520
FXUS65 KGJT 291145
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
545 AM MDT Mon Apr 29 2024

.KEY MESSAGES...

- A disturbance passing to our north will bring rain showers and
  mountain snow to the northern half of the CWA tonight. Snow
  accumulations of 1-3 inches expected.

- Afternoon winds will remain gusty this week, as a series of
  disturbances along the jet stream impact the region.

- A brief cool spell on Thursday in the wake of a cold front
  will drop temperatures, before things warm back up heading
  into the weekend.

&&

.SHORT TERM /THROUGH TUESDAY/...
Issued at 332 AM MDT Mon Apr 29 2024

Skies have begun to clear out across the CWA this morning with some
drier air arriving under a weak ridge traversing the region. Remnant
moisture is still hung up on the west side of the Divide, with a few
low/mid cloud ceilings being reported in Craig, Eagle, Aspen, and
Gunnison. Unfortunately, much of this cloud cover will remain hung
up on the terrain until reinforcements arrive later today. Desert
valleys along the state line will see generous sunshine today
though. The respite from the clouds will be brief today, as another
trough of low pressure approaches from the northwest this evening
and pushes additional cloud cover across the region, primarily north
of I-70. Winds will pick up ahead of this disturbance across
northeast Utah and northwest Colorado this afternoon. Southwesterly
winds will gust on the order of 20-30 mph until about sunset. Warm
air advection will push temperatures back into the range of late
April climatology too. A few early showers from this disturbance are
possible late afternoon on the eastern Uintas, but most
precipitation will hold off into the overnight hours after midnight.
Showers will struggle to reach the I-70 corridor, but northward we
will see light rain early Tuesday morning for most locales below
8000 feet. Snow accumulations on the eastern Uintas, Elk Heads, Flat
Tops and the Park Range will hover around 1-3 inches, with a few
higher totals up on the upper peaks. Precipitation tapers quickly
around lunch Tuesday and we get back to our regularly scheduled
spring programming of breezy conditions under cloud free skies.
Winds will, once again, pick up to around 20-30 mph around the
region Tuesday afternoon, thanks to a generous jet streak draped
over northern Colorado all day. Afternoon highs will have no problem
getting back into the 70`s for most of our lower elevations.&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Issued at 332 AM MDT Mon Apr 29 2024

Zonal flow sets up across the region at the start of the long term
period. A messy area of low pressure will be situated over Idaho and
Montana bringing some widespread precip to those areas all the way
back to the Pacific Coast. During the day Wednesday, the system
becomes a bit more organized as one center of low pressure forms
along the US/Canadian border and upper level support causes a
midlevel trough to form which will be reflected at the surface as a
cold front. A jet streak will ride above these features and as it
rounds the base of the upper level trough, will bring the cold front
into our CWA while also providing some lift. The front itself will
also cause some lift so with all these ingredients in place, there`s
no wonder the models are bringing some valley rain and mountain snow
to the the northern half of the CWA along with some isolated
thunderstorms. Some differences kept popping up between models and
with the latest runs there are some minor timing differences but the
general gist of said precip forming ahead of, and along, the cold
front is in reasonable agreement. With that, look for precip chances
to increase during the Wednesday and continuing through Thursday
morning/early afternoon. After that, model agreement is awful. Both
the EC and GFS pick up on small wave moving across the northern
Intermountain West as an area of low pressure moves into the PacNW.
The GFS brings this low ashore into Washington State Friday night
and has it filling (weakening) while the EC brings the low down the
West Coast and does NOT have it filling. All that being said, we may
see a few showers for the rest of the long term period as small
disturbances brush our northern and southern neighbors but nothing
significant noted. Will be interceding to see how the models resolve
themselves with regards to that area of low pressure.

As far as temperatures are concerned, Thursday will be the coolest
day as the cold front moves through. Won`t be short lived though as
temps increase 5 to 10 degrees Friday and continue the upward trend
into the weekend.

&&


.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 536 AM MDT Mon Apr 29 2024

Some scattered to broken low clouds will remain trapped along
the Divide this morning, including some low stratus in KGUC.
Much of this will get burnt off by sunshine and mixing this
morning as winds pick up across the region. Winds will gust
20-30 mph at many locations, especially farther north, as
another disturbance approaches this evening. This will bring
more cloud cover and scattered rain and snow showers across
northeast Utah and northwest Colorado. A strong jet streak aloft
over northern Colorado will lead to some LLWS concerns late in
the TAF period when surface winds subside.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...LTB
LONG TERM...TGR
AVIATION...TGJT