Silver Plume, Colorado Weather Forecast Discussion

205
FXUS65 KBOU 292342
AFDBOU
Area Forecast Discussion
National Weather Service Denver/Boulder CO
542 PM MDT Mon Sep 29 2025
.KEY MESSAGES...
- Scattered showers and thunderstorms this afternoon and early
  evening.
- Isolated weak showers and thunderstorms Tuesday PM.
- Temperatures will remain above normal through Friday.
- Precipitation potential will increase again come Saturday.
&&
.DISCUSSION /Through Monday/...
Issued at 114 PM MDT Mon Sep 29 2025
Showers and thunderstorms have thus far remained confined to the
mountains and Palmer Divide, mainly east of the Continental
Divide, with diurnal northeasterly flow aiding in initiation and
providing some surface convergence to keep things going. Largely
southerly flow aloft is also hampering their ability to extend
into the lower elevations, but with ACARS soundings showing the
weakly capped environment over the urban corridor inching closer
to eroding, the activity over the southern foothills and Palmer
Divide should begin to migrate north and drift into portions of
the Denver metro and plains with isolated to scattered coverage
later this afternoon. Instability and shear parameters are not
too robust however, and will certainly limit any organization.
Thus, main hazards with any convection will continue to be briefly
heavy rain, gusty outflows up to ~40 mph, and some small hail
with the strongest storms. Activity will dwindle quickly as we
enter the early evening hours, with a slightly cooler but still
milder than normal night in store for most.
The open wave evident at 500mb over Colorado today will depart to
the northeast tomorrow as it continues to fizzle. Southwest flow
will remain in place aloft stemming from a deepening low pressure
system offshore of the PacNW, but conditions will be inching drier
and less unstable. This should lead to much more isolated
coverage for afternoon showers or a weak thunderstorm, with the
best chances again in the high country.
For the Wednesday through Friday period we`ll see a reinforcement
of warmer than average conditions, with the increasingly negative
tilt of the western US trough keeping our area on the northwestern
periphery of the high pressure centered over the southern CONUS.
Highs will range from to upper 70`s to mid 80`s for a majority of
the plains and urban corridor. Precipitation chances will be near
zero for this period, although a few showers may creep into the
high country come Friday if the trough can speed up enough.
Ensemble guidance seems to be loosely coalescing around a
transition to a wetter pattern by Saturday as a closed low or
shortwave lifts into the Rocky Mountain region, with more
uncertainty as far as how this would progress Sunday onwards. Some
winter weather impacts can`t be ruled out for the mountains over
the weekend depending on system trajectory, but not much can be
said beyond that yet. At the very least, almost all ensemble
members suggest a return to at minimum near-seasonal
temperatures, if not below average, by Sunday.
&&
.AVIATION /00Z TAFS through 00Z Wednesday/...
Issued at 533 PM MDT Mon Sep 29 2025
VFR conditions likely through the TAF period. Ongoing convection
is continuing to quickly weaken, per satellite and lightning
trends. Expect at least some SHRA to continue at DEN over the next
hour or two. Main impacts will be from some shifting winds, with
two distinct mesovortices noted on KFTG/TDEN velocity products.
The combination of those and continued outflow from collapsing
convection may be enough to push wind directions around a bit
through 02z. Drainage winds should be quick to develop this
evening.
Tomorrow looks to see a typical diurnal wind pattern, with
drainage becoming light and variable, and eventually turning to
some sort of east component. There are some hints of a few high
based showers again tomorrow afternoon, but overall coverage does
not appear high enough to justify any sort of PROB or TEMPO group.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION...Rodriguez
AVIATION...Hiris

NWS BOU Office Area Forecast Discussion