258
FXUS65 KGJT 151738
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1138 AM MDT Tue Jul 15 2025

.KEY MESSAGES...

- Above-normal temperatures remain status quo through the seven-
  day forecast though 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 WEDNESDAY/...
Issued at 334 AM MDT Tue Jul 15 2025

Satellite imagery shows the high pressure that models place over the
Desert Southwest centered on western Arizona has developed farther
north about 75 miles south-southeast of Ely NV as a well defined
anticyclonic flow with weak disturbances rotating around it. One of
these disturbances is moving into northern Utah producing an area of
scattered light showers that will push southeast through
northeastern Utah and northwestern Colorado through the morning
hours. High res models have picked up on this signal supporting this
convective activity with showers changing over to thunderstorms by
noon due to diurnal heating. Coverage of showers and thunderstorms
rapidly spread across much of the higher terrain of eastern Utah and
Western Colorado through the afternoon with the southern mountains
continuing to be favored with moisture moving up from the southwest.
Concerns remain localized areas of near critical fire weather
conditions with temperatures remaining five degrees above normal,
very dry lower layers of the atmosphere and breezy west winds.
Additionally, the convective activity will produce areas of dry
lightning favoring the northern and central mountains, and all of
these storms will be capable of producing outflow gusts over 50 mph
due to the dry lower layers. 30% chances for wetting rain remains
limited mostly to the Uinta Mountains in eastern Utah the the San
Juan Mountains in southern Colorado. Look for these storms to
diminish through the evening hours with a few isolated showers
continuing through Tuesday night. The weak monsoonal pattern will
continue to pull moisture north out of Mexico through the Desert
Southwest and into the region overnight Tuesday improving chances
for wetting rain Wednesday into the latter half of the week.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
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 WEDNESDAY/...
Issued at 1132 AM MDT Tue Jul 15 2025

Showers and storms are possible this afternoon and evening. The
main impact will be wind gusts of 30-50 mph mainly in the late
afternoon into the evening. Otherwise VFR conditions are
expected through the period.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...DB
LONG TERM...KAA
AVIATION...DB