929
FXUS65 KPUB 312039
AFDPUB

Area Forecast Discussion
National Weather Service Pueblo CO
239 PM MDT Sat Oct 31 2026

.KEY MESSAGES...

- High impact heavy precipitation/flooding event still on track
  for the eastern San Juans and portions of the San Luis Valley
  Sun/Mon, with flooding along the mainstem Rio Grande possible
  Mon-Wed.

- Showers and isolated thunderstorms elsewhere over the
  mountains/valleys (snow higher peaks) Sun/Mon, with windy
  conditions and showers over the plains on Mon/Mon evening.

- Drier Tue, then a weak weather system will bring back a chance
  for showers to the region Wed/Thu.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 100 PM MDT Sat Oct 31 2026

Quiet today across the region as initial s/w trough has moved
through, though satellite images show large area of Pacific
moisture poised to move onshore tonight as West Coast upper
trough begins to move eastward. Precip will reach the
Continental Divide after midnight as sw flow deepens, with
steadier/heavier activity developing by sunrise on Sun as
upward motion increases. Could see some snow briefly mix in down
to 10k feet or so early in the morning, before snow level
begins to climb toward 12k by midday as warm/moist Pacific air
mass spreads in. Heavy rain then continues over the San Juans
through the day on Sun, with lighter spillover showers into the
San Luis Valley/Sangres/central mountains during the afternoon.
Forecast QPF for Wolf Creek Pass for the 12hr period of 12z Sun
through 00z Mon is over 2 inches, with 1-2 inches forecast
farther south over the headwaters of the Conejos River. This
rainfall, along with some melting of the snowpack above 10k
feet, will likely cause widespread flooding, especially along
the Conejos River and the South Fork of the Rio Grande.

Sunday night, first piece of energy ejects from the upper
trough, spreading at least some weakening showers and isolated
thunderstorms eastward out of the mountains and into the plains,
while steadier/heavier precip continues along the Continental
Divide. Snow level finally begins to fall toward 10k feet around
midnight over the San Juans, then a quicker fall to below 9k
feet is forecast by 12z, as upper trough and colder air finally
move overhead. Another 1 to 2 inches of liquid is forecast from
00z Mon through 12z Mon, though a portion of this will fall as
snow as temps cool.

Overall, previous forecast was in good shape, main changes were
to increase QPF slightly, start snow in the San Juans a few
hours later, and to decrease snow amounts given later start to
snowfall. Upgraded winter storm watch to a warning for the San
Juans, as once precip switches, could get a quick foot or more
from Wolf Creek Pass up through the higher peaks. Also added
pops to the plains Sun night, as precip moves off the mountains,
and a few thunderstorms develop along the surface trough over
sern CO.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 100 PM MDT Sat Oct 31 2026

On Monday, upper trough ejects eastward across CO, with precip
tapering off over the southwest mountains through the day as
flow becomes more w-nw, while showers linger elsewhere over the
remaining mountains and valleys. Strong cold front will swing
through the plains early Mon as surface/mid level low moves
into KS, with strong north winds and a period of showers and
thunderstorms likely along and east of I-25 as vertical motion
increases under the deformation band. Will have to watch for a
burst of heavier precip (rain and snow) along the east
slopes/Palmer Divide/Raton Mesa Mon afternoon/evening, especially
if surface winds can take on a a slightly more nely component.
Wind gusts could get close to 60 mph on the plains as low wraps
up, and will have to monitor areas near the KS border for a
potential wind highlight if model trends continue. Precip then
ends Mon evening, with a dry day on Tue as upper ridge briefly
returns to the area.

Still some uncertainty concerning the mid/late week forecast, as
model solutions now show weak energy sliding through the Rockies
Wed/Thu, generating a few showers/mtn snow showers across the
region through the period. Not expecting heavy precip as system
will be rather moisture-starved, though some light snow
accumulations over the higher mountains look possible. Solutions
regarding the position and timing of the next major upper
trough for late week into the weekend still vary widely, though
an eastward shift in the trough position has been noted in the
overall model/ensemble data, which could limit impacts to srn
CO.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1200 PM MDT Sat Oct 31 2026

At KALS, VFR conditions expected for the remainder of today and
much of tonight, with lowering VFR cigs by 11z Sun morning.
Showers become more widespread after 15z Sun, with MVFR
conditions developing and likely to continue for much of the
day.

At KCOS and KPUB, VFR today and this evening, then IFR cigs
return after 08z as low level winds turn back weak easterly.
Haven`t hit fog/low visibility too hard yet with still a few
degf of t/td spread at the surface, though won`t be too
surprised if vis drops lower than forecast after 12z as winds
turn more sely, especially at KCOS.

&&

.HYDROLOGY...
Issued at 100 PM MDT Sat Oct 31 2026

Main concern continues to be flooding along the Conejos River
and the South Fork of the Rio Grande, especially Sunday night
into Monday morning. Models today have come in slightly wetter
and warmer with incoming Pacific weather system, and a
prolonged period of rain on snow looks likely in the San Juans
well into Sunday evening. Snow level rises to above 11000 feet
during the day Sunday, and only slowly falls to around 10000
feet Sunday evening, then below 9000 feet by Monday Morning. QPF
over/along the Continental Divide has come up to between 3-4
inches of liquid (some of which will be snow) which will be
sufficient to cause flooding even without the additional
potential runoff from melting snow. Runoff peak should be late
Sun evening, before snow level falls and run-off starts to
decrease early Mon morning. River stage forecasts continue to
indicate significant flooding, with the South Fork of the Rio
Grande at South Fork and the Conejos River at Mogote rising well
above flood stage Sunday evening, cresting overnight into early
Monday morning. These high flows will then move downstream
Mon/Tue/Wed with flooding possible on the mainstem Rio Grande at
Del Norte/Monte Vista and Alamosa and along the Conejos River
east of Mogote through the period. Flood watch remains in effect
for all of the San Luis Valley from late Sun night into Tue
morning, mainly for mountain runoff, as rainfall in the Valley
itself should be between .5 and 1.5 inches.

&&

.PUB WATCHES/WARNINGS/ADVISORIES...
Flood Watch from late tonight through Monday morning for
COZ067-068.
Winter Storm Warning from 5 PM Sunday to 11 AM MDT Monday for
COZ068.
Flood Watch from Sunday afternoon through late Tuesday night
for COZ069>071.

&&

$$

SHORT TERM...PETERSEN
LONG TERM...PETERSEN
AVIATION...PETERSEN
HYDROLOGY...PETERSEN