469
FXUS65 KGJT 092102
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
302 PM MDT Thu May 9 2024

.KEY MESSAGES...

- Snowfall will favor the eastern Uinta mountains in northeast
  Utah and the higher elevations of the San Juans and central
  Colorado mountains through Friday.

- Snow amounts in excess of 6 inches have a 50 to 60 percent
  probability of occurring over the highest peaks of the eastern
  Uintas...eastern San Juans and Elk mountain over the next 36
  hours...with lesser probability of at least 30 percent along
  the travel corridors.

- Unsettled conditions will persist through the weekend along
  with a slow warming trend...however temperatures will remain
  below normal.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 301 PM MDT Thu May 9 2024

The Plains Rex block has successfully retrograded back to the
Intermountain West this afternoon with the main shear axis
laying across our CWA. Water vapor is showing a clearly defined
wave moving eastward across northern Utah which has been
enhancing the precipitation rates over the past 12 hours. Web
cams have shown heavy snow rates falling over the eastern Uintas
but as expected this modified airmass and time of year has kept
snow off the roadways for minimal travel impacts. Ascent has
been increasing across our southern CWA as a jet streak is
rounding the main circulation...with this area of ascent
continuing to lift northward across the CWA overnight as a well
defined zone of deformation. In additions the increasing low to
mid E/SE flow pulling in Gulf moisture that is pooling on the
eastern side of the divide in a post frontal environment. So
basically the heavier precipitation we have seen across the
northwest CWA will be moving out while redeveloping over higher
spine of our Southwest/Western CWA over the next 12 to 18
hours. In between is looks like a general downturn in
precipitation will occur overnight. On Friday a combination of
increasing isentropic upglide and heating of the day will get
this conditionally unstable atmosphere bubbling and more
widespread showers break out through the afternoon. With the
loss of heating another downturn looks to arise tomorrow night
before the main low to our West begins to eastward for the
weekend. The forecast trend remains on track with our eastern
high peaks seeing significant snowfall rates/amounts over the
next 24 hours where 6 to 12 inches of new snow has at least a 60
percent probability of occurring. There could be some brief
impacts to roadways overnight into the mid morning hours in our
Southwest and central high passes...with melting likely taking
care of any snowfall on roads by mid-day. Snowfall amounts and
rates look limited Friday night with large scale ascent again on
the increase by sunrise over our southern CWA. Below normal
temperatures continue.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Issued at 301 PM MDT Thu May 9 2024

The weekend will continue to be active as the pesky area of low
pressure slowly exits the region. By Saturday the closed low will be
centered over the Four Corners with ample wraparound moisture
resulting in scattered to numerous showers throughout the day. Mild
antecedent conditions will keep snow levels high, generally above
9kft, but areas at and above this elevation can expect upwards of 2
to 5 inches of snow on Saturday. The high sun angle will mitigate
impacts but, due to increased instability and forcing as the low
starts to lift northeast, convection could briefly drive snow levels
down. Either way, the vort max associated with the low will pass
through Saturday evening before subsidence begins to settle overhead
by Sunday morning. Even so, lingering moisture paired with a colder
airmass and orographics will allow at least scattered showers to
persist on Sunday, favoring the higher elevations along the Divide.
An additional couple of inches of snow will be possible at the
higher peaks but, again, little to no impact is expected.

Unsettled northerly flow will keep showers in the forecast for
Monday morning but a weak transitory ridge will build in from
the west for the afternoon. This advection of drier air will
see showers taper off in coverage, though scattered activity will
continue over the mountains. For Tuesday and Wednesday moisture will
once again be on the rise as a trough of low pressure begins to dig
into the Intermountain West. This will kick the ridge east and see
flow aloft shift to the west/southwest. Winds don`t look to increase
too much ahead of this system but, by the midweek point, scattered
to potentially numerous showers and some storms can be expected.

Temperatures through the period will generally be below normal given
the unsettled pattern. A gradual rebound will occur as we head into
the new work week as flow begins to shift to a more mild component.
A similar trend is expected for low temperatures through the
period.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1139 AM MDT Thu May 9 2024

VFR conditions are in place with shower activity beginning to
expand across the region under daytime heating. If showers move
over an airfield temporary ILS/MVFR conditions will be possible
through the early evening hours. The best chance of MVFR or
below conditions will be in the Gunnison Basin as moisture
spills over the higher terrain in the valley. Northeast winds
will also be strong at times over the Uinta Basin through the
evening with gusts of 25 to 40 mph possible.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...15
LONG TERM...MMS
AVIATION...TGJT