368
FXUS65 KGJT 172326
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
526 PM MDT Mon Aug 17 2026

.KEY MESSAGES...

- Dry conditions and near-normal temperatures this afternoon
  with an isolated mountain shower possible.

- A frontal boundary promises additional showers mainly over
  high terrain Tuesday and Wednesday with afternoon gusty winds.

- A warming trend will continue. Triple digits will remain
  confined to the Four Corners and low desert valleys.

- Monsoonal flow begins to appear in model outputs this weekend.

&&

.DISCUSSION...
Issued at 1133 AM MDT Mon Aug 17 2026

Dry, southwesterly flow will begin to shift this afternoon into
a more zonal regime, ahead of a ridge of high pressure
developing over the Great Basin later this week. This will set
up a weak frontal boundary Tuesday and Wednesday with a
concentration of moisture across our northern counties. These
westerly plumes tend to get chewed up crossing the Great Basin.
We should get some cloud cover Tuesday and an uptick in shower
activity on the Uintas and Flat Tops, as well as along the west
edge of the Continental Divide. The amplifying ridge bumps the
frontal boundary eastward Wednesday, while models try to resolve
some moisture under the center of the high(located over western
UT). It looks like shower and storm development becomes more
centralized over the terrain of Colorado from the Flat Tops down
to the San Juans Wednesday afternoon. Moisture remains rather
vague, as it doesn`t ever tap a true monsoonal plume.

Late week begins to embrace another pattern shift. Temperatures
surge beneath the subsident high straddling the Four Corners.
Triple digits become more widespread in the desert valleys and
red rock of Utah. Ensembles begin to grapple with monsoonal
moisture Thursday and beyond. Statistical spread remains high,
cluing some uncertainty in the model outputs. For now, planning
around an uptick in monsoonal thunderstorms after Thursday
would be optimum. Model solutions point to strengthening
moisture over the weekend, with the caveat of uncertainty in
statistical spread. Given the showery, monsoonal regime over
the region, temperatures take a return towards cooler, normal
values this weekend.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 524 PM MDT Mon Aug 17 2026

The convective clouds over the terrain should continue to
flatten and dissipate through the evening...leaving skies mainly
clear overnight and into mid morning. Similar scenario for
Wednesday but there could be some isolated showers and storms
during the peak heating hours tomorrow. Overall winds remain
light and VFR conditions prevail over the next 24 hours.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

DISCUSSION...LTB
AVIATION...TGJT