868
FXUS65 KBOU 121926
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
126 PM MDT Sun Jul 12 2026

.KEY MESSAGES...

- Hot weather through the entire week ahead. First Heat Advisory
  of the season issued for the I-25 Corridor.

- Only hints of monsoonal moisture reaching the high country by
  late in the week or next weekend.

- Prolonged hot and dry conditions will bring fire weather
  concerns, although we`ll likely stay just shy of Red Flag
  criteria most days.

&&

.DISCUSSION /Through Sunday/...
Issued at 127 PM MDT Sun Jul 12 2026

The main concern remains the prolonged heat, and the lack of any
relief through the week ahead.

Into this evening, only isolated showers/storms will be possible
from the Palmer Divide area into Park County. There was also some
cumulus along the I-25 Corridor, but for the most part these
updrafts are expected to have too much dry air entrainment to
survive or produce anything more than a brief sprinkle/gusty
outflow. Overnight low temperatures will be a couple degrees
warmer than last night thanks to increasing southeast breezes
across the plains. It`s not impossible that parts of Denver don`t
drop below 70 tonight, while most other plains locations should
still be able to reach the lower to mid 60s.

On Monday, there is good agreement that we`ll see 2-4 degrees F
of warming as mid level temps warm another 1-2C from those
observed today. Thus, we`ll be reaching the upper 90s over most of
the I-25 Corridor from Denver to Fort Collins. That, along with
full sunshine and warm overnight lows, mean we`ll be right near
Heat Advisory criteria. Considering the building heat stress of
the last couple days and relatively warm overnight temperatures
discussed above, we`ve went ahead and issued the first Heat
Advisory of the season for the I-25 Urban Corridor. Temperatures
farther east over the plains will remain a few degrees cooler and
closer to climatology so no Heat Advisories needed there.
Meanwhile, mountain areas will see temperatures warming a couple
more degrees than today. That sets the stage for daily, if not
all time record high temperatures Tuesday through Thursday as the
mid level thermal ridge maxes out over west central and northwest
Colorado. 00Z Guidance showed 700 mb temperatures still reaching
an astonishing +23-24C those three days, although there was some
indication in the latest operational runs that those values might
not be reached.

The reason for the slight cooling was that the latest operational
runs did not elongate the upper high nearly as much as previous
runs, thereby reducing the amount of drying/subsidence in the
middle to latter portion of the week. That`s where more
uncertainty enters the forecast, as a less elongated high could
could allow a little monsoonal moisture to sneak under the ridge.
Most of this would still be confined to the west slope, with our
mountains remaining on the edge of any monsoonal moisture. Dry
conditions will almost certainly persist on the plains through
Friday.

As the heat and stress on vegetation builds, we`ll see increasing
risk of fire growth and potentially long burn periods well into
the evening hours each day. That`s despite staying just below Red
Flag conditions each day as the wind component will be lacking
slightly in the mountains, while the humidity component will be
slightly above thresholds over the breezier plains east of I-25.

As we get towards next weekend into early the following week,
moisture associated with the monsoon appears to have a better
chance of working its way toward our forecast area. However,
outside of the latest operational runs, model guidance was still
bit slower with the eastward push due to the unfavorable
positioning of the ridge. Guidance has consistently shown better
precipitable waters arriving sometime next Monday or Tuesday, but
until we see this finally start advancing forward, it`s difficult
to have too much confidence. On the more optimistic side, there
is still a strong ensemble signal that once this moisture arrives,
it should stick around.

&&

.AVIATION /18Z TAFS through 18Z Monday/...
Issued at 1123 AM MDT Sun Jul 12 2026

VFR conditions will prevail for all terminals through the TAF
period. ESE winds will become more established through the next
couple of hours, with increasing emergence of 18-24 kt gusts by
mid to late afternoon. Winds will veer towards drainage overnight
but gusts will be rather persistent. Expect very similar wind
patterns Monday with lighter and more variable winds in the
morning transitioning to breezy SE winds in the afternoon.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 10 AM to 9 PM MDT Monday for COZ038>040.

&&

$$

DISCUSSION...20
AVIATION...BRQ

NWS BOU Office Area Forecast Discussion