535
FXUS65 KBOU 070611
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1211 AM MDT Sun Jul 7 2024

.KEY MESSAGES...

- Cooler temperatures and scattered storms are possible early
  Sunday morning until late afternoon across the region.

- Lower thunderstorm chances and warmer next week.

&&

.UPDATE...
Issued at 933 PM MDT Sat Jul 6 2024

Light convection is still around at this hour with plenty of
outflow boundaries. Tonight`s cold front is right around Cheyenne
currently and is moving around 25 knots southward. For this
evening`s grid update, altered pops down a bit and did some wind
repairs. Some of the models show a decent Stratus deck to develop
overnight into Sunday morning. That could affect tomarrow`s, later
in the day, instability.

&&

.SHORT TERM /Through Sunday/...
Issued at 200 PM MDT Sat Jul 6 2024

It`s rather dry across the plains today, while the bulk of the
moisture remains confined to the mid levels and to our east into
Kansas. There`s plenty of shallow cumulus development evident on
satellite over the high country, but instability today will be
meager outside of the far northern/northeast plains. Ongoing and
organized convection across Kansas and Nebraska should promote
some decent moist easterly outflow late afternoon, with dewpoints
progged to rise into the mid to upper 50`s for our northeast
plains. This should translate into a fairly late window for
convective activity today. Suspect most if not all storms this
evening would remain sub-severe, and it`s possible that activity
could be tapered a fair bit if we cool down enough to result in a
weak low-level cap. Perhaps the better opportunity for convection
would arrive with the approaching cold front near or just after
midnight, providing some additional lift.

This front will bring enhanced low-level moisture, and some low
stratus, to most areas east of the foothills. Although a few light
showers can`t be ruled out during the morning, believe moisture
will be a little too shallow to support anything too meaningful.
It`ll certainly be considerably cooler, with highs dropping below
normal into the lower to mid 70`s across our lower elevations. The
cooling will be more subdued in the high country, but increased
afternoon cloud cover will still provide for some moderation in
temperatures.

It`s across our higher elevations, which will be largely free of
morning cloud cover, where conditions will be much more favorable
for initiation of afternoon convection near midday, especially in
Larimer County. Some CAMs depict robust thunderstorm development
over the urban corridor instead, but this seems at odds with the
pattern considering the likelihood of relatively widespread and
persistent cloud cover early on under a largely weak upslope
regime. Thus, likely (60%+) PoPs look reasonable for much of our
Front Range mountains and foothills for Sunday afternoon, with
lower potential (30-50%) for the Denver metro, mainly from
convection rolling off the higher terrain. We could see some late
day enhancement across the plains where instability will be
slightly more favorable, but all in all, the threat for any severe
weather should remain on the low side.

&&

.LONG TERM /Sunday night through Saturday/...
Issued at 200 PM MDT Sat Jul 6 2024

An upper level ridge approaches Colorado starting Sunday night.
Lingering storms and showers are possible for South Park, Palmer
Divide, and adjacent plains through midnight. Winds shift to
southwest flow especially for the foothills to the lower elevations.
Not many changes to PoPs during Monday to Wednesday. It seems
each afternoon, drier air will limit thunderstorm development
mainly for the foothills, Park county, and parts of the Palmer
Divide. During the afternoon hours Monday through Wednesday, the
combination of daytime heating, weak instabilities of MLCAPE
200-500 J/kg, and DCAPE values approaching 1000 J/kg will likely
lead to sub-severe storms producing strong winds. PWATs vary
between 0.50-0.80 inches during this period thus it is possible
storms could produce brief heavy rainfall.

Status quo in the long-term outlook towards the end of next week.
Thursday, the upper level ridge becomes stationary over Colorado.
This will likely lead to increasing surface temperatures and light
winds across the region. Although winds do not meet fire weather
criteria, widespread low relative humidities are expected across
the foothills to plains through next weekend. By Friday, there is
excellent agreement amongst ensembles that lower elevations
rebound back to the upper 90s with a few spots possibly reaching
the lower 100s. Additionally, 500mb heights display the upper
ridge persisting through next weekend limiting thunderstorm
development mainly for the Front Range foothills.

&&

.AVIATION /06Z TAFS through 06Z Monday/...
Issued at 1155 PM MDT Sat Jul 6 2024

A cold front is moving towards the terminals currently that will
shift winds to the north shortly. Gusts behind this front could
reach 35 knots. While there are very weak virga showers in
northeast Colorado, these will have no impact on airport
operations tonight. By the morning hours, it still seems more
likely than not that stratus clouds develop with ceilings in the
2-3 kft range.

Recent model runs have shown much better coverage of showers and
storms in the Denver metro tomorrow afternoon. While the VCTS was
left in all three TAFs, it may need to be increased to a TEMPO for
-TSRA. There is potential for small hail and wind gusts up to 30
 knots with these storms.

&&

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

&&

$$

UPDATE.......RJK
SHORT TERM...Rodriguez
LONG TERM....AD
AVIATION...Danielson