417
FXUS65 KBOU 200600
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1200 AM MDT Wed Aug 20 2025

.KEY MESSAGES...

- Hot temperatures Wednesday and Thursday with temperatures
  nearing record highs Thursday.

- Dry conditions Wednesday and Thursday.

- Cooler and wetter weather arrives this weekend with the
  conditions lasting into next work week.

&&

.DISCUSSION /Through Tuesday/...
Issued at 207 PM MDT Tue Aug 19 2025

A much quieter day is on tap for the forecast area today. This
morning`s upper-air maps show the upper-level ridge has shifted
northward since yesterday, centering itself around the Four
Corners region. This is still expected to dominate the synoptic
pattern for the next few days, bringing hot temperatures and drier
conditions through Thursday. There is still an isolated chance
for afternoon showers and storms today and Wednesday, but coverage
will be sparse with little precipitation expected, and the lower
elevations are generally expected to remain dry. Modest
instability is in place across the Palmer Divide today, and is
expected to be the main area where storms will develop. Currently
the SPC mesoanalysis shows between 250-500 J/kg of MLCAPE in place
coinciding with DCAPE values between 1000-1400 J/kg. We could see
some smaller hail and gusty winds between 40-50 mph with any
storms that develop in this environment today. With light steering
winds in place, storms will be slow moving and could see some
very localized heavy rainfall under any developing storms. Today`s
afternoon high temps will be similar to what we saw yesterday
before gradually increasing Wednesday and Thursday. Still looking
like Thursday will be the warmest day of the week as the lower
elevations will see the mid to upper 90s.

The upper-level low is still on track to begin moving into
southwestern Canada tomorrow (Wednesday). Ensembles continue to
show decent agreement that this will traverse across southern
Canada through the week, flattening out the Four Corners ridge by
Thursday. While the main forcings will stay to the north, an
associated cold front will slide south across Colorado on Friday,
bringing cooler temperatures and potential for widespread precipitation
across the forecast area. Increasing northwesterly flow aloft
will bring chances for daily doses of moisture across the forecast
area through the forecast period as the upper-level ridge
retrogrades west. Ensembles also show PWAT values slowly increase
through Saturday, ranging from 130-170% of normal across the
forecast area for the weekend. Between the increased moisture and
deep-layer shear, severe weather and flooding concerns will need
to be monitored as the week progresses. The cooler and wetter
conditions are expected to stick around through the forecast
period.

&&

.AVIATION /06Z TAFS through 06Z Thursday/...
Issued at 1153 PM MDT Tue Aug 19 2025

VFR conditions throughout the TAF period. Drainage winds will
shift to southeasterly or easterly winds during the late morning
hours. During the afternoon, there will be healthy easterly winds
at all terminals that will shift to southeasterly around sunset.
Drainage winds expected Wednesday night.

&&

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

&&

$$

DISCUSSION...Bonner
AVIATION...Danielson