438 
FXUS65 KBOU 151123
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
523 AM 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 /12Z TAFS through 12Z Thursday/...
Issued at 523 AM MDT Wed Jul 15 2026

VFR expected and no convection near the terminals through 
Thursday. Smoke is likewise not expected to pose any issues for
approaches given deep (but weak) easterly winds. In terms of winds
near the surface, current south winds at APA and DEN will briefly
weaken between 15-17Z, then transition to east and ESE 10-15 kts
with gusts to 20 kts throughout the afternoon and into the evening
hours. By 02Z they should be southeast, and work their way to
drainage out of the south after 08Z at 12-16kts. At BJC, winds in
general will be weaker, with north winds under 10 kts through
midday, transitioning to east winds 10-14kts gusting to near 20
kts from the afternoon into the evening hours. Like APA and DEN, 
BJC's winds should be southeast during the late evening hours 
before weakening and going northwest after 09Z. Overall confidence
in the winds through Thursday is pretty high, especially given we
do not expect any convective outflows to approach the terminals.

&&

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

&&

$$

DISCUSSION...Schlatter
AVIATION...Schlatter