than double its average rain for June through September in 2021 when 12.79 inches poured down. Phoenix picked up 4.20 inches of rain, compared to an average of 2.43 inches, while less rain fell in Las Vegas which received 0.65 of an inch. The normal rainfall total for Sin City during the four-month period is only 1.06 inches.
"The overall weather pattern is very similar to that of 2012, which many of our forecasts have been based upon for this summer," Pastelok said. "The timing of the extreme heat and busy nature of derechos in the Central states is similar to 10 years ago."
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