Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 251232
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
632 AM MDT Mon Mar 25 2024

.KEY MESSAGES...

- Light to moderate mountain snow is expected through continue
  this morning with travel impacts over the passes. Light snow
  will continue at times through the afternoon but additional
  accumulations are expected to be minimal.

- Unsettled weather continues through the mid week period with
  additional light accumulations of snow in the mountains.

- Below normal temperatures hang on through mid week with a
  warming trend pushing temps back toward near or slightly above
  normal late this week into the weekend.

- The next storm looks to impact the area late this weekend into
  early next week but still some uncertainty with track and
  timing.

&&

.UPDATE...
Issued at 614 AM MDT Mon Mar 25 2024

Snow stake cams and SNOTELS indicate accumulations since
midnight have been minimal, so rates have lessened considerably.
Webcams still indicate some light snow falling in spots but the
there is a noticable downtrend as this system moves further east
and satellite indicates some breaks in the upper level cloud
cover while radar indicates a lessening in the precipitation
intensity. Although light snow will continue through the morning
and afternoon, additional accumulations are expected to be
minimal. Therefore, felt confident enough to let the Winter
Weather Advisory expire on time at 6 am MDT this morning. Roads
among the higher elevations and passes remain snowpacked so
take it slow if traveling this morning.

&&

.SHORT TERM /THROUGH TUESDAY/...
Issued at 440 AM MDT Mon Mar 25 2024

Northerly flow is evident on radar as showers continue to move
through behind the departing trough. The H7 and H5 low are
already into western Kansas, so dynamic forcing is waning at
this time. Having a look at webcams and observations across the
area, some light snow continues here and there over the area but
remains isolated to scattered at this time. The snowfall rates
in the southern mountains seem to have lessened considerably
with not much additional accumulation since yesterday evening.
The central mountains and northern mountains seem to still be
seeing some impacts as roads remain snowpacked with burst of
light to moderate snow causing reduced visibility at times.
Snow accumulations have come up a bit last evening into the
early morning, however, these rates have lessened over the last
few hours since midnight. Am a bit concerned with the northwest
San Juans and the Uncompahgre Gorge area as light northerly
flow is a good setup for continued snowfall due to favored
orographics and radar indicates snow showers continuing to feed
into that area. The webcam in Ouray though is indicating light
snow and nothing much right now over Red Mountain Pass, but
unsure at this time of night how much could be falling in the
Gorge area between Ouray and Red Mountain Pass at this time.
This will be something to monitor.

Although most snow should lessen today, orographics will
continue to be the primary driver of additional snowfall.
Additional accumulations appear light and minimal at this time,
so am good with keeping the Winter Weather Advisories through
12Z (6 am MDT), but will reevaluate if any need to be extended.
As the trough shifts eastward, a deformation zone looks to form
over the eastern San Juans with some easterly winds at H7. It is
subtle, but this light easterly flow tends to favor upslope
snowfall over the eastern San Juans which falls on PUB and ABQ
side of the San Juans. On the western side of the San Juans, we
may see downslope over our side which would limit snowfall. In
addition, northerly flow should dominate, which would not
produce much additional snowfall for the southern San Juans and
could keep some light orographic snow going through the
afternoon over the northern San Juans. Regardless, additional
accumulations look to be in the 1 to 3 inch range over the
northwest San Juans with locally higher amounts over the eastern
San Juans and much less in the trace to 2 inch range over the
northern and central mountains...not enough to warrant extending
the Winter Weather Advisories at this time. Also, just like
yesterday during the heart of the storm, the roads should remain
wet due to the milder afternoon temps and higher March sun
angle, limiting impacts on the roads during the daytime.

