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000
FXUS65 KGJT 122345
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
545 PM MDT Fri Apr 12 2024

.KEY MESSAGES...

- Warm and breezy conditions will prevail today and tomorrow,
  with high temperatures 10-15 degrees above normal.

- A weak wave will bring scattered light showers to the southern
  and central mountains tonight, although only limited moisture
  will reach the ground.

- Active weather returns Monday through Wednesday as a pair of Pacific
  storms impact the region bringing showers, cooler
  temperatures and accumulating mountain snow.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 228 PM MDT Fri Apr 12 2024

Skies are mostly clear this afternoon, aside from a few cumulus
clouds over the higher terrain. High pressure remains in control
aloft, and with the axis east of the Divide now, strong southerly to
southwesterly flow aloft has helped advect much warmer air into the
region. Temperatures across the area are already around 5 degrees
above yesterday`s highs, and with a few hours yet to go until peak
heating, expect that temperature to keep right on climbing.
Afternoon highs will be in the upper 70s to low 80s across the lower
valleys, with 70s for the higher valleys, and 50s to low 60s for the
mountain towns. Winds will also be breezy this afternoon, as daytime
mixing taps into the southwesterly jet aloft. With these winds and
relative humidity values near or below 15%, isolated critical fire
weather conditions are possible today. Current fuels guidance
indicates low susceptibility, but it never hurts to be mindful of
potential spark sources when out enjoying the unusually nice spring
weather.

A shortwave trough in the southwesterly flow will drift
northeastward during the day today, swinging into eastern Utah and
western Colorado this evening. Associated with this wave will be
some modest midlevel moisture that will combine with the dynamic
forcing of the wave and some favorable orographics to produce clouds
and showers over the southern and central mountains tonight. Little
in the way of precipitation is expected to make it to the ground
thanks to the dry surface layer, making the main threat with any
shower activity gusty outflow winds. The increased cloud cover,
shower activity, and potential for gusty nighttime winds will keep
low temperatures quite mild tonight, with current guidance favoring
values 10-15 degrees above normal.

This wave will be east of the Divide by daybreak tomorrow, with only
a slight chance of a shower or two over the Park Range during the
early morning hours. Ridging rebuilds into the Intermountain West
tomorrow as a cutoff Pacific low meanders its way toward the
Northern California coast. This will bring a return of strong
southwesterly flow aloft and much drier air at midlevels. The
warmest 700 hPa temperatures will be to the east, leaving surface
temperatures across eastern Utah and western Colorado a few degrees
cooler tomorrow afternoon as compared to today. Even still, highs
will run 10-15 degrees above normal for mid-April. Saturday night
will be quiet, clear, and relatively mild across the region.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 228 PM MDT Fri Apr 12 2024

The large closed low will be spinning over Nevada and California by
Sunday morning with a 100+ kt jet rounding its base through the
Desert Southwest into Arizona and Utah. The southwest gradient will
tighten ahead of this low over the Western Slope where sufficient
mixing could bring stronger winds aloft down to the surface.
Currently it`s looking like H7 winds peak in the 30 to 35 kt range
so winds could gusts 30 to 45 mph at the surface in many valleys,
with potential for higher gusts in spots. No wind highlights needed
yet, but something to monitor as it looks breezy to windy Sunday
ahead of this system. Conditions will be dry out ahead of this low
as the low pressure system slowly marches eastward through the Great
Basin during the day on Sunday. Temperatures will continue to be
warm with upper 70s to near 80 in the lower desert valleys of west-
central Colorado to east-central and southeast Utah with 60s in the
higher valleys and 50s for the mountain towns. This is still about 8
to 12 degrees above normal.

This low is expected to drive a cold front across the area with
widespread showers Monday afternoon through Tuesday morning.
Temperatures Monday take a 10 to 15 degree hit compared to Sunday,
bringing highs to near or 5 degrees or so below normal. Even though
showers hit all the mountain ranges, the northern and central
Colorado mountains still appear favored at this time for the better
snow accumulations. Snow levels will be high so this really limits
the lower elevations to rain if anything does reach the ground. The
peak in snowfall accumulation or rates appears to be Monday night
into Tuesday morning. Wraparound moisture may continue snow over the
northern mountains through Tuesday afternoon as the low exits
eastward to the Plains. Amounts did come up a bit during this Monday
night into Tuesday morning period but the overall trend has been to
decrease accumulations. Still looking like sub-advisory at this
time. A shortwave ridge builds in for Tuesday afternoon, providing a
quick warm up back towards 4 to 8 degrees above normal for highs.

Another large low pressure trough drops in out of Canada into the
northern Rockies with the jet diving through the Pacific Northwest
into the Intermountain West and clipping our northern areas. The
timing is a bit later than models indicated earlier, which is a
trend we`ve been seeing with these systems to slow down their
progress at least at the onset. Again, the latest models are
trending further north, so the northern mountains look to see the
snow from this system...still with sub-advisory numbers. It now
drops in Wednesday afternoon and exits by Thursday morning with the
northern mountains to maybe as far south as the Elk Mountains see
the better accumulations even though these look to be minor (much
less than previous runs indicated), packing less of a punch. Areas
north of I-70 look to feel the effects of this troughiness more with
cooler below normal highs, but areas along and south of I-70
(central and southern areas) will see 4 to 8 degrees above normal
through this period. The gradient will be tighter with the jet
across the north, so breezy conditions remain each afternoon. Much
has changed since yesterday and over the course of the last few days
with the evolution of these systems and what impacts or how far
south they may be. So, stay tuned as a lot can still change as we
get closer. However, based on recent trends, odds are greater that
most areas will remain dry, breezy and milder with exception of
those northern and central mountains.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 540 PM MDT Fri Apr 12 2024

Breezy conditions will continue this evening before pressure
gradients relax after sunset. Scattered to broken mid level
clouds will dissipate overnight, with many terminals returning
to clear skies again Saturday. Mountain terminals will likely
hold on to their clouds again tomorrow, with scattered mid level
clouds appearing during afternoon heating on the terrain. Winds
will pick back up again from the southwest Saturday afternoon
with gusts 15 to 25 mph expected at most terminals during
afternoon heating.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...BGB
LONG TERM...MDA
AVIATION...TGJT