015
FXUS65 KBOU 072331
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
531 PM MDT Fri Aug 7 2026

.KEY MESSAGES...

- Elevated to locally critical fire weather conditions possible
  across the mountains and high valleys through the weekend.

- Hot this weekend with highs reaching 95 to 105 across northeast
  Colorado. A Heat Advisory is in effect for the northern I-25
  Corridor and Denver metro from 11 AM Saturday to 8 PM Sunday.

- Precipitation chances increase towards midweek next week.

&&

.DISCUSSION /Through Friday/...
Issued at 147 PM MDT Fri Aug 7 2026

Current visible satellite imagery shows cumulus developing over the
mountains, as a slight increase in mid-level moisture might allow a
few virga showers for the high terrain this afternoon. With the
upper level ridge centered over the Desert Southwest, heat will
continue to build this afternoon and through the weekend. Current
surface observations show temperatures in the mid/high 80s across
the plains, and we will likely be able to reach mid/upper 90s like
yesterday. Due to west/northwest flow aloft, it looks like smoke
will continue to be in the area through the weekend.

Over the weekend, the axis of the mid-level thermal ridge will shift
eastward, with 700-mb temperatures reaching up to 19-21 C. We are
still on track for surface temperatures to reach up to the upper
90s/low 100s both Saturday and Sunday. With expected cloud cover to
increase Saturday night, overnight low temperatures will struggle to
cool down. Guidance even has some areas not reaching below 80
degrees F till 10 PM. For this reason, have decided to expand and
extend the Heat Advisory to now include the northern I-25 Corridor
from 11 AM Saturday to 8 PM Sunday.

Due to the dry airmass in place, elevated fire weather conditions
will persist through the weekend, particularly for the mountains and
high valleys. However, guidance does keep winds marginal (gusts
generally below 25 mph) and thus shy of Red Flag criteria. The only
exception could be the northern mountains and high valleys (North
Park) where brief gusts of 25-30 mph is possible Saturday afternoon.
Due to the localized nature of these gusts, have held off on any
highlights.

In terms of precipitation this weekend, guidance does keep most of
the region dry. However, with the slight increase in mid-level
moisture, the mountains could see a few afternoon showers. Models do
try to resolve a few virga showers spilling off the foothills and
onto the plains and thus have increased PoPs to show this potential
(10-15% chance). Modeled Skew-T soundings indicate steep low/mid-
level lapse rates, with DCAPE up to 1500-1800 J/kg, so gusty outflow
winds will be the main concern.

Temperatures in the mid/upper 90s will likely continue towards the
beginning of next week. Ensemble guidance has the upper level
ridge weakening through the week and eventually shifting more east
into New Mexico/Texas (although GFS has this occurring later in
the week compared to ECMWF). This will result in "cooler"
temperatures but it is still unclear when exactly that will occur
next week. Right now, NBM has max temperatures of low-to-mid 80s
by Thursday for the plains, which could occur if the ridge evolves
how the ECMWF depicts it to. However, if the high pressure area
is slower to track east like the GFS depicts, we might not see
those "cooler" temperatures till later. Regardless, with the
breakdown of the ridge, moisture should continue to filter into
the region, with increasing widespread precipitation chances for
the mountains and plains by the end of next week/weekend. Seems
like a promising signal as of now, but will continue to monitor.

&&

.AVIATION /00Z TAFS through 00Z Sunday/...
Issued at 525 PM MDT Fri Aug 7 2026

GOES-19 satellite imagery at this hour shows smoke over all three
terminals with some high-based cumulus clouds moving off the
higher terrain, especially in the vicinity of KAPA. HRRR Smoke
continues to show smoke affecting all three terminals throughout
the TAF period and beyond. This could lead to slantwise visibility
issues at times.

Winds will turn to drainage overnight and then to the northeast
by tomorrow afternoon. Wind speeds and cloud cover will increase
by then, as well. There is a ~30% chance of virga showers
affecting the terminals on Saturday afternoon, which could lead to
some gusty winds of at least 40 kts and briefly lowering ceilings
to about 12,000 ft AGL. Confidence has increased in this
possibility and thus have now included a PROB30 at all three TAF
sites generally between 21z and 2z tomorrow afternoon and evening.
Outflow winds from these showers should lead to a period of
easterly to southeasterly winds for tomorrow evening following
sunset before drainage kicks in.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 11 AM Saturday to 8 PM MDT Sunday for
COZ038>040.

&&

$$

DISCUSSION...MAI
AVIATION...MV

NWS BOU Office Area Forecast Discussion