468 FXUS65 KBOU 271126 AFDBOUArea Forecast Discussion National Weather Service Denver/Boulder CO 526 AM MDT Sat Sep 27 2025
.KEY MESSAGES...
- Warm and dry today.
- The next disturbances will be weak, bringing a chance of light precipitation Sunday to Wednesday, mainly for the mountains.
- Temperatures will remain above normal most days.
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.DISCUSSION /Through Friday/... Issued at 233 PM MDT Fri Sep 26 2025
The upper level ridge axis is expected to amplify across the forecast area Saturday, limiting any moisture advection from the Desert Southwest. As a result, we expect another mostly sunny day, although temperatures will be a few degrees cooler thanks to a cold front that will be moving across the northeast plains this evening. However, the forecast highs in the mid to upper 70s over most of the plains and I-25 Corridor will still be a degree or two above normal.
On Sunday, models are still consistent shifting the ridge axis to our east, and shearing the upper low in the deep Desert Southwest. This will allow moisture advection to begin, although with southerly flow the best moisture advection and main shower/storm chances Sunday afternoon and evening will remain over the mountains. It appears that most lower elevation areas will stay dry, with only an isolated high based weak storm/sprinkle given high cloud bases and limited instability. That should change a little by Monday as models do show the shearing trough pushing northeast across Colorado. As a result, we expect a little more forcing, higher moisture, and a better chance of scattered showers/few storms spreading onto the plains.
By Tuesday, we`ll likely be in between disturbances but more uncertainty enters the picture since there are some timing differences between models/ensemble members. The best consensus is for a weak shortwave passage late Tuesday night or Wednesday with another chance of showers and a few storms. However, any precipitation is expected to be light with limited moisture availability and minimal instability.
We then see another totally dry day or two Thursday into Friday, before the next weather disturbance arrives in west/southwest flow aloft. It should be noted there`s quite a bit of uncertainty regarding timing here.
Temperatures will average a few degrees above normal through this entire forecast period; highs mostly in the mid 70s to lower 80s degree range in lower elevations, mid 60s to lower 70s foothills and high valleys, and 50s to lower 60s mountains.
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.AVIATION /12Z TAFS through 12Z Sunday/... Issued at 526 AM MDT Sat Sep 27 2025
VFR through the TAF period. We`ll see mainly light and variable winds through 18Z as southerly drainage winds battle a weak northerly flow. After 18Z, southeast winds begin to develop and increase around 21Z with gusts up to 25 knots. Southeast to south winds are then expected to persist through Saturday evening and Saturday night.
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.BOU WATCHES/WARNINGS/ADVISORIES... None.
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DISCUSSION...Barjenbruch AVIATION...Meier
NWS BOU Office Area Forecast Discussion