681
FXUS65 KPUB 080112
AFDPUB

Area Forecast Discussion
National Weather Service Pueblo CO
712 PM MDT Fri Jun 7 2024

.KEY MESSAGES...

- Showers and thunderstorms expected on Saturday, with strong
  to severe thunderstorms likely along and east of the I-25
  corridor.

- Shower and thunderstorm chances continue Sunday through
  Tuesday, with the most widespread precipitation Sunday and
  Monday.

&&

.UPDATE...
Issued at 659 PM MDT Fri Jun 7 2024

Dropped severe tstm watch for the plains as main line of storms
is well east. Still some weaker convection and even some
lightning back west over the higher terrain, so will keep some
low pops for storms going a few more hours until most activity
ends by midnight.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 319 PM MDT Fri Jun 7 2024

Currently..

Satellite and radar imagery depict isolated to scattered showers and
thunderstorms across our mountains and portions of our plains.
Convection is very high based today, and at first glance looks a bit
unimpressive on radar, but it is important to note that many of
these smaller cells are producing damaging outflow winds. Area
observations are showing thunderstorm outflow winds of anywhere from
45 to 60 mph across Fremont, El Paso, and Pueblo counties as of 2
pm. Temperatures have soared into the 90s and low 100s across the
plains this afternoon, though convective cloud cover is starting to
limit temperatures for our mountain adjacent plains. Dewpoints are
in the 40s for most of our plains, with some low 50s on our far
eastern plains. SPC mesoanalysis indicates 2000 J/Kg of DCAPE across
the the entire lower Arkansas River Valley for the next 2 to 4
hours.

Rest of Today and Tonight..

As storms continue to push south and east across the plains over the
next few hours, expecting damaging wind gusts to continue to be the
main concern for most locations. The main exception to this will be
our far southeastern plains, where convection was slightly later to
get going, but, as of 2:30pm, it is starting to ramp up a bit. This
area is seeing slightly higher dewpoints, with area observations
showing Td in the mid 50s this hour. This area will see more of a
threat for hail up to 1 inch in diameter, along with the damaging
winds gusting 60 to 70 mph through around 6 pm this evening. High
res model guidance suggests that all convection should come to an
end or push east by around midnight or so at the latest.

Later tonight, models bring a weak cold front across our plains.
While this front will not bring much of noticeable change in our
winds or temperatures through the overnight hours, it will set the
stage for a cooler and more active weekend.

&&

.LONG TERM /SATURDAY THROUGH FRIDAY/...
Issued at 319 PM MDT Fri Jun 7 2024

Cold front is expected to push across the region late tonight into
early Saturday, providing some relief with the heat. However,
highest temps on Saturday are still expected to reach the 80s to low
90s over much of the area. Quickly turn attention to returning
thunderstorm chances along with the risk of severe weather Saturday
afternoon into the evening, especially across the plains. General
synoptic pattern looks to remain the same, however, guidance in fair
agreement with showing a more defined short wave trough pushing
across the region during the day Saturday. This increased large
scale ascent along with veering low level flow and backing mid level
flow looks to strengthen forcing/focus across southern Colorado.
This will help set the stage for thunderstorm development initially
over the mountains and plains interface by mid to late afternoon,
and then over the remaining plains later in the day into the
evening. The strong to severe risk will be higher on this day given
the forcing/focus, but more importantly the increased moisture and
instability as far west as the mountains and plains interface. This
will be something to monitor as guidance continues to vary to the
placement of the axis of highest moisture and instability, which
could easily vary from north to south.

Given this setup, thunderstorm development will have a higher chance
to quickly strengthen as it pulls off the higher terrain, as some
moisture pooling is possible up against the mountains and along the
Palmer Divide. Forecast soundings do indicate a cap in place, though
you can see this cap mechanically erode along the I-25 corridor
during the afternoon with the arrival of the forcing. Further to the
east, the cap is even stronger and will have to see how this factors
with additional thunderstorm development later in the day and
evening. I don`t think it will limit thunderstorm development
especially given the increased instability and dew points possibly
in the low 60s, but I think it will help to keep storms more limited
and discrete. This will be something else to closely monitor,
especially given the instability and abundance of shear that will
support the risk of all hazards on Saturday.

By Sunday, will see rising heights and weakening flow, but will see
moisture and instability remain in place. It does look as if the
moisture/instability axis shifts further west, with increased
chances for showers and thunderstorms over the mountains and
mountain valleys. With weakening flow, the risk for more widespread
organized development lowers. That being said, still think there
will be a risk for at least isolated strong to severe storms on
Sunday. Large hail is possible, but think damaging winds would be
more of the threat on this day. What will be more concerning on this
day and even again on Monday given a persistent pattern, is the risk
for heavy rainfall and flash flooding. The highest risk looks to be
situated right along the southeast mountains into the I-25 corridor.
Once again, the risk of heavy rainfall and flash flooding continues
Monday, but will need to see how guidance evolves over the next
couple of days, as more recent runs are showing a closed low
developing across the region. It does appear that by Tuesday, we`ll
see coverage of precip chances lower that continues on Wednesday as
upper ridging is the trend. This will return building heat to the
area though, with well above normal temperatures in the 80s and 90s,
and quite possibly 100 degrees, returning to southern Colorado by
mid week.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 551 PM MDT Fri Jun 7 2024

VFR conditions are expected to prevail for all TAF sites (KALS,
KCOS, and KPUB) throughout the forecast period. Winds will be mostly
influenced by synoptic forcing, due to an approaching system. They
will begin to increase out of the SW at KALS, and SE-SSE at KPUB and
KCOS, by later in the day with gusts around 25 to 30 kts at all
terminals. SHRA and TSRA are expected to be in and around the
vicinity of KCOS and KPUB by later in the afternoon and through the
evening tomorrow, mainly between 20 and 23z, and only a slight
chance of occurrence at KALS (which is why VCSH/VCTS has been left
out of the KALS TAF at this time). If SHRA/TSRA does develop, it
could temporarily reduce CIGs and VIS to MVFR/IFR criteria. It could
also result in periodic windshifts and increased wind speeds for all
terminals. High res models also suggest that a windshift will occur
at KCOS around 23Z, due to a frontal boundary and outflow from
convection, and may occur sooner than this depending on timing of
convective initiation. -Stewey

&&

.HYDROLOGY...
Issued at 348 PM MDT Fri Jun 7 2024

Rapid snow melt will continue across the mountains leading to
elevated flows along the Arkansas River from Leadville to Canon
City through the weekend as well as on smaller creeks and
streams in and near the mountains. Flows are expected to remain
within banks for most locations along the Arkansas River but
fast flows can still be dangerous. Slightly cooler temperatures
may decrease the snow melt this weekend into early next week,
however the potential for heavy rainfall will increase Saturday
through Monday for the southeast mountains and plains. This
could cause localized flash flooding and push flows above the
projected bank full forecast for localized areas depending on
where the rain falls. Confidence in this scenario unfolding is
low for the major river stems for now. Continue to monitor
weather forecasts closely.

&&

.PUB WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

UPDATE...PETERSEN
SHORT TERM...EHR
LONG TERM...RODRIGUEZ
AVIATION...STEWARD
HYDROLOGY...MOZLEY