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:

A weak monsoon will be in place across the Southwest and Southern Rockies this week, but rainfall will be spotty with most thunderstorms. A series of Pacific shortwaves will also track across the Northern Rockies, which will trigger early-week thunderstorms. Overall, most areas will see a warming trend to above-average levels this week.

COLORADO

Mon – Isolated afternoon thunderstorms are possible across the Front Range, Sangres, and San Juans, but moisture levels will be limited, so this is a "dry" thunderstorm setup with storms producing light/spotty rain and gusty outflow winds.

Wildfire smoke and poor air quality will continue to be an issue across most of the state, with the most active smoke-producing fires currently located across Southeast Utah and Southern Colorado.

Tue – A shortwave will track across the Northern/Central Rockies, and this will open up the door for subtropical moisture and unstable air to arrive from the west/southwest, leading to a significant uptick in thunderstorm activity statewide.

Thunderstorms could begin across the western ranges (San Juans, Elks, Grand Mesa) prior to noon, with a high chance of lightning across all major mountain ranges, and to some extent surrounding lowlands, by early to mid afternoon. Storms will generally track from WSW to ENE.

Stronger storms will be capable of producing locally heavy rain in the mountains, but drier air in the low levels of the atmosphere will result in more of a "dry thunderstorm" setup across the low elevations with gusty outflow winds and limited rainfall expected. 

This pattern will be a temporary uptick in moisture and not the start of a more sustained monsoon (at least for now). The moisture source will be a combination of a low-grade monsoon and the remnants of tropical activity in the South Pacific.

Wildfire smoke is still expected to be an issue across most of the state on Tuesday, but temporary relief is possible in some areas once thunderstorms get going. There is still some concern about what thunderstorm outflow winds could do to ongoing wildfires if these fires themselves do not receive meaningful rain.

Wed – Another active day is expected, but the focus of thunderstorm coverage will shift to the east side of the Continental Divide, where more numerous thunderstorms are likely.

Stronger storms east of the Divide will be capable of producing locally heavy rain, as well as large hail, but weaker storms will likely produce only light/spotty rain with strong outflow wind gusts.

Lightning Risk:

Large Hail (1" Diameter) Risk:

Areas west of the Divide will still see thunderstorms (including a pre-noon threat up high), but coverage and rainfall potential will be lower compared to Tuesday as drier air begins to work its way in from the west. 

Thu – A similar setup to what we'll see on Wednesday with thunderstorm coverage and intensity favoring areas east of the Divide, while areas west of the Divide will see more scattered "dry" thunderstorms with limited moisture in place.

Storms east of the Divide should have slightly more moisture to work with than on Wednesday and wind shear will also be higher (change in wind speed/direction with height), resulting in an increased threat of large hail, while locally heavy rain is also possible with stronger storms. 

Fri – Thunderstorm coverage should decrease statewide compared to Tuesday-Thursday, but we'll still hang onto a threat of scattered thunderstorms along and east of the Divide with more isolated activity west of the Divide.

Most storms will produce little rain, though localized downpours couldn't be ruled out east of the Divide, depending on how much low-level moisture hangs around.

UTAH

Mon – A Pacific shortwave trough moving through from the southwest will result in scattered afternoon thunderstorms across Northern and Eastern Utah, with coverage favoring the Wasatch. This looks like a dry thunderstorm setup with most storms producing light rain and gusty winds, which also increases wildfire risk.

Tue – A somewhat similar setup is expected as another shortwave arrives, but thunderstorm coverage looks a bit higher further east across the Uintas and across the higher terrain of South Central and Southeast Utah. While stronger storms could produce locally heavy downpours, dry thunderstorms will be more common and associated fire risk remains a concern.

Wed – The last in a series of shortwaves will arrive with an uptick in thunderstorm coverage expected throughout Northern Utah, while Southeast Utah will see more isolated activity. While locally heavy downpours couldn't be ruled out under stronger storms, most storms will produce only light rain and strong winds.

In fact, our StormNet Model is picking up on a risk of severe thunderstorm wind gusts (58 mph or higher) across Northern Utah on Wednesday, which is strong enough to produce damage and increase the fire danger.

Thu-Fri – Hotter and drier conditions will prevail across most of the state, though we'll hang onto some isolated afternoon thunderstorm chances mainly across central and eastern Utah. Once again, it's not a favorable pattern for significant rainfall-producing storms, and fire danger will remain high due to the threat of lightning and strong winds.

SOUTHWEST

Mon – A weak monsoon pattern is in place with scattered early afternoon thunderstorms expected, favoring New Mexico and the eastern/northern Mogollon Rim in Arizona. Most storms will produce light rain and gusty winds, but stronger storms could produce locally heavy downpours.

Storms aside, smoke from the Pocket Fire in Arizona will continue to result in poor air quality around Flagstaff.

Tue – A similar setup is expected with greater thunderstorm coverage in New Mexico compared to Arizona. Once again, most storms will produce only light rain and gusty winds, but strong storms could produce locally heavy rain.

