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:

This week will see active weather across the Western US and Canada with major changes by the end of the week.

To start the week, a storm system moving through the Canadian Rockies will dip into the Upper Midwest, bringing showers and thunderstorms around the Continental Divide and through the Front Range of CO. This storm will keep temperatures cool around and to the east of the Divide where showers fall, and storms occur. Temperatures on the west side of the Divide will remain above normal with dry conditions.

Changes move in toward the end of the week with two large-scale weather features.

First, monsoonal moisture will increase through the southwest and into the southern Rockies on Wednesday and Thursday. This will bring increasing chances of thunderstorms across the region with flash flood possibilities. 

Second, a storm will track into the Northwest, bringing significant changes with precipitation and cooler temperatures. This storm will move in Thursday, with showers expected that will continue through this weekend. Even high-elevation light snow is possible across the Pacific Northwest, northern Rockies, and western Canada.

5-Day Regional Forecast Breakdown below as follows...

• Colorado
• Utah
• Southwest
• California/Sierra
• Pacific Northwest
• Northern Rockies
• BC Interior & Canadian Rockies

COLORADO

Mon & Tue – Scattered afternoon thunderstorms are likely across the eastern half of Colorado on Monday and Tuesday associated with a storm system dipping into the Upper Midwest from the Canadian Rockies. This storm, combining with moisture from the Plains, will develop afternoon and evening thunderstorms. Thunderstorms will become more likely and more frequent the further east you travel, with the greatest threat of severe weather in the Front Range toward the Plains.

 

Lightning and strong winds are the biggest threat across the Front Range on Monday and Tuesday. However, there is a chance of hail and even a tornado (mainly further east in the Plains) on Monday and Tuesday afternoon/evening. 

Wed - Fri – Starting on Wednesday, monsoonal moisture will increase across the southwest and transport into CO. This will bring another round of scattered afternoon thunderstorms on Wednesday, with a slightly higher chance of storms now occurring across the mountains.

Storms will become more frequent across the mountains on Thursday and Friday, due to additional monsoonal moisture transporting north.

Lightning and heavy rain remain the main threat from these storms, with localized areas of flash flooding possible if isolated storms dump heavy amounts of rain. 

An additional weather feature to watch this week across CO is smoke from wildfires in Utah, Arizona, and New Mexico. While storm activity will limit air quality concerns, morning skies could be hazy.

UTAH

Mon & Tue – Moisture will drastically decrease to the west, and Utah will stay dry and mostly clear on Monday and Tuesday. A couple of storms are possible in the Uintas, but those storms will be isolated. The main weather on Monday and Tuesday will be smoke and poor air quality associated with a couple of wildfires.

The Iron Fire is the biggest threat that is growing to the west of Provo. Additional wildfires on the border of Utah and Nevada (Grapevine and Kane Springs) will also transport smoke into southern Utah.

Wed - Fri – Similar to CO, the weather will change across Utah on Wednesday. Monsoonal moisture will transport across the southwest and increase moisture in Utah. This will bring scattered thunderstorms on Wednesday, with a higher chance of storms on Thursday. Friday should still see a couple of storms, but weaker southwest transport is forecasted.

Lightning is the main threat across Utah, but flash flood chances will also increase due to localized heavy areas of rain that could remain semi-stationary.

Rainfall amounts will be locally higher associated with strong and semi-stationary storms.

SOUTHWEST

Mon – The southwest will stay dry, mostly clear, and hot as we await monsoonal moisture to move in this week. Wildfires in the region will produce localized areas of smoke, hazy skies, and poor air quality.

Tue-Fri – Monsoonal moisture is expected across the southwest from Tuesday through Friday with varying levels of intensity depending on the strength of the moisture transport. Tuesday will see a couple of storms, mainly across the higher elevations along the Arizona and New Mexico border.

Wednesday will see southwest winds increase, and favorable moisture transport will develop afternoon/evening thunderstorms. Storms will primarily stay across the higher elevations and remain orographically driven.

Thursday will see the most favorable monsoonal conditions with widespread thunderstorms across AZ and NM. Flash flooding is possible, associated with the heaviest storms that remain semi-stationary in flash flood prone areas. 

Friday will also see thunderstorms, but weaker winds are forecasted to keep thunderstorms more scattered. Most areas across the southwest will see 0.1 - 0.5 inches of rain, and isolated storms will bring heavier precipitation greater than 1 inch.

Rainfall amounts will be locally higher associated with strong and semi-stationary storms.

CALIFORNIA/SIERRA

Mon & Tue – Quiet and mostly dry weather will start this week with above-normal temperatures for the northern half of the state. Southwest flow off the California coast will start to increase moisture on Tuesday, with a couple of scattered thunderstorms possible in southern California late Tuesday.

