Welby, Colorado Weather Forecast Discussion

064
FXUS65 KBOU 051937
AFDBOU
Area Forecast Discussion
National Weather Service Denver/Boulder CO
137 PM MDT Fri Sep 5 2025
.KEY MESSAGES...
- Still hazy/smoky in/near the mountains today, possibly lasting
  through Saturday.
- Increase in coverage of showers and storms today
  through this weekend, but mainly over the higher terrain.
- Warmer with fewer showers and thunderstorms next week.
&&
.DISCUSSION /Through Friday/...
Issued at 137 PM MDT Fri Sep 5 2025
An upper level ridge centered over the Great Basin will produce a
northwest flow aloft. This will continue to help transport
wildfire smoke from the Pacific Northwest and western Canada into
Colorado today and Saturday. There will be enough moisture and
instability for scattered showers and thunderstorms. The
showers/storms will be most numerous across the higher terrain
south of I-70. For the lower foothills and eastward, cloud cover
and smoke will help keep the airmass cool and capped. Chances for
showers or storms to move off the higher terrain are low. If a
couple happen too, they are expected to be weak and short lived.
Much of the same is expected for Saturday, though high
temperatures warm up into the mid to upper 70s.
The ridge flattens some by Sunday as it begins to drift eastward.
Temperatures warm more with highs expected to reach to the lower
to mid 80s across northeast Colorado. Another round of afternoon
and evening showers and thunderstorms are expected over the higher
terrain. Chances for showers and thunderstorms will be higher
across the urban corridor and eastern plains Sunday, due better
instability, weaker cap, and westerly flow pushing the storms more
eastward.
For next week, the upper level ridge will slide east across
Colorado Monday. This will bring warmer temperatures with highs
climbing into the 80s across northeast Colorado. There may be
enough moisture for weak showers and storms over the higher
terrain, but most areas should remain dry.
The upper level ridge will be east of Colorado Tuesday and stays
east of the state through Thursday. This will produce a southwest
flow aloft through at least Thursday. High temperatures will be
above normal under this pattern with mid to upper 80s expected
over northeast Colorado each day. The GFS and ECMWF ensemble
members don`t favor any organized waves or precipitation events
Tuesday through Thursday. However, there`s just enough moisture
for isolated/scattered showers and thunderstorms, mostly over the
higher terrain each day.
For Friday and into next weekend, models trending towards an
upper level trough digging south into the Desert Southwest or
southern California. This should produce some sort of southwest to
southerly flow aloft across Colorado. Too soon to tell how much,
but this pattern should be able to tap into some subtropical
moisture. Will trend temperatures down and PoPs up for this
pattern, but if this pattern is slow to evolve, we could see
another warm and dry day.
&&
.AVIATION /18Z TAFS through 18Z Saturday/...
Issued at 1150 AM MDT Fri Sep 5 2025
VFR conditions expected through this evening. With expected
increasing wildfire smoke aloft, smoke will linger through today
and tomorrow for all TAF sites, which will cause slant-range
visibility issues. Short term models do hint at a reprieve in the
early morning hours tomorrow. However, due to the uncertainty,
kept smoke in the TAF for the period. In addition, with the lower
ceilings being slow to erode this morning, have kept a BKN050
through 02Z at the latest.
Winds should gradually turn NE for all TAF sites later this
afternoon as a cyclone moves out of the area. There is a chance of
showers for APA as early as 22Z, but should not impact BJC or DEN.
However, can`t rule out an outflow boundary pushing through DEN,
causing brief SW winds. Light drainage winds are expected
overnight.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION...Meier
AVIATION...Ideker

NWS BOU Office Area Forecast Discussion