704
FXUS65 KGJT 061803
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1203 PM MDT Mon May 6 2024

.KEY MESSAGES...

- A strong spring storm will continue to bring widespread
  precipitation this morning with significant mountain snow
  expected across the northern Colorado ranges. Light snow
  accumulations are possible for the higher valleys as well as
  most other mountain ranges.

- Another disturbance will bring more snow showers across the
  north on Tuesday. This system will also drag another strong
  cold front through the region, setting up the potential for
  widespread freezing temperatures Tuesday night.

- Much cooler and unsettled weather will be the rule for the
  rest of the week ahead as several disturbances keep mountain
  showers in the forecast most afternoons.

&&

.UPDATE...
Issued at 1201 PM MDT Mon May 6 2024

Winds gusting over 40 mph in the southern Uinta Basin so added
a wind advisory through this evening for that area. Will
continue to monitor the Upper Colorado/Eagle Valleys from Rifle
to Eagle for the same and possibly the Gunnison Basin. These
same areas and more will continue to see some stronger winds on
Tuesday as well.

&&

.SHORT TERM /THROUGH TUESDAY/...
Issued at 355 AM MDT Mon May 6 2024

As expected, a strong cold front came blasting across eastern
Utah and western Colorado overnight, leaving us with much colder
temperatures in its wake. Temperatures are some 20 to 30
degrees colder than just 24 hours ago, which has allowed rain
along and behind the front to change to snow in many of the
higher elevations above 5000 feet early this morning. Even
places like Meeker, Rifle, and Montrose have changed to snow,
with some minor grassy accumulations possible there. Widespread
precipitation, some heavy at times, will continue through the
early daylight hours before drier air and subsidence builds in
behind the departing shortwave trough. Thus, am expecting a
gradual downtrend in shower activity in most places by late
morning or early afternoon. The exceptions will be across the
central and northern Colorado mountains and their adjacent high
valleys as moisture, instability, and favorable orographics will
keep snow showers going deep into the afternoon. Several more
inches of accumulation are likely in those areas, with the Flat
Tops, Elkheads, and Park Range favored the most. Given the time
of year, roads should mostly just stay wet or quickly melt back;
however, any heavier rates of 1 inch per hour or more can lead
to roads becoming snow-covered and slick. This will especially
be the case for the high mountain passes such as Rabbit Ears
Pass and Vail Pass. Overall, think we have the potential impacts
well covered with the ongoing Winter Weather Advisories, so no
changes were made with this forecast package. Despite
precipitation ending for most and clouds likely breaking for
some sun this afternoon, high temperatures will be a good 10 to
20 degrees below normal, which is quite a stark contrast from
yesterday. Overnight lows will be much chillier too, especially
up north where snow showers are likely to linger before tapering
off late.

On Tuesday, another shortwave rounding along the southern
periphery of a closed low spinning across the northern High
Plains will dig across the northern Four Corners. This wave,
which will act on residual moisture and daytime instability,
will spark a fresh round of showers across the eastern Uintas,
portions of northwest Colorado, and the northern Colorado
mountains. Snow levels will continue to hover between 5000 and
6000 feet, so most of the showers will fall as snow (perhaps
mixed with a little rain closer to 5000 feet) in those areas.
With that being said, the largest accumulations will be found
across the the highest elevations of the Park Range, which is
where the most favorable orographics, moisture, and instability
reside. Latest 00Z model guidance shows accumulations of 3 to 6
inches in the Park Range, with isolated amounts up to 7 or 8
inches. Given that this is only expected to impact a fairly
small portion of COZ004, have opted not to issue any additional
winter highlights at this time. Use caution if you`ll be
traveling over Rabbit Ears Pass, however. Accumulations outside
of the Park Range will generally amount to 3 inches or less.
Outside of those northern mountains and high valleys, mainly dry
weather is in store, but it will be another cool day with
temperatures well below seasonal normals once again. It will
also be another breezy to borderline windy day as the shortwave
pressing in from the north will be accompanied by a strong mid
and upper level jet which will help to tighten the pressure
gradient across eastern Utah and western Colorado. Wind gusts of
35 to 45 mph will be common Tuesday afternoon, with some spots
(particularly in the higher elevations) seeing gusts closer to
55 or 60 mph. Still a bit too early for wind highlights yet, but
something that will certainly be considered with the next
couple of forecast packages.

If you`re a fan of the cool spring weather, you`re in luck. The
passing shortwave will throw another cold front through the
forecast air later Tuesday afternoon and evening, with an even
colder blast of air rushing in behind it. That will set up a
very chilly period from Tuesday night into Wednesday.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Issued at 355 AM MDT Mon May 6 2024

A mid-level short wave trough in the southwest quadrant of the
storm over the Dakotas sweeps southeastward over the northern
most zones Tuesday night. This will keep scattered showers going
over the northern and central Colorado mountains and adjacent
valleys through Wednesday morning. Additional snow accumulations
will be light.

During the remainder of the week an interesting pattern
develops where a piece of the polar jet wraps back around the
Dakotas low flowing westward across the northern Rockies. This
causes a broad east-west oriented mid-level low to form over the
forecast area which is expected to persist for the remainder of
the week and into the weekend. General instability and
lingering moisture trapped within the weak cyclonic flow under
the low suggests less organized shower activity over the area
with an uptick in activity each afternoon in response to daytime
warming. There is less certainty by Sunday however, as the
GFS/Canadian solutions diverge from the ECMWF`s. The latter
showed the low lingering overhead during the weekend while the
others suggested the low will finally breakdown and become
absorbed into the main northwesterly flow over the central
Plains. This would bring drier conditions Sunday while the ECMWF
solution suggested more of the same. Since blends get
significant input from the EC, the current forecast remains
showery, but do expect that will change over the next few days.

Expect temperatures to run 10 to 15 degrees below normal on
Wednesday with morning lows near or below freezing for the Grand
Valley and southeast Utah where some vegetation is susceptible
to damage. However, temperatures are expected to moderate during
the remainder of the long range period, reaching near normal
levels Friday, then rising to around 5 degrees above normal this
weekend.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1138 AM MDT Mon May 6 2024

Winds will continue to be an issue region-wide over the next 24
hour with gusts of 25 to 45 mph again possible through
sunset...followed by areas of LLWS as the valleys
decouple...then gusts reform by mid morning on Tuesday. Cold air
aloft will continue to force showers over much of northern
Colorado and the Continental Divide through early evening. A
thunderstorm or two is also possible with gusty winds and
possibly some small hail possible. Another system rolls through
by the early morning hours and snow will again spread over much
of northern Colorado with terrain obscuration likely through the
day.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...Winter Weather Advisory until 6 PM MDT this evening for COZ004-
     010-013.
UT...Wind Advisory until 9 PM MDT this evening for UTZ024.

&&

$$

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