Western US Daily Snow
By Alan Smith, Meteorologist Posted 8 hours ago June 24, 2025
Monsoon Season Begins in New Mexico, Southern Rockies
Summary
An early season surge of monsoon moisture will result in numerous thunderstorms and flash flooding potential across New Mexico on Tue & Wed. Colorado & Eastern Wyoming will also see an uptick in showers & t-storms, especially on Tue with stronger storms capable of large hail & damaging winds. Later in the week, CO will see a reduction in storms while New Mexico will continue to be favored.
Short Term Forecast
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Monday Afternoon Conditions:
Large wildfires are currently burning across Southern Utah and near the California/Mexico border, and smoke from these fires will likely drift into the Salt Lake City area and other portions of the Interior West from time to time.
Meanwhile, monsoon moisture is streaming into New Mexico, leading to an uptick in thunderstorms. As of late afternoon (5pm Mountain Time), most of the storm activity is confined to areas east of the Rockies in New Mexico.
But check out the high volume of lightning strikes south of the border over the mountains of Mexico – a precursor to the increase in moisture that will occur on Tuesday...
5-Day Temperature Outlook (June 24-28):
Following last weekend's cool snap, temperatures will gradually warm back up to slightly above normal levels this week from California to the Central Rockies.
However, below-normal temperatures are expected over the Pacific Northwest and over the Southwest thanks to the uptick in moisture and cloud cover.
Tuesday (June 24):
On Tuesday, a more significant surge of monsoonal moisture will push into New Mexico, resulting in numerous showers and thunderstorms during the morning, afternoon, and evening hours.
Heavy rainfall is expected with thunderstorms, and training of thunderstorms (multiple storms tracking over the same area) will result in an elevated risk of flash flooding.
This is earlier than normal for a major monsoon moisture surge, and moisture from the remnants of Hurricane Erick in the Eastern Pacific is a factor in this pattern.
A second focus area will be the eastern ranges of the Rockies and adjacent foothills of Colorado and Wyoming as a trough approaches from the west.
Southeasterly winds blowing cyclonically (counterclockwise) around a surface low pressure area over Southern Colorado will transport Gulf moisture toward the eastern slopes of the Rockies, supporting an uptick in thunderstorms.
Wind shear (the change in wind speed and direction with height) will also increase thanks to the approaching trough, resulting in the potential for strong to severe thunderstorms. Large hail and damaging straight-line winds will be possible across this region, and a tornado also couldn't be ruled out over the plains.
Elsewhere, scattered thunderstorms with light to moderate rain can be expected in the vicinity of the trough over portions of the Great Basin and Northern Rockies, with more isolated activity expected in the Sierra. A few light showers are also possible across the Interior Northwest.
Wednesday (June 25):
As the trough continues to track eastward across the Rockies, southerly flow will increase along and east of the Continental Divide, supporting another active thunderstorm day across New Mexico, Colorado, and Wyoming.
Once again, areas along and east of the Continental Divide will be favored for higher thunderstorm coverage and heavier rainfall potential.
West of the Divide, thunderstorm activity will be more isolated with generally light and spotty rainfall expected.
Thursday (June 26):
On Thursday, drier air will push into Wyoming, Colorado, and Northern New Mexico with monsoonal moisture becoming suppressed into Central and Southern New Mexico. The Sacramento Mountains and Southern New Mexico will be most favored for thunderstorms, though the flash flooding risk looks lower compared to prior days.
Across the Northern Rockies, an uptick in thunderstorms is expected from Central Idaho and Western Montana as a trough passes across the area. Thunderstorms will be scattered in nature, with storms producing light to moderate rain.
Elsewhere, only isolated thunderstorms are expected across the Central Rockies and over Eastern Arizona, with light rain and gusty winds expected with any storms. A few light showers are also possible over the Cascades, Olympics, and coastal areas of the Pacific Northwest.
Friday (June 27) to Saturday (June 28):
Monsoonal moisture will largely remain confined to New Mexico, where more numerous thunderstorms are expected, while activity will be isolated further north in Colorado.
To the north, a backdoor cold front will slide into Montana and Wyoming with an uptick in thunderstorms expected along and east of the Continental Divide, including mountain ranges such as the Beartooths, Bighorns, Absarokas, and Wind Rivers.
Extended Forecast
Outlook for June 29 to July 3:
The early season monsoon pattern looks to pick up heading into early July, with New Mexico remaining favored for above-normal rainfall, while coverage should gradually increase across Arizona, Colorado, and Utah as well.
Above-normal precipitation chances are also noted over portions of the Northwest, including Northern California and Oregon... but keep in mind that we are heading into the dry season in these areas, so it only takes a little bit of rainfall to be considered "above normal".
In terms of temperature, it looks like most of the West is really going to heat back up heading into early July, with a high likelihood of above-normal values for most of the West.
Exceptions include New Mexico, where near-to-below-normal temperatures are projected, and along the coast of California, where near-normal temperatures are projected.
Thanks so much for reading!
This will be my only post of the week, so check back in for my next post on Tuesday, July 1st.
Alan Smith
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