Wed-Fri – We will continue to see daily rounds of thunderstorms favoring New Mexico and Eastern Arizona. Similar to previous days, most storms will produce light rain and gusty winds but stronger storms could produce locally heavy rain. Storm motions will generally be from NW to SE.

CALIFORNIA/SIERRA

It will be a quiet weather week for the Golden State. Temperatures will start out a little below average for many areas early in the week, but will warm up to above-average levels toward the end of the week as a persistent trough along the West Coast gradually fades, and high pressure ridging builds in from the southeast.

Starting around July 12th or 13th, we will likely see thunderstorm chances develop across the Sierra and possibly the SoCal Mountains as monsoon moisture arrives. 

PACIFIC NORTHWEST

Mon – Dry and mostly sunny conditions will prevail across Washington and Northwest Oregon, while a shortwave arriving from the southwest will generate afternoon thunderstorms across Central and Southeast Oregon

On Monday, early afternoon thunderstorms will favor the Southern Cascades (Crater Lake, etc.), while late day thunderstorms will favor the Bend area as well as Southeast Oregon. This looks like a mixed dry and wet thunderstorm setup, with some storms producing minimal rain and gusty outflow winds, while stronger storms could produce locally heavy rain.

Tue – A similar setup with warm and dry conditions across Washington and Western Oregon, while Eastern Oregon will see a threat of thunderstorms as another shortwave arrives from the southwest.

Bend and the Oregon Cascades will likely stay thunderstorm-free, while a higher threat is expected across Eastern Oregon and far Southeast Washington, most notably across the Blue and Wallowa Mountains. Most storms will produce only light rain and gusty winds, but stronger storms could produce locally heavy rain.

Wed-Fri – Dry conditions will prevail across most of the region, although two cold fronts (on Wed & Fri) will produce increased clouds and a chance of light/spotty showers across Western Washington. These fronts will also bring some mid to late week heat relief after a toasty start to the week on Monday-Tuesday. 

NORTHERN ROCKIES

Mon – A shortwave arriving from the southwest will result in afternoon and evening thunderstorms across Idaho, Wyoming, and Western/Southern Montana. This shortwave will be transporting moisture from the remnants of tropical activity in the Southern Pacific, so mountainous terrain could see some meaningful rainfall in this setup, including the potential for localized heavy rain.

Tue – We will be "in between" shortwaves in this setup, with moisture and thunderstorm chances favoring Southern Idaho and Southern Wyoming, as well as the eastern ranges and adjacent plains in Wyoming and Montana.

Rainfall will be lighter and more spotty overall compared to Tuesday, but locally heavy downpours couldn't be ruled out under stronger storms. 

Wed – Another Pacific shortwave will move through from the west/southwest, resulting in a good chance of thunderstorms across much of the region. Moisture levels will be limited west of the Continental Divide, resulting in more of a "dry" thunderstorm setup with light rain/gusty winds, while areas east of the Divide will have more moisture to work with and could see locally heavy rain.

Thu-Fri – Conditions will dry out and heat up across most of the region, aside from some isolated thunderstorm chances east of the Divide in Wyoming on Thursday. 

BC INTERIOR & CANADIAN ROCKIES

Mon-Tue – Warm, dry, and mostly sunny conditions will prevail, resulting in a good window for outdoor recreation.

Wed-Fri – The pattern will turn a bit more unsettled as a series of shortwave troughs moves across Western Canada along with a cold front on Wednesday.

This will result in daily chances of showers and thunderstorms, mainly along and north of the Hwy-1 corridor from Revelstoke to Golden to Banff, with lower chances further south near the U.S. border. Rainfall will also be lighter and more spotty in this pattern compared to recent weeks, though locally heavy downpours could occur with thunderstorms.

Saturday (July 11) to Wednesday (July 15):

Over the weekend, a highly amplified pattern will set up with a strong ridge of high pressure over the Rockies and Interior West and a trough of low pressure just off the West Coast. As the ridge builds, we will likely see a couple of very hot days across the Central and Northern Rockies.

However, the strengthening subtropical ridge and the amplified southerly flow associated with the ridge/trough interface will open up the door for monsoonal moisture to surge into the Western U.S. Models have been in good agreement on this pattern for a while now, so that gives us some confidence in the big picture despite being 7-10 days out.

By the middle of next week, medium-range models are projecting well above average precipitable water (a measure of water vapor in the atmosphere) across the Southwest, Great Basin, Sierra, and Central/Northern Rockies. 

The core of this monsoon moisture surge is coming out of the Gulf of California with strong southerly flow, which may favor Arizona, Utah, Wyoming, Nevada, Eastern Idaho, and the Sierra in California. But this moisture should eventually spread into Western Colorado as well, which is in great need of meaningful rains given the ongoing fire situation. 

Longer-range models are hinting at an overall active monsoon for the second half of July and into August, so hopefully (for water and fire concerns) it will have more staying power compared to the past couple of summers. But keep in mind that long-range outlooks are always less certain.

If you have hiking, peak bagging, or any other outdoor plans coming up, be aware of the uptick in thunderstorm chances that is likely to occur across much of the West next week.

Thanks so much for reading! Next update on Wednesday.

Alan Smith