We have a late-season soaker headed to Colorado this week and it will deliver some delicious rain to the mountains. It will also bring lighter amounts or rain (though still beneficial) to the Front Range. This is a fun forecast.

Cue Lady Gaga’s song, Rain On Me. Colorado is going to be wedged in between a deep, strong cut off low over California to the west and a large high pressure to the east. This will allow for a deep, moist fetch of sub-tropical air to move and stay over the region for much of this week.

For some, rain will fall Monday-Friday. For others Tuesday-Thursday will be the wettest days. Let’s talk about it.

Quick forecast:

MONDAY: Southwesterly flow will bring some light rain showers to the San Juan mountains Monday afternoon but the ridge of high pressure will be more dominant on Monday so expect mostly clear and hotter conditions.
TUESDAY: The sub-tropical moisture begins to work into western Colorado. Expect rain showers and heavy thunderstorms with flooding concerns Tuesday west of the Continental Divide. Mainly warm and dry along I-25.
WEDNESDAY: Cold front moves through in the morning. Deep moisture in place. Wettest day of the week with widespread rain and cool temps statewide. Cloudiest, coolest, most fall like day with widespread rain.
THURSDAY: Cloudy and rainy before slight clearing in the afternoon. Still cool.
FRIDAY: Drying out and warming up.

Forecast discussion:

A pretty strong cut off low is impacting California and bringing them some much needed rain. This will dampen the fires and smoke that are impacting people out there while bringing flooding concerns to some areas. This cut off low will begin to push from Northern Cali towards Idaho and Wyoming. As it does, it’ll continue to pull tropical moisture in towards the Rockies.

Additionally, a strong high pressure system will be sitting over Texas and will bring additional sub tropical moisture in to the Colorado area. The flow around this high pressure system is the same as during the monsoon. Monsoon season is ‘technically’ over but since it’s not a strict season, this could still be considered monsoon flow. These two features will combined will bring extremely moist air to the state. We’re talking 200-300% of normal moisture levels.

Atmospheric River to impact Colorado

The greens, blues and occasional pinks on the map above is the plume of moisture poised to impact us this week. We rarely see that pink level of moisture over Colorado since we’re so far inland so this is truly going to be a wet storm. No doubts.

Region-wide, some heft rain’s are expected from this event.

For Colorado, look at all that moisture! This is going to be such a great event to occur just before the winter season takes hold. This will also be great for leaf peepers. A drenching like this really helps to push colors out of the leaves so expect peak color in the next one to two weeks (depending on elevation).

Here’s a look at Colorado’s rain forecast this week in motion. Notice not much action Monday or Tuesday morning but then from Tuesday evening to Thursday evening, the bulk of the rain will fall.

Some areas of Colorado are looking to get between 2″ and 3″ of rain! This will be huge for drought concerns. I’d anticipate flood watches being issued anytime now for the incoming rain. Burn scars will have the biggest concerns but other areas could see flooding as some of this rain – especially Tuesday – is looking to be very heavy at times.

*5:00pm update* Flood watches have been issued across Colorado. Remember, flood WATCH means WATCH out for flooding. A warning means flooding is happening or imminent.

You’ll note that a lot of the moisture will be in the mountains while the Front Range does not get as much. With that said, still some beneficial rain will fall over the I-25 corridor.

The Urban Corridor should end up with a half inch to an inch of rain by Thursday while mountain locations get 1-3″ of rain.

There is no snow expected from this system since it has warm, tropical origins.

Here’s a look at several 7-day forecast for around the state.

Most areas will see some cool weather midweek this week. Wednesday will be a very cloudy, wet, overcast day so expect that.

Looking past this storm, it looks like we’ll be trending drier and warmer again. The end of this month should end with decent weather statewide.

Enjoy the wet forecast this week!

~Andy
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3 Comments on “Atmospheric River to Bring Cool, Drenching Rains to Colorado This Week.

  1. Have a kid headed to Outdoor Lab in Bailey this week, are they close enough to town to have an effectively identical forecast?

    • I would say Bailey has a better shot at seeing rain Tuesday and Thursday and it will definitely be wet Wednesday. So, yeah pretty much haha

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