324
FXUS65 KBOU 152340
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
540 PM MDT Wed Oct 15 2025

.KEY MESSAGES...

- Isolated evening showers and thunderstorms possible, but a
  decreasing threat. A few gusts to around 60 mph if a stronger
  storm develops.

- Patchy frost expected for portions of the plains Thursday
  night/Friday morning, with more widespread freeze anticipated
  Saturday night for the rural plains.

- Cooler and breezy most days through this weekend. Next potential
  for more widespread precipitation arrives Monday.

&&

.DISCUSSION /Through Wednesday/...
Issued at 1254 PM MDT Wed Oct 15 2025

After a morning of dense fog for many locations along and north of
I-76, the stratus has finally eroded, not without leaving a swath
of notably cooler air in these areas. In the meantime, healthy
southerly flow continues to overspread the southern half of our
forecast area, with clear skies and the downslope pattern off the
Palmer Divide boosting temperatures to around 80F in the warmest
locations. This surface warming will allow for modest instability
to develop this afternoon (MLCAPE 300-700 J/Kg across the eastern
plains). Water vapor imagery already depicts some elevated
convection to our east embedded within a moist warm advection
layer aloft, and convection should develop over/near the Palmer
Divide by mid to late afternoon as we tap into this elevated
moisture. Steering flow will remain robust, thus keeping storms
moving very quickly, but simultaneously increasing the outflow
wind potential with any storms that do develop. A severe storm
can`t be ruled out late afternoon or early evening, primarily from
the wind threat (the strongest storms could produce localized
gusts up to 70 mph) and favoring Lincoln/Washington Counties, but
confidence isn`t overly high. For the lower elevations,
thunderstorm activity should remain confined to locations south of
I-76. Radar shows a well-defined DCVZ boundary currently south of
Denver International Airport and, while some northward migration
of this boundary can be expected throughout the afternoon, it
seems unlikely to cross that I-76 corridor.

Come this evening, most areas will stand a chance (20-50%) of
seeing some pre-frontal showers as the trough axis and jet max
approach. The bulk of the shower activity will be focused over our
northern mountains, where light snow could accumulate to around 1"
above 9,500 ft by Thursday morning (mainly for the Park and
Medicine Bow Ranges). Expect cooler temperatures Thursday
following the associated morning cold front, with the change being
most pronounced in our mountains (15 to 20 degrees cooler than
today). Showers will generally subside by the afternoon, save for
perhaps our far northeast corner. With clearing skies and our
post-frontal airmass in place, patchy frost will return to
portions of the plains, particularly around the South Platte River
Valley and in Lincoln County, prompting the issuance of a Frost
Advisory for these locations. Seasonal conditions are in store
for Friday under weak flow aloft as the trough shears off, with
highs in the 60`s for the plains and urban corridor, and 40`s to
50`s for our mountain communities.

Saturday`s weather will be influenced by an amplifying trough
dipping down from the northern plains. Brushing us to the
northeast, it will usher in slightly cooler temperatures once
more, including overnight when lows look to fall below freezing
for much of the plains. Additionally, breezy conditions will
become increasingly widespread. The shortwave would also support
at least a chance (~30%) for some light snow showers in our
northern mountains during the day.

Highly transient ridging will follow suit for Sunday, bringing
about 10 degrees of warming and keeping all areas dry. Eyes then
turn to Monday, with ensembles highlighting another developing
trough over the PacNW approaching the Central Rockies. This
feature will give way to our next opportunity for more widespread
precipitation, although uncertainty in the track remains
particularly notable and could significantly impact precipitation
chances. Nonetheless, the airmass should be colder, supporting
snow for most of our higher elevations and, if the coldest
solutions were to verify, perhaps introduce some wintry
precipitation to the lower elevations Monday night into Tuesday.
Plenty of time for those details to change still, of course.
Finally, will need to monitor the spatial extent of any lingering
drier airmass on Monday, which if remaining far enough north, may
result in locally critical fire weather conditions for portions
of our southern plains Monday as winds strengthen.

&&

.AVIATION /00Z TAFS through 00Z Friday/...
Issued at 536 PM MDT Wed Oct 15 2025

VFR is expected to continue through the TAF period. A nearly
stationary surface boundary continues to be the focal point of the
near term forecast. This boundary currently sits between DEN/CFO
and extends towards Parker/Castle Rock (south-southeast of APA).
Radar trends suggest this is just beginning to retreat back to the
west and could eventually produce wind shifts at DEN/APA by
02-03z. There is also a limited chance of a shower or thunderstorm
developing near this boundary, though that potential continues to
diminish as we`ve remained mostly capped in the area.

Southeast winds behind that boundary will eventually transition to
drainage winds later this evening, and should continue into the
overnight hours. A gradual clockwise turn to the winds is
expected during the day Thursday, with west-northwest gusts likely
by the afternoon.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from 2 AM to 8 AM MDT Friday for COZ042-043-046.

&&

$$

DISCUSSION...BRQ
AVIATION...Hiris

NWS BOU Office Area Forecast Discussion