The week begins right where it left off from the weekend with highs near 80 degrees on Monday. A deep trough approaches Tuesday into Wednesday with widespread rain showers and chilly temperatures expected. Don’t worry though, by the end of the week a large dome of high pressure will return sending highs back into the 80’s just in time for the weekend.
This week’s highlights include:
- Warmth continues to start the week with upper 70’s to possibly 80 degrees under increasing clouds
- Rain showers and thunderstorms are likely Tuesday afternoon and Tuesday night with a cold front, snow above 6000 feet
- Cooler Tuesday to Wednesday with highs below normal in the 50’s
- Above average temperatures and sunshine return Thursday through the weekend with 80’s taking shape
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.
Most of week warm & dry with exception of Tuesday into Wednesday
Below shows the weekly forecast for Denver in terms of precipitation, using the GEFS ensemble model as a guide. You’ll notice that there is but one period (Tue) where we have a good probability of unsettled weather. The rest of the week will largely remain dry. It is this mid-week stretch where we will have a trough and cold front approach resulting in chillier temperatures and likely rain showers and some snow showers for the Foothills. Let’s get on with the forecast for the week!
Warm Monday!
The week starts out more or less where we left off on our Sunday. With temperatures yesterday in the upper 70’s and some areas around 80, temperatures will largely be at or a few degrees below that on Monday. A deep trough makes its way onshore this afternoon across California, with a near 120 knot jet streak positioned from southern California into Utah. It is this trough that will result in some unsettled and cooler weather tomorrow into early Wednesday.
With the trough inching slowly eastward today and tonight, clouds will be on the increase this afternoon and especially tonight, mostly at the mid and high-levels of the atmosphere. As a result, temperatures will be in the upper 70’s today, a degree or two lower than Sunday with a slight breeze from the southwest. Still a great day to be out and about if you have a chance after work.
Unsettled and cooler Tue/Wed
Come Tuesday, the aforementioned trough of low pressure will dig into Baja California by the evening hours. The system partially becomes cut off from the jet stream and main flow. Even though the main system will dig south of Colorado, it will still send a decent amount of mid-level energy and forcing through the area Tuesday evening.
At the surface on Tuesday, the southward moving trough will allow for a cold front to push through the Front Range around midday (below). Clouds will become rather prevalent, as will chillier temperatures in the upper 50’s to lower 60’s.
Decent upslope, albeit rather weak at times, combined with enough moisture, will favor a period of rain showers from about late afternoon Tuesday to early Wednesday, with the trough and cold front.
There will also be some weak instability in addition to the upslope at the surface (below left) to add to the mid-level forcing. This will be enough to aid in producing convective rain showers across the Plains with a few thunderstorms mixed in.
As for precipitation amounts, the models have backed off somewhat in the last few days, but this will still be a widespread soaking precipitation event for most of northeast Colorado. The GFS ensemble average produces over an inch of liquid for the entire Denver Metro area with this system (below, the large panel in the bottom right). However, we can see from the individual panels that this average is boosted substantially by a handful of ensemble members dumping 2-4″ across the area, a sign that models are likely struggling to resolve the convective elements of this system Tuesday afternoon and evening. A more likely outcome in our opinion will be somewhere between 0.5″ to 1.25″ for the Boulder-Denver area.
Any snow showers tied to the system Tuesday will largely be confined to the High Country and Foothills. This system has really warmed in the models over the last few days, shifting from a rain/snow event for Boulder to an all rain event. Snow levels (below right) for the most part stay above 6000 feet, enough to keep the Denver Metro area in just a chilly rain with this system.
As for the Foothills, though, we’d expect wet snow accumulations come Tuesday night to early Wednesday, perhaps 3 to 8″ above 7500 feet. We’ll also need to watch for a potential change-over to snow late in the game across the Palmer Divide late Tuesday night into Wednesday morning. Unless the forecast guidance trends colder, we don’t see much if any snow in Denver or Boulder. Our Snowfall Probabilities indicate very low odds of seeing a dabble of snow south and southwest of Denver around Centennial and Littleton. These odds are slim, and arise only from the absolute coldest model scenarios. Still, don’t be surprised to see a few snowflakes heading south of Denver as you rise up slightly in elevation late Tuesday night.
Ridge returns late week into the weekend
By Thursday, the trough of low pressure will have moved eastward into Texas. As it does so, a large and expansive dome of high pressure at the surface and at the mid-levels will build northward. This will create an above average height pattern over the Western United States. Can you guess what we should expect from that? If you said warmer weather and sunny skies, you’d be right!
The warmth starts to build Thursday, with highs getting back to the middle to upper 60’s. However by Friday, the warmth will be in full swing, with upper 70’s expected across the region. Notice the large area of positive temperature anomalies aloft from Colorado all the way into Montana.
This warmth will be with us for the weekend as well. Expect partly cloudy skies on Saturday in the lower 80’s, possibly some middle 80’s as well. The GFS is actually hinting at a high temperature close to 90 degrees on Saturday. By Sunday, there is a decent signal in the long-range guidance that the ridge may flatten a tad and get shunted to the south across northwestern Mexico. This would result in slightly lower temperatures and some increasing high clouds. But all in all, temperatures likely still in the upper 70’s so great weather overall this coming weekend.
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Forecast Specifics:
Monday: Sunshine giving way to afternoon cloudy skies. Breezy at times from the southwest with gusts of 20 to 25 MPH. Temperatures in the upper 70’s to possibly 80 on the Plains and upper 60’s in the Foothills.
Tuesday: Mostly cloudy with rain showers and a few thunderstorms likely for the Plains through the afternoon and evening. Snow is expected in the Foothills mainly above 7500 feet, but could see some flakes as low as 6000 feet Tuesday night into early Wednesday. Highs in the upper 50’s to around 60 on the Plains and middle 40’s in the Foothills. Heavy wet snow accumulations are possible in the Foothills, generally 3-8″ above 7500 feet, less than 4″ below that.
Wednesday: Expect morning drizzle on the Plains and light snow in the Foothills. Clouds then give way to partly cloudy skies through the day. Highs in the upper 50’s to 60 on the Plains and middle to upper 40’s in the Foothills.
Thursday: Partly sunny and warmer with highs in the upper 60’s on the Plains and middle 50’s for the Foothills.
Friday: Sunny and much warmer with highs close to the upper 70’s on the Plains and middle 60’s in the Foothills.
Mountains: Cloudy and windy conditions Monday will give way to periods of rain/snow showers Tuesday into early Wednesday. Sunny skies return Thursday and Friday with warming temperatures.
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