882
FXUS65 KGJT 180533
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1133 PM MDT Sat May 17 2025

.KEY MESSAGES...

- Isolated to widely scattered showers or storms will continue
  this afternoon and evening for areas north of I-70, with
  potential for strong wind gusts to 50 mph and little in the
  way of rainfall.

- A Red Flag Warning remains in effect for southeast and east-
  central Utah through 8 pm this evening due to low relative
  humidity, gusty winds and critical fuels.

- Cooler and unsettled conditions return for Sunday through
  Monday, with mountain snow and valley rain expected. A Winter
  Weather Advisory is in effect for the western Colorado
  mountains for elevations above 9,500 feet where 4 to 10 inches
  of snow is expected through Monday morning. Travel likely to
  be impacted over the higher passes.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 346 PM MDT Sat May 17 2025

Showers developed north of I-70 this afternoon as expected with
gusty outflow winds of 40 to 50 mph on average. South of I-70,
relative humidity has dropped into the teens and single digits
with gusts 25 to 35 mph with critical fire weather conditions
being met, so the Red Flag Warning remains in effect for east-
central and southeast Utah where fuels are critical through 8 pm
this evening. Clouds are increasing from the west and expect
this to continue through the late afternoon into the evening
ahead of the approaching low pressure trough, dropping into the
Great Basin from the PacNW. Highs are warmer than yesterday so
far with the lower valleys seeing 70s and temps pushing 80
degrees across the desert valleys of east-central and southeast
Utah and the Grand Valley.

The low pressure trough becomes negatively tilted as it moves
through Utah and enters eastern Utah and western Colorado late
tonight into Sunday morning. The best period of precipitation
looks to occur Sunday morning through Monday morning with more
widespread showers and scattered thunderstorms. PWAT anomalies
increase to around 140 to 180 percent of normal during this
period with a steep drop off Monday morning, so moisture looks
more abundant and much of the area looks to get some beneficial
precipitation. Snow levels will start off fairly high around
9,000 to 9,500 feet Sunday morning and lower to around 6,500
feet by Monday morning. Lower elevations will see rain with snow
in the mountains, but impacts look to be felt at mountain pass
level with the better snow accumulations at elevations above
9,500 feet.

Given the late season nature of this event and potential
impacts to travel over the passes as well as snow accumulations
expected, decided to issue a Winter Weather Advisory for our
western Colorado mountains for elevations above 9,500 feet for 4
to 10 inches. The southern and southwest facing central
mountains look to be more favored for better snowfall than the
northern mountains but included both in the advisory from 6 am
(12Z) Sunday to 6 am (12Z) Monday during the peak period of
forcing and better moisture. Cold front moves through late
Sunday afternoon into the evening where the best precipitation
rates look to occur, especially given steep lapse rates and
convective potential. Temperatures will also be much cooler on
Sunday as highs drop 10 to 15 degrees from today`s highs...with
highs around 8 to 15 degrees below normal.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 346 PM MDT Sat May 17 2025

Another closed low dives southwards from Washington over the
CWA on Monday, bringing a second wave of precipitation to the
area, albeit to a much milder degree than seen over the weekend.
This comes from the lacking moisture content on the backside of
the departing trough as ensemble-indicated PWAT`s are generally
below normal. As a result, storm formation will be heavily
dependent on orographics. However, with relatively weak flow
from broadening height gradients, our forecasted snow
accumulation on Monday peaks out at an additional 2-3 inches.

Following Monday, a very broad, low-amplitude ridge (nearly
zonal flow) develops over the majority of the western CONUS.
This allows temperatures to once again rise in eastern Utah and
western Colorado. Near-normal high temperatures persist on
Tuesday and Wednesday before increasing to 5-10 degrees above
normal on Friday. Drier conditions (single-digit RH in most
valleys) and moderate gusts (exceeding 25 mph or higher at high
elevations) may yield some fire concerns towards the end of the
week. However, with this recent bout of moisture paired with
fuels not yet critical for much of the region, it remains to be
seen if the setup will be in place for an increased fire risk or
not. Nonetheless, it is worth watching going forward.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1130 PM MDT Sat May 17 2025

Mid and high level clouds are moving into the region, bringing
gradually lowering ceilings. Showers have moved into eastern
Utah but are not impacting any TAF sites at this time. Over the
course of the night showers will fill in from southwest to
northeast. In addition to showers, thunderstorms are expected to
develop tomorrow afternoon. South to southwesterly winds will
remain elevated through the night, with gusts up to 30 knots
during the afternoon. VFR conditions will prevail, but drops
into MVFR/IFR conditions will be possible as showers fill in,
especially for higher elevation terminals where snow will be the
precipitation type.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...Winter Weather Advisory from 6 AM Sunday to 6 AM MDT Monday
     for COZ004-009-010-012-013-018-019.
UT...None.

&&

$$

SHORT TERM...MDA
LONG TERM...BW
AVIATION...TGJT