493
FXUS65 KGJT 202302
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
502 PM MDT Thu Mar 20 2025

.KEY MESSAGES...

- Light snow showers tonight will produce minor accumulations
  for the northern and central mountains of Colorado.

- A more potent winter storm will arrive late Friday night and
  produce 6-12 inches of new snow for the northern and central
  mountains, along with gusty winds, and difficult driving
  conditions on mountain passes.

- A substantial spring warm up is expected next week with desert
  valleys nearing 80 degrees and mountain valleys seeing highs
  in excess of 15 degrees over climatology.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 350 PM MDT Thu Mar 20 2025

A brief transitory ridge has rippled through this afternoon, giving
way to a series of shortwave ripples ahead of a bigger disturbance
that is coming ashore in the PACNW. This system will deliver a punch
of atmospheric river moisture and resultant snow across the CWA.
First things first, shortwave energy working through this evening
will keep some cloud cover working through and some light snow
showers on the Northern and Central Mountains. Snowfall tonight in
the 1 to 2 inch range for the Flat Tops and Park Range can be
expected, with a lighter dusting southward of there. Cloud cover
will keep overnight lows a touch warmer tonight than we saw this
morning. Zonal, westerly flow continues Friday, with a hint of
ridging working through. Cloud cover will increase steadily on
Friday ahead of the incoming system. Temperatures will increase
slightly over today, but a race against clouds and peak afternoon
heating will keep a forecaster cautious on much of a warm up. The
first big push of AR moisture arrives late Friday night and a
resident frontal boundary draped across the CWA will produce
accumulating snow across the mountains after midnight, with a focus
on the Flat Tops, Park Range, Elk Heads, Gores, and Elks. A Winter
Weather Advisory was issued, beginning Friday night for these
mountains. Blowing snow will add to travel heartaches Friday
night and Saturday morning as this system works through.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 350 PM MDT Thu Mar 20 2025

By Saturday, PWAT anomalies jump up to 150 to 200 percent of normal
as a moderate AR event moves inland from the west. Precipitation
looks to start in earnest early Saturday morning and continue
through the day Saturday before ending by sunrise Sunday morning.
This AR event looks to favor the northern and central Colorado
mountains with accumulating snowfall in the realm of 6 to 12 inches
with locally higher amounts above a foot over the Park Range. The
IVT is projected to be up to 150 to 200 kg/m/s. Lapse rates steepen
Saturday afternoon upwards of 8 C/km with CAPE up to 200 J/kg along
with the favored westerly orographic lift, so enough instability for
the convective element to spring-time showers and potential for some
thunder as well which could lead to locally higher amounts and brief
reductions in heavier snow bands. Given all the above factors,
decided to issue Winter Weather Advisories for those NW Colorado
mountains, including the Park Range, Flattops and Gore and Elk
Mountains (COZ004-013-010) from midnight Friday night through
midnight Saturday night.

Cloud cover remains through Sunday though in the northwest flow
behind the departing trough but should clear out by Sunday night as
a ridge of high pressure builds in from the west. Lingering NW
orographics could keep light snow falling over the Elkheads and Park
Range through Monday but additional accumulations remain light.
Overall, we will see a drier trend heading into next week with a
significant warmup in store as well. Temperatures start off the long
term this weekend with near normal values (slightly below normal
across north and higher elevations along the Divide with slightly
above normal values across SE Utah and SW Colorado). Once this
remnant AR clears the area and the ridge moves in by next week,
strong WAA takes place with highs rising to around 10 to 15 degrees
above normal by mid week with potential for higher by the end of
next week. Lower valleys look to rise into the 70s with some lower
desert valleys approaching or exceeding 80 by the latter half of
next week.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 458 PM MDT Thu Mar 20 2025

VFR conditions are expected through the period. Afternoon gusts
around 20 mph are possible at a few sites. ILS breakpoint cigs
could be reached tomorrow with the clouds that build in the
afternoon.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...Winter Weather Advisory from midnight Friday night to midnight
     MDT Saturday night for COZ004-010-013.
UT...None.

&&

$$

SHORT TERM...LTB
LONG TERM...MDA
AVIATION...TGJT