557 FXUS65 KBOU 080005 AFDBOUArea Forecast Discussion National Weather Service Denver/Boulder CO 605 PM MDT Sun Sep 7 2025
.KEY MESSAGES...
- Better chance for storms across the plains through early evening. A couple storms could be strong/severe over the far eastern plains.
- High based isolated showers/storms Monday. Very little to no rainfall, but gusty winds of 40-50 mph possible.
- Better chances for showers/storms (and rainfall) mid to late next week.
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.DISCUSSION /Through Sunday/... Issued at 207 PM MDT Sun Sep 7 2025
Scattered showers and thunderstorms will continue to track eastward across the area. Brief moderate to heavy rain and winds to 40 mph will be possible with most of this activity. Across far eastern Colorado, better moisture and instability will reside east of a surface trough and may lead to a couple strong to briefly severe thunderstorms through the early evening hours.
Upper level ridging slides east over Colorado for Monday. This will bring warmer and slightly drier air with it. Models in good agreement showing very little rainfall, but the hi-res models show high-based showers and a few weak storms Monday afternoon. So we likely see isolated showers/storms with very little to no rainfall and gusty outflow winds of 40-50 mph. Temperatures trend warmer as well with highs in the mid to upper 80s over northeast Colorado.
The ridge slowly slides east of the state Tuesday with southwest flow aloft prevailing behind through Thursday and beyond. This will keep temperatures above normal with highs in the mid to upper 80s over northeast Colorado. Would not be surprised if we end up seeing a few low 90s as well. Precipitable water values are slightly above normal ranging from 0.75 (in) to one inch over the plains. Enough moisture for isolated/scattered showers and thunderstorms. There is an uptick in moisture for Thursday along with a shortwave trough. This is expected to lead to better chances for showers and thunderstorms.
For Friday and next weekend, the upper level ridge off to the east amplifies and stretches into the Great Lakes and possibly into Canada. This will start to block the flow aloft to the west across western North America. Models generally show some sort of an upper level longwave trough or closed low over western Canada and the northwest part of the country. A lot of uncertainty what the main pattern will look like. Colorado should be at the base of whatever trough/low that forms off to the northwest. This is expected to keep temperatures at or above normal. Precipitation chances will depend on the amount of moisture that is able make it into the region. Southwest flow aloft could transport desert air into the area, so will generally keep PoPs in the 10-30 percent range at this time.
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.AVIATION /00Z TAFS through 00Z Tuesday/... Issued at 547 PM MDT Sun Sep 7 2025
VFR conditions through the TAF period. Isolated showers and thunderstorms are still possible for all TAF sites through 02Z this evening, with VRB wind gusts up to 35 kts. Winds should turn east/southeast behind the convection before returning to drainage overnight.
Tomorrow, southwest winds should weaken and turn northerly by 18Z. Another round of isolated to scattered showers/thunderstorms is expected between 21-02Z with gusty outflow winds as the main threat.
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.BOU WATCHES/WARNINGS/ADVISORIES... None.
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DISCUSSION...Meier AVIATION...Ideker
NWS BOU Office Area Forecast Discussion