669
FXUS65 KBOU 131133
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
533 AM MDT Tue Oct 13 2026

.KEY MESSAGES...

- Change in the weather to cool, wet conditions is still on track.

- Showers will become more numerous in and near the mountains late
  Tuesday and Tuesday night, but then more widespread rain and
  mountain snow still on schedule for Wednesday - Wednesday night,
  before winding down Thursday.

- Several inches of snow expected for the mountains above
  9,500-10,000 feet with some travel impacts late Wednesday -
  Thursday morning. Lighter snow and at least a dusting into the
  mountain valleys and higher foothills.

- Drier and warmer again for next weekend.

&&

.DISCUSSION /Through Monday/...
Issued at 1018 PM MDT Mon Oct 12 2026

An upper level low will be over central Nevada by 12z Tue and then
will move to near the Four Corners area by 12z Wed.  Will gradually
see a better chc of showers along with a few tstms by Tue aftn in
the mtns.  Across the plains, cooler temps will occur behind a front
as weak upslope flow develops.  Highs will drop into the lower to
mid 60 across nern CO. Any chc of showers by late aftn will be
confined to areas closer to the foothills.

By Tue night, will see widespread showers across the higher terrain
with snow levels lowering to 9500 ft overnight.  Across the plains,
best chc of showers overnight will be mainly along the I-25 Corridor
with lessor chances further east.

For Wed thru Wed night, the main question is where will the upper
level low track, as it begins to move from swrn CO east northeast
towards ern CO. The Canadian, ECMWF and NAM have a more northern
track as it moves into nern CO by 12z Thu. Meanwhile, the GFS has
a more southern track with the upper level low being over east
central CO. Looking at ensemble data from the ECMWF and GFS shows
a more northern solution with the low being over nern CO.
Meanwhile, sfc high pres will continue to build into nern CO with
the low level flow becoming ESE. Overall, with favorable QG ascent
should continue to see showers/isold tstms over the higher
terrain thru the aftn with snow levels down to 9000 ft by late
aftn. Across nern CO, should see showers thru the aftn, especially
along the I-25 Corridor with a chc across the plains. Highs on
Wed, will only be in the mid 40`s to lower 50`s over nern CO.

By late Wed night into Thu, additional precipitation will depend on
the exact track of the upper level low.  If it takes a more northern
track across nern CO, then best chc of precipitation will be across
the higher terrain along and north of I-70 and over nrn portions of
the plains.  Naturally, if it were to take a more southern track
across east central CO, then much of the area would have additional
widespread precipitation late Wed night thru midday Thu.
Meanwhile snow levels Wed night into Thu morning may drop down to
8000 ft or so. At this time, snow amounts look to be mainly in the
advisory range for mtn areas, except over the higher peaks which
may have higher amounts.

For Thu aftn into Thu night, the upper level low will weaken and
move east of the area. Thus, will see precipitation gradually end
during the aftn hours in most areas. Highs on Thu will be in the
50`s across the plains. For Thu night into Fri morning, some areas
across the plains may see freezing temps with frost possible in
those places that don`t get down to freezing.

Looking ahead to Fri and Sat, an upper level ridge will develop over
the area.  This will lead to dry conditions with a warming trend.
Highs will rise into the upper 50`s to mid 60`s on Fri, over nern
CO, and then into the lower to mid 70`s by Sat.

On Sun, a very weak upper level trough will move across the area.
Latest cross-sections show very little moisture associated with this
feature. Thus it will remain dry with above normal temperatures.

&&

.AVIATION /12Z TAFS through 12Z Wednesday/...
Issued at 428 AM MDT Tue Oct 13 2026

Low clouds have moved over the TAF sites bringing ceilings around
700ft to 1700ft. Low clouds will continue into the late morning,
brining MVFR and potentially IFR conditions to KAPA and KBJC and
ILS to KDEN. Ceilings should start to lift and clear around 17Z.
Rain chances will start to increase in the late afternoon for KBJC
and this evening for KDEN and KAPA. Showers are expected to move
east off of the higher terrain, but coverage on the plains will
be more limited through this evening and overnight. The best
chance for showers during this period will be at KBJC. Low clouds
are expected to return around midnight at all TAF sites, with
potential for IFR and ILS conditions. Rain chances and coverage
will continue to increase tomorrow.

&&

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

&&

$$

DISCUSSION...RPK
AVIATION...AP

NWS BOU Office Area Forecast Discussion