A cool and dry Canadian airmass will lead to pleasant conditions for the first half of the week. However, moisture and storm chances increase by Thursday and continue right into the upcoming weekend.
Beautiful early week
The cold front that moved through Saturday evening left behind a dry and nearly record-breaking chilly airmass in our area. Monday morning’s temperature bottomed out at 41 degrees at BoulderCAST Station. This is within just a couple degrees of the record low for June 10th in Boulder. In fact, today was the second consecutive morning in which low temperatures dropped into the 40’s across the area resulting from the cool airmass and clear skies overnight.
The current surface map for Monday morning shows that the cold front has pushed southward all the way into the Gulf of Mexico. A potent 1030 mb high pressure system sits directly over Colorado. A high this strong is not very common in June.
GFS sea-level pressure and precipitation map for Monday
The residual dry air is easily visible in Monday’s precipitable water forecast map. We’re only looking at around 0.2″ in the Metro area. This will translate into a beautiful Monday with sunshine and temperatures warming up quite significantly as the day progresses into the middle 70’s.
GFS precipitable water forecast map for Monday
While sunny skies and mostly dry weather will persist through mid-week, another secondary wave is scheduled to drop south out of Canada into the upper Midwest on Tuesday. This will turn low and mid-level flow to be northerly across Colorado, bringing in slightly cooler air Tuesday night and Wednesday. The coldest of the air will remain well to our east in Nebraska and Kansas, however. This reinforcing shot of cool air will allow temperatures to stay slightly below normal Tuesday and Wednesday with a very small chance of afternoon thunderstorms both days. Moisture is very limited, so we’re expecting very isolated coverage and most storms being high-based with little to no rainfall reaching the ground.
GFS 500 mb height anomaly forecast for Tuesday and Wednesday
Stormier Thursday into the weekend
Late in the week, the potent mid-level ridge over the Pacific Northwest breaks down and a series of shortwave disturbances are progged to flood into the Rockies. The flow in general turns southwesterly across Colorado which will lead to warming temperatures and also an increase in deeper moisture to the state. At the same time, a lee trough will help to pull in low-level moisture from the east across the Plains. This combination will increase instability for the Front Range leading to better chances for late-day storms.
GFS 500 mb vorticity map for Thursday evening
Temperatures on Thursday and Friday will warm into the low to middle 80’s with scattered afternoon and evening storms. The late-week storm chances could go slightly up or down depending on the time of day that each shortwave arrives. If they align with peak daytime heating, coverage could be more widespread. Though it’s definitely too early to say for sure, conditions could be ideal for severe weather later this week as well, especially across the far eastern Colorado Plains.
GFS CAPE and shear forecast for Thursday evening. Severe weather looking possible for eastern Colorado
As we head into the weekend, several models are showing the likelihood for a stronger cold front to move into northeast Colorado with moist upslope flow taking hold for Saturday and Sunday at the surface. Consequentially, both days this weekend could be fairly rainy with scattered to widespread storms possible in the Metro area alongside cooler than normal temperatures.
Who doesn’t love cool and wet weekends?!
A photo from a hike we did this past Saturday. Can you guess the location?
Forecast Specifics:
Monday: Sunny and dry. Highs in the middle 70’s on the Plains and low 60’s in the Foothills.
Tuesday: Mostly sunny with isolated late-day high-base storms. Little if any rainfall will reach the surface. Highs in the middle 70’s on the Plains and lower 60’s in the Foothills.
Wednesday: Mostly sunny and slightly cooler with isolated afternoon and evening storms. Expect temperatures in the lower 70’s on the Plains and upper 50’s in the Foothills.
Thursday: Partly cloudy and warmer with a chance of scattered storms. Highs in the low 80’s in the Denver Metro and upper 60’s in the Foothills.
Friday: Morning sunshine, then increasing clouds with scattered afternoon and evening thunderstorms. Highs in the lower to middle 80’s on the Plains and lower 70’s in the Foothills.
High Country: A very dry airmass in place will lead to no chance of storms on Monday and only isolated storm coverage across the Mountains on Tuesday and Wednesday. An increase in moisture and several shortwave disturbances will lead to scattered afternoon and evening storms Thursday and Friday. Check SummitCAST for daily updated forecasts for more than 120 hiking destinations across Colorado.
DISCLAIMER: This weekly outlook forecast was 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.
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