328
FXUS65 KGJT 201218
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
618 AM MDT Mon Jul 20 2026

.KEY MESSAGES...

- Showers and storms will continue this week each afternoon and
  evening, with coverage becoming more widespread by Tuesday and
  Wednesday.

- Primary threats include heavy rainfall, lightning, and outflow
  winds (30-40 mph). Some small hail will also be possible.

- Storms have the ability to produce flash flooding and debris
  flows in vulnerable terrain, including areas near and
  downstream of burn scars.

&&

.DISCUSSION...
Issued at 1003 PM MDT Sun Jul 19 2026

A stagnant high-pressure system remains parked over the area.
This is leading to many rinse and repeat days when it comes to
the current forecast. Shower and thunderstorm chances remain
each afternoon and evening, at least for the first half of the
week. Shower activity appears to become more widespread by
Tuesday and Wednesday as PWATs increase to upwards of 200% of
normal in some places at that time. Primary threats continue to
be heavy rainfall, lightning, and gusty outflow winds (35-45
mph). Small hail is also a possibility. With that being said,
depending on where these storms choose to materialize, they
introduce a threat for flash flooding and debris flows. This
remains a concern for areas with vulnerable terrain, including
recent burn scars in addition to burn scars from previous years.
For greater detail on the flash flooding risk, see the
hydrology section below.

By midweek, the high-pressure system will shift slightly,
altering our storm tracks. While storms have recently been
taking an unusual east-to-west path, the new pattern will likely
steer them up from the south. Because high-pressure systems
circulate clockwise, this shift will pull deep moisture further
northward, extending our chances for rain.

As far as temperatures are concerned, daytime highs will
continue to be above normal for the next few days, with near
normal temperatures expected Wednesday and beyond.

A special note for outdoor enthusiasts: Please continue to
monitor the forecast and adjust your plans as needed. These
storms can develop rapidly, bringing sudden hazards. Your best
bet is to head out early in the morning, as storm activity
typically strengthens in the afternoon. Always ensure you have
multiple ways to receive weather warnings.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 604 AM MDT Mon Jul 20 2026

Isolated showers and thunderstorms will develop over the higher
terrain across the region between 18Z and 00Z with more
scattered coverage over the Uinta Mountains in northeastern Utah
and over the San Juan Mountains in southwestern Colorado.
This convection will end by about 06Z Tuesday. Included PROB30
in most TAFs along and south of I-70. Expect brief periods of
MVFR in precipitation. Otherwise, look for VFR conditions and
light winds through the TAF period.

&&

.HYDROLOGY...
Issued at 1003 PM MDT Sun Jul 19 2026

Anomalous moisture remains entrenched across portions of eastern
Utah and western Colorado. Rainfall rates of 1-2 inches per hour
will be possible with stronger storms. These rates could lead to
flash flooding and debris flows especially over recent burn scars.

Storms over the last few days have helped prime lower levels of the
atmosphere and saturate the ground where rain was observed.
Several locations across southwest Colorado have reported 0.5 to 1.0
inches of rain within 30 minutes which is more than sufficient to
create issues in our steep, rocky terrain. This terrain will further
exacerbate areas that are already susceptible to flash flooding.
This environment has heightened awareness over recent (or actively
burning) fires due to the burnt ground`s inability to absorb
moisture under heavy rainfall. As such, we will continue to
emphasize the potential for flash flooding and debris flows in this
regime. By Tuesday and Wednesday, precipitation coverage appears to
become more widespread, which will extend the flash flooding
concerns through at least mid week.

As a reminder: Keep an eye on our forecasts through the end of the
week and stay tuned for updated hydrology alerts if visiting or if
you reside below vulnerable terrain to flash flooding and/or debris
flows. Storms across the west develop quickly, leaving little room
for lead time in flashy terrain.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

DISCUSSION...BS
AVIATION...DB
HYDROLOGY...TGJT