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000
FXUS65 KGJT 201735
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1135 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 /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1130 AM MDT Sat Apr 20 2024

Webcams and satellite are showing broken skies forming over the
higher terrain along the Continental Divide and across the CWA.
This will keep those broken skies around KASE, KEGE, KHDN and
KTEX. Some showers are possible, maybe even a quick thunderstorm
this afternoon, as instability remains over the area.
Confidence not high enough to include in TAFS but will amend as
necessary if/when convection gets going. Some ILS breakpoints
may be reached for KASE and KEGE this afternoon whether they
persist or not is the question. For now, kept them just above.
Skies will clear out later this evening into tonight.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...15
LONG TERM...BGB
AVIATION...TGJT