My Favorite Summer Weather Map Layers:

• StormNet Lightning Risk
• Current Lightning Strikes and 1-Hour Risk
• Current Radar
• Forecast Radar
• Forecast Total Precipitation
• Current Air Quality
• Smoke Surface Forecast (ground level)
• Smoke Sky Forecast (average smoke ground level to upper atmosphere)
• Forecast Air Quality (low-res 3-5 day smoke outlook)

5-Day Big Picture Overview:

An active monsoonal flow will remain in place across the Southwest and the Rockies, with moisture levels peaking on Wednesday before subsiding somewhat heading into the weekend. 

Temperatures will remain well above average across the Inland Northwest and Northern Rockies, but a Pacific disturbance will bring cooler air and showers to the Cascades, Olympics, and BC Coast Range this weekend.

COLORADO

Wed – An active day is expected both west and east of the Divide as a shortwave trough moves through. The first thunderstorms could develop prior to noon over the higher peaks, then more widespread showers and thunderstorms are expected through the afternoon and evening hours.

Abundant moisture will be in place, and strong storms will be capable of producing heavy rain, while there is also some potential for flash flooding, especially near recent wildfire burn scars. 

Storms will be relatively slow-moving (but there will be some movement) from south to north across most of the state, except across the Front Range Mountains and adjacent I-25 corridor where motions will be more WSW to ENE.

Storm coverage and rainfall amounts will favor the mountains, but localized downpours could occur across the Denver metro area and I-25 corridor as well.

Thu – Another active day is expected with numerous showers and thunderstorms developing in the afternoon. The main difference is that the Southern Front Range (Pikes Peak area) and Sangres will see an uptick in storm coverage and rainfall amounts compared to Wednesday. Lightning probabilities will also be highest across the southern mountains, including the Sangres and San Juans.

Heavy rain will still be possible with storms statewide, even if moisture levels (i.e. fuel for showers/storms) drop off slightly in some areas compared to Thursday. 

Storms will also be slightly faster moving compared to Wednesday, and will travel in a SW to NE or WSW to ENE direction.

Fri-Sun – Atmospheric moisture levels will decrease some compared to Wednesday-Thursday, but will still remain above average, with scattered afternoon thunderstorms expected each day, favoring areas along and west of the Divide. Stronger storms will still produce locally heavy rain.

Our PEAKS Model total rainfall projection through Sunday favors the Front Range, Never Summers, Gores, and San Juans for the highest rainfall totals, with 1 to 2 inches expected, while the central mountains are projected to receive 0.75 to 1.5 inches. Isolated higher amounts are possible anywhere in the state depending on where strong thunderstorms develop. 

UTAH

Wed – A shortwave will move through the area with deep monsoonal moisture in place, which both help to trigger widespread showers and thunderstorms during the afternoon hours. The lightning threat will first emerge across the Northern Utah mountains by early afternoon.

Heavy rain will be possible with storms throughout the state, with a high threat of flash flooding in Southern Utah canyon country, especially in slot canyons, small streams, dry washes, and burn scars.

Storms will be slow-movers from SW to NE or WSW to ENE across Northern Utah, with more erratic to at times stationary motion across Southern Utah.

Thu – The atmosphere will stabilize a bit, resulting in a less active day compared to Wednesday, especially across Northern Utah.

However, there will still be abundant moisture across Southern Utah with scattered afternoon thunderstorms expected, and the flash flood risk will continue as storms will produce locally heavy rain. Storms will be slow-moving from NW to SE.

Fri-Sat – Moisture levels will remain above-average throughout Utah, which will help to fuel daily rounds of terrain-driven afternoon thunderstorms across both Southern and Northern Utah. Heavy rain can be expected with stronger storms, and a daily threat of flash flooding will exist in canyon country.

Our PEAKS Model total rainfall projection through Sunday shows a general range of 0.75 to 1.5 inches across the mountains of Southern and Northern Utah. Isolated higher amounts will be possible in areas where strong thunderstorms develop.

SOUTHWEST

Wed – The pattern will be somewhat less active as the best energy moves northward, but abundant moisture will still be in place with scattered afternoon thunderstorms developing. Coverage looks to favor the higher ranges of New Mexico, but heavy rain will be possible with storms across both New Mexico and Arizona.

Thu – Scattered terrain-driven thunderstorms can be expected across both Arizona and New Mexico, and heavy rain can be expected with stronger storms. The lower deserts and basins are less likely to see any storms or meaningful rain. 

Fri-Sun – More of the same can be expected with daily rounds of afternoon thunderstorms across both Arizona and New Mexico, with coverage favoring the higher elevations. Strong storms will produce locally heavy rain. 

Our PEAKS Model total rainfall projection through Sunday favors the Mogollon Rim, Southeast Arizona Ranges, the San Francisco Peaks, and the Grand Canyon, where pockets of 1-2 inch totals are expected. Isolated higher amounts are also possible in areas where strong thunderstorms develop. 

