Milliken, Colorado Weather Forecast Discussion

454
FXUS65 KBOU 301956
AFDBOU
Area Forecast Discussion
National Weather Service Denver/Boulder CO
156 PM MDT Tue Sep 30 2025
.KEY MESSAGES...
- Isolated, high-based showers late Tuesday afternoon and evening.
- Dry with warmer than normal conditions Wednesday through Friday.
- Cooler temperatures along with unsettled weather likely
  returning for the weekend.
&&
.DISCUSSION /Through Tuesday/...
Issued at 105 PM MDT Tue Sep 30 2025
A narrow moisture layer aloft has allowed for plenty of shallow
stratocumulus to develop over the high country, but stable upper
levels have thus far ensured echo-free radar scans as of ~1pm.
Forecast soundings suggest that this stable layer near 500mb
should erode by late afternoon across most of the region, leading
to marginally unstable conditions and a better shot at expansion of
isolated to scattered showers into the urban corridor and plains,
along with a potential thunderstorm or two through this evening.
Cloud bases look to be quite high, with the saturation level
closer to 600mb, so precipitation shouldn`t be as heavy or
widespread relative to previous days. With healthy low-level lapse
rates exceeding 9 C/Km, gusty outflow winds to around 40 mph
would be the main threats from any late day and high-based
convection. For tonight, a lifting jet maxima will provide a boost
to winds in the foothills and mountains, and the subsident flow
will make for a mild night area-wide.
High pressure to our south and east will gain increased prominence
Wednesday through Friday, keeping northeast Colorado dry and
making for progressively warmer conditions. Temperatures look to
peak Friday, particularly for the lower elevations, where highs
will climb to the mid to locally upper 80`s - approximately 15
degrees above average. Winds look to pick up slightly on Friday
ahead of an approaching trough, and would favor areas of elevated
fire weather conditions in our southern plains where humidity will
be lowest, although recent precipitation will serve to buffer the
threat.
The next feature to watch will be a developing closed low over
California and Nevada around Friday, which ensemble guidance
indicates will accelerate northeastward as we enter the weekend
and bring us our next shot at meaningful precipitation. The latest
guidance has trended quicker with the progression of this low,
rapidly merging the dissipating shortwave into the broader
longwave flow by Sunday, which would limit precipitation potential
to a degree. Regardless, it still appears we should see a
transition to more unsettled weather for the weekend and notably
cooler temperatures, with higher confidence in precipitation
potential for the high country and northern counties given the
more northerly track depicted by current ensemble mean solutions.
There is little model consistency thereafter, however it looks
likely that a general troughing pattern will be favored for the
western half of the CONUS into early/mid next week, thereby
providing additional opportunities for active and cooler weather.
&&
.AVIATION /18Z TAFS through 18Z Wednesday/...
Issued at 1122 AM MDT Tue Sep 30 2025
VFR conditions will prevail for all terminals through the TAF
period. Similar to prior days, expect transition to predominantly
easterly flow mid-afternoon. ISO-SCT high-based showers will push
east through Denver area 23-03Z, with between 20-30% chance of
-SHRA and VRB outflow impacts (up to 25 kts) at the terminals.
 Chances will be highest for KDEN (hence PROB30), and marginally
 lower for KBJC and KAPA.
Expect any shower activity to push east into the plains after 03Z
this evening, with winds returning to southerly drainage flow for
the afternoon period.
Typical diurnal wind patterns anticipated for Wednesday, with no
convection/shower activity forecast.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION...Rodriguez
AVIATION...Rodriguez

NWS BOU Office Area Forecast Discussion