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000
FXUS65 KGJT 241754
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1154 AM MDT Wed Apr 24 2024

.KEY MESSAGES...

- Warm and breezing conditions continue today with temperatures
  10-15 degrees above normal and gusty winds 20 to 30 mph
  creating elevated fire concerns this afternoon.

- Precipitation chances increase Thursday with widespread
  rainshowers expected across the mountains with some light snow
  showers expected on the higher terrain Thursday night and
  beyond.

- Cooler and unsettled conditions expected through the weekend
  with an increasing probability of significant high elevation
  snow accumulations and travel impacts through early Monday.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 248 AM MDT Wed Apr 24 2024

The split flow pattern over the Pacific Coastline will be
breaking down over the next 24 hours but for now the southern
stream has taken hold of Intermountain West to the Rockies. This
has pushed the main plume of moisture to the North of our border
as seen in the ALPW plots. Surface dew points indicate some low
level moisture has pooled across our northern CWA however and
will likely lead to some afternoon build ups and perhaps a few
isolated showers with more wind than rainfall expected. The main
storm system in southern stream will reach the SoCal coast by
this evening move over Vegas by sunrise and then invade our CWA
through Thursday brining wetter and cooler conditions back into
the picture. Today however looks to be another very warm day
with high still running some 10 to 15 degrees above normal in
most areas. The current windy and dry period has created large
vapor pressure deficits and when combined with another breezy
afternoon fire weather concerns remain quite
elevated...especially where fuels are susceptible to burning.
So again this cannot be stressed enough...in parts of southwest
Colorado and southeast Utah outdoor burning will be a high risk
venture. A fairly mild night is expected as winds strengthen
aloft with the downstream height falls and keep things well
mixed. The bulk of the precipitation should hold off until
after sunrise on Thursday. However moisture entrained in the
stronger flow aloft will likely lead to showers over at least
the higher portions of eastern Utah in the early morning hours
as ascent increases with the emergence of the jet core around
the base of the upstream trough. The core of the ascent then
lift across the remainder of the CWA Thursday as the trough
arrives and the cooler air aloft helps trigger more convection.
Much cooler temperatures can be expected on Thursday as we
settle back toward normal.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Issued at 248 AM MDT Wed Apr 24 2024

The low that moved up through SoCal will open into a wave passing
over eastern Colorado by Thursday evening. As the trough moves out
onto the Plains, the northerly flow on the backside pulls a cooler
airmass down over the region dropping temps aloft about 4C.
This instability will keep showers going overnight into Friday
morning mostly over the higher terrain of the northern and
central Colorado mountains with snow levels around 8500 feet.
The flow aloft behind the trough is weak and won`t scrub out the
moisture in the lower levels of the atmosphere that saturated
from the showers Thursday and Thursday night. The next trough,
the second of the one-two punch, drops in through the Pacific
Northwest Friday, cutting off over Utah Friday night and
tracking east across the southern areas of the region Saturday
before moving out onto the plains Saturday night. This second
system is a bit stronger, pulling deeper moisture out of the
northern Great Basin and Pacific Northwest with pwats of 0.6 to
0.7 inches and colder air aloft dropping temps another 4C. This
system has a fairly clear cold frontal boundary that passes west
to east across the region overnight Friday leading the trough.
Look for a round of widespread moderate showers and
thunderstorms Friday afternoon with snow levels around 9,000
feet ahead of the front as the deeper moisture moves into the
region. These storms will continue overnight with the frontal
boundary and Saturday as the upper-level low passes overhead.
Convective activity will decrease Saturday night into Sunday as
the low moves east out over the Plains and ridging starts to
build in from the west. Wrap-around moisture and orographics
will keep light showers going mostly across the northern and
central mountains with thunderstorms possible Sunday afternoon
with diurnal heating. Skies clear out by Monday as ridging moves
into the region.

Models are in remarkable agreement through Sunday with these systems
and even the ensembles show little dispersion. The one outlier seems
to be the GEFS that digs the second trough farther west along the
California-Nevada Border and deeper south over southern New Mexico,
yet it still show little dispersion among its members. Guidance is
bullish on the moisture with this system, especially in the lower
valleys though pwats aren`t all that impressive. Wouldn`t be
surprised if QPF drops in these areas when all is said and done, but
the MJO does seems to be getting more active over the Pacific and it
may be this that guidance is picking up. We`ll just have to wait and
see.

For planning purposes, the higher elevations in the central and
northern Colorado mountains could see over a foot of heavy snow
between Friday morning and Saturday night with this system that may
impact Vail and Rabbit Ears Passes Friday night and Saturday. Much
like the system last week, conditions look to be worse to the east
of our area in Summit and Grand Counties. Be sure to check for
updates on this forecast and prepare accordingly if you`ll be
travelling in these areas this weekend.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1143 AM MDT Wed Apr 24 2024

VFR conditions will prevail at terminals this TAF period with
gusty southwest winds this afternoon. A few scattered mid clouds
will continue to form on the mountains today, with an isolated
shower or gusty outflow possible under virga showers in
northwest Colorado and northeast Utah.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...15
LONG TERM...DB
AVIATION...TGJT