Track City, Colorado Weather Forecast Discussion

673
FXUS65 KPUB 060919
AFDPUB
Area Forecast Discussion
National Weather Service Pueblo CO
Issued by National Weather Service Denver CO
319 AM MDT Sat Sep 6 2025
.KEY MESSAGES...
- Patchy fog early this morning.
- Another round of showers and thunderstorms this afternoon and
  evening, but mostly over the mountains.
- A couple of strong to severe storms will be possible across
  the plains Sunday.
- Daily showers and thunderstorms are expected next week, though
  mostly along the mountains and increasing toward the end of
  the week.
&&
.SHORT TERM /THROUGH SUNDAY/...
Issued at 319 AM MDT Sat Sep 6 2025
Currently, fairly widespread stratus and fog across most of the
southeast plains, as weak low level upslope flow continues, with
even some patchy drizzle at times around KCOS. Clouds are more
scattered farther west, though low clouds and fog have developed as
of midnight across portions of the San Luis Valley. For today,
upper ridge builds across CO, leading to warming mid-level temps and
only very light upslope sely flw on the plains. Maxes will bounce
back considerably from Fridays cool readings, with a return of
70s/80s at many locations as morning low clouds and fog burn off by
midday and plentiful sunshine returns into early afternoon. Moisture
is still plentiful enough for scattered to numerous afternoon
showers and thunderstorms over mainly the high terrain/interior
valleys, best coverage back toward the ern San Juans where
moisture/instability are greatest. For the I-25 corridor and
southeast plains, a few storms may survive as they move off the
higher terrain late this afternoon into the evening, as air
mass is weakly unstable (CAPE 300-700 J/KG) along the Interstate and
across the Raton Mesa. Instability falls off quickly farther east on
the plains, suggesting a rapid drop-off in storm chances east of I-
25. Convection slowly fades overnight, with activity ending by
midnight and skies clearing by early Sunday morning.
On Sunday, mid level heights/temps continue to build/warm, while
drier air begins to spread into the higher terrain by afternoon.
Should see a decrease in storm coverage and strength as a result,
though still some gusty high based convection possible over the
mountains in the afternoon.  On the plains, weak surface trough
develops and moves east of I-25, with deeper moisture/instability
(CAPE 1000-1500 J/KG) pooling east of the boundary by late
afternoon. Bulk shear of 30-40 kts would be sufficient for some
stronger storms, the main question is whether or not storms will
form at all. NAM points to nern CO for most convection, GFS is in
sern CO, and at least a few CAMs show no storms at all, as forcing
will be weak. Current forecast has low/no pops for the daytime hrs
on Sun, then just some isolateds near the KS border in the
evening, which will suffice for a first guess at this point. Max
temps Sun continue to rise, with plains deep into the 80s, and
70s/lower 80s at most other low/mid elevation locations.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Issued at 319 AM MDT Sat Sep 6 2025
Sunday Night: The potential for strong to severe thunderstorms
last through around 10PM with the best axis of instability over
the far eastern plains with MUCAPE values reaching around 1500
J/kg with around 30 kts of deep shear. So overall, if a storm
starts up over the far eastern plains on Sunday night, 1 to 1.5
hail and 60 MPH wind gusts will be possible under the strongest
storms. Lingering non-severe thunderstorms will continue across
the region past midnight, but nothing severe should develop
after the aforementioned ending time above.
Monday and Tuesday: Isolated to scattered showers and
thunderstorms are expected to form over the mountains, mountain
valleys, and the I-25 corridor. The instability values are less
than 1000 J/kg, so the chance for severe thunderstorms are low,
but gusty winds, small hail, and torrential rain are possible
under the strongest thunderstorms on Monday and Tuesday. High
temperatures will be in the 80s to low 90s over the plains and
the 70s over the mountain valleys.
Wednesday through Friday:
A closed low begins to impact the region as it propagates from
the Pacific Northwest all the way down to the four-corners
region of the United States. Having a closed low develop like
this when it is still summer is a bit rare, but what it does do
is transport a lot of Pacific moisture towards Colorado.
Guidance is creating a prolonged period of rainfall over the
mountains, in particular, over the Continental Divide, from
Wednesday afternoon/evening through Friday evening. Instability
values arent very high, but having the instability present plus
having the southwesterly winds orthogonal to the mountains
heavy rain is expected which does bring flash flooding concerns,
especially once the soils become saturated. High temperatures
remain in the 80s to low 90s over the plains and the 70s over
the mountain valleys through Thursday, but by Friday
temperatures cool off to the 80s over the plains and the 60s to
low 70s over the mountain valleys.
&&
.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1157 PM MDT Fri Sep 5 2025
At KCOS, IFR/occasional LIFR in stratus and fog overnight as light s-se
surface winds persist. Light n-nw drainage wind after 12z will start to
improve conditions, with improvement back to VFR around 16z. VFR then
expected during the day into Sat evening, and with the bulk of afternoon
convection staying back over the higher terrain, wont include any
-shra/-tsra mention at this point.
KPUB will see cigs in the MVFR/occasional IFR range overnight, with some
MVFR vis in fog possible as well. Cigs break 15z-16z, with VFR conditions
through the afternoon and evening. Convection looks to stay back over the
higher terrain at this point, and wont include and -shra/-tsra mention
for now.
KALS IFR conditions in stratus and fog through the night, with clearing
in the 15z-16z timeframe as winds begin to increase slightly. VFR through
the afternoon and into the evening, though will include a vcts mention after
21z as convection moves off the higher terrain into the San Luis Valley.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...PETERSEN
LONG TERM...SKELLY
AVIATION...WFO Pueblo

NWS PUB Office Area Forecast Discussion