598
FXUS65 KBOU 252347
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
547 PM MDT Sun Oct 25 2026

.KEY MESSAGES...

- Another round of showers and even a couple thunderstorms tonight
  into early Monday morning.

- Generally light snow accumulations in the mountains, with minor
  travel impacts over some of the high passes through early Monday
  morning.

- Warming trend and mostly dry much of upcoming week.

- Unsettled weather potentially returning next weekend, but odds
  favor western and southern Colorado once again.

&&

.DISCUSSION /Through Sunday/...
Issued at 136 PM MDT Sun Oct 25 2026

Satellite shows the upper level low over northeast Utah, with a
couple shortwaves rotating around it. The most impressive one was
now lifting quickly northward through central and eastern New
Mexico on the heels of an 80 kt upper level speed max. Other
showers and thunderstorms were developing in the slightly unstable
and still moist airmass over western and central Colorado ahead
of the upper level trough. It appears both of those features will
generate the highest coverage of showers at least early tonight
as there is ascent associated with each. That supports the
eastern plains and most of the mountains, while the I-25 Corridor
would see lower but still scattered coverage of mainly light
showers.

Later tonight into early Monday morning, another speed max is
forecast to eject from the base of the trough as it lifts into
the Central and Northern High Plains. By the time that shortwave
organizes again, the main precipitation shield is expected to be
mostly over the northern and far eastern plains. We still have
about a 30-50% chance of seeing a half inch of rain over the
northern tier of counties, with those odds decreasing rather
quickly to the south including most of the I-70 Corridor and
Denver metro. In fact, our deterministic forecast (essentially
50th percentile) has less than a tenth of an inch for Denver metro
area and only about a 50% chance of a measurable rain. For the
mountains, we still think the northern tier of mountains (e.g.
Park/northern Gore/Medicine Bow Ranges and Rocky Mountain National
Park) would see a 1-4" snow, while the rest of the mountains
including the I-70 Corridor through Summit County would see a
dusting to 2". Brief heavier showers and colder temperatures
overnight would allow some travel impacts on some of the higher
passes, but overall a pretty light snow event.

Precipitation will quickly end behind the trough passage early
Monday morning, with some sunshine returning. However, it may take
some time to clear as the plains will be shrouded in low clouds
and areas of fog in the morning, and mixing will be slow given
weak boundary layer winds and stronger inversions. Thus, another
cool day with temperatures generally at or slightly below seasonal
normals is on tap for Monday.

For Tuesday, a stronger zonal flow will develop, leading to dry
weather, more sunshine, and warmer temperatures due to increasing
downslope. Breezy conditions will develop over the mountains and
high valleys with moderate pressure gradients in place. Similar
conditions can be expected Wednesday and Thursday, with
temperatures warming a couple more degrees and highs pushing near
70F on the plains and I-25 Corridor.

There is still considerable uncertainty in next weekend`s weather
as seen in the ensemble output. There are indications a
subtropical push could occur as early as Friday but the main
impacts of this first wave would likely stay southeast of our
forecast area. A larger trough along with a possible pineapple
connection is forecast to move into the southwest U.S. next
weekend, but models are all over the place regarding it`s eventual
track and evolution. At this point, it still looks like areas
over southern and western Colorado would be most prone for more
significant precipitation.

&&

.AVIATION /00Z TAFS through 00Z Tuesday/...
Issued at 540 PM MDT Sun Oct 25 2026

Current radar shows some scattered showers in the foothills as
well as the shear zone/DCVZ located to the southeast of KCFO.
Wind speeds have increased in the last hour, but gusts should stay
at 15 kts or less over the next several hours. Scattered showers
are possible through this evening and overnight with PROB30s
lasting through 9/10z. There is the possibility that showers could
linger past then, but the CAMs have not done a good job of
resolving this potential, so confidence is low (~10-20%). Any
shower could lower ceilings to about 4 or 5 SM. Lighter winds
under 10 kts are expected once the showers pass. Winds could be a
little stronger at KBJC, but should stay under 12 kts. As for the
wind direction, winds look to be northwesterly with perhaps a
slight turn to the west as we get into early Monday morning.

Later tonight, the attention turns to lowering ceilings and fog.
MOS guidance remains in good agreement that we will be contending
with low ceilings and/or fog at all three sites as early as 5-7z
later this evening. It still looks like 10-14z is the period of
highest confidence for the potential of the most impactful
conditions as low-level advection from the north continues causing
MVFR conditions. Visibility could get as low as 3/4 SM to 2 SM
during this period when a TEMPO is in place which could even cause
IFR conditions. Have nudged the ceilings lower and lengthened the
TEMPO at KBJC in the latest TAF given the latest guidance.

Low ceilings will be slow to clear in the morning as the low
levels remain saturated, first lifting at KAPA, then KDEN, and
finally at KBJC. A sct deck around 2000 to 4000 ft AGL looks
likely for much of the day at the three sites. Winds for Monday
afternoon will be northerly and then eventually turn to the east
for the afternoon and stay under 12 kts. Monday evening, winds
start to briefly turn to drainage, but just after this TAF period
look to turn to the north. This has the potential to advect in low
clouds and/or fog on Tuesday morning once again, which could need
to be addressed in the next TAF period.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION...20
AVIATION...MV

NWS BOU Office Area Forecast Discussion