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000
FXUS65 KGJT 201115
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
515 AM MDT Sat Apr 20 2024

.KEY MESSAGES...

- Isolated to scattered mountain showers continue today before
  drier and warmer conditions move in for Sunday.

- Warm conditions will remain in place through at least the
  first half of the upcoming week with afternoons becoming more
  breezy.

- A few weak embedded waves in the flow could trigger an
  isolated afternoon shower or thunderstorm through Wednesday.

- Bigger changes look to arrive by late in the week with wetter
  and cooler conditions moving in through the weekend.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 329 AM MDT Sat Apr 20 2024

This split flow/downstream confluent pattern over the central
Rockies is finally breaking down...but not before bringing a
little bit of winter back to the Divide and Front Range. The
darkening in water vapor to our North and back over central Utah
show the next few high PV areas to move through the flow today before
ridging and more stable conditions move in for Sunday. Most of
the impacts will continue to be centered over the Colorado High
Country. First...early this morning by the Utah wave...then
this afternoon as instability is released by orographics and
weak ascent triggered by the passing cyclonic jet aloft. Lapse
rates are steep enough that an isolated strike or two of
lightning is possible. Increasing heights will be building in
from the West overnight with transitory ridging bringing quiet
and warmer conditions to the CWA for Sunday. The cooler air that
filtered in behind a front will be pushed out today and northern
areas should see a nice rebound in high temperatures with
similar conditions to the South. With more warming tomorrow
highs will end up in the 5 to 10 degrees above normal range.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Issued at 329 AM MDT Sat Apr 20 2024

On Sunday night, a trough sliding along the Canadian border will
work to flatten the ridge over much of the Western CONUS, including
over eastern Utah and western Colorado. As this trough moves east
during the day Monday, a weak cold front and tightened gradient
aloft will combine to bring gustier winds and maybe some light
showers to northeast Utah and northwest Colorado. Winds will relax
and showers taper Monday night into Tuesday as the trough continues
east and the ridge reestablishes itself over the Great Basin,
leading to generally dry and sunny conditions for Tuesday and
Wednesday. A weak little wave in the flow will bring about another
round of mountain showers Tuesday afternoon, however. By Wednesday
morning the ridge axis will be overhead, and a deep trough will be
located along the West Coast, with a northern trough over British
Columbia and a southern cutoff low off the SoCal coast. Flow aloft
shifts to southwesterly over the course of the day Wednesday as the
trough moves eastward, with yet another round of mountain showers
taking advantage of the Pacific moisture now pumping into the area.
It is at this point that substantial disagreements crop up in the
forecast, as some model solutions are much faster than others with
moving the southern portion of the trough into the Great Basin. The
faster solutions bring widespread precipitation to eastern Utah and
western Colorado by Thursday morning, while the slower solutions
break out in precipitation almost 12 hours later. Regardless of the
model discrepancies, the overall pattern for the late week period
looks to be increasingly unsettled, with a long-wave trough setting
up over the Western CONUS and multiple waves dropping through the
Great Basin and into eastern Utah and western Colorado.

The first half of the coming week will see temperatures 10-15
degrees above normal across the majority of eastern Utah and western
Colorado. Typical afternoon gusts of 20-25 mph will be possible
through Wednesday, with higher gusts possible in and around showers
or thunderstorms over the higher terrain. As the pattern begins to
shift from Thursday on, look for a gradual cooling trend to round
out the work week. Current blended guidance indicates high
temperatures dropping back to near normal values by Friday and
Saturday, so be sure to enjoy the unusual warmth while you can.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 512 AM MDT Sat Apr 20 2024

VFR conditions can be expected to prevail over the next 24 hours
though ILS conditions will be possible at times at KEGE and
KASE. Isolated thunderstorms are possible this afternoon but
this coverage reduces confidence and this reflected in the
outgoing forecast for 12Z. Breezy afternoon conditions could
lead to an occasional gust of 25 to 30 mph through sunset.
Clear skies and light winds move in overnight.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...15
LONG TERM...BGB
AVIATION...GJT