250
FXUS65 KGJT 211804
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1204 PM MDT Fri Aug 21 2026

.KEY MESSAGES...

- Scattered storms capable of producing gusty outflow winds and
  lightning will develop over the high terrain on today.

- Thunderstorm coverage increases this weekend with monsoonal
  moisture moving in. Flash flooding will be possible,
  especially Saturday.

- Temperatures remain 5-10 degrees above normal through the
  seven-day forecast, with today looking to be the warmest day.

&&

.DISCUSSION...
Issued at 1149 AM MDT Fri Aug 21 2026

HOT WITH MOUNTAIN STORMS TODAY:

High pressure centered directly over our region will keep high
temperatures hot today, with highs around 10 to 15 degrees above
normal expected. The center of high pressure will gradually
shift to our southeast, eventually shifting flow over our area
to more southwesterly, which will support stronger moisture
advection into our region. Today showers and thunderstorms will
favor the high terrain, with the greatest chances and expected
rainfall amounts favoring the southern Colorado mountains. The
primary concerns with showers and thunderstorms today are gusty
outflow winds up to 35 mph, lightning, and periods of heavier
rainfall. Heavier rainfall could cause localized flash flooding
over burn scars and susceptible terrain.

COOLER WITH WET WEATHER THIS WEEKEND:

Southwesterly flow will allow for moisture to increase across
our region this weekend, with PWATs peaking around 150% of
normal. This will lead to more widespread precipitation chances.
Storms are still expected to favor the high terrain areas, but
valley areas could see a few storms as they move off of the
terrain. A shortwave moving through will provide additional lift
while atmospheric moisture is elevated on Saturday, meaning
stronger thunderstorms with heavier rainfall are possible, which
subsequently increases flash flooding and debris flow concerns.

Convection continues on Sunday while the increased atmospheric
moisture remains in place, but PoPs decrease and more strongly
favor the high terrain as no additional lift from synoptic
forcing is expected. Flash flooding concerns over burn scars and
susceptible terrain persists through at least Sunday. Moisture
looks to decrease but still remain above normal after Sunday,
which will keep afternoon mountain showers and thunderstorms in
the forecast daily.

High temperatures cool by about 5 degrees between today and
Saturday. Despite the drop in temperatures, highs will still be
around 5 to 10 degrees above normal for this time of the year.
Highs will remain around 5 to 10 degrees above normal through
early next week.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1149 AM MDT Fri Aug 21 2026

Isolated showers and thunderstorms will develop over the higher
terrain this afternoon, with more scattered coverage across the
Uintas in northeastern Utah and the San Juans in southwestern
Colorado. Mid-level clouds will increase from the west after 06Z in
eastern Utah ahead of a monsoonal push into the region. Otherwise,
expect VFR and light winds through the TAF period.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...None.
UT...None.

&&

$$

DISCUSSION...TGJT
AVIATION...MDA