761
FXUS65 KBOU 031945
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
145 PM MDT Mon Aug 3 2026

.KEY MESSAGES...

- Hot again today before a cold front arrives later this afternoon
  or evening. Highs of 97 to 105 across the plains with a Heat
  Advisory in effect for the I-25 corridor.

- Elevated fire weather conditions across the northeastern plains
  and across North Park/Middle Park this afternoon. Elevated to
  critical fire weather conditions likely to continue across the
  high mountain valleys through the next few days.

- Cooler for Tuesday and Wednesday before temperatures gradually
  warm back to the triple digits by next weekend.

&&

.DISCUSSION /Through Monday/...
Issued at 132 PM MDT Mon Aug 3 2026

As expected, it`s hot across the I-25 corridor and plains this
afternoon. Temperatures have already eclipsed 100F at several
locations, with places like KDEN not too far behind (currently
99F). These temperatures are rather impressive, especially given
the lingering haze/smoke across the plains along with some
scattered mid-level cloud cover. We probably have another couple
degrees of warming this afternoon, with highs generally hitting
the 100-103F range across the I-25 corridor.

What remains to be seen is how many showers are able to develop
this afternoon. ACARS soundings and SPC Mesoanalysis show very
meager instability, but DCAPE currently sits at about 1800 J/kg.
It also seems possible (probable) that the HRRR is overdoing the
amount of convection this afternoon, just based on satellite
trends to start the afternoon. We still expected isolated to
widely scattered showers, which would likely produce more wind
(gusts up to 50 mph) than rain.

Meanwhile, a strong cold front is still on track to arrive later
this afternoon. The front looks to be moving through Cheyenne at
the moment, with notable pressure rises across eastern Wyoming.
This is expected to reach the Denver metro by about 5-6PM today,
which should provide substantial relief from the heat... while
also advecting some near surface smoke into the area for the
evening hours. While smoke will persist through most of Tuesday,
we will at least see much cooler temperatures for the plains...
with highs in the mid/upper 70s. Temperatures will warm back into
the low to mid 80s by Wednesday.

The higher elevations won`t feel the effects of the cold front,
and will instead have to contend with fire weather concerns over
the next few days, as zonal flow aloft begins to strengthen. A Red
Flag Warning has been issued for North Park and Middle Park on
Tuesday and additional highlights may be needed for Wednesday and
Thursday.

Our brief cooldown will quickly be replaced by hotter and drier
conditions as the upper ridge once again strengthens over the
Four Corners region late this week into the upcoming weekend. With
mid-level temperatures once again approaching 20-22C this would
likely lead to highs approaching 100F on Saturday and Sunday. The
position of the upper ridge would also limit any chance of monsoon
moisture making a return until at least early next week.

&&

.AVIATION /18Z TAFS through 18Z Tuesday/...
Issued at 1210 PM MDT Mon Aug 3 2026

Four concerns to address this TAF period...gusty microburst
winds, timing of front, smoke, and potential stratus.

Regarding microbursts, the initial smoke plume that moved over the
area slowed diurnal heating. However, the smoke is thinning west
to east and inversions are quite shallow per ACARS. Thus, we
should see a fairly quick runup to convective temps. Cloud bases
are very high (near 18,000-20,000 MSL), and with deep dry
adiabatic lapse rates and DCAPE near 1500-1800 J/kg there`s
potential for 45 kt gusts from any and all high based
virga/sprinkles 20Z-02Z. We`ll go with TEMPO VRB G35 kts in the
most likely time frame of 20Z-24Z for now given favorable
parameters, but again peak gusts could be stronger (20% chance of
G45+ kts).

For the timing of the front, current observations show a front
approaching Cheyenne, WY and pretty healthy pressure rises behind
it. It does have a little momentum but at the same time it will
be fighting peak diurnal heating and mixing. Thus, it should slow
this afternoon but could easily get another surge late in the day.
Therefore, we expect one surge by 23Z-00Z, and another stronger
one closer to 02Z with stronger gusts to 30 kts. Those N-NE winds
will gradually weaken and turn more easterly by 12Z Tuesday.
Easterly winds will hold through the entire day Tuesday but get
gusty up to 20 kts after 21Z.

With regard to smoke, the current smoke aloft is exiting which
should bring some slight improvement. However, next surges toward
23Z-02Z will usher in thicker low level smoke and IMC due to
limited slant range visibility. Surface visibility could even drop
down to 5-6SM per upstream observations in eastern Wyoming and
southeast Montana.

Finally, for stratus potential we see increasing probabilities of
a ceiling around 5,000 feet AGL developing for the Front Range TAF
sites 06Z-15Z. The greatest likelihood (>60%) would essentially
hug the foothills along/west of KDEN-KGXY line. There is a low
(>20%) chance that we drop down to 2,000 feet, but enough to
mention FEW-SCT020 at this time. Any stratus is expected to burn
off/erode 14Z-17Z, but FEW-SCT stratocu possible into the
afternoon as shallow moisture gets trapped under a very strong
inversion.

&&

.FIRE WEATHER...
Issued at 132 PM MDT Mon Aug 3 2026

Observations early this afternoon show some spotty elevated fire
weather conditions across the high mountain valleys, where
humidity has fallen to around 15-20% with a few gusts of 20-25
mph. We may eventually see some elevated fire weather conditions
across the plains as winds increase this evening ahead of a fairly
strong cold front.

While the cold front will limit fire danger across the plains for
the next couple of days, the front doesn`t look to be deep enough
to provide much relief for the higher elevations. Zonal flow is
expected to develop on Tuesday, and with deep mixing... it looks
likely that North Park and Middle Park will see deep enough mixing
to support a few hours of Red Flag conditions during the afternoon
and early evening hours.

The flow aloft is expected to turn a little bit more northwesterly
by Wednesday and Thursday, with 700-500mb winds also weakening
slightly. Most guidance still supports at least elevated fire
weather conditions across most of the high mountain valleys... and
additional highlights may be needed later this week.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 1 PM to 7 PM MDT Tuesday for COZ211-213.

Heat Advisory until 6 PM MDT this evening for COZ038>043.

&&

$$

DISCUSSION...Hiris
AVIATION...20
FIRE WEATHER...Hiris

NWS BOU Office Area Forecast Discussion