497
FXUS65 KGJT 071726
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1126 AM MDT Fri Jun 7 2024

.KEY MESSAGES...

- Hot conditions expected again today with a few triple digit
  readings in the lower desert valleys...most areas will be 10
  to 15 degrees above normal.

- Thunderstorms develop this afternoon as moisture begins a push
  back into the region. A few storms will produce strong
  outflow gusts.

- Low valleys remain warm and dry, while afternoon mountain
  showers and thunderstorms remain a threat into the early half
  of next week.

&&

.SHORT TERM /THROUGH SATURDAY/...
Issued at 300 AM MDT Fri Jun 7 2024

There is probably no better indicator that a push of moisture is
underway that having ACCAS showing up on the radar during the
early morning hours. This moisture on top of the deep EML will
help aid an uptick in thunderstorm development today. Getting
this moisture to the ground as precipitation is another matter
and this looks more likely to happen across the northern CWA
today where low level moisture has been pooling...possibly from
the help of hydrology. Another meteorological cool happening is
the moisture being forced over the southern divide in NM as a
front backs up along the lee of the Rockies. Dewpoints in the
teens are now in the upper 40s near ABQ and this moisture will
get advected into our southern CWA this morning. Models suggest
this southern moisture source being mixed out through the
day...and though it will aid in the elevated formation of
convection the hot dry airmass should win out with virga and
possible gusty winds being the main threat. Farther north the
low level moisture profile and upper level wind profile suggest
better storm organization and moderate to heavy rainfall rates
and gusty winds stand a better chance of getting to the surface.
Most of this activity should wane by sunset but an well defined
wave currently upstream of us in W.NV will be moving through
late tonight. This will likely keep some isolated showers/storms
going closer to the WY border overnight with the subsidence in
the wake of the shear zone providing somewhat of a stronger cap
to overcome on Saturday across our southern CWA. Terrain
forcing...left over boundaries and residual moisture will favor
storm formation again mainly across the northern half of the CWA
later in the day with most of the CAMS firing storm on the high
plateaus and Uintas by early afternoon. Overall both
instability and shear look weaker but after a few storm
generations some of this activity should spread to adjacent
valleys before sunset. Hot temperatures are expected again today
but the added moisture has trended most guidance downward
compared to a few days ago. Still expect triple digits over some
of the lower desert/red rock country with a drop across the
board of about 3 to 5 degrees on Saturday. This warm temperature
continues to take it`s toll on the snowpack and many river
systems will continue to rise and approach their peak in the
next few days. More below on this.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Issued at 300 AM MDT Fri Jun 7 2024


With plenty of moisture to work with and a front dropping through
eastern Utah and western Colorado, look for showers and storms to
linger well into overnight hours Saturday into Sunday, before
finally tapering off. Subtropical moisture continues to pump into
the Four Corners region through the weekend, as clockwise flow
around the high now located over the Gulf Coast draws it northward.
PWATs peak around 150-200% of normal for Sunday and Monday. By
Sunday morning, the low that had been lurking off the coast of Baja
California will have made its way into Arizona, now as an open wave.
This will provide some extra dynamic lift during the afternoon and
evening hours Sunday, on top of typical diurnal heating acting on
the terrain. With the extra moisture and lift, look for more
widespread shower and thunderstorm activity, beginning over the
higher terrain early in the afternoon and then spreading across the
valleys. The main threat will remain gusty outflow winds, as surface
levels will still be rather dry, but as the day wears on, chances
for moderate or even brief heavy rain will increase. What`s left of
the Baja low will be east of the Divide by Monday morning, leading
to a downturn in shower and storm coverage over the lower
elevations. With plenty of moisture to work with but only diurnal
heating to use a source of lift, look for convection to favor the
higher terrain, especially along the Divide. A trough passing by to
the north during this period may drag a front through the northern
half of the CWA, providing a focus for some more intense activity,
but which will be out of the area by Monday evening.

The trough moving across the Northern Rockies on Monday evening is
actual the remnant of a larger Pacific trough that had moved
onshore late Sunday and split. The northern packet of energy is to
become this trough, while the southern packet of energy drifts south
to the coast of Baja and becomes yet another cutoff low pressure. As
this low drifts slowly over the eastern Pacific and the northern
stream trough and its associate front sweeps through, ridging once
again tries to build into the Desert Southwest for Tuesday. This
will mean a general drying trend with diminishing convective
coverage and increasing temperatures for the remainder of the week.

As far as temperatures are concerned, Sunday and Monday will see
temperatures around 3 to 5 degrees above normal, with Monday being
the coolest day of the period. As the atmosphere dries out and warm
high pressure reasserts itself over the Desert Southwest, look for a
warming trend from Tuesday onward, back up to around 10 degrees
above normal for most locations.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1122 AM MDT Fri Jun 7 2024

Isolated thunderstorms blossomed early this morning. Confidence
on direct impacts to terminals due to isolated storm coverage
remains low, though gusty outflow winds are the more likely
threat. Storms will continue to roll across the CWA through this
afternoon with another wave skirting northwest Colorado counties
around midnight tonight. However, VFR conditions are expected to
prevail for the next 24 hours.

&&

.HYDROLOGY...
Issued at 727 AM MDT Fri Jun 7 2024

High pressure building overhead through the end of the week
will result in an unseasonably warm period across the Western
Slope. Simultaneously, as those temperatures rise, so will the
rate of snowmelt across our high terrain. Even though low to mid
elevations have already melted out, there`s still an abnormally
high amount of snow left over basins generally at and above
11,000 ft...and it`s melting...fast. As a result, creeks,
streams and major tributaries along the Upper Colorado River
Basin are on the rise. Seasonal peak flows are expected over
the next 10 days, with the Upper Gunnison, Upper Yampa and
Colorado Headwaters basins likely peaking for the season this
weekend.

Current highlights include a Flood Warning over the Elk River
near Milner, where river flows are expected to exceed Minor
Flood Stage. As for Flood Advisories, current conditions have
oscillated diurnal peaks above the Action Stage for portions of
Gore Creek and guidance continues to show the Eagle River
cresting Action Stage each morning through the weekend. The
East River near Almont is forecast to exceed Action Stage each
morning through Sunday, with the potential for exceeding Flood
Stage by Saturday. For now, a Flood Advisory is in effect for
this stretch of river. However, stay tuned for the potential
upgrade to a warning and/or extending the advisory downstream
into the Gunnison at Gunnison. Elsewhere, action stage may be
briefly surpassed along the Yampa near Deerlodge and along the
Duchesne near Randlett, UT. No products are in effect for the
latter reaches, but please check back as these conditions
evolve. Additional precipitation this afternoon and through the
weekend may make hydrologic conditions extra spicy depending on
how much rainfall reaches the ground and if over remaining
snow cover.

As scorching temperatures lure folks to the water, please
remember the potential hazards associated with high flows during
the snowmelt season. Fast flows are not just dangerous for
those choosing to float the rivers. In addition, high diurnal
swings may drastically change the depth and flow for normally
small creeks and streams. Swift currents and cold water
temperatures can catch you off guard, so please be vigilant with
current conditions and look for forecast updates when
recreating or working near the water`s edge.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...15
LONG TERM...BGB
AVIATION...TGJT
HYDROLOGY...ERW