166
FXUS65 KGJT 172340
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
540 PM MDT Thu Jul 17 2025

.KEY MESSAGES...

- Scattered to widespread thunderstorms tomorrow afternoon will
  be capable of producing strong winds, frequent lightning,
  hail, and periods of heavy rain.

- Conditions dry out early next week increasing the potential
  for elevated fire weather conditions.

- Smoke will continue to ebb and flow around the forecast area
  this weekend with multiple large wildfires burning in eastern
  Utah and western Colorado.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 227 PM MDT Thu Jul 17 2025

With the moisture plume currently centered over southeast Utah
and southwest Colorado progged to lift to the north overnight,
shower chances will continue tonight along the leading edge of
the moisture transport gradient. Cloud cover will also persist
overnight, mainly along and north of I-70.

The biggest forecast question is how much cloud lingers into
Friday morning, especially across the northern half of the
forecast area. The hi-res models indicate that these clouds will
hang on, limiting the amount of daytime heating at the surface.
South of I-70 and in the north if enough clearing is achieved,
CAPE values are expected to build to 500-1000 J/kg in the
afternoon leading to the potential for some stronger storms.
With a jet overhead, shear also looks higher than usual. But
with the highest shear draped across the northern half of the
forecast area and the highest CAPE in the southern half, we may
not get the alignment needed for strong, sustained storms.
Strong pulse storms are still likely south of I-70 with the
ability to produce half inch to quarter-size hail and strong
winds. Flash flooding cannot be ruled out if high rain rates
develop over burn scars and steep, hydrophobic terrain, but it
is not a primary threat for much of the region given the dry
antecedent conditions.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 227 PM MDT Thu Jul 17 2025

On Saturday not much changes to the overall pattern with high
pressure still over the Southern Plains and a weak low over
southern Cal. One thing notable is that slightly drier air will
advect in from the southwest. Although enough moisture remains
in place to support afternoon convection especially over the
higher terrain. Storms may be capable of producing brief
downpours, gusty winds and small hail. The same conditions will
be in place for Sunday so expect similar afternoon convection on
the higher terrain. Monday looks to be even slightly drier so
there should be a decrease in the coverage of showers and
storms. This will increase the potential for stronger outflow
wind gusts than previous days. By Tuesday a low pressure system
moves into the Pacific Northwest with the ridge anchored over
the southern US. This is a favorable pattern for moisture
advection from the south. In fact, the models are hinting at
another moisture surge on Tuesday. This signal is showing up in
a few operational models and ensemble means as well. Some of
that energy may stay in the PacNW keeping us in southerly flow.
Although the models show fairly dry air just to our west and
southwest, and that could easily come our way mid week. If that
happens the chances for showers and storms will decrease. That
seems to be the more likely scenario late next week. With that
we would see a slight increase in the temperatures.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 536 PM MDT Thu Jul 17 2025

Mid and high level clouds continue to stream across the area
this evening, with a few embedded showers and thunderstorms
north of I-70. Some additional convection may develop over the
San Juans over the next few hours. However, most activity will
taper off after sunset. Moisture builds in tonight, with showers
expected to linger over KDRO into the morning. More widespread
convection is expected tomorrow afternoon. Main threats will be
gusty outflow winds, brief heavy rain, frequent lightning, and
small hail. VFR conditions are expected to prevail, although
drops to MVFR will be possible in areas affected by wildfire
smoke (KGJT, KMTJ), and during shower activity.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...KAA
LONG TERM...KJS
AVIATION...TGJT