Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 280958
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
358 AM MDT Thu Mar 28 2024

.KEY MESSAGES...

- Warmer and breezy conditions expected today with showers
  developing over the northern and a few central mountain
  locations.

- A cold front will move into northern portions of Utah and
  Colorado overnight providing a focus for heavier
  precipitation. Travel over northern mountain routes will be
  impacted after sunset through Friday morning.

- There is a low (>40%) chance of a persistent band or bands
  of heavier snow developing between I-70 and Highway 40
  overnight...which could bring significant snow amounts.

- Unsettled conditions will continue through the weekend and
  into Tuesday morning. Sunday and Monday and look like the core
  of the storm, with the greatest snowfall accumulations for
  the period.

&&

.SHORT TERM /THROUGH FRIDAY/...
Issued at 358 AM MDT Thu Mar 28 2024

A transitory ridge is passing through the Rockies this morning
providing the advertised short break in precipitation. This ends
later this morning as it slides onto the Plains and a persistent
SW flow pattern sets up with low pressure digging along the
Pacific coast. There is a decent AR plume caught up in this flow moving
over the crest of the northern Sierras and spreading moisture
across the Intermountain West thanks to a 120kt jet. We are
currently on the fringe of this moisture as indicated by the
thickening high cloudiness. Large scale forcing will increase
through the late morning and into the afternoon hours as the jet
begins to dip farther south and bring the core across Utah. Some
light orographic snow is likely to break out over some of our
our high peaks of the northern and possibly central mountains by
mid day as top down saturation commences. However we will get
the most bang for our buck when the energy crossing the Northern
Rockies forces a frontal band southward into our NW CWA early
this evening. Expect a breezy day over much of eastern Utah and
western Colorado in this pre-frontal environment. The front
looks to slowly progress across the northern CWA and hang up on
the high plateaus and northern mountains under the SW flow
pattern. This is when things get interesting. Low level forcing
along and behind the front will be coupled with the larger
scale ascent aloft by a tightening thermal gradient in the
indirect circulation of the jet core aloft. This should produce
at better defined SW-NE oriented band of heavier precipitation
for at least a few hours overnight. In addition negative
EPV/static stability profiles favor other bands of precipitation
over the central and northern CWA as the synoptic/mesoscale
lift and likely orographics release this instability. The big
question attm is how widespread/prolonged will the moderate to
heavier precipitation rates in these bands occur. Ptype is
likely to be snow in most lower to mid elevation areas in the
post frontal environment. Expect some decent snow in the higher
elevations of our northern mountains with Rabbit Ears the most
likely to be impacted overnight. Lower elevation roadways are
likely to be able to take some snowfall after a warm
day...though still near to below normal...but if a persistent
heavier snow band sets up all bets are off. Overall confidence
not currently high enough to hoist winter headlines and there is
chance this may occur on the fly if the expected banding
becomes reality tonight. Bottom line is from the I-70 mountain
corridor to the northern border the possibility exists for this
snow banding and quickly changing conditions tonight into
Friday morning. Frontogenesis will slowly ease though the
afternoon as the jet lifts northward and overall the lower
profile should begin to warm enough to limit snowfall potential
on the roadways below pass level. Instability remains and
banded/convective precipitation will continue through tomorrow
afternoon with likely some decent heavy snow showers at times in
the mountains along with threat of graupel/snow pellets and/or
lightning about anywhere else. Unfortunately all the action will
in the north with this first round of precipitation with the
southern mountains missing out. This will only be temporary
however with more details below. Temperatures in the south will
have the best chance of getting up to or exceeding normal the
next few afternoons with highs well into the 60s over red rock
country. Farther north clouds and precipitation will keep things
much cooler.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Issued at 358 AM MDT Thu Mar 28 2024

Weak shortwaves...embedded within southwest flow and acting on
a nearly stationary boundary draped over the northern half of
the CWA... will continue to support intermittent valley rain and
mountain snow showers across northeast Utah and northwest
Colorado Friday night into Saturday. Most of the snow will be
confined to the higher elevations across the Flat Tops, the Park
Range, and the Eastern Uinta Mountains where a few inches or
more can be expected. And while conditions will be fairly
unsettled along and north of the boundary through the first half
of the weekend, south of it will be a much different story.
Warm advection and deeper mixing across southeast Utah and
southwest Colorado will help to boost high temperatures well
into the 60s to near 70 for many places. Additionally, the
deeper mixing will tap into a belt of strong winds aloft and
bring frequent gusts of 35 to 45 mph down to the surface. The
one potential fly in the ointment is cloud cover, given the
enhanced moisture streaming in from the southwest. Depending on
how thick the clouds are, temperatures and wind gusts could end
up lower than progged. For now, we`ll assume enough breaks and a
strong late March sun angle will be enough to keep current
forecasts on track.

Heading into Sunday, attention then turns to a large and deep low
pressure system making landfall across the Desert Southwest. As this
system tracks through the Great Basin and Four Corners states
through Monday, dynamic forcing will increase and precipitation will
become more widespread. There`s not a whole lot of cold air to work
with given mild Pacific origins, but elevations above 6000 to 7000
feet will still be favored to pick up some more snow. Most valleys
will only see plain rain, perhaps mixed with a little snow as the
storm wraps up. Forecast snowfall amounts in the mountains still
look drawn out enough to be sub-advisory for now, but that can
change in the coming days. Since the system is likely to be a slow
mover, any increase of QPF or precip intensity could drastically
increase snow totals. Something to keep an eye on going forward.
Either way, cooler and unsettled weather will be the rule from
Sunday through early Tuesday. High temperatures will generally be
near to slightly below normal for this period.

In the wake of the storm, another ridge of high pressure builds in
across the Great Basin and Four Corners on Wednesday. Dry and warm
weather will round out the long term period as a result with high
temperatures quickly rebounding back above normal by 4 to 8
degrees.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1117 PM MDT Wed Mar 27 2024

High level clouds are in place across the northern 2/3 of the
area supplying moisture ahead of the next approaching system.
This will not arrive until late in the forecast leaving VFR to
prevail through the bulk of the next 24 hours. Some cigs will
lower late and could approach ILS where this marker is above
6000ft AGL. Otherwise winds will be the main issue as they
increase from the southwest today with many areas seeing gust
approach or exceed 25 mph. The increasing winds aloft will lead
to pocket of LLWS and eventually mountain wave turbulence by
tomorrow afternoon.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...15
LONG TERM...MDM
AVIATION...TGJT


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