139
FXUS65 KGJT 142138
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
338 PM MDT Mon Jul 14 2025

.KEY MESSAGES...

- Above-normal temperatures remain status quo through the seven-
  day forecast through a slight downward trend is expected after
  midweek.

- Outflow winds...lightning and storms with little rainfall
  remain threats through midweek.

- The trend for increased moisture by the end of the week
  continues to boost confidence that storms will transition from
  dry to wet. Storm coverage should increase as a result of the
  moisture as well from late week into the weekend.

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 337 PM MDT Mon Jul 14 2025

As mentioned in previous discussion water vapor is telling much
of the story. A well defined wave has been progressing through
the eastern Great Basin providing ascent across our CWA. This
has led to a scattered thunderstorm coverage over our eastern
CWA under a lingering plume of mid level moisture. This wave is
also forcing isolated orographic convection back to the West and
likely allowing conditions favorable our fires to become plume
dominated. Our biggest concern will remain gusty outflow winds
interacting with our ongoing fires with new fire starts from
lightning a close second. Low humidity remains in place thanks
to the very dry low layers and well above normal temperatures.
Low humidity and gusty winds will keep a localized threat of
critical fire weather conditions in place through at least late
evening. Isolated showers could linger will into the morning
hours across the South as the back edge of this wave moves
through over increasing easterly flow. The upper high centered
over the Southwest will begin to be impinged upon by a digging
northern stream trough across the PacNW. This will begin to
nudge the high eastward which is a positive trend for pulling up
southerly moisture into our area. A batch of elevated moisture
caught between the digging low and the top of the ridge will be
accelerated across our area tomorrow and theoretically provide a
boost in thunderstorm coverage. However a well defined wave is
the missing ingredient attm and the convection remains isolated
to widely scattered and likely tied mainly to the orographic
forcing for the first few generations. Will again have to watch
for gusty outflows firing new cells and the wind interactions
with our fires. So status quo for now as we continue to watch
trends in better moisture advection later in the week.
Temperatures will remain well above normal in the short term
even with a bit more cloud cover possible tomorrow.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Issued at 337 PM MDT Mon Jul 14 2025

On Wednesday, a shortwave trough is progged to pass through Montana
and Wyoming to the north which will work to flatten the upper-level
heights locally. In the zonal upper-level flow north of I-70, PWATs
rise to 125-150% of normal leading to higher chances of afternoon
convection over the high terrain north of I-70. In the meantime, the
southern moisture feed continues to advect enough moisture northward
along the Divide for another round of afternoon convection over the
San Juans.

High pressure builds once more on Thursday another round of
afternoon showers and storms, especially over the southern
mountains. With a southwesterly flow pattern setting up aloft,
moisture advection begins to intensify. Most of that moisture
arrives to the local area on Friday leading to more numerous showers
and storms across eastern Utah and western Colorado by the afternoon
hours. There remains a lot of uncertainty for how effective these
showers and storms will be at producing wetting rains as it will
likely take some time to saturate the lower levels and there`s also
are notable differences in moisture between the global ensembles.
With above-normal PWATs remaining in place through the weekend,
afternoon/evening showers and storm chances persist.

With increasing moisture and cloud cover, high temperatures begin a
steady decline towards more seasonable temperatures by the time the
weekend arrives. However, this will also prevent nighttime
temperatures from cooling off as much. Lows are projected to be 5-10
degrees above normal through much of the extended forecast.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 222 PM MDT Mon Jul 14 2025

Isolated to scattered afternoon convection will throw out more
wind than rainfall which could be the main threats at TAF sites.
This is most likely at KASE...KGUC...KMTJ...KDRO and KTEX. Gusts
up to 50 mph will be possible in the strongest outflows. This
threat continue again tomorrow afternoon with quiet weather
expected in between. VFR should prevail unless these winds
temporarily mix up the dust or smoke.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...15
LONG TERM...KAA
AVIATION...TGJT