Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 230607
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1207 AM MDT Sat Mar 23 2024

.KEY MESSAGES...

- Isolated to widely scattered showers expected from this
  evening through the overnight hours.

- Breezy to windy conditions in an above normal temperature
  regime on Saturday with showers and thunderstorms increasing
  through the evening.

- Showers become more widespread Saturday night through Sunday
  as colder air arrives and brings temperatures and snow levels
  down.

- Significant mountain snow is likely through Monday morning
  with travel impacts over the passes increasing during the
  overnight hours.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 245 PM MDT Fri Mar 22 2024

The 22/12Z H500 hand analysis map has a high amplitude/high
latitude pattern transitioning to a more progressive pattern
over the lower 48. The axis of the transitory ridge was just
upstream this morning and is moving over the CWA presently.
Southwest flow will be moving in aloft this evening and water
vapor imagery is showing the next weak embedded wave in this
flow moving into W.Nevada attm. This wave will arrive to our CWA
by mid evening and lift across the divide near sunrise.
Moisture transport vectors/IVT suggest this wave is pulling
along some moisture but the main AR plume remains along the Cali
coastline. Moderately steep lapse rates...weak ascent and this
moisture looks to bring isolated to widely scattered showers to
the area tonight into the morning hours on Saturday. The
CAMS/HiRes models show the better coverage across NE Utah into
NW Colorado transitioning to very isolated/virga over the far
southern CWA. Upstream heights will continue to crash as the
next trough pushes farther onshore. The AR will be forced south
of the Sierras early tomorrow giving it a direct route toward
the Central Rockies in the tightening SW flow regime aloft. We
are looking at IVT numbers in in the 150-200 range arriving by
late afternoon to our CWA and this will set the stage for
another decent QPF event into the early week period. The highly
mixed/prefrontal atmosphere in place tomorrow afternoon will
lead to some gusty afternoon winds with temperatures pushing
back up to 5 to 10 degrees above normal. Isolated to scattered
showers and thunderstorms by tomorrow afternoon will become more
widespread through the evening and overnight as the dynamics
arrive. The precipitations will should continue to be oriented
SW to NE with the trough axis still upstream through sunrise on
Sunday. Much of the focus will be along the mid level front with
frontogenetic forcing helping to release instability and lead
to a more defined band dropping across SE Utah into NW Colorado.
The surface front will ooze into our northwest CWA in the
predawn hours and bring another areas of more organized
precipitation there. Lastly moisture SW orographics will favor
heavier precipitation over the perpendicular UncPlateau to the
San Juans overnight. Snow levels looks to remain aoa 8000ft
going into the evening then dropping below 7000 feet by
sunrise...with the caveat that stronger convective bands will
drive these lower. Overall looks like 2 to 5+ inches over many
ranges by morning and the start of another decent snow maker
through the weekend for many of these ranges. More details
below.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Issued at 245 PM MDT Fri Mar 22 2024

The surface cold front will push through the forecast area on Sunday
as the upper level trough lifts northeast from the Four Corners
region. Impressive QG evident during this timeframe as broad scale
ascent becomes maximized Sunday morning and afternoon while,
additionally, PWATs remain elevated at 130 to 160 percent of normal.
All this to say, Sunday will be another busy day across the Western
Slope with widespread showers through Sunday evening. The front will
knock snow levels down to the foothills and potentially some of the
mid valleys between 6000 and 7000 ft. Otherwise, it looks to be a
rain event for the remaining valleys. Instability associated with
the front could lead to locally reduced snow levels in any
convective showers. The high March sun angle will kick in Sunday
afternoon, allowing levels to rebound and resulting in slushy roads,
even in the high country. As a result, confidence on overall impacts
regarding this system remains uncertain, so have opted not to issue
any highlights with this afternoon`s package. All the same, there
will be some heavier rates with this system on favored slopes with
hourly rates potentially reaching 1 inch per hour. Stay tuned to the
next couple of packages as we continue to nail down this system.

The trough will exit the region on Sunday night before it closes off
over the Northern Great Plains on Monday. Weak northwest flow will
set up across eastern Utah and western Colorado in its wake as
showers taper off across the lower elevations. Orographics and
additional embedded moisture will keep light snow showers going
through Monday afternoon. Outside of showers, partly to mostly
cloudy skies are expected. A secondary wave will drop south from the
Intermountain West Monday night and into Tuesday, washing out along
the Divide sometime Tuesday night. This will provide another shot of
mainly scattered showers with only a couple inches of snow at the
most likely in the mountains. Another weak ripple brushing northwest
Colorado will keep light snow going in the northern ranges through
Wednesday afternoon.

A transitory ridge will slide overhead late Wednesday and into
Thursday. Apart from isolated mountain showers, dry weather will
prevail. The high is quickly ushered east Thursday afternoon as a
larger, broader trough of low pressure digs into the western states.
At the same time, the jet rounding the backside of the previous
trough will settle across the region, resulting in breezy conditions
and a quick warm-up to near/slightly above normal temperatures.
Confidence is increasing that a shortwave ejected out ahead of the
parent low will impact our forecast area by Friday, but there are
still some concerns regarding how south it will drop as well as how
long it will stick around. Needless to say, March will remain active
through much of the long term period and beyond.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1153 PM MDT Fri Mar 22 2024

A weak disturbance is moving west to east through the region
currently with light light rain showers over northeastern Utah
and northwestern Colorado. These showers will move over KHDN,
KEGE and KASE by about 10Z and last for a few hours before
passing east of the divide. Expect brief periods below ILS
breakpoints at KEGE and KASE. Southwest winds pick up in the
late morning across the region gusting 25-35 kts and continue
into the early evening hours. Ceilings will drop through the
afternoon as deep moisture advects into the region from the
southwest with widespread showers developing after about 21Z,
intensify after 00Z and continue overnight into Sunday.
..
&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...15
LONG TERM...MMS
AVIATION...DB


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