It will feel like August, not October, this week as the same old pesky ridging pattern holds across the western United States. As a result, we’ll largely see a continuation of dry and unseasonably warm weather across the Front Range as many days flirt with record high temperatures. Read on for our complete outlook of the week ahead, including discussion of when our next chance of precipitation may edge into the forecast.
This week’s highlights include:
- A ridge of high pressure will dominate our weather this week
- A high fire danger exists on Monday with gusty winds and low humidities
- Near-record warmth possible just about every day with highs in the low to middle 80’s
- It will be mostly sunny through the week with no chance of precipitation
- Our next potential storm system won’t arrive until late in the upcoming weekend at the earliest
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.
No more 90-degree days!
Today isn’t just the fifth day of the tenth month of the year. It’s also the latest date in Boulder’s history for which a 90-degree temperature reading was recorded (10/05/1947). Yes the worst of the heat is now behind us, at least according to climatology. If we do somehow manage to squeak out another 90-degree day, it would be the latest ever in Boulder, but no one wants that! We wouldn’t put it past 2020 to ink another record into the books, but for now we’ll consider this “case closed” on one of the most persistently hot summers in recent history. 2020 will likely conclude with a count of 51 90°F days in Boulder. This ties for 6th place all-time dating back to the late 1800’s. The city still came up surprisingly short of the top calendar years, as shown in the table below.
Despite keeping close pace with the higher years through the summer, as shown in the cumulative 90-degree day plot below, 2020 never turned the corner and moved up the ladder.
The persistent ridge slowly shuffles east
The blocking ridge of high pressure that has helped to keep Colorado mostly dry over the last several weeks will slowly shimmy eastward as the week progresses. On this Monday, there are two centers of high pressure connected by a ridge axis spanning from northern California into southern Arizona. This axis, as shown below, will slide east and across Colorado by late-week.
Right now our steering winds are out of the northwest which has kept our temperatures here in the Denver Metro area in-check with frequent but weak cold fronts moving through. This direction of winds will change to west and eventually southwest through the week. The GFS ensemble forecast animation below shows the large-scale pattern’s evolution from Monday through Saturday night. Hopefully you can pick out our anomalous ridge (red shading) meandering eastward from the beginning to the end of the animation.
In short, this overhead ridge will allow for the persistence of warm and dry conditions across our area. There really isn’t any moisture or organized lifting mechanisms to support precipitation in the atmosphere. In fact, clouds will be rather hard to come by many days this week. It’s remarkable just how consistent our temperatures will be over the next five or six days. Readings at the 700mb level (near 10,000 feet elevation) are forecast to remain right around +13°C each afternoon, as shown in the series of panels below. With mainly clear skies and no surface fronts expected, these temperatures aloft will mix nicely down the surface and equate to highs for us peaking in the low to middle 80’s each day.
This time of year, we could actually see a few record highs pop with this extent of warming. Middle 80’s is about all it takes in early October to set records. Here’s a look at our forecast highs in Boulder versus the record highs for each day this week. As you can see, we’ll be in the running for new records every day after Monday.
There are notable model differences on just how quickly a trough set to come ashore late this week in the Pacific Northwest may influence our weather here in Colorado. Let’s just say that the pattern will be on the verge of change over the upcoming weekend. We could see a cold front and a decent Pacific storm system move through late Saturday, but it’s also possible the front holds off a few more days. Whenever it does arrive, it should spread clouds and precipitation into the higher elevations along with cooler temperatures to the entire state. Some precipitation will also be possible across the Front Range Plains, though we are not optimistic for anything significant at this time. It should also be cold enough for snow in the Mountains with this system, but the origins of the storm will limit the cold air for snow in the Foothills and certainly the Plains. We’re likely to see just rain from this system if and when it does arrive.
That’s all for now. If you haven’t read our La Niña update and outlook for autumn, you can find it at the link below. Have a super week!
Forecast Specifics:
Monday: Just a few afternoon clouds, warm and breezy with high fire danger region-wide. Gusts up to 25 MPH will be possible during the day. Highs in the lower 80’s on the Plains and near 70 degrees in the Foothills.
Tuesday: Mostly sunny and warm with near-record highs. Temperatures in the middle 80’s for the Plains and lower 70’s in the Foothills.
Wednesday: Lots of sun and warm with highs in the middle 80’s on the Plains and lower 70’s in the Foothills.
Thursday: Potentially the warmest day of the week with mostly sunny skies. Highs in the mid 80’s or better on the Plains and lower 70’s in the Foothills.
Friday: Partly cloudy, continued near-record warmth, and dry with high temperatures in the middle 80’s on the Plains and lower 70’s for the Foothills.
High Country: Another boring week is expected for the higher terrain. Dry conditions and sunny skies will persist over most areas and hiking destinations. This will lead to continued prime fuels for wildfire spread and development. Fortunately the wind will be rather light, except on Monday where Red Flag Warnings are already posted. Check our SummitCAST page for daily updated forecasts for more than 120 mountain hiking destinations across Colorado. Here’s the peak top forecasts for sustained wind speed on all the 14ers on Monday.
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