621
FXUS65 KBOU 151800
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1200 PM MDT Wed Jul 15 2026

.KEY MESSAGES...

- Hot weather continues through this weekend.

- Prolonged hot and dry conditions will bring elevated fire
  weather conditions across most of the area, though we`ll likely
  stay shy of Red Flag criteria.

- Monsoonal moisture is initially lacking with only isolated to
  scattered afternoon/early evening storms in the mountains
  through Saturday. Dry plains.

- More significant monsoonal moisture and cooler temperatures
  expected next week, when a threat of locally heavy rainfall
  arrives.

&&

.DISCUSSION /Through Tuesday/...
Issued at 328 AM MDT Wed Jul 15 2026

Not much will change between today and Sunday, with dry and hot
conditions prevailing east of the mountains, and isolated
afternoon thunderstorms across the high country. The reason is a
persistent and elongated ridge across the middle of the U.S., and
594 dm heights at 500 mb expected to be overhead most if not all
of time today through Sunday. Starting with today, north to
northeast winds in the mid levels will keep any convection
confined to the higher terrain, especially along and south of
I-70. The West Slope of our area should remain along the far edge
of the monsoonal moisture each afternoon through Friday, while the
I-25 corridor and eastern plains remain dry and hot. But the
thermal ridge should remain north of us through Friday, resulting
in seasonably hot but not overly hot, with highs reaching the low
to mid 90s across the plains and I-25 corridor each afternoon.
Today through Friday will likewise have strong southeast winds
gusting 20-30 mph (weakest winds on Friday) across the eastern
plains each afternoon and evening but RH should remain above RH
thresholds at between 20-30 percent each afternoon such that we
don`t expect any fire wx highlights. Winds from the eastern
foothills west across the West Slope and mountain valleys should
be weak enough to likewise not need any fire wx highlights.

The main thing to watch are the daily afternoon thunderstorms across
the high country. PW values look to remain in the 0.5-0.6" range
from the Front Range west across the mountain valleys and West
Slope, resulting in very little threat of even localized heavy rain.
Main impacts each afternoon would be gusty winds to 40 mph,
lightning, and at best a wetting rain. Chances go from 40-60
percent today, to 50-70 percent tomorrow. However, for now Friday
looks like the sub-tropical moisture will get removed somewhat by
drier east flow aloft at 700 and 500 mb, with PW dropping perhaps
below 0.5". PoPs are lower on Friday across the mountains at
around 15-30 percent. As mentioned earlier, that east to northeast
flow in the mid levels will keep any storms from moving off the
higher terrain through at least Saturday.

For this weekend, the heat continues as models are in close
agreement that the center of the ridge will be over Colorado with
continued weak east or northeast flow aloft.  Saturday especially
the flow pattern is not favorable to advect moisture in from the
southwest. At best isolated showers are possible (5-25%) across the
Front Range and central mountains, and given the steering flow it
will continue to stay dry as storms remain over the higher terrain.
If there is a saving grace it`s that east flow from the surface to
over 500 mb on both days will prevent any additional downslope
warming from occurring east of the mountains. Ensemble model
spread is very small for high temps on both Saturday and Sunday,
with highs Saturday below 6,000 feet elevation easily in the mid
90s, with 80s in the mountain valleys and east slope foothills
below 10,000 ft. Sunday there is high confidence based on ensemble
output from all the global systems that it should be the hottest
day of the next 7. About half of all ensemble members of the GEFS
and Canadian models have a high temp of 100 or higher for Denver,
with the Euro ensembles cooler across the board by 2-4 degF.
Monsoonal moisture from the southwest should seep into the west
slope and Front Range on Sunday, resulting in higher PoPs for
those areas on Sunday and a better chance of thunderstorms across
the eastern foothills and adjacent plains along I-25. However,
with continued deep (but weak) east flow, the chances of anything
moving off the mountains very far to the east of the Front Range
is low, though there are some hints in the models of a westerly
component to the steering-level flow. Thus, for the first time in
the next 5 days, low PoPs (10-30 percent) have been introduced
along and east of I-25 for Sunday evening.

Monday and beyond ensemble spread in PW and temperatures increase
with GEFS generally the warmest/driest and the Euro the
coolest/wettest. However, confidence overall is increasing in
moisture advection into much of our area next week, with PW values
exceeding 1" and perhaps as high as 1.25" by Tuesday and beyond. As
with previous forecasts, ensemble trends are in in our favor for
showers and thunderstorms next week which would absolutely take the
edge off the hot temperatures. Chances of heavy rainfall based on
ensemble output (a fair number of members from each modeling
system show one or more heavy rain events next week from the
mountains to the plains) are also increasing next week with at
least one cool front bringing high theta-e, moisture-laiden air
westward to the Front Range. Needless to say with the surge of
monsoonal moisture aloft, and low-level moisture from the east,
there is plenty of evidence to say that at a minimum
afternoon/evening thunderstorms chances will be much higher
(50-75%) across much of the area next week. And thankfully cooler.

&&

.AVIATION /18Z TAFS through 18Z Thursday/...
Issued at 1202 PM MDT Wed Jul 15 2026

VFR conditions throughout the TAF period. East winds have made it
to DEN and will shortly make it to APA. These east winds will be
persistent through the early evening with the direction slowly
moving from 120 to 100. The winds will then veer towards southeast
this evening and will become drainage overnight. Similar wind
conditions are expected on Thursday with slightly less wind speeds
and more of a northeasterly direction.

&&

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

&&

$$

DISCUSSION...Schlatter
AVIATION...Danielson

NWS BOU Office Area Forecast Discussion