CALIFORNIA/SIERRA

Wed – Moisture levels will be on the decrease, but there will still be enough for isolated mid to late afternoon thunderstorms over the Eastern Sierra. The flash flood risk will be lower compared to prior days, but stronger storms over the higher terrain will still be capable of producing locally heavy rain.

Thu-Sun – Warmer and drier conditions will prevail as the monsoon shifts eastward. Some isolated thunderstorm activity couldn't entirely be ruled out on any given day across the Eastern Sierra, but this looks to be more the exception than the rule.

PACIFIC NORTHWEST

Wed – Wildfire smoke will continue to impact the region, with the heaviest smoke expected across Eastern Washington and Northern Idaho.

A low pressure area moving from south to north off the coast will also help to pull in some monsoonal moisture from the south, resulting in a good chance of afternoon and evening thunderstorms.

The highest threat of lightning will be across the Central Oregon Cascades, including the Bend area, but thunderstorms are also possible over the western lowlands, including Portland. Storm motions will be from south to north. 

Isolated thunderstorms will also sneak into Southern and Western Washington on Wednesday night, including a chance of storms around Seattle.

This will be a mixed wet and dry thunderstorm setup. Stronger thunderstorms will be capable of producing heavy rain, and some localized flash flooding couldn't even be ruled out. However, dry lightning and gusty outflow winds are also possible away from thunderstorm cores, which could lead to elevated fire weather concerns.

Thu – As the low lifts northward, scattered showers can be expected across Western and Northern Washington as well as Northeast Oregon. Lightning potential will primarily be confined to areas east fo the Cascade Crest.

Spotty rain with isolated downpours can be expected across Western Washington. However, this will primarily be a dry thunderstorm setup with light rain and gusty winds across Eastern Washington and Eastern Oregon, which could potentially exacerbate the wildfire situation. 

Fri – Hot and dry conditions will return, with the heaviest wildfire smoke expected east of the Cascade Crest.

Sat-Sun – A trough will approach the area with rain showers possible across the Washington Cascades and Olympics and the BC Coast Range. Confidence in meaningful rain is greatest across Western BC, while confidence is lower across Western Washington due to poor model agreement.

Rain chances aside, a cold front will move through the PNW over the weekend, ushering in a much cooler airmass with temperatures dropping to below-average levels for late July.

NORTHERN ROCKIES

Wed – Anomalously high moisture levels (water vapor in the atmosphere) will be in place while a shortwave will also move through, resulting in widespread showers and thunderstorms across Wyoming, Central/Eastern Idaho, and Southwest Montana. Lightning probabilities will be highest across Wyoming.

Significant rainfall is possible across this region, including an elevated potential for localized flash flooding with stronger thunderstorms or training of storms. 

Outside of this wetter region, heavy wildfire smoke from Pacific Northwest wildfires will continue to impact Western and Northern Idaho, as well as Northwest Montana.

Thu – Showers and thunderstorms will be more isolated to scattered in coverage west of the Continental Divide, while Northern Idaho and Northwest Montana will see an uptick in storms compared to Wednesday. Storms along and west of the Divide in Montana and Idaho will produce spotty rain but locally heavy downpours are possible.

Areas east of the Divide in Wyoming (Absarokas, Bighorns, Winds, Snowys) will see more numerous showers and thunderstorms along with heavier and more widespread rainfall.

Smoke impacts are also expected to continue across Western/Northern Idaho and Northwest Montana.

Fri-Sun – Daily rounds of isolated to scattered thunderstorms will favor Wyoming, Eastern Idaho, and Southwest Montana. Moisture levels will be lower compared to prior days, but stronger storms will still be capable of producing localized downpours. 

There is a possibility that smoke conditions could decrease across Northern Idaho/Northwest Montana later in the weekend as a cooler airmass overspreads the Pacific Northwest, but confidence is low. 

BC INTERIOR & CANADIAN ROCKIES

Wed – Hot and dry conditions can be expected, with smoke impacting much of the area from wildfires burning across the Pacific Northwest.

Thu – A Pacific disturbance will move across the area, triggering scattered to numerous afternoon thunderstorms. This looks to be a mixed wet/dry thunderstorm setup with some storms producing locally heavy rain, while others will produce only light rain and gusty winds, which could lead to fire weather concerns.

Fri – Warm temperatures will prevail with isolated afternoon thunderstorms and generally light/spotty rain at most.

Sat-Sun – A cold front will arrive, ushering in much cooler air, especially by Sunday. Scattered showers and thunderstorms are possible, but confidence is low as models are in poor agreement on how much moisture reaches this area. 

Monday (July 27) to Friday (July 31):

An active monsoon will continue across the Southern Rockies, likely favoring Utah, Colorado, Northern Arizona & New Mexico, and Southern Wyoming. Temperatures are expected to warm up to above-average levels across most of the West despite the monsoonal flow.

The PNW will hold onto cooler temperatures early in this period, with a warm-up expected later on. A mostly dry pattern is also expected, aside from possibly some rain showers on the 27th. 

Thanks so much for reading! Next update on Friday (July 24).

Alan Smith