274
FXUS65 KGJT 022320
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
520 PM MDT Thu May 2 2024

.KEY MESSAGES...

- A disturbance will brush the northern tier of eastern Utah and
  western Colorado Friday morning and afternoon, bringing a few
  valley rain and mountain snow showers. Light accumulations are
  expected with little to no impacts.

- Warmer and mainly dry conditions return on Saturday before
  turning windy on Sunday and more unsettled early next week.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 303 PM MDT Thu May 2 2024

Fairly benign weather today with mostly sunny skies and much
drier conditions in the wake of yesterday`s cold front.
Temperatures are a couple degrees below normal but should warm
back up a few degrees to around 5 or so degrees above normal by
Friday for areas along and south of I-70, so central and
southern areas. The exception to this is across the northern
tier north of I-70 where a shortwave trough is expected to move
through tonight into Friday afternoon. Temperatures on Friday
compared to today will stay fairly neutral across the north,
maybe slightly cooler than today with highs around 5 to 10
degrees below normal. In terms of sensible weather, this
shortwave will allow some showers to develop after midnight
tonight but mostly occurring Friday morning through late Friday
afternoon across northeast Utah and northwest Colorado. Expect
some scattered light rain in the valleys with light snow in the
northern mountains. Conditions still remain fairly dry though
with this system so virga may be more likely in the northern
lower elevations with maybe an inch or two at the higher peaks
of the northern mountains. The rest of the CWA will experience
warming temps Friday as the jet stays across the north and
doesn`t really dive that far south, keeping the cooler air up
north. We will also see some breezier winds Friday afternoon.
Given the drier air mass, this leads to potential fire weather
concerns across the lower elevations of east-central and
southeast Utah as well as portions of west-central and southwest
Colorado. At this time, the fuels status for eastern Utah is not
critical but there is still some uncertainty regarding fuels
status for the Colorado valley zones. Given this information,
elected not to hoist any Fire Weather highlights but this is
something to keep an eye on if the fuels status changes.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 303 PM MDT Thu May 2 2024

With the longwave pattern set in motion, by Saturday morning the
ridge that was over the Eastern Pacific will have shifted east
inland over the Rockies, and the cold core low will be approaching
the Pacific Northwest Coastline. Eastern Utah and Western Colorado
will see temperatures warming about ten degrees across the northern
areas and about five degrees through the central areas. Look for a
few lingering showers mostly along the Continental Divide and to the
east through the afternoon, ending by the evening. The ridge will
push east of the Divide by evening as the low moves on shore into
southern Oregon and Northern California. With the weak ridge passing
to the north and a weak trough to the south, the gradient winds
aloft dropping off, surface winds Saturday will be much lighter than
Friday`s winds. The flow shifts southwest overnight with warm-air
advection keeping the morning low temperatures Sunday ten degrees or
more above normal through much of the area.

The pressure core of the low tracks into the Great Basin over Nevada
Sunday and ejects to the northeast into Wyoming Sunday night while
the cold air in the core continues tracking southeast with the cold
front across southern Colorado and northern New Mexico. The
ensembles show this with the low moving up into Wyoming, but the
height anomaly staying to the south in the base of the trough. As
you would think, the models that had been well correlated up to
Sunday begin to diverge from here on out into next week. Hence, much
of the forecast confidence in timing and impacts fall beyond Sunday.

Expect strong southwest winds Sunday at 25-35 mph gusting 45 to 55
mph in the lower valleys across the region ahead of the cold front
with stronger winds at the higher elevations. Winds will definitely
be advisory level approaching warning levels, but will hold off for
another run or two of the models to get a better idea of the winds
before considering wind highlights for Sunday. The cold front
moves through the region west to east Sunday evening with winds
shifting northwest and dropping off, and temperatures falling 15
degrees behind the front. Though PWATs with this system remain
at about 0.6 inches, about average for a showery system,
impressive IVTs of 300 to 500 kg/m/s move up over eastern Utah
and Western Colorado Sunday afternoon and evening. There isn`t
much upper-level dynamics to support convection ahead of this
system so showers and thunderstorms through the afternoon will
generally be on the light side through the afternoon, but strong
lift will accompany the frontal boundary through the evening
making strong thunderstorms possible, especially along the west
to southwest faces of higher terrain. Stay tuned for more
details as we get closer to this storm.

Monday will be the coolest day with temperatures running 10 to 15
degrees below normal with some warming into mid next week.
Showers continue Monday as this system moves on out to the east
with convection ending in the evening. The Park Range looks to
get the most snow at possibly advisory depths, but it too soon
to really say one way or the other. Unsettled weather continues
through the week with isolated to scattered afternoon showers
each day through the mountains.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 520 PM MDT Thu May 2 2024

Gusty winds of 25 to 35 mph will decrease to under 10 mph by
sunset in most areas under partly to mostly cloudy skies through
sunrise. VFR should hold over the next 24 hours though cigs will
be lowering up north in the afternoon as the next system works
through. KHDN should see a passing shower with an outside chance
of MVFR conditions by mid afternoon but confidence low at this
point. Gusty afternoon winds of 25 to 40 mph are again expected
most areas by late morning on Friday as well.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

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