Wed & Thu – The strongest monsoonal moisture transport will be to the east of California on Wednesday and Thursday. This will keep thunderstorms scattered in southern to central California on Wednesday and Thursday. Models currently do not show much moisture making it to the central Sierra, but this might change. 

Fri – Changes will move into northern California on Friday, associated with a storm system tracking into the Northwest. This storm will bring scattered light rain showers and much cooler temperatures through the weekend.

PACIFIC NORTHWEST

Mon - Wed – This week will start dry, clear, and warm with above-normal temperatures. Moisture ahead of the upcoming storm will sneak into the higher elevations Wednesday evening with increasing clouds and a small chance of a high-elevation rain shower or thunderstorm.

Thu & Fri – A storm system will move into the PNW on Thursday evening and bring a big change in weather. A weak atmospheric river and a strong cold front will bring areas of rain showers and drop temperatures significantly into the 50s and 60s through the valleys, and 30s and 40s through the Cascades.

Thunderstorm chances are low across the PNW, and rainfall accumulations will be 0.1 - 0.75+ inches. This storm will be strong enough to lower snow levels to 6,000 - 7,000 feet on Friday evening, bringing a few inches of snow to the higher elevations late Friday and into the weekend.

NORTHERN ROCKIES

Mon – A storm system will move across the Canadian Rockies into the Canadian Plains, then into the Upper Midwest to start this week. This will bring active weather primarily to Montana, but also northern Idaho and northern Wyoming. Afternoon showers will develop on Monday, but lightning chances will remain low and stay east.

Tue & Wed – The storm system will move out into the central Plains on Tuesday and Wednesday, but lingering low-level moisture from the Plains will bring scattered showers across the region. The highest chance of showers will be across Wyoming due to higher moisture levels. A couple of thunderstorms are possible as well on the eastern side of the Divide through Wyoming.

Thu & Fri – Scattered rain showers return to the region on Thursday and Friday, featuring two different weather systems. Thursday will see scattered showers that will mainly be orographically driven. Overall, light impacts are expected.

Friday will start clear and dry, but the storm moving into the Northwest will quickly bring showers and cooler temperatures on Friday afternoon to evening. A strong cold front will drop temperatures across the region, and snow levels will approach 6,000 - 7,000 feet late Friday and into the weekend. A couple of inches of snow could fall, depending on how cold it gets.

BC INTERIOR & CANADIAN ROCKIES

Mon & Tue – A storm moving off the Canadian Rockies will enter the Plains to start this week. Scattered showers on Monday will move east, with a few high-elevation snow showers as well. A couple of isolated weak thunderstorms are possible, but otherwise this storm will not pose a severe weather threat, unless you are much further into the Plains.

Wed – Drier conditions will move in Wednesday, but a few afternoon and evening scattered showers are still possible across the higher elevations. These showers will be orographically driven.

Thu-Fri – A storm moving into the Northwest will bring significant changes to Western Canada at the end of this week and into the weekend. This storm will move into BC on Thursday with widespread areas of rain associated with a weak atmospheric river. Rain will continue through Friday, as the storm moves further inland

A strong cold front will also drop temperatures significantly and bring chances of snow to higher elevations above 6,000 - 7,000 feet.

Saturday (June 27) to Wednesday (July 1):

The storm moving into the Northwest will push into the northern Rockies and bring cooler temperatures with areas of widespread precipitation and high-elevation light snow. This storm will bring a significant late-season cold air mass and lower snow levels to 6,000 - 7,000 feet across the Northwest and northern Rockies. Several inches of snow are likely across the mountains, depending on how low snow levels drop.

This storm is expected to lift to the northeast into the Canadian Plains on Monday and Tuesday, with wrap-around moisture continuing in the northern Rockies. Temperatures will stay below normal across the region.

This storm is expected to bring below normal temperatures across other areas of the West this weekend, but precipitation will primarily stay north. Temperatures will stay colder closer to the storm, and precipitation chances will drastically decrease south of the CA-OR, ID-NV, and ID-UT borders.

This storm will likely disrupt the Pacific jet stream as well, with shortwave troughs moving into the Northwest on Tuesday and Wednesday with cooler temperatures and chances of light precipitation.

This forecast will keep windy conditions across the West and bring unseasonably cold weather for late June into early July. If snow falls across the Northwest and northern Rockies, it will be light, with maybe 1-6 inches of snow. It is still fun and cool to see snow in the forecast so late in the season!

Thanks so much for reading, and have a great week. The next update is on Wednesday!

Zach Butler