000
FXUS65 KGJT 111716
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1116 AM MDT Thu Apr 11 2024

.KEY MESSAGES...

- Warm, dry, and breezy weather prevails through the weekend
  with high pressure in control.

- Unsettled weather returns next week with cooler temperatures
  and the potential for minor accumulating mountain snow.

&&

.SHORT TERM /THROUGH FRIDAY/...
Issued at 410 AM MDT Thu Apr 11 2024

A ridge of high pressure will build in from the west today,
leading to sunny skies, light winds, and pleasantly warm
temperatures. Strengthening warm air advection within a stout
thermal ridge overspreading the Four Corners states will support
highs in the highest valleys and mountain towns in the 40s and
50s... and highs in the 60s and 70s elsewhere.

Tonight, the ridge axis passes overhead and will be east of the
Continental Divide by Friday morning. Clear skies and light
winds will lead to ideal radiational cooling conditions in the
typically sheltered cold spots in eastern Utah and western
Colorado; however, everywhere else, warm air advection will
offset the cooling by quite a bit. As a result, low temperatures
will be roughly 5 to 10 degrees warmer than this morning`s
readings and 5 to 15 degrees above seasonal norms.

As the ridge axis continues to slide well to our east on
Friday, a strong Pacific storm will drop southward along the
California coastline. In between these two synoptic features,
deep southerly to southwesterly flow develops across the Desert
Southwest and Four Corners. The brisk flow aloft will pump even
warmer air into the region, with 700mb temperatures progged to
soar to between +6C and +9C. This would support surface highs
well into the 70s and low 80s for the lower desert valleys of
eastern Utah and western Colorado. In fact, the record high on
Friday at the Grand Junction Regional Airport is 82F set way
back in 1934. The latest official high temperature forecast for
KGJT sits at 81F with the NBM probability of breaking the record
sitting at 10% and the probability of a tie at around 20%. The
one potential fly in the ointment is cloud cover as there will
be some mid-level moisture associated with a weak shortwave
embedded within the flow aloft. Should there be more clouds than
expected, highs may struggle to reach 80. The mid-level
moisture will also likely lead to virga given a very dry
subcloud layer and surface RHs in the teens and 20s. Precip
evaporating prior to reaching the ground can quickly cool the
surrounding air, which then makes it more dense. The cooler and
higher density air then picks up momentum and rapidly descend
towards the ground, aided by strong boundary layer mixing. Thus,
the presence of virga can help to enhance surface wind gusts.
Gusts Friday afternoon should mostly top out between 30 and 40
mph, but virga enhancement could add another 10 to 15 mph on top
of that. This likely won`t be widespread enough to consider
wind highlights, but something to keep an eye on for now.
Otherwise, models continue to print out some spotty QPF here and
there across the higher terrain along the Divide Friday
afternoon. Again, given the very dry air in the low levels of
the atmosphere, don`t think much more than a hundredth or two
reaches the ground, if that. All in all, Friday will be a dry,
breezy, and unseasonably warm spring day with likely the warmest
temperatures of the year thus far.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Issued at 410 AM MDT Thu Apr 11 2024

Gusty winds are likely to persist Friday evening as a weak
shortwave trough in the southwesterlies aloft sustains virga and
light showers, mainly over the central and southern Colorado
mountains. This feature will pass north of the area early
Saturday with models showing an influx of drier air moving over
the region in the broad area of mid-level difluence ahead of a
deep closed mid-level low off the northern California coast.
There`s a slight chance that enough moisture will remain along
the Continental Divide to generate isolated showers or a
thunderstorm during the afternoon. What`s more certain however,
is that deep mixing will result in another breezy day across the
forecast area Saturday afternoon. Sunday looks pretty similar
as relatively strong southwesterlies aloft continue while the
storm off the West Coast splits and shifts slowly inland. By
12Z/Monday, the latest operational runs showed the trough over
the Great Basin and Desert Southwest with dry air continuing to
stream into the area from the south. The NBM appeared to be
holding onto moisture from previous model runs and expect we`ll
see a decrease in shower chances Sunday night. Despite southerly
flow, advection of cooler air ahead of the Pacific storm will
bring modest cooling this weekend, though readings will still
run close to 10 degrees above normal.

The Pacific storm and its associated cold front sweep eastward
across the forecast area Monday which is expected to result in
widespread precipitation for all but southeast Utah and the
southwest border of Colorado. Colder air behind the front will
cause temperatures to drop by almost 10 degrees with
temperatures nearing normal for the first time in a week.
Residual moisture and orographics will keep showers going over
the northern and central mountains Monday night, then a second
system drops out of the northwest on Tuesday bringing another
round of widespread showers for the central Colorado mountains
and areas along and north of the I-70 corridor. The system
stalls there Tuesday night and Wednesday so shower chances
continue for the aforementioned areas. The cold front associated
with this system will bring much cooler temperatures to the
northern forecast zones while the southernmost zones can expect
modest warming.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1115 AM MDT Thu Apr 11 2024

With high pressure moving in, skies will be clear and winds will
follow typical terrain driven patterns. Some terminals may see
gusts up to 20 knots in the afternoon. VFR conditions will
prevail for the next 24 hours.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

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