995
FXUS65 KGJT 221735
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1135 AM MDT Sat Jun 22 2024

.KEY MESSAGES...

- Shower and thunderstorm activity will be reduced today compared
  to Thursday and Friday, mainly impacting higher terrain. The
  potential for excessive rainfall or severe storms is low.

- Temperatures return to near normal levels today, climbing to
  between 5 and 10 degrees above normal from Sunday through the
  end of next week.

- Afternoon/evening showers and thunderstorms are expected each
  day from Sunday to Friday with higher terrain favored.
  Coverage is expected to be isolated to scattered for all but
  Thursday when numerous storms are expected.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 444 AM MDT Sat Jun 22 2024

Subsidence in the wake of a mid-level short wave trough which
moved over the forecast area last evening brought clearing
skies to the north. However, deep moisture to the south and weak
jet divergence sustained isolated showers and a thunderstorm
near the Four Corners early this morning. A more zonal flow
aloft has shifted the subtropical moisture plume to just south
of the CO/NM state line.

For today, HREF guidance indicated ample moisture remains with
precipitable water (PW) levels near an inch across the southern
two-thirds of the forecast area. Early sunshine working on the
deep residual moisture is forecast to yield SBCAPE values of
1000 to 1300 J/Kg today. HREF and model soundings indicated the
highest CAPE will be realized between 16Z and 20Z before mixing
transfers drier air aloft into the lower elevations. This
suggests storms will fire early, becoming less vigorous during
the latter part of the afternoon. Enough shear remains for
multicellular storms early on, but not enough for supercells. As
the day progresses, shear decreases and storms will become
shorter lived as downdrafts increasingly interfere with storm
updrafts. Given PW levels mentioned previously, heavy rain is
possible with stronger cells, though the potential for flooding
is low due to the low potential for long lived organized
storms.

Showers/thunderstorms are expected to diminish early this
evening as diurnal cooling and a lack of upward forcing allow
the atmosphere to stabilize. Fewer showers and thunderstorms are
expected Sunday as the region continues to dry under a shallow
transitory ridge.

Temperatures should return to near normal today as early
sunshine and reduced storm coverage allows for better solar
insolation. By Sunday, temperatures jump by close to 5 degrees
as drying continues.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Issued at 444 AM MDT Sat Jun 22 2024

With high pressure to the south and troughing to the north, eastern
Utah and Western Colorado will stay under a dry zonal flow aloft
through the coming week, but residual moisture remains trapped near
the surface with dewpoints generally in the 40`s across the region
with light winds. This will lead to skies clearing out each night
allowing diurnal heating the following day to charge the atmosphere
the with cumulus build-ups in the late morning into the early
afternoon turning into isolated to scattered showers and
thunderstorms over the higher terrain through the afternoon into
the early evening before the clouds evaporate under subsidence
overnight and the cycle repeats. Thew ensembles suggest the high
building into a ridge up the Rocky Mountains through mid week with
another deep trough descending into the Pacific Northwest late in
the week. Some of the models and guidance are hinting that another
band of tropical moisture that is just moving into northern Mexico
off the Gulf of Mexico today will work its way around the high or
sneak under it Wednesday into Thursday to bring another surge of
moisture generating widely scattered showers and thunderstorms
across the region Wednesday afternoon favoring the higher terrain
that will linger overnight, spinning up into widespread showers and
thunderstorms Thursday afternoon. Showers will linger overnight in
the mountains becoming widely scattered showers and thunderstorms
again Friday afternoon. Confidence is low due to the wide dispersion
in the solutions on any specifics in the forecast beyond widely
scattered showers and thunderstorms each afternoon favoring the
higher terrain with some days seeing more activity and others less.
Stay tuned for updates to the forecast as we see how the high
pressure to the south develops.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1133 AM MDT Sat Jun 22 2024

Showers and storms are expected to develop over the high terrain
in the next several hours. The coverage is not high enough to
include in the tafs. Brief MVFR conditions and gusty outflow
winds are possible with these showers. They should dissipate
around sunset or shortly after.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...NL
LONG TERM...DB
AVIATION...TGJT