944
FXUS65 KBOU 312004
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
204 PM MDT Thu Jul 31 2025

.KEY MESSAGES...

- A couple severe storms possible on the plains into this evening.

- Areas of smoke, getting thicker and more near surface smoke expected
  Friday.

- Chance of thunderstorms gradually decreases into this weekend.

- Dry and hot early to mid portion of next week, with increasing
  fire danger Jackson and Grand Counties.

&&

.DISCUSSION /Through Thursday/...
Issued at 204 PM MDT Thu Jul 31 2025

Scattered thunderstorms have developed in the mountains as of
early afternoon. The main question surrounds how these will evolve
and/or survive eastward onto the plains. MLCAPE on the plains is
up to 1000-1500 J/kg, and should increase a bit more with further
daytime heating. CIN was still present on the plains, with a
maximum over the northern I-25 Corridor. ACARS soundings still
show a pretty healthy cap as well, but it is weakening with
further heating. CAMs are still showing scattered quasi-linear
type storms developing along the Front Range late this afternoon,
but with the amount of CIN still present (and some smoke limiting
daytime heating), there`s a considerable amount of uncertainty
whether these can get going along the northern I-25 Corridor. As a
result, the most likely area for initiation in the lower
elevations would be near the Wyoming border and Palmer Divide
where CIN is weakest. At this point, this puts northern Weld
County into the northern adjacent plains toward Sterling, Fort
Morgan, and Akron as being the most susceptible to any severe
storm development (both hail and damaging wind threat). Bulk
shear is greater up there, although storms over the Palmer Divide
could also produce strong winds. It`s not impossible the metro
area gets skipped over again with any significant storms, but
can`t rule that totally out either given some weak support by
glancing upper level disturbance moving into Wyoming and northwest
Colorado.

For Friday, the airmass will start to dry with precipitable water
values dropping back below normal. HRRR Smoke model shows
considerable smoke arriving from the fires in Utah and northern
Arizona, both thicker and higher concentration of near surface
smoke. Thus, we expect air quality to degrade further tomorrow.

Tomorrow will also start a prolonged drying and warming trend
which will last through the middle of next week. That is supported
by good ensemble agreement of strong ridging over Colorado
transitioning to more west/southwest flow aloft into the middle of
next week. This keeps a very dry airflow (Precipitable Water
dropping to 50% or less of normal) out of the Desert Southwest
and Great Basin, with little or no storm activity. This also
supports a strong warming trend especially by Tuesday and
Wednesday. Highs are likely to reach the mid to upper 90s across
the I-25 Corridor and plains, and a low probability (20%) of
reaching 100F. Fire danger concerns will also be increasing in
this period, mainly for the mountains and high valleys west of the
Front Range where strongest southwest flow is expected.

&&

.AVIATION /18Z TAFS through 18Z Friday/...
Issued at 1151 AM MDT Thu Jul 31 2025

One plume of smoke aloft has had some impact on slant range
visibility this morning. The brunt of this plume is shifting
slowly east, so hopefully a little improvement by late afternoon.
Then main concern will shift to thunderstorms. So far, ACARS
soundings are showing a pretty capped off environment and only
slow weakening of the cap. The smoke is not helping destabilization,
so we`ve delayed the PROB30 -TSRA a bit, with most likely time
frame 22Z-02Z - if storms do maintain themselves as they come off
the foothills. VFR and mostly clear conditions will prevail
tonight. Then, another smoke plume (from today`s fire activity
over Utah and Arizona) arrives tomorrow. With active fire
behavior, that plume is expected to be thicker than today and
HRRR smoke models also shows an increase of near surface smoke.
Thus, we`ll drop forecast visibility into the 6SM range for most
of tomorrow, with the biggest restriction to slant range
visibility and arrival rates.

&&

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

&&

$$

DISCUSSION...Barjenbruch
AVIATION...Barjenbruch