766
FXUS65 KGJT 161756
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1156 AM MDT Wed Apr 16 2025

.KEY MESSAGES...

- Above normal temperatures continue through Thursday, before
  much cooler temperatures arrive for the weekend.

- Showers and thunderstorms are once again possible this
  afternoon over the higher terrain, mainly north of I-70.

- Localized critical fire weather conditions are possible south
  of I- 70 this afternoon, with more widespread critical fire
  weather conditions expected tomorrow afternoon as
  southwesterly winds increase, with gusts of 35-45 mph
  possible.

- A strong spring storm will move into the area Thursday
  evening, bringing valley rain and mountain snow lasting
  through late Saturday, with a high chance (>75%) of at least 6
  inches of snow over the higher peaks.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 243 AM MDT Wed Apr 16 2025

Looking at the synoptic scale pattern this morning, low amplitude
ridging is in place over the Four Corners, while troughing lies just
to the west. This troughing is composed of two centers of low
pressure, a closed low just off the Southern California coast and
another closed low over northern Saskatchewan. It is this northern
low that will be the dominate player in our weather starting
tomorrow, as it drops south through the Intermountain West and even
absorbs the SoCal low. Today, however, that high pressure stays in
control, along with strong, moist southwesterly flow aloft. This
will keep skies partly cloudy and temperatures 10-15 degrees above
normal. However, a weak shortwave and some channelized vorticity is
expected to move through northeastern Utah and northwestern Colorado
this afternoon, acting on the present moisture to kick off showers
and even a few thunderstorms over the higher terrain. Little
precipitation is expected to make it to the ground with these
showers and storms, with enhanced winds instead the main threat. And
that is on top of the already gusty conditions expected today as
stronger winds mix down from the southwesterly jet aloft. Across the
southern half of the CWA, where conditions are expected to be a bit
drier, this will lead to borderline critical fire weather conditions
where fuels are receptive.

As the northern low drops into the Northern Rockies tonight, the
pressure gradient aloft will start to tighten, driving gusty winds
well into the overnight hours. This in combination with increasing
cloud cover will keep lows mild tonight. By tomorrow morning, the
cold front associated with this northern low will be just on our
doorstep. Ahead of this front, strong southwesterly winds are
expected, with gusts of 35-45 mph possible. For the lower valleys of
southwestern and west-central Colorado, where fuels are susceptible,
this will result in critical fire weather conditions tomorrow
afternoon. Fire Weather Watches are currently in effect from 11AM to
8PM tomorrow. Across northeast Utah and northwest Colorado, showers
and possible a few thunderstorms will overspread the area during the
afternoon as the cold front pushes through. Precipitation will be in
the form of rain for the most part, with snow being confined to
elevations above 10k feet, at least to start. Temperatures across
the area will also run a few degrees cooler than today, although
still around 5 degrees above normal.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Issued at 243 AM MDT Wed Apr 16 2025

The phasing of the northern and southern streams will be complete by
Thursday evening as the system dropping out of the Northern Rockies
absorbs the meandering Southwest system. This phasing will merge
moisture pulled in from the southern system with stronger dynamics
and cold air from the northern system to re-introduce winter to the
area through the weekend. PWAT is not off the charts nor is the cold
air but we will be swinging from 1-2 stdev above normal for H500
heights and H700 temps to 1-2 stdev below as this phased trough
works through Friday into early Saturday. Much of the heavier
precipitation will initially be focused on the surface cold
front/mid level frontogenesis interaction over the northern CWA
Thursday evening through early Friday morning. With the trough
lagging upstream the front, mid-level thermal forcing looks to stall
over southeast Utah and southwest Colorado and lead to a band of
heavier precipitation. This and southerly orographics looks to feed
the precipitation machine across the southern and central CWA on
Friday and lead to some of the higher snow amounts in the southern
mountains. The main trough swings trough Friday night with lingering
cold air advection aiding convective showers into Saturday mainly
across the southern and central CWA. The challenge of this forecast
period will be time of year with the high sun angle and recent
warmth fighting the heavier precipitation rates produced by forcing
and the release of instability/convective showers. Impacts are more
likely to be limited to the overnight hours through the mountain
corridors. The coldest air will move through the northern mountains
and Rabbit Ears and Vail Passes may see some impacts during the day
under heavier snow bands. Feel QPF output in the blended grids may
be influenced to much by convective feedback but there remains a
high probability (>75%) of 6 or more inches of snow across the many
of the higher peaks by late Saturday evening. There is also a high
likelihood of some of the snotels and high peaks seeing up to a foot
of new snow. Temperatures drop to well below normal Friday and
Saturday as this slightly anomalous trough rolls through with a
rebound closer to normal by Sunday. Unsettled but warming conditions
move in through early next week.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1155 AM MDT Wed Apr 16 2025

Breezy afternoon southwest winds of 20 to 30 mph will develop
with scattered virga showers. Showers should be high based with
gusty winds nearby but low confidence on any showers impacting
TAF sites this afternoon. Best chance would be higher terrain
sites like KASE and KTEX. Winds increase aloft overnight as
winds decouple in lower valleys, leading to areas of LLWS and
mountain wave turbulence. Winds will mix to the surface after
15Z Thursday, with gusts in the 30s and 40s by Thursday
afternoon. Showers look to develop tonight into Thursday across
the north, with best chance for VCSH at KHDN. VFR is expected to
prevail for the majority of the next 24 hours aside from brief
MVFR CIGS if any showers impact TAF sites.

&&

.FIRE WEATHER...
Issued at 243 AM MDT Wed Apr 16 2025

With southwesterly winds gusting 25-35 mph today but borderline
relative humidity values, some localized critical fire weather
conditions will be possible south of I-70 this afternoon. More
widespread critical fire weather conditions are expected Thursday as
southwesterly winds increase, with gusts of 35-45 mph possible, and
drier air moving in from the south. A Fire Weather Watch remains in
place for CO Zone 292, and thanks to a fuels update, CO Zone 207 has
been added to this Fire Weather Watch.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...Fire Weather Watch from Thursday morning through Thursday
     evening for COZ207-292.
UT...None.

&&

$$

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