Weather Service Report


268 
FXUS65 KGJT 290943
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
343 AM MDT Fri Mar 29 2024

.KEY MESSAGES...

- Moderate to heavy narrow bands of snow will continue to impact
  northern portions of Utah and Colorado through at least mid
  morning today. Travel will be impacted in these snow bands. 

- The precipitation will begin to taper off and lift north
  through the afternoon and evening hours...but continue over
  the northern mountains of Colorado and Utah.

- Gusty winds will develop over southern and central portions of
  Colorado and Utah on Saturday with a few gusts exceeding 45
  mph in the southern desert valleys in the afternoon. 

- Unsettled conditions continue through the weekend into Monday
  as another Pacific storm moves through the Intermountain West
  and Rockies. Significant mountain snow is likely brining
  travel issues...especially during the overnight hours. 

&&

.SHORT TERM /THROUGH SATURDAY/...
Issued at 342 AM MDT Fri Mar 29 2024

The banded precipitation has set up as across the CWA as
expected and as much snow had likely fallen in some of the lower
elevations as is being reported at SNOTELs. Through 3AM the
northern mountains have generally received 2-4 inches with a few
webcams over the Park showing a bit higher. This is likely what
has fallen over portions of NW Colorado in the post frontal
environment with the current band moving through Rangely attm.
The front looks to have pushed up against the Tavaputs and
stalled with the snow band being generated by the mid-level
thermal circulation situated between an exiting jet core and one
arriving from upstream. It is this upstream jet and an embedded
wave that will continue to feed ascent and help release
instability through the early afternoon hours. The mid level
circulation weakens through the afternoon as the jet begins to
lift northward in an increasing southerly flow pattern due to
the digging trough off the Cali coast. So it looks like a fairly
wet forecast to start the day over at least the northern half of
the CWA though the southern mountains will likely get some light
snow through the morning as the wave works through. The radar at
least suggests we are saturating the mid levels with virga and
we should eventually get some of that to the ground over the
next few hours along and South of I70. The precipitation shield
will continue to lift across the northern CWA this
evening and clear the northern border by sunrise on Saturday.
The exception will be lingering orographics across the northern
mountains of Utah and Colorado. IVT suggest we will continue to
see SubTrop moisture pumped into the area in the SW flow
downstream of the system that will begin to edge onshore. The
bulk of the dynamics are upstream however and we should see a 
rather quiet start to Saturday. This only lasts through the 
morning as eventually instability showers develop in the highly 
mixed atmosphere in the afternoon as we tap into the moisture 
aloft. This deep mixing also means winds pick up and there is at
least a moderate probability (40%) of gusts exceeding 45 mph 
near the 4 Corners. Temperatures remain cooler across the north 
under the threat of more cloudiness and precipitation. In the 
south however it looks like we should warm near to slightly 
above normal the next few afternoons and may even see some 70s 
in the lower desert valleys of SE Utah. 

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Issued at 342 AM MDT Fri Mar 29 2024

The mid-level closed low pressure center just off the central 
California coast splits on Saturday night forming a dipole of low 
pressure centers. The low forming the northern pole shifts east-
northeast to the Great Basin by 12Z/Sun while the southern system 
moves over the Catalina Islands. As the pattern evolves the northern 
portion of the forecast area will fall under an area of overrunning 
enhanced by divergence in the left exit region of the 140+ kt jet 
moving through the base of the positive tilt trough linking the two 
low centers. Precipitation will favor the northern zones with the 
mountains favored. The trough shifts east on Sunday and as the 
northern low moves over central Wyoming, the cold front associated 
with this system slides eastward across the forecast area during the 
day. Mid-level forcing is maximized over the region during this 
period according to Q derived omega fields and consequently, 
precipitation will become widespread. The upper level trough moves 
overhead Sunday night and Monday placing the forecast area under the 
col between the low over the northern Plains and the southern system 
over the Southwest. As a result, showers will continue across the 
area, though moisture levels are indicated to decline and shower 
activity will become less organized with convective cells become 
more prevalent. Snow amounts during this period suggest the 
potential for another round of advisories. 

Subsidence and drying sets in Monday night bringing an end to the 
active weather. From Tuesday to Wednesday a ridge of high pressure 
trailing this weekend's storm will move from the Inter-Mountain West 
to the northern Rockies. This will place the forecast under a dry, 
northerly flow aloft through midweek and the weather will remain 
uneventful. The next storm moves along the Canadian coast on 
Thursday driving the ridge east and results in strengthening 
southwest flow ahead of the front associated with the system. As a 
result, breezy conditions will be developing with a chance of pre-
frontal showers over the north Thursday afternoon. 

The long range period begins with below normal temperatures in 
response to the cold front which moves through on Sunday with cold 
air likely to remain entrenched over the area on Monday. The 
remainder of the week will bring a steady rise in temperatures with 
highs near normal Tuesday then climbing to near 10 degrees above 
normal by Thursday.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1120 PM MDT Thu Mar 28 2024

Widespread showers across northern Utah and Colorado transition
to more scattered in nature across the central CWA late this
evening. MVFR to LIFR conditions will occur as a result of snow
and low clouds across the northern TAF sites well past sunrise
with a mixture of ILS to MVFR occur in the central and VFR stays
in place to the South. Improvement will be slow to arrive on
Friday but after 18Z ILS/VFR should become more common across 
the central and North. Passing convective showers however could 
quickly change conditions to LIFR through the afternoon. 
Moderate winds aloft will keep a threat of LLWS and mountain 
wave turbulence in place over the next 24 hours with some gusts 
over 30 mph reaching the surface at times.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...Winter Weather Advisory until 6 AM MDT Saturday for COZ004-009-
     010-012-013.
UT...None.

&&

$$

SHORT TERM...15
LONG TERM...NL
AVIATION...TGJT

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Western Regional Climate Center, wrcc@dri.edu