554
FXUS65 KBOU 171750
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1150 AM MDT Fri Jul 17 2026

.KEY MESSAGES...

- Hot weather continues through Monday. The highest temperatures
  will occur Sunday and Monday, and a Heat Advisory may be issued
  for the Denver Metro/I-25 corridor later today.

- Scattered afternoon/early evening storms in the mountains
  expected through Sunday with the plains remaining dry.

- Significant monsoonal moisture and cooler temperatures will
  arrive on Tuesday of next week. The thunderstorms that develop
  will be capable of producing locally heavy rainfall.

&&

.DISCUSSION /Through Thursday/...
Issued at 214 AM MDT Fri Jul 17 2026

Water vapor satellite looks very similar to the last couple of
nights, with a plume of moisture wrapping around a broad ridge
over the central CONUS. The better moisture remains well off to
our west (generally over AZ/NM/northwest WY), with rather dry air
noted in our forecast area.

The forecast remains relatively unchanged over the next few days.
Slightly drier/warmer air aloft should limit coverage of any
showers and storms this afternoon to portions of the high country,
with less coverage compared to yesterday. High temperatures today
should be a couple of degrees warmer in most locations with mostly
sunny skies.

The ridge is expected to rebuild across the region this weekend,
leading to another period of well above normal temperatures and
generally dry weather. Saturday`s highs should again be a degree
or two warmer across the plains (mid 90s). With the ridge directly
overhead on Saturday, only a couple of weak showers are forecast
over the higher elevations. Sunday looks to be the hotter day of
the weekend, as the upper level ridge starts to slide off to the
south and east, while the mid-level thermal ridge axis remains
directly over Colorado. While the GFS is much more bullish with
700mb temperatures, other guidance would still support high
temperatures in the upper 90s to perhaps lower 100s across the
I-25 corridor and plains. Combined with warm overnight lows (upper
60s) both Saturday and Sunday night, Heat Risk values are in the
"Major" category (level 3 out of 4) for most of the urban
corridor. We`ll let the day shift take another look before issuing
any heat headlines.

As the day shift noted yesterday, guidance is still trending a
touch slower with the shift of the ridge off to our east, which
will allow better moisture to finally work into the forecast area
sometime next week. Overnight 00z ensemble data continues to
support this idea... meaning that Monday may end up just as warm
as Sunday across the plains. While increased moisture will lead to
scattered showers/storms across the high country, most of the
lower elevations may need to wait until Tuesday or Wednesday
before the deeper moisture and better instability arrive.

Given that we`re still a few days out, it`s worth mentioning that
forecast QPF amounts, particularly from deterministic models, are
far from reliable at this timeframe. This is especially true in
weakly forced convective regimes... and while any given
deterministic or ensemble forecast may be useful in determining
the overall coverage/location of storms... they are less useful in
determining exact rainfall totals. The overall pattern would still
support slow moving thunderstorms capable of producing heavy
rain... and we`ll continue to watch this potential over the next
few days.

&&

.AVIATION /18Z TAFS through 18Z Saturday/...
Issued at 1150 AM MDT Fri Jul 17 2026

VFR will persist through the TAF period, with a similar wind
pattern to the last couple days. E-ESE winds will persist through
about 03Z, with gusts increasing to around 20 kts by 21Z. Winds
then turn more southeasterly at KDEN and KAPA before eventually
settling to SSW 09Z-14Z. KBJC meanwhile, will turn more NW for
the overnight and early morning hours. There is just a slight
(20-30% chance) of an outflow from mountain convection reaching
KAPA - again similar to yesterday, so we did a PROB30 of SW winds
there 23Z-02Z. Chance of the outflow reaching KDEN is less than
10%.

&&

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

&&

$$

DISCUSSION...Hiris
AVIATION...20

NWS BOU Office Area Forecast Discussion