While most snow will come to an end this evening, a weak
shortwave will move across the north tonight into Tuesday
morning in the unsettled northwest flow, producing some light
snow over northwest Colorado. Lapse rates steepen to 8+ C/km
Tuesday afternoon with enough instability with CAPE values near
200 J/kg to produce some more widespread convective showers.
There really is no discernible feature other than instability
and enough moisture as well as orographics to produce some light
snow showers over the mountains. At this time, additional
accumulations appear minor with 1 to 3 inches possible across
the western Colorado ranges, with the northern mountains
potentially seeing a little higher with 2 to 4 at the higher
peaks. Roadways are expected to be wet with the high March sun
angle and limited impact. Temperatures will remain cool with
highs around 10 or so degrees below normal through Tuesday.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Issued at 440 AM MDT Mon Mar 25 2024

The synoptic pattern Tuesday evening is consistent among the
models with ridging along both the Pacific and Atlantic Coasts,
a longwave trough across the continent, the low along the
Manitoba-North Dakota Border with a trough extending south
through the Dakotas, Nebraska, Kansas and Oklahoma to the Texas
Panhandle, and the next system, a deep cold low off the coast of
British Columbia descending from the Aleutian Islands to off
the Pacific Northwest. As the next system drops to off the
Pacific Northwest Thursday, the axis of the Pacific Coast Ridge
will have shifted east of the Rockies, shifting the whole
longwave pattern about 1,000 miles to the east.

So, that being said, eastern Utah and Western Colorado can
expect unsettled weather in the form of light snow showers to
continue Tuesday night favoring the central and northern
Colorado mountains with little new snow accumulation. Wednesday
will see mostly clear skies as the ridge moves into the region.
Clouds move in from the northwest Thursday as the ridge axis
slides east of the Divide putting the region under a
southwesterly flow, and a weak shortwave brushes the northern
boundary bringing a slight chance for light snow showers across
the northern mountains. Another shortwave passes to the north
again Friday night with increased chances for showers in the
northern mountains, spreading south into the central Colorado
mountains. Blended model guidance gives a chance for widely
isolated to scattered showers across the region Saturday with
better chances for widely scattered to widespread showers Sunday
indicating the uncertainty of the timing and track of this next
system as discussed below. I wouldn`t be too worried about
plans for Saturday, but I`d have a backup plan for Sunday in
case the storm comes in early.

Temperatures will warm to five degrees below normal Wednesday
with the mostly clear skies letting the sun warm us. As the
ridge moves to the east, the southwesterly flow will advect warm
air into the region warming temperatures to near normal
Thursday and around 5 or so degrees above normal Friday into the
weekend.

Looking ahead to the coming weekend, the low pressure system
discussed above continues to descend south off the Pacific
Coast through Sunday night when it finally makes landfall to
track east along or north of the US-Mexican Border. At a week
out, the models continue to show strong agreement and the GEFS
and European ensembles indicate an amazingly tight grouping of
their members. One would think with such tight agreement among
the models and ensembles, the solution/forecast should be highly
reliable, but as we saw with the last system that consistently
forecasted another Rex blocking pattern with this last system a
week out that didn`t materialize, with springtime weather
patterns, all the models can be fooled at the same time. Hence,
the forecast in the long term is for the next system to impact
eastern Utah and Western Colorado sometime Sunday into early
next week as a trough moving overhead to a low tracking to the
south. Looking at the jet support for this system, the Arctic
leaf of the jet that descends with the low meets up with a
subtropical leaf Sunday to kick the low to the east or
northeast, and favors the ejected low tracking across the
southern half of the region in the early next week. This system
will likely generate descent to strong atmospheric river (AR)
action leading to significant impacts moisture wise to the
region. It will be interesting to see how this plays out.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 614 AM MDT Mon Mar 25 2024

Light snow will continue over the mountains this morning and
some higher valleys with brief MVFR to IFR conditions. CIGS will
be below ILS breakpoints through the morning with improvement
seen this afternoon. Otherwise, VFR conditions will prevail
outside of areas with showers with some breezy conditions
possible at times.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

UPDATE...MDA
SHORT TERM...MDA
LONG TERM...DB
AVIATION...TGJT


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