694
FXUS65 KGJT 300008
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
608 PM MDT Tue Jul 29 2025

.KEY MESSAGES...

- Showers and thunderstorms on terrain will continue to produce
  gusty outflow winds, favoring areas closer to the Continental
  Divide Wednesday.

- Hot and dry conditions persist across the lower elevations
  through most of the forecast period, with localized critical
  fire weather returning Thursday.

- Smoke and haze from regional wildfires will remain visible
  through the period.

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 328 PM MDT Tue Jul 29 2025

Monsoon moisture is streaming north, skirting our eastern counties
this afternoon. Dry slotting in the lower atmosphere over the Four
Corners has produced a steep moisture gradient along the UT/CO state
line. This allowed for ample sunshine this morning to ramp up
convective initiation on area terrain features. Closer to the
Divide, where the richer monsoonal plume is concentrated, dense
cloud cover has limited some of the convection. The synoptic pattern
remains unchanged Wednesday, thereby keeping the hot, dry air mass
along the state line, with moisture continuing to stream north over
the Continental Divide. This will find us under another round of
terrain based thunderstorms and showers Wednesday afternoon.
Ensemble PWAT`s are less than 60 percent of climatology in eastern
Utah, while barely reaching 100 percent of normal near our side of
the Continental Divide. This doesn`t inspire confidence in shower
production. There will be remnant moisture to work with, but dry
boundary layers are expected to chew up rainfall rates. High res
guidance is pretty anemic for showers tomorrow afternoon, with the
best chances closer to the Divide, dropping off near zero at the
Utah line. The Abajos and La Sals, having received some rainfall
this afternoon will keep non zero chances for showers. The jet
streak nested in the base of the upper level trough over SOCAL
continues to duel with the monsoonal plume Wednesday night.
Ensembles suggest moisture will increase across the Four Corners,
despite dry air intruding from the west. Temperatures will hover
around normal for the mountain towns, but the low deserts ramp up
above climatology Wednesday thanks to the abundant sun and
negligible cloud cover.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 328 PM MDT Tue Jul 29 2025

The center of high pressure will be in the process of shifting west
on Thursday, with the associated ridge stretching north through the
Intermountain West. This shifting of the high will disrupt the
already weak moisture tap from Mexico, cutting eastern Utah and
western Colorado off. However, enough moisture will remain trapped
near the surface to fuel afternoon showers and thunderstorms over
the higher terrain into the weekend, but with decreasing coverage
daily. Thursday will see the best coverage, with activity starting
over the higher terrain and then moving out over adjacent valleys.
This day will also see the highest probability of localized heavy
rain, although gusty outflow winds and lightning remain the primary
concerns. As the high establishes itself over the border between
Mexico, California, and Arizona, drier air will be advected into the
Four Corners on westerly to southwesterly flow. This will contribute
to the daily downturn in convective activity.

Across the lower elevations of eastern Utah and western Colorado,
low minimum relative humidity values will persist through the
period. However, synoptic winds remain light through the end of the
week and into the weekend, resulting in localized critical fire
weather conditions where afternoon gusts manage to over-perform.
However, a trough approaching the West Coast late in the weekend
will nose an upper level jet into the region, and create a
tightening pressure gradient aloft, all resulting in strengthening
surface winds. This means that more widespread critical fire weather
conditions are looking increasingly likely for early next week.
Temperatures will remain near normal through the period.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 542 PM MDT Tue Jul 29 2025

Scattered showers with embedded thunderstorms on the terrain
around the region will diminish over the next few hours, ending
by 06Z. Winds will be generally light drainage winds overnight
shifting to the west southwest after 18Z. Expect scattered
showers and thunderstorms again over the higher terrain after
18Z with outflow gusts 30-40 kts.


&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...LTB
LONG TERM...BGB
AVIATION...DB