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000
FXUS65 KGJT 190829
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
229 AM MDT Fri Apr 19 2024

.KEY MESSAGES...

- Light rain showers, with possibly some thunder, will continue
  over the higher terrain today, with the northern and central
  mountains most favored. Light snow is possible at the highest
  elevations.

- Look for a warming trend and a return of dry and breezy
  conditions early next week.

- Daily showers with a thunderstorm or two are expected over the
  higher terrain through late next week.

&&

.SHORT TERM /THROUGH SATURDAY/...
Issued at 228 AM MDT Fri Apr 19 2024

A band of light showers has been hanging out along the Book Cliffs
and I-70 corridor for the last several hours. Thanks to very dry
surface air, this band has produced mainly virga and gusty winds,
although a few spots, such as Rifle and Eagle, have reported rain
making it to the surface. Multiple vorticity maximums embedded in
the westerly flow will help to keep shower activity going through
the day today, with two areas of banded precipitation setting up by
the afternoon. The northern one is a continuation of the band
currently located along the I-70 corridor, while the second band
will set up over the central mountains. Some moistening of the
surface air will allow for more precipitation to reach the ground,
but forecast QPF remains on the low end, a tenth of an inch or less,
so any activity that does reach the ground will be more on the order
of sprinkles than downpours. Elsewhere, conditions will be generally
dry, although partly to mostly cloudy. Winds will ease off today as
the pressure gradient aloft relaxes in the wake of the Canadian low
now centered over the Great Lakes, although typical afternoon gusts
of 20-25 mph will still be possible.

Flow aloft begins to turn southwesterly tonight as a wave moves into
the Desert Southwest. Modest dynamic lift and increased moisture
will combine with orographic lift to produce scattered showers over
all Colorado mountain ranges Friday night into Saturday. By Saturday
morning the trough axis will be east of the Divide and unstable
northwest orographics will take over Saturday afternoon, leading to
yet another round of mountain showers and thunderstorms. Some snow
showers will be possible but will be combined to the highest
elevations and with limited accumulations of an inch or less.

Afternoon high temperatures across much of the area will continue to
run 10-15 degrees above normal. The exception to this will be
northeast Utah and northwest Colorado, where highs this afternoon
will be near normal, and will increase to a few degrees above normal
by tomorrow. Overnight lows will remain mild thanks to the increased
clouds and showers.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Issued at 228 AM MDT Fri Apr 19 2024

Some light showers may linger over the western Colorado high terrain
along the Divide Saturday evening but should end by midnight as a
ridge of high pressure ushers in a drier northwest flow as it
traverses the Great Basin and across Colorado by Sunday morning.
Sunday looks to provide a relatively dry day across the western
slope with exception of some very light isolated showers over the
high terrain possible, with the beginning of a warming trend through
the coming week. A trough moving across the northern Rockies will
act to flatten the high pressure ridge a bit on Monday, resulting in
a more zonal westerly flow. A front will move down the central
plains, extending a boundary across the Front Range and enough
instability to produce some afternoon showers over the high terrain,
possibly a few thunderstorms. The flow will shift to southwest
Monday as a low pressure trough approaches the west coast.

The coming week looks to be met with quite a bit of uncertainty in
regards to the precipitation forecast as even though temperatures
will be warming to around 10 to 15 degrees above normal from Monday
through at least mid week, a Pacific trough moving over the west
coast will eject a series of shortwaves through the period,
resulting in a chance for some isolated to scattered afternoon
showers and storms each day favoring the high terrain, while most
lower elevations remain dry. Timing these waves is a bit problematic
as models are not in the best agreement, but it sure is looking like
a spring time afternoon convective type pattern. A more robust
shortwave trough is projected to track across the area Thursday with
another possibly to follow to close out the coming week, which could
result in more widespread shower and storm activity as well as a
cooldown towards near normal temperatures by the week`s end. Given
the unsettled pattern and model uncertainty, things can change.

So, the warming temperatures under this southwest flow will mean
that most lower desert valleys of west-central Colorado, east-
central and southeast Utah will be in the low to mid 80s, the higher
elevation valleys will be in the 70s and the mountain towns will
settle in the upper 50s to low 60s. Very pleasant temperatures.
Higher elevations do stand the better chance of shower activity
during each afternoon with the spring time convection, however, the
lower elevations remain dry. Breezy afternoon winds will also be
common under this warm, southwest flow. So, as mentioned in previous
discussions that we will reiterate, caution is urged with any
planned fires or burning under these warm, dry and breezy conditions
despite fuels not yet being declared critical.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1142 PM MDT Thu Apr 18 2024

Overall, VFR conditions are expected next 24 hours. SCT to BKN
cloud cover will continue to traverse the central and southern
portions of the forecast area through the overnight hours and
into the day on Friday with CIGS remaining above ILS breakpoints.
Scattered showers will also continue to move across the central
portions of the area due to a lingering surface boundary. While
lower valleys may see more virga with breezy winds, the higher
elevations may see some light showers from time to time. Kept
VCSH at ASE, EGE and RIL for the time being based on radar
trends. Overall, expect periods of clouds and sun Friday
afternoon with gusts 20 to 30 kts expected at most sites.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...BGB
LONG TERM...MDA
AVIATION...MDA