771
FXUS65 KGJT 221120
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
520 AM MDT Wed Jul 22 2026

.KEY MESSAGES...

- Showers and storms will continue this week each afternoon and
  evening. The greatest coverage will be on Wednesday.

- Primary threats include heavy rainfall, lightning, and outflow
  winds up to 30-50 mph. Hail cannot be ruled out in stronger
  storms.

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

&&

.UPDATE...
Issued at 130 AM MDT Wed Jul 22 2026

After several days of heavy rainfall rates and reports of flash
flooding and debris flows have decided to hoist a Flash Flood
Watch for all of eastern Utah and western Colorado today into
this evening. The peak of anomalous moisture occurs today along
with a passing wave to tap into the moderate instability in
place. Expect storms to continue to produce rainfall rates in
excess of 1-2 inches per hour with burn scars especially
vulnerable. Models are still scouring out much of the convective
debris clouds through late morning. The eastern AZ wave arrives
at peak heating to help release the instability and produce
scattered to widespread convection. Storms today take on a bit
more northerly track which could also help it align on terrain
which has been sheltered in the E/SE flow the past few days.

&&

.DISCUSSION...
Issued at 950 PM MDT Tue Jul 21 2026

The main concern over the next 24-48 hours will be a weak
shortwave tracking over portions of the area. The moisture we
have in place is already modest, but the wave is going to bring
a slight uptick (PWAT 175-215 percent of normal). It will also
supply some lift to aid convective development, which should
translate to widespread coverage. The 00z GJT sounding revealed
steep midlevel lapse and those will still be in place tomorrow.
The lapse rates and moisture combo should result in CAPE around
1000 j/kg. Given this environment storms tomorrow will be
capable of producing strong winds, hail and heavy rainfall. The
heavy rain may result in flash flooding and debris flows
especially around steep terrain and recent burn scars. This
potential is for most locations across the area. Many spots have
been getting heavy rainfall the past several days, which has
lead to saturated soils. This further increases the potential
for excessive runoff. If this increased moisture leads to
expansive cloud cover that lingers through mid day tomorrow then
the atmosphere will not be as unstable. This could ultimately
cause a decrease in coverage and intensity of storms. Therefore
held off on issuing a flash flood watch, but it is certainly
possible especially if the skies are clear in late morning.
Models show the shortwave trough still tracking overhead
Wednesday night. This could support showers and storms
continuing overnight. Although by late evening the rainfall
rates should be on the decrease.

On Thursday the trough crosses the Divide at some point leaving
behind westerly flow. Plenty of moisture will still be around
for peak heating, so it looks like terrain-driven storms are
likely in the afternoon. Despite some dry air behind the wave
the moisture values still support the potential for heavy
rainfall. On Friday northwest flow will be in place and models
hint at dry air trying to filter into the area. When that
happens is a pretty good bet the coverage decreases. Although
low level moisture is usually slow to filter out, so it should
support another round of terrain-driven storms in the afternoon.
Behind that the confidence lowers as models are not sure how to
handle the pool of moisture. How far south does it go and when
will return flow bring it back into the area? Is there enough
lingering moisture to keep orographic showers going into the
weekend? Stay tuned

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 520 AM MDT Wed Jul 22 2026

Scattered showers with embedded thunderstorms continue to drift
across portions of the area earl this morning. Light rain is
falling at or near several TAF sites but VFR remains firmly in
place. Lingering convective debris clouds will persist through
sunrise with cigs at or above 120kft agl. Another active day and
overnight is forecast for Wednesday into Thursday. VFR is
prevailing in TAF sites with ILS possible in the PROB30 groups
at some sites. Confidence not high enough for MVFR or below attm
but if a heavy rain shower moves over the airfield this is very
possible over the next 24 to 36 hours.

&&

.HYDROLOGY...
Issued at 1148 AM MDT Tue Jul 21 2026

A rich plume of monsoonal moisture has become established
across portions of eastern Utah and western Colorado. Scattered
thunderstorms capable of producing heavy rain are expected to
continue this afternoon into late evening hours. Rainfall rates
of 2- 3 inches per hour will be possible with the stronger
storms. These rates could lead to flash flooding and debris
flows especially over steep terrain and recent burn scars. Also,
rain over the past several days has lead to saturated soils,
which increase the chances for excessive runoff.

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 terrain vulnerable to flash flooding
and/or debris flows. Dry creeks and arroyos can fill quickly and
without warning from storms miles away.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...Flood Watch from 11 AM MDT this morning through late tonight
     for COZ001>014-017>023.
UT...Flood Watch from 11 AM MDT this morning through late tonight
     for UTZ022>025-027>029.

&&

$$

UPDATE...TGJT
DISCUSSION...KAA/TGJT
AVIATION...TGJT
HYDROLOGY...ERW