240
FXUS65 KBOU 201746
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1146 AM MDT Mon Jul 20 2026

.KEY MESSAGES...

- Hot weather continues today, with highs pushing near 100F over
  the I-25 Corridor and adjacent plains. A Heat Advisory remains
  in effect for the Denver Metro/I-25 corridor through 9 PM this
  evening.

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

- Arrival of monsoonal moisture by Tuesday which will continue
  through Thursday. Storms from Tuesday through Thursday will be capable
  of producing locally heavy rainfall.

- Only a slight cooling trend forecast this week with the arrival
  of better moisture.


&&

.DISCUSSION /Through Sunday/...
Issued at 302 AM MDT Mon Jul 20 2026

An upper level high will still remain over the area today with
very hot temps as readings reach the upper 90`s to lower 100`s
across nern CO. Meanwhile, satellite imagery continues to show
some influx of monsoon moisture across nrn portions of the CWA. PW
values are fcst to be around 150% above normal over the nrn mtns
this aftn. As a result, will see sct showers and tstms across
portions of the higher terrain with localized areas of heavier
rainfall as storms will be slow moving. Across nern CO, it will be
dry this aftn. However, by early evening an outflow boundary may
come off the higher terrain so can`t rule out a slight chc of
showers and storms along nrn portions of the I-25 Corridor.

On Tue, the upper level high will weaken a bit and shift some what
to the southeast. As a result, this will allow for monsoon
moisture to move into most of the area with weak flow aloft.
Meanwhile, a cool front will move across nern CO late tonight
into Tue morning with easterly low level flow. As a result, it
won`t be as hot across the plains as readings drop into the upper
80`s to mid 90`s for Tue aftn. As far as precip, will see sct
slow moving showers and storms in the aftn over the higher
terrain. PW values will be 150% to 175% above normal over the
higher terrain so expect some heavier rainfall in some areas. As
far as the plains, outflow boundaries from tstms over the higher
terrain will move across the I-25 Corridor by late aftn or early
evening. As a result, should see additional tstm activity develop
by late aftn or early evening from Denver north to the WY border.
With increasing ESE low level flow Tue evening along with PW`s
above 150% may see heavier rainfall across nrn portions of the
I-25 Corridor.

For Wed, will continue to see monsoon moisture moving across the
area as the main upper level high is centered to the southeast of
the area.  PW`s across the high terrain will be from 150% to 200%
above normal so expect areas of heavier rainfall during the aftn
with the stronger storms.  Across the plains, the low level flow
will become southeast so expect a Denver cyclone to develop by aftn.
Should see tstms develop along the associated convergence zone with
storms moving slowly to the east from late aftn thru the evening
hours. Once again with PW`s aoa 150% or normal expect areas of
heavy rainfall. Highs on Wed, will remain in the upper 80`s to mid
90`s over nern CO.

By Thu, monsoon moisture will continue over the area as a weak upper
level trough moves across Thu aftn and night.  PW`s are still fcst
to be from 150% to 200% above normal.  Thus should see another round
of showers and storms across much of the area with areas of heavy
rainfall.  Highs on Thu will be in the upper 80`s to lower 90`s
across the plains.

Looking ahead to Fri and Sat, the upper level high will gradually
build back into the area as monsoon moisture decreases.  As a
result, will see lower tstm chances both days with warmer
temperatures. Highs across nern CO will rise back into the 95 to 100
range by Sat.

&&

.AVIATION /18Z TAFS through 18Z Tuesday/...
Issued at 1138 AM MDT Mon Jul 20 2026

VFR conditions expected through the TAF period. Easterly winds are
currently setting in place at all terminals and will likely
continue throughout the afternoon before shifting more southeast.
With the plume of the monsoon moisture slowly shifting east into
Colorado, there are increasing chances for showers along the I-25
Corridor late this afternoon/evening. However, there is high
uncertainty with exactly where the showers will occur. For this
reason have kept the PROB30 in the TAF. Most likely, all airports
would see gusty outflow winds from surrounding showers, rather
than any showers impacting the terminals. PROB30 currently ends at
04Z, however there could be gusty outflows through 06Z.

Drainage flow expected overnight. A `cool` front will arrive
sometime between 10Z-14Z which will bring northerly winds, with
speeds generally between 10-15 kts. Another round of showers and
thunderstorms are possible tomorrow, however models indicate
another late show (starting as early as 23Z) so have kept it out
of the TAF for now. Will likely need to introduce a PROB30 in the
next TAF issuance.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 9 PM MDT this evening for COZ038>040-043.

&&

$$

DISCUSSION...RPK
AVIATION...MAI

NWS BOU Office Area Forecast Discussion