We continue the cool, monsoonal stretch with 80’s for the majority of the week. We are watching a weak system to affect northeast Colorado through Thursday, bringing our best chance of storms on Tuesday. Will the 90’s rear their ugly head for the first weekend in August? We discuss this and more in our weekly outlook.
This week’s highlights include:
- A welcomed, monsoonal cool-down is expected as temperatures stay in the 80’s for most of the week
- Showers and storms are possible each day, but are most likely on Tuesday
- High pressure rebuilds over the Southwest late in the week with a likely return to 90’s for the weekend
DISCLAIMER: This weekly outlook forecast is created Monday morning and covers the entire upcoming week. Accuracy will decrease as the week progresses as this post is NOT updated. To receive daily updated forecasts from our team, subscribe to BoulderCAST Premium.
The week at a glance
Before going into the detailed weekly forecast, below shows the nation’s weather on this Monday at the 500 mb level (18,000 feet aloft). We can see the remnants of Hurricane Hanna over central Mexico. A trough and its associated cold front is present from Minnesota back into Kansas and New Mexico. This is the same front which cooled us off on Sunday and will do so again today. There are a few weak areas of low pressure over Louisiana and off the coast of Florida, too. The feature important for us this week will be the low pressure in southern California. The current forecast guidance is showing that this system will take a rather interesting track through the week, going north and around Colorado. It will be a player for us through Thursday, after which high pressure rebuilds in for possible 90’s just in time for the beginning of August.
Cool to start
Today’s weather continues where we left off yesterday. As you can see in the image below, the temperature anomalies are still slightly below average for late-July (blue shaded areas), thanks to the cold front continuing to dive southward into the Midwest. High pressure overhead today will largely keep things dry, though showers and storms will again be present in southeastern Colorado and the higher terrain and Foothills. Over the Front Range, we can’t rule out some isolated storms, but these won’t be a major factor as drier conditions should be the dominant pattern. We have a 10% chance of storms today in the Denver Metro area (and even that may be generous) with highs in the lower to middle 80’s.
A stormy Tuesday
Tomorrow, the aforementioned low pressure system over California is expected to track northeastward into central Wyoming (below left). This is going to allow for a trough axis to move across Colorado during the afternoon and evening hours. The northward track should allow for deeper moisture to build back into the Plains (below right).
Along with the mid-level pattern, at the surface, a warm front is expected to move northeastward during the day. Given the moisture in place and trough aloft, this should focus lift for more widespread showers and thunderstorms for the Mountains and Plains. Some of the storms will produce heavy rainfall with moisture well above seasonal normals. Tuesday’s highs should be a tad warmer in the middle 80’s.
Low pressure remains a factor through Thursday
As we discussed briefly earlier, the low pressure system will affect us not only on Tuesday. By Wednesday, its position could be across western Nebraska. This location favors a downslope pattern over the Front Range, with west-northwest winds poised to advect in from the High Country. Current wind gusts look to be in the 20-30 mph range at the surface, so we may need to watch for possible Red Flag conditions with the ongoing drought across the state. This pattern Wednesday should also bring drier conditions, but a 10% chance of late-day storms can’t be ruled out. Highs should be into the mid to upper 80’s thanks to downslope warming.
Come Thursday, the location of the system will be less certain, being more than 72 hours out. However, in the current trend of guidance, its position should still be affecting northeast Colorado. A possible resurgence of cooler air could build in from the north if the storm system takes a more westward track than currently projected (currently expected to be in Kansas). That would bring in some potential low clouds on Thursday/Friday. This is too difficult to predict at this point, so our current forecast simply calls for a tad cooler weather on Thursday, along with a slight chance of storms.
Watching heat returning for weekend?
By the end of the week, the low pressure system will be on its way out. However, the 90’s should hold off one more day as upslope flow transitions to a southerly and southwesterly wind. The real heat, potentially into the 90’s, looks more likely for the weekend to kick off the first few days of August. Can you believe we’re transitioning into August already? The summer is just flying by!
The upcoming weekend will see high pressure rebuild back across Arizona and Baja California. This is the pattern we warned about in our recent monsoon update. This set-up will block the flow of monsoonal moisture into the Desert Southwest and ultimately Colorado. Thus, we should be fairly dry this weekend with lower moisture across the state and temperatures creeping back up into the 90’s. We know…just what you were hoping for!
Forecast Specifics:
Monday: Mostly sunny to give way to partly cloudy skies with a 10% chance of isolated storms. Highs in the lower to middle 80’s on the Plains and lower 70’s in the Foothills.
Tuesday: Partly cloudy becoming mostly cloudy with scattered showers and thunderstorms (60%) in the late afternoon/evening. Some storms could produce heavy rainfall. Highs in the middle 80’s on the Plains and lower 70’s in the Foothills.
Wednesday: Drier, sunny, and breezy out of the northwest at 20-30 mph. A 10% chance of late-day storms. Highs in the mid to upper 80’s for the Plains and middle 70’s in the Foothills.
Thursday: A mixture of clouds and sunshine with temperatures near the low to middle 80’s on the Plains and lower 70’s in the Foothills with a slight chance of afternoon/evening storms.
Friday: Mostly sunny skies with isolated late-day storms, mainly across the higher terrain. Highs in the middle 80’s on the Plains and middle 70’s in the Foothills.
Weekend: Storm chances should lessen or disappear, along with a return to 90’s for both Saturday and Sunday.
High Country: Scattered showers and thunderstorms will be likely on Monday. By Tuesday, widespread storm activity will be possible, starting earlier in the day as well. Much drier conditions are expected Wednesday through Friday, with only minor chances for wet weather. The upcoming weekend looks dry too, with reduced chances of typical daytime summer storms. Check our SummitCAST page for daily updated forecasts for more than 120 mountain hiking destinations across Colorado. Here’s the early week forecast at the top of Grays Peak:
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